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Transcriber Note

Text emphasis is denoted by _Italics_ and =Bold=. Whole and fractional
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[Illustration: Cape Trinity on the Saguenay. A salient point of
Laurentian Gneiss, on an old fiord of Pliocene erosion (p. 99). (_From a
Photograph by Henderson._)]




                          SOME SALIENT POINTS

                                IN THE

                         SCIENCE OF THE EARTH


                                  BY

       SIR J. WILLIAM DAWSON C.M.G., LL.D., F.R.S., F.G.S., &c.


                    _WITH FORTY-SIX ILLUSTRATIONS_


                            [Illustration]


                               NEW YORK

                     HARPER & BROTHERS PUBLISHERS

                                 1894




PREFACE.


The present work contains much that is new, and much in correction
and amplification of that which is old; and is intended as a closing
deliverance on some of the more important questions of geology, on the
part of a veteran worker, conversant in his younger days with those
giants of the last generation, who, in the heroic age of geological
science, piled up the mountains on which it is now the privilege of
their successors to stand.

                                                          J. W. D.

  _Montreal_ 1893.




CONTENTS.


  CHAPTER I.                                              Page
    The Starting-point                                       3


  CHAPTER II.
    World-making                                             9


  CHAPTER III.
    The Imperfection of the Geological Record               39


  CHAPTER IV.
    The History of the North Atlantic                       57


  CHAPTER V.
    The Dawn of Life                                        95


  CHAPTER VI.
    What May Be Learned from Eozoon                        135


  CHAPTER VII.
    The Apparition and Succession of Animal Forms          169


  CHAPTER VIII.
    The Genesis and Migrations of Plants                   201


  CHAPTER IX.
    The Growth of Coal                                     233


  CHAPTER X. PAGE
    The Oldest Air-breathers                               257


  CHAPTER XI.
    Markings, Footprints, and Fucoids                      311


  CHAPTER XII.
    Pre-determination in Nature                            329


  CHAPTER XIII.
    The Great Ice Age                                      345


  CHAPTER XIV.
    Causes of Climatal Change                              363


  CHAPTER XV.
    The Distribution of Animals and Plants As Related
      to Geographical and Geological Changes               401


  CHAPTER XVI.
    Alpine and Arctic Plants in Connection With
      Geological History                                   425


  CHAPTER XVII.
    Early Man                                              459


  CHAPTER XVIII.
    Man in Nature                                          481




LIST OF ILLUSTRATIONS.


                                                          Page

  Cape Trinity on the Saguenay                  _Frontispiece_

  Folding of the Earth's Crust                   _To face_   9

  Cambro-Silurian Sponges                           "       39

  Map of the North Atlantic                         "       57

  Nature-print of Eozoon                            "       95

  Laurentian Hills, Lower St. Lawrence                     100

  Section from Petite Nation Seigniory to St. Jerome       101

  The Laurentian Nucleus of the American Continent         103

  Attitude of Limestone at St. Pierre                      109

  Weathered Eozoon and Canals                    _To face_ 112

      "        "          "                                113

  Group of Canals in Eozoon                                115

  Amœba and Actinophrys                                    119

  Minute Foraminiferal Forms                               123

  Section of a Nummulite                                   127

  Portion of Shell of Calcarina                            128

  Weathered Eozoon with Oscular tubes            _To face_ 135

  Diagram showing different States of Fossilization
    of a Cell of a Tabulate Coral                          139

  Slice of Crystalline Lower Silurian Limestone            141

  Walls of Eozoon penetrated with Canals                   141

  Joint of a Crinoid                                       145

  Shell from a Silurian Limestone, Wales                   146

  Casts of Canals of Eozoon in Serpentine                  147

  Canals of Eozoon                                         147

  Primordial Trilobites                          _To face_ 169

  Primitive Fishes                                   "     184

  Devonian Forest                                    "     201

  Coal Section in Nova Scotia                              233

  Skeleton of _Hylonomus Lyelli_                 _To face_ 257

  Footprints of _Hylopus Logani_                     "     260

  Humerus and Jaws of _Dendrerpeton_                 "     272

  Reptiliferous Tree                                 "     276

  Microsaurian, restored                             "     278

  _Dolichosoma longissimum_, restored                "     286

  _Pupa_ and _Conulus_                               "     288

  Millipedes and Insect                              "     296

  Footprints of _Limulus_                            "     311

  _Rusichnites Grenvillensis_                        "     322

  Restoration of _Protospongia tetranema_            "     329

  Giant Net-sponge                                   "     336

  Boulder Beach, Little Metis                        "     345

  Palæogeography of North America                    "     383

  Distribution of Animals in Time                    "     401

  Tuckerman's Ravine and Mount Washington            "     425

  Pre-historic Skulls                                "     459

  Primitive Sculpture                                "     481


TABLE OF GEOLOGICAL HISTORY.

Non-Geological readers will find in the following table a condensed
explanation of the more important technical terms used in the following
pages. The order is from older to newer.

  GREATER     SYSTEMS OF              CHARACTERISTIC FOSSILS.
  PERIODS.    FORMATIONS.

  Archæan or Eozoic

              Pre-Laurentian
              Laurentian            Protozoa            Protophyta

  Palæozoic

              Huronian            { Crustaceans         Algæ
              Cambrian            { Molluscs            Cryptogamous
              Cambro-Silurian[A]  { Worms                 and
              Silurian[B]         { Corals, etc,        Gymnospermous
              Devonian              Fishes                Plants.
              Carboniferous         Amphibians
              Permian

  Mesozoic

              Triassic            { Reptiles            Pines and
              Jurassic            { Birds                 Cycads
              Cretaceous          { Earliest Mammals.   Trees of modern
                                                          types.

  Kainozoic or Tertiary

              Eocene                Higher Mammals
              Miocene                 of extinct forms
              Pliocene              Recent Mammals      Modern Plants,
              Pleistocene               and
              Modern                    Man.

[A] Ordovician of Lapworth.

[B] Salopian of Lapworth.




                         _THE STARTING-POINT._


                      DEDICATED TO THE MEMORY OF

                         PROF. ROBERT JAMESON,

     Of the University of Edinburgh, my first Teacher in Geology,

         whose Lectures I attended, and whose kind Advice and

            Guidance I enjoyed, in the Winter of 1840-1841.


Headlands and Spurs--Popular Papers on Leading Topics--Revisiting Old
Localities--Dedications--General Scope of the Work




CHAPTER I.

_THE STARTING-POINT._


An explorer trudging along some line of coast, or traversing some
mountain region, may now and then reach a projecting headland, or bold
mountain spur, which may enable him to command a wide view of shore
and sea, or of hill and valley, before and behind. On such a salient
point he may sit down, note-book and glass in hand, and endeavour to
correlate the observations made on the ground he has traversed, and
may strain his eyes forward in order to anticipate the features of
the track in advance. Such are the salient points in a scientific
pilgrimage of more than half a century, to which I desire to invite
the attention of the readers of these papers. In doing so, I do not
propose to refer, except incidentally, to subjects which I have already
discussed in books accessible to general readers, but rather to those
which are imbedded in little accessible transactions, or scientific
periodicals, or which have fallen out of print. I cannot therefore
pretend to place the reader on all the salient points of geological
science, or even on all of those I have myself reached, but merely to
lead him to some of the viewing-places which I have found particularly
instructive to myself.

For similar reasons it is inevitable that a certain personal element
shall enter into these reminiscences, though this autobiographical
feature will be kept as much in the background as possible. It is
also to be anticipated that the same subject may appear more than
once, but from different points of view, since it is often useful to
contemplate certain features of the landscape from more than one place
of observation.

To drop the figure, the reader will find in these papers, in a plain
and popular form, yet it is hoped not in a superficial manner, some
of the more important conclusions of a geological worker of the old
school, who, while necessarily giving attention to certain specialties,
has endeavoured to take a broad and comprehensive view of the making of
the world in all its aspects.

The papers are of various dates; but in revising them for publication
I have endeavoured, without materially changing their original form,
to bring them up to the present time, and to state any corrections or
changes of view that have commended themselves to me in the meantime.
Such changes or modifications of view must of necessity occur to every
geological worker. Sometimes, after long digging and hammering in some
bed rich in fossils, and carrying home a bag laden with treasures, one
has returned to the spot, and turned over the _débris_ of previous
excavation, with the result of finding something rare and valuable,
before overlooked. Or, in carefully trimming and chiselling out the
matrix of a new fossil, so as to uncover all its parts, unexpected
and novel features may develop themselves. Thus, if we were right or
partially right before, our new experience may still enable us to
enlarge our views or to correct some misapprehensions. In that spirit
I have endeavoured to revise these papers, and while I have been able
to add confirmations of views long ago expressed, have been willing to
accept corrections and modifications based on later discoveries.

In the somewhat extended span of work which has been allotted to me,
I have made it my object to discover new facts, and to this end have
spared no expenditure of time and labour; but I have felt that the
results of discoveries in the works of God should not be confined to a
coterie, but should be made public for the benefit of all. Hence I have
gladly embraced any opportunities to popularise my results, whether in
lectures, articles, popular books, or in the instruction of students,
and this in a manner to give accurate knowledge, and perhaps to attract
the attention of fellow-workers to points which they might overlook if
presented merely in dry and technical papers. These objects I have in
view in connection with the present collection of papers, and also the
fact that my own pilgrimage is approaching its close, and that I desire
to aid others who may chance to traverse the ground I have passed over,
or who may be preparing to pass beyond the point I have reached.

To a naturalist of seventy years the greater part of life lies in the
past, and in revising these papers I have necessarily had my thoughts
directed to the memory of friends, teachers, guides, and companions in
labour, who have passed away. I have therefore, as a slight token of
loving and grateful remembrance dedicated these papers to the memory
of men I have known and loved, and who, I feel, would sympathise with
me in spirit, in the attempt, however feeble, to direct attention to
the variety and majesty of those great works of the Creator which they
themselves delighted to study.

Since the design of these papers excludes special details as to
Canadian geology, or that of those old eastern countries to which I
have given some attention, I must refer for them to other works, and
shall append such reference of this kind as may be necessary. At the
same time it will be observed that as my geological work has been
concerned most largely with the oldest and newest rocks of the earth,
and with the history of life rather than with rocks and minerals, there
must necessarily be some preponderance in these directions, which might
however, independently of personal considerations, be justified by
the actual value of these lines of investigation, and by the special
interest attaching to them in the present state of scientific discovery.

Having thus defined my starting-point, I would now with all respect and
deference ask the reader to accompany me from point to point, and to
examine for himself the objects which may appear either near, or in the
dim uncertain distance, in illustration of what the world is, and how
it became what it is. Perhaps, in doing so, he may be able to perceive
much more than I have been able to discover; and if so, I shall
rejoice, even if such further insight should correct or counteract
some of my own impressions. It is not given to any one age or set of
men to comprehend all the mysteries of nature, or to arrive at a point
where it can be said, there is no need of farther exploration. Even in
the longest journey of the most adventurous traveller there is an end
of discovery, and, in the study of nature, cape rises beyond cape and
mountain behind mountain interminably. The finite cannot comprehend
the infinite, the temporal the eternal. We need not, however, on that
account be agnostics, for it is still true that, within the scope of
our narrow powers and opportunities, the Supreme Intelligence reveals
to us in nature His power and divinity; and it is this, and this alone,
that gives attraction and dignity to natural science.




                            _WORLD-MAKING._


                      DEDICATED TO THE MEMORY OF

            ADAM SEDGWICK AND SIR RODERICK IMPEY MURCHISON,

                      Whose joint Labours carried

               our Knowledge of the History of the Earth

                       two Stages farther back,

              and whose Differences of Opinion served to

                 render more glorious their Victories.


[Illustration: Fig. 1. Diagram illustrating Folding of the Crust
of the Earth.--(_a_) Undisturbed crust. (_b_) Primary depression
and deposition. (_c_) Mountain-making folds with their relations
to an upper and lower magma. Fig. 2. Result of folding, faulting,
and denudation, as seen at Cascade Mountain, Western Canada (after
McConnell, p. 33).]




CHAPTER II.

_WORLD-MAKING._


Geological reading, especially when of a strictly uniformitarian
character and in warm weather, sometimes becomes monotonous; and I
confess to a feeling of drowsiness creeping over me when preparing
material for a presidential address to the American Association for the
Advancement of Science in August, 1883. In these circumstances I became
aware of the presence of an unearthly visitor, who announced himself
as of celestial birth, and intimated to me that being himself free
from those restrictions of space and time which are so embarrassing
to earthly students, he was prepared for the moment to share these
advantages with me, and to introduce me to certain outlying parts of
the universe, where I might learn something of its origin and early
history. He took my hand, and instantly we were in the voids of space.
Turning after a moment, he pointed to a small star and said, "That is
the star you call the sun; here, you see, it is only about the third
magnitude, and in a few seconds it will disappear." These few seconds,
indeed, reduced the whole visible firmament to a mere nebulous haze
like the Milky Way, and we seemed to be in blank space. But pausing for
a moment I became aware that around us were multitudes of dark bodies,
so black that they were, so to speak, negatively visible, even in the
almost total darkness around. Some seemed large and massive, some a
mere drift of minute particles, formless and without distinct limits.
Some were swiftly moving, others stationary, or merely revolving on
their own axes. It was a "horror of great darkness," and I trembled
with fear. "This," said my guide, "is what the old Hebrew seer called
_tohu ve bohu_, 'formless and void,' the 'Tiamat' or abyss of the
old Chaldeans, the 'chaos and old night' of the Greeks. Your mundane
physicists have not seen it, but they speculate regarding it, and
occupy themselves with questions as to whether it can be lightened
and vivified by mere attractive force, or by collision of dark bodies
impinging on each other with vast momentum. Their speculations are
vain, and lead to nothing, because they have no data wherefrom to
calculate the infinite and eternal Power who determined either the
attraction or the motion, or who willed which portion of this chaos was
to become cosmos, and which was to remain for ever dead and dark. Let
us turn, however, to a more hopeful prospect." We sped away to another
scene. Here were vast luminous bodies, such as we call nebulæ. Some
were globular, others disc-like, others annular or like spiral wisps,
and some were composed of several concentric shells or rings. All were
in rapid rotation, and presented a glorious and brilliant spectacle.
"This," said my guide, "is matter of the same kind with that we have
just been considering; but it has been set in active motion. The fiat
'Let there be light!' has been issued to it. Nor is its motion in
vain. Each of these nebulous masses is the material of a system of
worlds, and they will produce systems of different forms in accordance
with the various shapes and motions which you observe. Such bodies
are well known to earthly astronomers. One of them, the great nebula
of Andromeda, has been photographed, and is a vast system of luminous
rings of vapour placed nearly edgewise to the earth, and hundreds of
times greater than the whole solar system. But now let us annihilate
time, and consider these gigantic bodies as they will be in the course
of many millions of years." Instantaneously these vast nebulæ had
concentrated themselves into systems of suns and planets, but with
this difference from ours, that the suns were very large and surrounded
with a wide luminous haze, and each of the planets was self-luminous,
like a little sun. In some the planets were dancing up and down in
spiral lines. In others they were moving in one plane. In still others,
in every variety of direction. Some had vast numbers of little planets
and satellites. Others had a few of larger size. There were even
some of these systems that had a pair of central suns of contrasting
colours. The whole scene was so magnificent and beautiful that I
thought I could never weary of gazing on it. "Here," said he, "we have
the most beautiful condition of systems of worlds, when considered from
a merely physical point of view: the perfection of solar and planetary
luminousness, but which is destined to pass away in the interest of
things more important, if less showy. This is the condition of the
great star Sirius, which the old priest astronomers of the Nile Valley
made so much of in their science and religion, and which they called
Sothis. It is now known by your star-gazers to be vastly larger than
your sun, and fifty times more brilliant.[1] Let us select one of these
systems somewhat similar to the solar system, and suppose that the
luminous atmospheres of its nearer planets are beginning to wane in
brilliancy. Here is one of them, through whose halo of light we can see
the body of the planet. What do you now perceive?" The planet referred
to was somewhat larger in appearance than our earth, and, approaching
near to it, I could see that it had a cloud-bearing firmament, and
that it seemed to have continents and oceans, though disposed in more
regular forms than on our own planet, and with a smaller proportion of
land. Looking at it more closely, I searched in vain for any sign of
animal life, but I saw a vast profusion of what might be plants, but
not like those of this world.[2] These were trees of monstrous stature,
and their leaves, which were of great size and shaped like fronds of
seaweeds, were not usually green, but variegated with red, crimson and
orange. The surface of the land looked like beds of gigantic specimens
of _Colias_ and similar variegated-leaved plants, the whole presenting
a most gorgeous yet grotesque spectacle. "This," said my guide, "is the
primitive vegetation which clothes each of the planets in its youthful
state. The earth was once so clothed, in the time when vegetable life
alone existed, and there were no animals to prey upon it, and when the
earth was, like the world you now look upon, a paradise of plants; for
all things in nature are at first in their best estate. This vegetation
is known to you on the earth only by the Carbon and Graphite buried
in your oldest rocks. It still lingers on your neighbour Mars,[3]
which has, however, almost passed beyond this stage, and we are
looking forward before long to see a still more gigantic though paler
development of it in altogether novel shapes on the great continents
that are being formed on the surface of Jupiter. But look again." And
time being again annihilated, I saw the same world, now destitute of
any luminous envelope, with a few dark clouds in its atmosphere, and
presenting just the same appearance which I would suppose our earth
to present to an astronomer viewing it with a powerful telescope from
the moon. "Here we are at home again," said my guide; "good-bye." I
found myself nodding over my table, and that my pen had just dropped
from my hand, making a large blot on my paper. My dream, however, gave
me a hint as to a subject, and I determined to devote my address to a
consideration of questions which geology has not solved, or has only
imperfectly and hypothetically discussed.

[1] In evidence of these and other statements I may refer to Huggins'
recent address as President of the British Association, and to the
"Story of the Heavens," etc., by Sir Robert Ball.

[2] We shall see farther on that there is reason to believe that the
primitive land vegetation was more different from that of the Devonian
and Carboniferous than it is from that of the present day.

[3] Mars is probably a stage behind the earth in its development, and
the ruddy hue of its continents would seem to b: due to some organic
covering.

Such unsolved or partially solved questions must necessarily exist in
a science which covers the whole history of the earth in time. At the
beginning it allies itself with astronomy and physics and celestial
chemistry. At the end it runs into human history, and is mixed up with
archæology and anthropology. Throughout its whole course it has to deal
with questions of meteorology, geography and biology. In short, there
is no department of physical or biological science, with which this
many-sided study is not allied, or at least on which the geologist may
not presume to trespass. When, therefore, it is proposed to discuss
in the present chapter some of the unsolved problems and disputed
questions of this universal science, the reader need not be surprised
if it should be somewhat discursive.

Perhaps we may begin at the utmost limits of the subject by remarking
that in matters of natural and physical science we are met at the
outset with the scarcely solved question as to our own place in the
nature which we study, and the bearing of this on the difficulties
we encounter. The organism of man is decidedly a part of nature. We
place ourselves, in this aspect, in the sub-kingdom vertebrata and
class mammalia, and recognise the fact that man is the terminal link
in a chain of being, extending throughout geological time. But the
organism is not all that belongs to man, and when we regard him as
a scientific inquirer, we raise a new question. If the human mind
is a part of nature, then it is subject to natural law, and nature
includes mind as well as matter. Indeed, without being absolute
idealists we may hold that mind is more potent than matter, and
nearer to the real essence of things. Our science is in any case
necessarily dualistic, being the product of the reaction of mind on
nature, and must be largely subjective and anthropomorphic. Hence,
no doubt, arises much of the controversy of science, and much of the
unsolved difficulty. We recognise this when we divide science into
that which is experimental, or depends on apparatus, and that which is
observational and classificatory--distinctions these which relate not
so much to the objects of science as to our methods of pursuing them.
This view also opens up to us the thought that the domain of science
is practically boundless, for who can set limits to the action of mind
on the universe, or of the universe on mind. It follows that science,
as it exists at any one time, must be limited on all sides by unsolved
mysteries; and it will not serve any good purpose to meet these with
clever guesses. If we so treat the enigmas of the sphinx nature, we
shall surely be devoured. Nor, on the other hand, must we collapse into
absolute despair, and resign ourselves to the confession of inevitable
ignorance. It becomes us rather boldly to confront the unsolved
questions of nature, and to wrestle with their difficulties till we
master such as we can, and cheerfully leave those we cannot overcome to
be grappled with by our successors.

Fortunately, as a geologist, I do not need to invite attention to those
transcendental questions which relate to the ultimate constitution of
matter, the nature of the ethereal medium filling space, the absolute
difference or identity of chemical elements, the cause of gravitation,
the conservation and dissipation of energy, the nature of life, or the
primary origin of bioplasmic matter. I may take the much more humble
_rôle_ of an inquirer into the unsolved or partially solved problems
which meet us in considering that short and imperfect record which
geology studies in the rocky layers of the earth's crust, and which
leads no farther back than to the time when a solid rind had already
formed on the earth, and was already covered with an ocean. This record
of geology covers but a small part of the history of the earth and of
the system to which it belongs, nor does it enter at all into the more
recondite problems involved; still it forms, I believe, some necessary
preparation at least to the comprehension of these. If we are to go
farther back, we must accept the guidance of physicists rather than
of geologists, and I must say that in this physical cosmology both
geologists and general readers are likely to find themselves perplexed
with the vagaries in which the most sober mathematicians may indulge.
We are told that the original condition of the solar system was that
of a vaporous and nebulous cloud intensely heated and whirling rapidly
round, that it probably came into this condition by the impact of two
dark solid bodies striking each other so violently, that they became
intensely heated and resolved into the smallest possible fragments.
Lord Kelvin attributes this impact to their being attracted together
by gravitative force. Croll[4] argues that in addition to gravitation
these bodies must have had a proper motion of great velocity, which
Lord Kelvin thinks "enormously" improbable, as it would require the
solid bodies to be shot against each other with a marvellously true
aim, and this not in the case of the sun only, but of all the stars.
It is rather more improbable than it would be to affirm that in the
artillery practice of two opposing armies, cannon balls have thousands
of times struck and shattered each other midway between the hostile
batteries. The question, we are told, is one of great moment to
geologists, since on the one hypothesis the duration of our system
has amounted to only about twenty millions of years; on the other,
it may have lasted ten times that number.[5] In any case it seems a
strange way of making systems of worlds, that they should result from
the chance collision of multitudes of solid bodies rushing hither
and thither in space, and it is almost equally strange to imagine an
intelligent Creator banging these bodies about like billiard balls in
order to make worlds. Still, in that case we might imagine them not
to be altogether aimless. The question only becomes more complicated
when with Grove and Lockyer we try to reach back to an antecedent
condition, when there are neither solid masses nor nebulæ, but only
an inconceivably tenuous and universally diffused medium made up of an
embryonic matter, which has not yet even resolved itself into chemical
elements. How this could establish any motion within itself tending to
aggregation in masses, is quite inconceivable. To plodding geologists
laboriously collecting facts and framing conclusions therefrom, such
flights of the mathematical mind seem like the wildest fantasies of
dreams. We are glad to turn from them to examine those oldest rocks,
which are to us the foundation stones of the earth's crust.

[4] "Stellar Evolution."

[5] Other facts favour the shorter time (Clarence King, _Am. Jl. of
Science_, vol. xlv., 3rd series).

What do we know of the oldest and most primitive rocks? At this moment
the question may be answered in many and discordant ways; yet the
leading elements of the answer may be given very simply. The oldest
rock formation known to geologists is the Lower Laurentian, the
Fundamental Gneiss, the Lewisian formation of Scotland, the Ottawa
gneiss of Canada, the lowest Archæan crystalline rocks. This formation,
of enormous thickness, corresponds to what the older geologists called
the fundamental granite, a name not to be scouted, for gneiss is only a
stratified or laminated granite. Perhaps the main fact in relation to
this old rock is that it is a gneiss; that is, a rock at once bedded
and crystalline, and having for its dominant ingredient the mineral
orthoclase, a compound of silica, alumina and potash, in which are
imbedded, as in a paste, grains and crystals of quartz and hornblende.
We know very well from its texture and composition that it cannot be
a product of mere heat, and being a bedded rock we infer that it was
laid down layer by layer in the manner of aqueous deposits. On the
other hand, its chemical composition is quite different from that
of the muds, sands and gravels usually deposited from water. Their
special characters are caused by the fact that they have resulted from
the slow decay of rocks like these gneisses, under the operation of
carbon dioxide and water, whereby the alkaline matter and the more
soluble part of the silica have been washed away, leaving a residue
mainly silicious and aluminous.[6] Such more modern rocks tell of dry
land subjected to atmospheric decay and ram-wash. If they have any
direct relation to the old gneisses, they are their grandchildren, not
their parents. On the contrary, the oldest gneisses show no pebbles or
sand or limestone--nothing to indicate that there was then any land
undergoing atmospheric waste, or shores with sand and gravel. For
all that we know to the contrary, these old gneisses may have been
deposited in a shoreless sea, holding in solution or suspension merely
what it could derive from a submerged crust recently cooled from a
state of fusion, still thin, and exuding here and there through its
fissures heated waters and volcanic products. This, it may be observed
here, is just what we have a right to expect, if the earth was once a
heated or fluid mass, and if our oldest Laurentian rocks consist of
the first beds or layers deposited upon it, perhaps by a heated ocean.
It has been well said that "the secret of the earth's hot youth has
been well kept." But with the help of physical science we can guess at
an originally heat-liquefied ball with denser matter at its centre,
lighter and oxidised matter at its surface. We can imagine a scum or
crust forming at the surface; and from what we know of the earth's
interior, nothing is more likely to have constituted that slaggy crust
than the material of our old gneisses. As to its bedded character,
this may have arisen in part from the addition of cooling layers
below, in part from the action of heated water above, and in part from
pressure or tension; while, wherever it cracked or became broken, its
interstices would be injected with molten matter from beneath. All this
may be conjecture, but it is based on known facts, and is the only
probable conjecture. If correct, it would account for the fact that the
gneissic rocks are the lowest and oldest that we reach in every part of
the earth.

[6] Carbon dioxide, the great agent in the decay of silicious rocks,
must then have constituted a very much larger part of the atmosphere
than at present.

In short, the fundamental gneiss of the Lower Laurentian may have
been the first rock ever formed; and in any case it is a rock formed
under conditions which have not since recurred, except locally. It
constitutes the first and best example of those chemico-physical,
aqueous or aqueo-igneous rocks, so characteristic of the earliest
period of the earth's history. Viewed in this way the Lower Laurentian
gneiss is probably the oldest kind of rock we shall ever know the limit
to our backward progress, beyond which there remains nothing to the
geologist except physical hypotheses respecting a cooling incandescent
globe. For the chemical conditions of these primitive rocks, and what
is known as to their probable origin, I may refer to the writings of
my friends, the late Dr. Sterry Hunt and Dr. J. G. Bonney, to whom we
owe so much of what is known of the older crystalline rocks[7] as well
as of their literature, and the questions which they raise. My purpose
here is to sketch the remarkable difference which we meet as we ascend
into the Middle and Upper Laurentian.

[7] Hunt, "Essays on Chemical Geology"; Bonney, "Addresses to British
Association and Geological Society of London."

In the next succeeding formation, the middle part of the Laurentian
of Logan, the Grenville series of Canada, we meet with a great and
significant change. It is true we have still a predominance of
gneisses which may have been formed in the same manner with those
below them; but we find these now associated with great beds of
limestone and dolomite, which must have been formed by the separation
of calcium and magnesium carbonates from the sea water, either by
chemical precipitation or by the agency of living beings. We have also
quartzite, quartzose gneisses, and even pebble beds, which inform us
of sandbanks and shores. Nay, more, we have beds containing graphite
which must be the residue of plants, and iron ores which tell of the
deoxidation of iron oxide by organic matters. In short, here we have
evidence of new factors in world-building, of land and ocean, of
atmospheric decay of rocks, of deoxidizing processes carried on by
vegetable life on the land and in the waters, of limestone-building in
the sea. To afford material for such rocks, the old Ottawa gneiss must
have been lifted up into continents and mountain masses by bendings
and foldings of the original crust. Under the slow but sure action of
the carbon dioxide dissolved in rainwater, its felspar had crumbled
down in the course of ages. Its potash, soda, lime, magnesia, and part
Of its silica had been washed into the sea, there to enter into new
combinations and to form new deposits. The crumbling residue of fine
clay and sand had been also washed down into the borders of the ocean,
and had been there deposited in beds. Thus the earth had entered into
a new phase, which continues onward through the geological ages; and I
place in the reader's hands one key for unlocking the mystery of the
world in affirming that this great change took place, this new era was
inaugurated in the midst of the Laurentian period, the oldest of our
great divisions of the earth's geological history.[8]

[8] I follow the original arrangement of Logan, who first defined this
succession in the extensive and excellent exposures of these rocks in
Canada. Elsewhere the subject has often been confused and mixed with
local details. The same facts, though sometimes under different names,
are recorded by the geologists of Scandinavia, Britain, and the United
States, and the acceptance of the conclusions of Nicol and Lapworth has
served to bring even the rocks of the Highlands of Scotland more into
line with those of Canada.

Was not this a fit period for the first appearance of life? should we
not expect it to appear, independently of the evidence of the fact, so
soon at least as the temperature of the ocean falls sufficiently low
to permit its existence?[9] I do not propose to enter here into that
evidence. This we shall have occasion to consider in the sequel. I
would merely say here that we should bear in mind that in this latter
half of the Lower Laurentian, or if we so choose to style it, Middle
Laurentian period, we have the conditions required for life in the
sea and on the land; and since in other periods we know that life was
always present when its conditions were present, it is not unreasonable
to look for the earliest traces of life in this formation, in which we
find, for the first time, the completion of those physical arrangements
which make life, in such forms of it as exist in the sea, possible.

[9] Dana states this at 180°F. for plants and 120° for animals.

This is also a proper place to say something of the disputed doctrine
of what is termed metamorphism, or the chemical and molecular changes
which old rocks have undergone.

The Laurentian rocks are undoubtedly greatly changed from their
original state, more especially in the matters of crystallization and
the formation of disseminated minerals, by the action of heat and
heated water. Sandstones have thus passed into quartzites, clays into
slates and schists, limestones into marbles. So far, metamorphism is
not a doubtful question; but when theories of metamorphism go so far as
to suppose an actual change of one element for another, they go beyond
the bounds of chemical credibility; yet such theories of metamorphism
are often boldly advanced and made the basis of important conclusions.
Dr. Hunt has happily given the name "metasomatosis" to this imaginary
and improbable kind of metamorphism. I would have it to be understood
that, in speaking of the metamorphism of the older crystalline rocks,
it is not to this metasomatosis that I refer, and that I hold that
rocks which have been produced out of the materials decomposed by
atmospheric erosion can never by any process of metamorphism be
restored to the precise condition of the Laurentian rocks. Thus,
there is in the older formations a genealogy of rocks, which, in the
absence of fossils, may be used with some confidence, but which does
not apply to the more modern deposits, and which gives a validity to
the use of mineral character in classifying older rocks which does
not hold for later formations. Still, nothing in geology absolutely
perishes, or is altogether discontinued; and it is probable that,
down to the present day, the causes which produced the old Laurentian
gneiss may still operate in limited localities. Then, however, they
were general, not exceptional. It is further to be observed that the
term gneiss is sometimes of wide and even loose application. Beside the
typical orthoclase and hornblendic gneiss of the Laurentian, there are
micaceous, quartzose, garnetiferous and many other kinds of gneiss; and
even gneissose rocks, which hold labradorite or anorthite instead of
orthoclase, are sometimes, though not accurately, included in the term.

The Grenville series, or Middle Laurentian, is succeeded by what Logan
in Canada called the Upper Laurentian, and which other geologists have
called the Norite or Norian series. Here we still have our old friends
the gneisses, but somewhat peculiar in type, and associated with
them are great beds and masses, rich in lime-felspar, the so-called
labradorite and anorthite rocks. The precise 'origin of these is
uncertain, but this much seems clear, namely, that they originated in
circumstances in which the great limestones deposited in the Lower or
Middle Laurentian were beginning to be employed in the manufacture,
probably by aqueo-igneous agencies, of lime-felspars. This proves the
Norian rocks to be younger than the Lower Laurentian, and that, as
Logan supposed, considerable earth-movements had occurred between the
two, implying lapse of time, while it is also evident that the folding
and crumpling of the Lower Laurentian had led to great outbursts of
igneous matter from below the crust, or from its under part.

Next to the Laurentian, but probably after an interval, the rocks
of which are yet scarcely known, we have the Huronian of Logan, a
series much less crystalline and more fragmentary, and affording more
evidence of land elevation and atmospheric and aqueous erosion than
those preceding it. It has extensive beds of volcanic rock, great
conglomerates, some of them made up of rounded fragments of Laurentian
rocks, and others of quartz pebbles, which must have been the remains
of rocks subjected to very perfect decay. The pure quartz-rocks tell
the same tale, while slates and limestones speak also of chemical
separation of the materials of older rocks. The Huronian evidently
tells of previous movements in the Laurentian, and changes which
allowed the Huronian to be deposited along its shores and on the edges
of its beds. Yet the Huronian itself is older than the Palæozoic
series, and affected by powerful earth-movements at an earlier date.
Life existed in the waters in Huronian times. We have spicules of
sponges in the limestone, and organic markings on the slaty beds; but
they are few, and their nature is uncertain.

Succeeding the Huronian, and made up of its _débris_ and that of the
Laurentian, we have the great Cambrian series, that in which we first
find undoubted evidence of abundant marine life, and which thus forms
the first chapter in the great Palæozoic book of the early history of
the world. Here let it be observed we have at least two wide gaps in
our history, marked by the crumpling up, first, of the Laurentian, and
then of the Huronian beds.

After what has been said, the reader will perhaps not be astonished
that fierce geological battles have raged over the old crystalline
rocks. By some geologists they are almost entirely explained away,
or referred to igneous action, or to the alteration of ordinary
sediments. Under the treatment of another school they grow to great
series of Pre-Cambrian rocks, constituting vast systems of formations,
distinguishable from each other chiefly by differences of mineral
character. Facts and fossils are daily being discovered, by which these
disputes will ultimately be settled.

After the solitary appearance of Eozoon in the Laurentian, and of a few
uncertain forms in the Huronian, we find ourselves, in the Cambrian,
in the presence of a nearly complete invertebrate fauna of protozoa,
polyps, echinoderms, mollusks and Crustacea, and this not confined to
one locality merely, but apparently extended simultaneously throughout
the ocean, over the whole world. This sudden incoming of animal
life, along with the subsequent introduction of successive groups of
invertebrates, and finally of vertebrate animals, furnishes one of
the greatest unsolved problems of geology, which geologists were wont
to settle by the supposition of successive creations. In the sequel
I shall endeavour to set forth the facts as to this succession, and
the general principles involved in it, and to show the insufficiency
of certain theories of evolution suggested by biologists to give any
substantial aid to the geologist in these questions. At present I
propose merely to notice some of the general principles which should
guide us in studying the development of life in geological time, and
the causes which have baffled so many attempts to throw light on this
obscure portion of our unsolved problems.

It has been urged on the side of rational evolution--and there are both
rational and irrational forms of this many-sided doctrine--that this
hypothesis does not profess to give an explanation of the absolute
origin of life on our planet, or even of the original organization of
a single cell, or of a simple mass of protoplasm, living or dead. All
experimental attempts to produce by synthesis the complex albuminous
substances, or to obtain the living from the non-living, have so far
been fruitless, and indeed we cannot imagine any process by which such
changes could be effected. That they have been effected we know, but
the process employed by their maker is still as mysterious to us as it
probably was to him who wrote the words:--"And God said, Let the waters
swarm with swarmers." How vast is the gap in our knowledge and our
practical power implied in this admission, which must, however, be made
by every mind not absolutely blinded by a superstitious belief in those
forms of words which too often pass current as philosophy.

But if we are content to start with a number of organisms ready made--a
somewhat humiliating start, however--we still have to ask--How do
these vary so as to give new species? It is a singular illusion, and
especially in the case of men who profess to be believers in natural
law, that variation may be boundless, aimless and fortuitous, and
that it is by spontaneous selection from varieties thus produced that
development arises. But surely the supposition of mere chance and
magic is unworthy of science. Varieties must have causes, and their
causes and their effects must be regulated by some law or laws. Now it
is easy to see that they cannot be caused by a mere innate tendency
in the organism itself. Every organism is so nicely equilibrated that
it has no such spontaneous tendency, except within the limits set by
its growth and the law of its periodical changes. There may, however,
be equilibrium more or less stable. I believe all attempts hitherto
made have failed to account for the fixity of certain, nay, of very
many, types throughout geological time, but the mere consideration
that one may be in a more stable state of equilibrium than another,
so far explains it. A rocking stone has no more spontaneous tendency
to move than an ordinary boulder, but it may be made to move with a
touch. So it probably is with organisms. But if so, then the causes of
variation are external, as in many cases we actually know them to be,
and they must depend on instability with change in surroundings, and
this so arranged as not to be too extreme in amount, and to operate
in some determinate direction. Observe how remarkable the unity of
the adjustments involved in such a supposition!--how superior they
must be to our rude and always more or less unsuccessful attempts to
produce and carry forward varieties and races in definite directions!
This cannot be chance. If it exists, it must depend on plans deeply
laid in the nature of things, else it would be most monstrous magic
and causeless miracle. Still more certain is this conclusion when we
consider the vast and orderly succession made known to us by geology,
and which must have been regulated by fixed laws, only a few of which
are as yet known to us.

Beyond these general considerations we have others of a more special
character, based on palæontological facts, which show how imperfect are
our attempts as yet to reach the true causes of the introduction of
genera and species.

One is the remarkable fixity of the leading types of living beings
in geological time. If, instead of framing, like Haeckel, fanciful
phylogenies, we take the trouble, with Barrande and Gaudry, to trace
the forms of life through the period of their existence, each along its
own line, we shall be greatly struck with this, and especially with the
continuous existence of many low types of life through vicissitudes of
physical conditions of the most stupendous character, and over a lapse
of time scarcely conceivable. What is still more remarkable is that
this holds in groups which, within certain limits, are perhaps the most
variable of all. In the present world no creatures are individually
more variable than the protozoa; as, for example, the foraminifera and
the sponges. Yet these groups are fundamentally the same, from the
beginning of the Palæozoic until now, and modern species seem scarcely
at all to differ from specimens procured from rocks at least half-way
back to the beginning of our geological record. If we suppose that the
present sponges and foraminifera are the descendants of those of the
Silurian period, we can affirm that in all that vast lapse of time they
have, on the whole, made little greater change than that which may be
observed in variable forms at present. The same remark applies to other
low animal forms. In types somewhat higher and less variable, this is
almost equally noteworthy. The pattern of the venation of the wings of
cockroaches, and the structure and form of land snails, gally-worms and
decapod crustaceans were all settled in the Carboniferous age, in a way
that still remains. So were the foliage and the fructification of club
mosses and ferns. If, at any time, members of these groups branched
off, so as to lay the foundation of new species, this must have been
a very rare and exceptional occurrence, and one demanding even some
suspension of the ordinary laws of nature.

We may perhaps be content on this question to say with Gaudry,[10]
that it is not yet possible to "pierce the mystery that surrounds
the development of the great classes of animals," or with Prof.
Williamson,[11] that in reference to fossil plants "the time has
not yet arrived for the appointment of a botanical King-at-arms and
Constructor of pedigrees." We shall, however, find that by abandoning
mere hypothetical causes and carefully noting the order of the
development and the causes in operation, so far as known, we may reach
to ideas as to cause and mode, and the laws of succession, even if
unable to penetrate the mystery of origins.

[10] "Enchainements du Monde Animal," Paris, 1883.

[11] Address before Royal Institution, Feb., 1883.

Another caution which a palæontologist has occasion to give with regard
to theories of life, has reference to the tendency of biologists to
infer that animals and plants were introduced under embryonic forms,
and at first in few and imperfect species. Facts do not substantiate
this. The first appearance of leading types of life is rarely
embryonic, or of the nature of immature individuals. On the contrary,
they often appear in highly perfect and specialized forms, often,
however, of composite type and expressing characters afterwards so
separated as to belong to higher groups. The trilobites of the Cambrian
are some of them of few segments, and so far embryonic, but the greater
part are many-segmented and very complex. The batrachians of the
Carboniferous present many characters higher than those of their modern
successors and now appropriated to the true reptiles. The reptiles of
the Permian and Trias usurped some of the prerogatives of the mammals.
The ferns, lycopods and equisetums of the Devonian and Carboniferous
were, in fructification, not inferior to their modern representatives,
and in the structure of their stems far superior. The shell-bearing
cephalopods of the Palæozoic would seem to have possessed structures
now special to a higher group, that of the cuttle-fishes. The bald and
contemptuous negation of these facts by Haeckel and other biologists
does not tend to give geologists much confidence in their dicta.

Again, we are now prepared to say that the struggle for existence,
however plausible as a theory, when put before us in connection
with the productiveness of animals and the few survivors of their
multitudinous progeny, has not been the determining cause of the
introduction of new species. The periods of rapid introduction
of new forms of marine life were not periods of struggle, but of
expansion--those periods in which the submergence of continents
afforded new and large space for their extension and comfortable
subsistence. In like manner, it was continental emergence that afforded
the opportunity for the introduction of land animals and plants.
Further, in connection with this, it is now an established conclusion
that the great aggressive faunas and floras of the continents have
originated in the north, some of them within the arctic circle, and
this in periods of exceptional warmth, when the perpetual summer
sunshine of the arctic regions coëxisted with a warm temperature.
The testimony of the rocks thus is that not struggle but expansion
furnished the requisite conditions for new forms of life, and that the
periods of struggle were characterized by depauperation and extinction.

But we are sometimes told that organisms are merely mechanical, and
that the discussions respecting their origin have no significance any
more than if they related to rocks or crystals, because they relate
merely to the organism considered as a machine, and not to that which
may be supposed to be more important, namely, the great determining
power of mind and will. That this is a mere evasion by which we
really gain nothing, will appear from a characteristic extract of an
article by an eminent biologist in the new edition of the Encyclopedia
Britannica, a publication which, I am sorry to say, instead of its
proper _rôle_ as a repertory of facts, has admitted partisan papers,
stating extreme and unproved speculations as if they were conclusions
of science. The statement referred to is as follows:--"A mass of living
protoplasm is simply a molecular machine of great complexity, the total
results of the working of which, or its vital phenomena, depend on the
one hand on its construction, and on the other, on the energy supplied
to it; and to speak of vitality as anything but the name for a series
of operations is as if one should talk of the horologity of a clock."
It would, I think, scarcely be possible to put into the same number
of words a greater amount of unscientific assumption and unproved
statement than in this sentence. Is "living protoplasm" different in
any way from dead protoplasm, and if so, what causes the difference?
What is a "machine"? Can we conceive of a self-produced or uncaused
machine, or one not intended to work out some definite results? The
results of the machine in question are said to be "vital phenomena";
certainly most wonderful results, and greater than those of any machine
man has yet been able to construct. But why "vital"? If there is no
such thing as life, surely they are merely physical results. Can
mechanical causes produce other than physical effects? To Aristotle
life was "the cause of form in organisms." Is not this quite as likely
to be true as the converse proposition? If the vital phenomena depend
on the "construction" of the machine, and the "energy supplied to it,"
whence this construction and whence this energy? The illustration of
the clock does not help us to answer this question. The construction of
the clock depends on its maker, and its energy is derived from the hand
that winds it up. If we can think of a clock which no one has made, and
which no one winds, a clock constructed by chance, set in harmony with
the universe by chance, wound up periodically by chance, we shall then
have an idea parallel to that of an organism living, yet without any
vital energy or creative law; but in such a case we should certainly
have to assume some antecedent cause, whether we call it "horologity"
or by some other name. Perhaps the term evolution would serve as well
as any other, were it not that common sense teaches that nothing can be
spontaneously evolved out of that in which it did not previously exist.

There is one other unsolved problem in the study of life by the
geologist to which it is still necessary to advert. This is the
inability of palæontology to fill up the gaps in the chain of being.
In this respect we are constantly taunted with the imperfection of the
record, a matter so important that it merits a separate treatment; but
facts show that this is much more complete than is generally supposed.
Over long periods of time and many lines of being we have a nearly
continuous chain, and if this does not show the tendency desired,
the fault is as likely to be in the theory as in the record. On the
other hand, the abrupt and simultaneous appearance of new types in
many specific and generic forms and over wide and separate areas at
one and the same time, is too often repeated to be accidental. Hence
palæontologists, in endeavouring to establish evolution, have been
obliged to assume periods of exceptional activity in the introduction
of species, alternating with others of stagnation, a doctrine differing
very little from that of special creation, as held by the older
geologists.

The attempt has lately been made to account for these breaks by the
assumption that the geological record relates only to periods of
submergence, and gives no information as to those of elevation. This
is manifestly untrue. In so far as marine life is concerned, the
periods of submergence are those in which new forms abound for very
obvious reasons, already hinted; but the periods of new forms of land
and fresh-water life are those of elevation, and these have their own
records and monuments, often very rich and ample, as, for example, the
swamps of the Carboniferous, the transition from the great Cretaceous
subsidence, when so much of the land of the Northern Hemisphere
was submerged, to the new continents of the Tertiary, the Tertiary
lake-basins of Western America, the Terraces and raised beaches of
the Pleistocene. Had I time to refer in detail to the breaks in the
continuity of life which cannot be explained by the imperfection of the
record, I could show at least that nature in this case does advance
_per saltum_--by leaps, rather than by a slow continuous process. Many
able reasoners, as Le Conte, in America, and Mivart and Collard in
England, hold this view.

Here, as elsewhere, a vast amount of steady conscientious work is
required to enable us to solve the problems of the history of life. But
if so, the more the hope for the patient student and investigator. I
know nothing more chilling to research, or unfavourable to progress,
than the promulgation of a dogmatic decision that there is nothing to
be learned but a merely fortuitous and uncaused succession, amenable
to no law, and only to be covered, in order to hide its shapeless and
uncertain proportions, by the mantle of bold and gratuitous hypothesis.

So soon as we find evidence of continents and oceans we raise the
question, Have these continents existed from the first in their present
position and form, or have the land and water changed places in the
course of geological time? This question also deserves a separate and
more detailed consideration. In reality both statements are true in a
certain limited sense. On the one hand, any geological map whatever
suffices to show that the general outline of the existing land began to
be formed in the first and oldest crumplings of the crust. On the other
hand, the greater part of the surface of the land consists of marine
sediments which must have been deposited when the continents were
in great part submerged, and whose materials must have been derived
from land that has perished in the process, while all the continental
surfaces, except, perhaps, some high peaks and ridges, have been many
times submerged. Both of these apparently contradictory statements
are true; and without assuming both, it is impossible to explain the
existing contours and reliefs of the surface.

In exceptional cases even portions of deep sea have been elevated, as
in the case of the Polycistine deposits in the West Indies; but these
exceptions are as yet scarcely sufficient to prove the rule.

In the case of North America, the form of the old nucleus of Laurentian
rock in the north already marks out that of the finished continent, and
the successive later formations have been laid upon the edges of this,
like the successive loads of earth dumped over an embankment. But in
order to give the great thickness of the Palæozoic sediments, the land
must have been again and again submerged, and for long periods of time.
Thus, in one sense, the continents have been fixed; in another, they
have been constantly fluctuating. Hall and Dana have well illustrated
these points in so far as eastern North America is concerned. Prof.
Hull of the Geological Survey of Ireland has had the boldness to
reduce the fluctuations of land and water, as evidenced in the British
Islands, to the form of a series of maps intended to show the physical
geography of each successive period. The attempt is probably premature,
and has been met with much adverse criticism; but there can be no
doubt that it has an element of truth. When we attempt to calculate
what could have been supplied from the old Eozoic nucleus by decay
and aqueous erosion, and when we take into account the greater local
thickness of sediments towards the present sea-basins, we can scarcely
avoid the conclusion that extensive areas once occupied by high land
are now under the sea. But to ascertain the precise areas and position
of these perished lands may now be impossible.

In point of fact we are obliged to believe in the contemporaneous
existence in all geological periods, except perhaps the very oldest, of
three sorts of areas on the surface of the earth: (1) Oceanic areas of
deep sea, which must always have occupied the bed of the present ocean,
or parts of it; (2) Continental plateaus sometimes existing as low
flats, or as higher table-lands, and sometimes submerged; (3) Areas of
plication or folding, more especially along the borders of the oceans,
forming elevated lands rarely submerged and constantly affording the
material of sedimentary accumulations. We shall find, however, that
these have changed places in a remarkable manner, though always in such
a way that neither the life of the land nor of the waters was wholly
extinguished in the process.

Every geologist knows the contention which has been occasioned by the
attempts to correlate the earlier Palæozoic deposits of the Atlantic
margin of North America with those forming at the same time on the
interior plateau, and with those of intervening lines of plication and
igneous disturbance. Stratigraphy, lithology and fossils are all more
or less at fault in dealing with these questions, and while the general
nature of the problem is understood by many geologists, its solution
in particular cases is still a source of apparently endless debate.

The causes and mode of operation of the great movements of the earth's
crust which have produced mountains, plains and table-lands, are still
involved in some mystery. One patent cause is the unequal settling of
the crust towards the centre; but it is not so generally understood
as it should be, that the greater settlement of the ocean-bed has
necessitated its pressure against the sides of the continents in
the same manner that a huge ice-floe crushes a ship or a pier. The
geological map of North America shows this at a glance, and impresses
us with the fact that large portions of the earth's crust have not only
been folded but bodily pushed back for great distances. On looking at
the extreme north, we see that the great Laurentian mass of central
Newfoundland has acted as a projecting pier to the space immediately
west of it, and has caused the gulf of St. Lawrence to remain an
undisturbed area since Palæozoic times. Immediately to the south of
this, Nova Scotia and New Brunswick are folded back. Still farther
south, as Guyot has shown, the old sediments have been crushed in sharp
folds against the Adirondack mass, which has sheltered the table-land
of the Catskills and of the great lakes. South of this again the rocks
of Pennsylvania and Maryland have been driven back in a great curve
to the west. Movements of this kind on the Pacific coast of America
have been still more stupendous, as well as more recent. Dr. G. M.
Dawson[12] thus refers to the crushing action of the Pacific bed on
the rocks of British Columbia, and this especially at two periods, the
close of the Triassic and the close of the Cretaceous: "The successive
foldings and crushings which the Cordillera region has suffered have
resulted in an actual change of position of the rocks now composing
its western margin. This change may have amounted since the beginning
of Mesozoic time to one-third of its whole present width, which would
place the line of the coast ranges about two degrees of longitude
farther west." Here we have evidence that a tract of country 400
miles wide and consisting largely of mountain ranges and table-lands,
has been crushed bodily back over two degrees of longitude; and this
applies not to British Columbia merely, but to the whole west coast
from Alaska to Chili. Yet we know that any contraction of the earth's
nucleus can crumple up only a very thin superficial crust, which in
this case must have slid over the pasty mass below.[13] Let it be
observed, however, that the whole lateral pressure of vast areas
has been condensed into very narrow lines. Nothing, I think, can
more forcibly show the enormous pressure to which the edges of the
continents have been exposed, and at the same time the great sinking of
the hard and resisting ocean-beds. Complex and difficult to calculate
though these movements of plication are, they are more intelligible
than the apparently regular pulsations of the flat continental areas,
whereby they have alternately been below and above the waters, and
which must have depended on somewhat regularly recurring causes,
connected either with the secular cooling of the earth or with the
gradual retardation of its rotation, or with both. There is, however,
good reason to believe that the successive subsidences alternated with
the movements of plication, and depended on upward bendings of the
ocean floor, and also on the gradual slackening of the rotation of the
earth. Throughout these changes, each successive elevation exposed the
rocks for long ages to the decomposing influence of the atmosphere.
Each submergence swept away and deposited as sediment the material
accumulated by decay. Every change of elevation was accompanied with
changes of climate, and with modifications of the habitats of animals
and plants. Were it possible to restore accurately the physical
geography of the earth in all these respects, for each geological
period, the data for the solution of many difficult questions would be
furnished.

[12] Trans. Royal Society of Canada, 1890.

[13] This view is quite consistent with the practical solidity of the
earth, and with the action of local expansion by heat, of settlement of
areas overloaded with sediment, and of downward sliding of beds. This
we shall see in the sequel.

We have wandered through space and time sufficiently for one chapter,
and some of the same topics must come up later in other connections.
Let us sum up in a word. In human history we are dealing with the
short lives and limited plans of man. In the making of worlds we are
conversant with the plans of a Creator with whom one day is as a
thousand years, and a thousand years as one day. We must not measure
such things by our microscopic scale of time. Nor should we fail to
see that vast though the ages of the earth are, they are parts of a
continuous plan, and of a plan probably reaching in space and time
immeasurably beyond our earth. When we trace the long history from an
incandescent fire-mist to a finished earth, and vast ages occupied by
the dynasties of plant and animal life, we see not merely a mighty
maze, an almost endless procession of changes, but that all of these
were related to one another by a chain of causes and effects leading
onward to greater variety and complexity, while retaining throughout
the traces of the means employed. The old rocks and the ancient lines
of folding and the perished forms of life are not merely a scaffolding
set up to be thrown down, but the foundation stones of a great and
symmetrical structure. Is it yet completed? Who can tell? The earth may
still be young, and infinite ages of a better history may lie before it.

  References[14]:--Presidential Address to the American Association
    for the Advancement of Science, meeting at Minneapolis, 1883. "The
    Story of the Earth and Man." Ninth edition, London, 1887.

[14] The references in this and succeeding chapters are exclusively
to papers and works by the author, on which the several chapters are
based.




             _THE IMPERFECTION OF THE GEOLOGICAL RECORD._

                      DEDICATED TO THE MEMORY OF

                           JOACHIN BARRANDE,

                 One of the most successful Labourers

                   in the Completion of the History

                    of Life in its earlier Stages.


Nature of the Imperfection--Questions as to its arising from
Want of Continuity, from Lack of Preservation, from Imperfect
Collecting.--Examples--Land Snails, Carboniferous Batrachians,
Palæozoic Sponges, Pleistocene Shells, Devonian and Carboniferous
Plants--Comparative Perfection in the Case of Marine Shells,
etc.--Possible Cambrian Squids--Questions as to Want of First Chapters
of the Record--Practical Conclusions

[Illustration: Cambro-Silurian Sponges restored.--_Protospongia_,
_Acanthodictya_, _Cyathospongia_, _Lasiothrix_, _Halichondrites_,
Palæosaccus, etc., from a single bed of shale in the Quebec Group,
Little Metis, Canada (p. 47).]




CHAPTER III.

_THE IMPERFECTION OF THE GEOLOGICAL RECORD._


Complaints of the imperfection of the geological record are rife among
those biologists who expect to find continuous series of fossils
representing the gradual transmutation of species. No doubt these gaps
are in some cases portentous, and unfortunately they often occur just
where it is most essential to certain general conclusions that they
should be filled up. Instead, however, of making vague lamentations
on the subject, it is well to inquire to what causes these gaps may
be due, to what extent they invalidate the completeness of geological
history for scientific purposes, and how they may best be filled.

Here we may first remark that it is not so much the physical record of
geology that is imperfect as the organic record. Ever since the time
of Hutton and Playfair we have learned that the processes of mineral
detrition and deposition are continuous, and have been so throughout
geological time. The erosion of the land is constantly going on, every
shower carries its tribute of earthy matter toward the sea, and every
wave that strikes against a beach or cliff does some work toward the
grinding of shells, pebbles or stone. Thus, everywhere around our
continents there is a continuous deposition of beds of earthy matter,
and it is this which, when elevated into new land, has given us our
chronological series of geological formations. True, the elevating
process is not continuous, but, so far as we know, intermittent; but
it has been so often repeated that we have no reason to doubt that the
wasting continents afford a complete series of aqueous deposits, since
the time when the dry land first appeared.

In recent years the _Challenger_ expedition and similar dredgings have
informed us of still another continuity of deposition in the depths
of the ocean. There, where no detritus from the land, or only a very
little fine volcanic ash or pumice has ever reached, we have, going on
from age to age, a deposit of the hard parts of abyssal animals and
of those that swim in the open sea; so that if it were possible to
bore or sink a shaft in some parts of the ocean, we should find not
only a continuous bed, but a continuous series of pelagic life from
the Laurentian to the present day. Thus we have continuous physical
records, could we but reach or completely put them together, and
eliminate the disturbing influence of merely local vicissitudes. It is
when we begin to search the geological formations for fossils, that
imperfection in our record first becomes painfully manifest.

In the case of many groups of marine animals, as, for example, the
shell-fish and the corals, and I may add the bivalve crustaceans, so
admirably worked up by my friend Prof. Rupert Jones, we have very
complete series. With the and snails the case is altogether different.
As stated in another paper of this series, a few species of these
animals appear in the later Palæozoic age, and after that they have no
successors known to us in all the great periods covered by the Permian,
the Trias, and the earlier Jurassic. A few air-breathing water-snails
appear in the upper Jurassic, and true land snails are not met with
again until the Tertiary. Were there no land snails in this vast lapse
of time? Have we two successive creations, so to speak, of these
creatures at distant intervals? Were they only diminished in numbers
and distribution in the intervening time? Is the hiatus owing merely
to the unlikelihood of such shells being preserved? Or is it owing to
the lack of diligence and care in collecting?

In this particular case we are, no doubt, disposed to say that the
series must have been continuous. But we cannot be sure of this. In
whatever way a few species of land snails were so early introduced in
the time of the Devonian or of the Coal formation, if from physical
vicissitudes or lack of proper pabulum they became extinct, there is
no reason known to us why, when circumstances again became favourable,
they should not be reintroduced in the same manner as at first, whether
by development from allied types or otherwise. The fact that the few
Devonian and Carboniferous species are very like those that still
exist, perhaps makes against this supposition, but does not exclude it.
If we suppose that new forms of life of low grade are introduced from
time to time in the course of the geological ages, and if we adopt the
Darwinian hypothesis of evolution, we arrive, as Naegeli has so well
pointed out, at the strange paradox, that the highest forms of life
must be the oldest of all, since they will be the descendants of the
earliest of the lower animals, whereas the animals now of low grade
may have been introduced later, and may not have had time to improve.
But all our attempts to reduce nature to one philosophic expression
necessarily lead to such paradoxes.

On the other hand, the chances of the preservation of land snails
in aqueous deposits are vastly less than those in favour of the
preservation of aquatic species. The first Carboniferous species
found[15] had been preserved in the very exceptional circumstances
afforded by the existence of hollow trunks of Sigillariæ on the borders
of the Coal formation flats, and the others subsequently found were
in beds no doubt receiving the drainage of neighbouring land areas.
Still it is not uncommon on the modern sea-shore, anywhere near the
mouths of rivers, to find a few fresh-water shells here and there.
The carbonaceous beds of the Trias, the fossil soils of the Portland
series, the estuarine Wealden beds would seem to be as favourably
situated as those of the coal formation for preserving land shells,
though possibly the flora of the Mesozoic was less suitable for feeding
such creatures than that of the Coal period, and they may consequently
have become few and local. After all, perhaps more diligent collecting
and more numerous collectors might succeed, and may succeed in the
future, in filling this and similar gaps.

[15] _Pupa vetusta_ of the Nova Scotia coal formation.

It is a great mistake to suppose that discoveries of this kind are made
by chance. It is only by the careful and painstaking examination of
much material that the gaps in the geological record can be filled up,
and I propose in the sequel of this article to note a few instances, in
a country where the range of territory is altogether out of proportion
to the number of observers, and which have come within my own knowledge.

It was not altogether by accident that Sir C. Lyell and the writer
discovered a few reptilian bones and a land-snail in breaking up
portions of the material filling an erect Sigillaria in the South
Joggins coal measures. We were engaged in a deliberate survey of the
section, to ascertain as far as might be the conditions of accumulation
of coal, and one point which occurred to us was to inquire as to the
circumstances of preservation of stumps of forest trees in an erect
position, to trace their roots into the soils on which they stood,
and to ascertain the circumstances in which they had been buried, had
decayed, and had been filled with mineral matter. It was in questioning
these erect trees on such subjects and this not without some digging
and hammering that we made the discovery referred to.

But we found such remains only in one tree, and they were very
imperfect, and indicated only two species of batrachians and one
land-snail. There the discovery might have rested. But I undertook to
follow it up. In successive visits to the coast, a large number of
trees standing in the cliff and reefs, or fallen to the shore, were
broken up and examined, the result being to discover that, with one
unimportant exception, the productive trees were confined to one of
the beds at Coal Mine Point, that from which the original specimens
had been obtained. Attention was accordingly concentrated on this, and
as many as thirty trees were at different times extracted from it, of
which rather more than one-half proved more or less productive. By
these means bones representing about sixty specimens and twelve species
were extracted, besides numerous remains of land shells, millipedes,
and scorpions. In this way a very complete idea was obtained of the
land life, or at least of the smaller land animals, of this portion
of the coal formation of Nova Scotia. It is not too much to say that
if similar repositories could be found in the succeeding formations,
and properly worked when found, our record of the history of land
quadrupeds might be made very complete.

When in 1855 I changed my residence from Nova Scotia to Montreal,
and so was removed to some distance from the carboniferous rocks
which I had been accustomed to study, I naturally felt somewhat out
of place in a Cambro-Silurian district, more especially as my friend
Billings had already almost exhausted its fossils. I found, however,
a congenial field in the Pleistocene shell beds; more especially as
I had given some attention to recent marine animals when on the sea
coast. The very perfect series of Pleistocene deposits in the St.
Lawrence valley locally contain marine shells from the bottom of
the till or boulder clay up to the overlying sands and gravels. The
assemblage was a more boreal one than that on the coast of Nova Scotia,
though many of the species were the same, and both the climatal and
bathymetrial conditions differed in different parts of the Pleistocene
beds themselves. The gap in the record here could at that time be
filled up only by collecting recent shells. In addition to what
could be obtained by exchanging with naturalists who had collected
in Greenland, Labrador, and Norway, I employed myself, summer after
summer, in dredging both on the south and north shore of the St.
Lawrence, until able at length to discover in a living state, but under
different conditions as to temperature and depth, nearly every species
found in the beds on the land, from the lower boulder clay to the top
of the formation, and from the sea-level to the beds six hundred feet
high on the hills. Not only so: I could ascertain in certain places and
conditions all the peculiar varieties of the species, and the special
modes of life which they indicated. Thus, in the cases of the Peter
Redpath Museum, and in notes on the Post-pliocene of Canada, the gap
between the Modern and the Glacial age was completely filled up in so
far as Canadian marine species are concerned. The net result was, as I
have elsewhere stated, that no change other than varietal had occurred.

In studying the fossil plants of the Carboniferous, so abundant in
the fine exposures of the coal formation in Nova Scotia, two defects
struck me painfully. One was the fragmentary and imperfect state of
the specimens procurable. Another was the question, What preceded
these plants in the older rocks? The first of these was to be met only
by thorough exploration. When a fragment of a plant was disclosed it
was necessary to inquire if more existed in the same bed, and to dig,
or blast away or break up the rock, until some remaining portions
were disclosed. In this way it has been possible to obtain entire
specimens of many trees of the Carboniferous; and to such an extent has
the laborious and somewhat costly process been effectual, that more
species of carboniferous trees are probably known in their entire forms
from the Coal formations of Nova Scotia than from any other part of
the world. I have been amused to find that so little are experiences
of this kind known to some of my _confrères_ abroad, that they are
disposed to look with scepticism on the information obtained by this
laborious but certain process, and to suppose that they are being
presented with imaginary "restorations." I think it right here to copy
a remark of a German botanist, who has felt himself called to criticise
my work: "Dawson's description of the genus (_Psilophyton_) rests
chiefly on the impression made on him in his repeated researches," etc.
"He puts us off with an account of the general idea which he has drawn
from the study of them." This is the remark of a closet naturalist,
with reference to the kind of work above referred to, which, of course,
cannot be represented in its entirety in figures or hand specimens.[16]

[16] Solms-Laubach, "Fossil Botany." A pretentious book, which should
not have been translated into English without thorough revision and
correction.

As to the precursors of the Carboniferous flora, in default of
information already acquired, I proceeded to question the Erian or
Devonian rocks of Canada, in which Sir William Logan had already found
remains of plants which had not, however, been studied or described.
Laboriously coasting along the cliffs of Gaspé and the Baie des
Chaleurs, digging into the sandstones of Eastern Maine, and studying
the plants collected by the New York Survey, I began to find that there
was a rich Devonian flora, and that, like that of the Carboniferous,
it presented different stages from the base to the summit of the
formation. But here a great advance was made in a somewhat unexpected
way. My then young friends, the late Prof. Hartt and Mr. Matthew, of
St. John, had found a few remains of plants in the Devonian, or at
least pre-Carboniferous beds of St. John, which were placed in my
hands for description. They were so novel and curious that inquiry was
stimulated, and these gentlemen, with some friends of similar tastes,
explored the shales exposed in the reefs near St. John, and when they
found the more productive beds, broke them up by actual quarrying
operations in such a way that they soon obtained the richest Devonian
plant collections ever known. I think I may truly say that these young
and enthusiastic explorers worked the St. John plant-beds in a manner
previously unexampled in the world. Their researches were not only thus
rewarded, but incidentally they discovered the first known Devonian
insects, which could not have been found by a less painstaking process,
and one of them discovered what I believe to be the oldest known
land shell. Still more, their studies led to the separation from the
Devonian beds of the Underlying Cambrian slates, previously confounded
with them; and this, followed up by the able and earnest work of Mr.
Matthew, has carried back our knowledge of the older rocks in Canada
several stages, or as far as the earliest Cambrian previously known in
Europe, but not before fully recognised in America, and has discovered
in these old rocks the precursors of many forms of life not previously
traced so far back.

The moral of these statements of fact is that the imperfections of the
record will yield only to patient and painstaking work, and that much
is in the power of local amateurs. I would enforce this last statement
by a reference to a little research, in which I have happened to take
part at a summer resort on the Lower St. Lawrence, at which I have from
time to time spent a few restful vacation weeks. Little Metis is on the
Quebec Group of Sir William Logan, that peculiar local representative
of the lower part of the Cambro-Silurian and Upper Cambrian formations
which stretches along the south side of the St. Lawrence all the way
from Quebec to Cape Rosier, near Gaspé, a distance of five hundred
miles. This great series of rocks is a jumble of deposits belonging
at that early time to the marginal area of what is now the American
continent, and indicating the action not merely of ordinary causes
of aqueous deposit, but of violent volcanic ejections, accompanied
perhaps by earthquake waves, and not improbably by the action of heavy
coast ice. The result is that mud rocks now in the form of black, grey,
and red shales and slates alternate with thick and irregular beds of
hard sandstone, sometimes so coarse that it resembles the angular
_débris_ of the first treatment of quartz in a crusher. With these
sandstones are thick and still more irregular conglomerates formed of
pebbles and boulders of all sizes, up to several feet in diameter, some
of which are of older limestones containing Cambrian fossils, while
others are of quartzite or of igneous or volcanic rocks.

The whole formation, as presented at Metis, is of the most unpromising
character as regards fossils, and after visiting the place for ten
years, and taking many long walks along the shore and into the
interior, and scrutinising every exposure, I had found nothing more
interesting than a few fragments of graptolites, little zoophytes,
ancient representatives of our sea mosses, and which are quite
characteristic of several portions of the Quebec Group. With these were
some marks of fucoids and tracks or burrows of worms. The explorers of
the Geological Survey had been equally unsuccessful.

Quite accidentally a new light broke upon these unpromising rocks.
My friend, Dr. Harrington, strolling one day on the shore, sat down
to rest on a stone, and picked up a piece of black slate lying at
his feet. He noticed on it some faintly traced lines which seemed
peculiar. He put it in his pocket and showed it to me. On examination
with a lens it proved to have on it a few spicules of a hexactinellid
sponge--little crosses forming a sort of mesh or lattice-work similar
to that which Salter had many years before found in the Cambrian
rocks of Wales, and had named _Protospongia_--the first sponge. The
discovery seemed worth following up, and we took an early opportunity
of proceeding to the place, where, after some search, we succeeded in
tracing the loose pieces to a ledge of shale on the beach, where there
was a little band, only about an inch thick, stored with remains of
sponges, a small bivalve shell and a slender branching seaweed. This
was one small layer in reefs of slate more than one hundred feet thick.
We subsequently found two other thin layers, but less productive.
Tools and workmen were procured, and we proceeded to quarry in the
reef, taking out at low tide as large slabs as possible of the most
productive layer, and carefully splitting these up. The results, as
published in the Transactions of the Royal Society of Canada,[17]
show more than twelve species of siliceous sponges belonging to six
genera, besides fragments indicating other species, and all of these
living at one time on a very limited space of what is practically a
single surface of muddy sea-bottom.[18] The specimens show the parts
of these ancient sponges much more perfectly than they were previously
known, and indeed, enable many of them to be perfectly restored. They
for the first time connect the modern siliceous sponges of the deep
sea with those that flourished on the old sea-bottom of the early
Cambro-Silurian, and thus bridge over a great, gap in the history of
this low form of life, showing that the principles of construction
embodied in the remarkable and beautiful siliceous sponges, like
Euplectella, the "Venus flower-basket," now dredged from the deep sea,
were already perfectly carried out in this far-back beginning of life.
This little discovery further indicates that portions of the older
Palæozoic sea-bottoms were as well stored with a varied sponge life
as those of any part of the modern ocean. I figure[19] a number of
species, remains of all of which may be gathered from a few yards of a
single surface at Little Metis. The multitude of interesting details
embodied in all this it is impossible to enter into here, but may be
judged of from the forms reproduced. These examples tend to show that
the imperfection of the record may not depend on the record itself, but
on the incompleteness of our work. We must make large allowance for
imperfect collecting, and especially for the too prevalent habit of
remaining content with few and incomplete specimens, and of grudging
the time and labour necessary to explore thoroughly the contents of
special beds, and to work out all the parts of forms found more or less
in fragments.

[17] Additional collections made in 1892 show two or three additional
species, one of them the type of a new and remarkable genus.

[18] 1889, section iv. p. 39.

[19] Frontispiece to chapter.

The point of all this at present is that patient work is needed to fill
up the breaks in our record. A collector passing along the shore at
Metis might have picked up a fragment of a fossil sponge, and recorded
it as a fossil, or possibly described the fragment. This fact alone
would have been valuable, but to make it bear its full fruit it was
necessary to trace the fragment to its source, and then to spend time
and labour in extracting from the stubborn rock the story it had to
tell. Instances of this kind crowd on my memory as coming within my own
experience and observation. It is hopeful to think that the record is
daily becoming less imperfect; it is stimulating to know that so much
is only waiting for investigation. The history never can be absolutely
complete. Practically, to us it is infinite. Yet every series of facts
known may be complete in itself for certain purposes, however many gaps
there may be in the story. Even if we cannot find a continuous series
between the snails of the Coal formation or the sponges of the Quebec
Group and their successors to-day, we can at least see that they are
identical in plan and structure, and can note the differences of detail
which fitted them for their places in the ancient or the modern world.
Nor need we be too discontented if the order of succession, such as
it is, does not exactly square with some theories we may have formed.
Perhaps it may in the end lead us to greater and better truths.

Another subject which merits attention here is the evidence which mere
markings or other indications may sometimes give as to the existence
of unknown creatures, and thus may be as important to us as the
footprints of Friday to Robinson Crusoe. As I have been taking Canadian
examples, I may borrow one here from Mr. Matthew, of St. John, New
Brunswick.

He remarks in one of his papers the manner in which the Trilobites
of the early Cambrian are protected with defensive spines, and asks
against what enemies they were intended to guard. That there were
enemies is further proved by the occurrence of Coprolites or masses
of excrement, oval or cylindrical in form, and containing fragments
of shells of Trilobites, of Pteropods (Hyolithes) and of Lingula.
There must therefore have been marine animals of considerable size,
which preyed on Trilobites. Dr. Hunt and myself have recorded similar
facts from the Upper Cambrian and Cambro-Silurian of the Province of
Quebec. No remains, however, are known of animals which could have
produced such coprolites, except, indeed, some of the larger worms of
the period, and they seem scarcely large enough. In these circumstances
Mr. Matthew falls back on certain curious marks or scratches with
which large surfaces of these old rocks are covered, and which he
names Ctenichnites or "Comb tracks." These markings seem to indicate
the rapid motion of some animal touching the bottom with fins or other
organs; and as we know no fishes in these old rocks, the question
recurs, What could it have been? From the form and character of the
markings Mr. Matthew infers (1) That these animals lived in "schools,"
or were social in their habits; (2) That they had a rapid, direct,
darting motion; (3) That they had three or four (at least) flexible
arms; (4) That these arms were furnished with hooks or spines; (5)
That the creatures swam with an easy motion, so that sometimes the
arms of one side touched the bottom, sometimes those of the other.
These indications point to animals allied to the modern squids or
cuttle-fishes, and as these animals may have had no hard parts capable
of preservation, except their horny beaks, nothing might remain to
indicate their presence except these marks on the bottom. Mr. Matthew
therefore conjectures that there may have been large cuttle-fishes in
the Cambrian. Since, however, these are animals of very high rank in
their class, and are not certainly known to us till a very much later
period, their occurrence in these old rocks would be a very remarkable
and unexpected fact.

A discovery made by Walcott in the Western States since Mr. Matthew's
paper was written, throws fresh light on the question. Remains of
fishes have been found by the former in the Cambro Silurian rocks
nearly as far back as Mr. Matthew's comb-tracks. Besides this, Pander
in Russia has found in these old rocks curious teeth, which he refers
conjecturally to fishes (Conodonts). Why may there not have been in
the Cambrian large fishes having, like the modern sharks, cartilage or
gristle instead of bone--perhaps destitute of scales, and with small
teeth which have not yet been detected. The fin rays of such fishes may
have left the comb tracks, and in support of this I may say that there
are in the Lower Carboniferous of Horton Bluff, in Nova Scotia, very
similar tracks in beds holding many remains of fishes. Whichever view
we adopt we see good evidence that there were in the early Cambrian
animals of higher grade than we have yet dreamt of. Observe, however,
that if we could complete the record in this point it would only give
us higher forms of life at an earlier time, and so push farther back
their possible development from lower forms. I fear, indeed, that I
can hold out little hopes to the evolutionists that a more complete
geological record would help them in any way. It would possibly only
render their position more difficult.

But the saddest of all the possible defects of the geological record
is that it may want the beginning, and be like the Bible of some of
the German historical critics, from which they eliminate as mythical
everything before the time of the later Hebrew kings. Our attention is
forcibly called to this by the condition of the fauna of the earliest
Cambrian rocks. The discoveries in these in Wales, in Norway, and in
America show us that the seas of this early period swarmed with animals
representing all the great types of invertebrate marine life. We have
here highly organized Crustaceans, Worms, Mollusks and other creatures
which show us that in that early age all these distinct forms of life
were as well separated from each other as in later times, that eyes
of different types, jointed limbs with nerves and muscles, and a vast
variety of anatomical contrivances were as highly developed as at any
subsequent time.[20] To a Darwinian evolutionist this means nothing
less than that these creatures must have existed through countless ages
of development from their imagined simple ancestral form or forms how
long it is impossible to guess, since, unless change was more speedy
in the infancy of the earth, the term of ages required must have far
exceeded that from the Cambrian to the Modern. Yet, to represent all
this we have absolutely nothing except Eozoon in its solitary grandeur,
and a few other forms, possibly of Protozoa and worms. An imaginary
phylogeny of animal life from Monads to Trilobites would be something
as long as the whole geological history. Yet it would be almost wholly
imaginary, for the record of the rocks tells little or nothing. In face
of such an imperfection as this, geologists should surely be humble,
and make confession of ignorance to any extent that may be desired. Yet
we may at least, with all humility and self-abasement, ask our critics
how they know that this great blank really exists, and whether it may
not be possible that the swarming life of the early Cambrian may, after
all, have appeared suddenly on the stage in some way as yet unknown to
us and to them.

[20] Walcott and Matthew record more than 160 species of 67 genera,
including Sponges, Zoophytes, Echinoderms, Brachiopods, Bivalve and
Univalve shellfishes, Trilobites and other Crustaceans from the Lower
Cambrian of the United States of America and Canada alone; and these
are but a portion of the inhabitants of the early Cambrian seas. There
is a rich Scandinavian fauna of the same early date, and in England and
Wales, Sailer, Hicks and Lapworth have described many fossils of the
basal Cambrian. From year to year, also, discoveries of fossil remains
are being made, both in America and Europe, in beds of older date than
those previously known to be fossiliferous. At present, however, these
remains are still few and imperfectly known, and it is not in all
cases certain whether the beds in which they occur are pre-Cambrian or
belong to the lowest members of that great system. It is unfortunate
that so many of the strata between the Laurentian and the Cambrian seem
to be of a character little likely to contain fossils; being littoral
deposits produced in times of much physical disturbance. Yet there must
have been contemporaneous beds of a different character, which may yet
be discovered.

  References:--"Fossil Sponges from the Quebec Group of Little Metis,
    Lower St. Lawrence": _Transactions Royal Society of Canada_,
    1890. "Rèsumè of the Carboniferous Land Shells of North America":
    _American Journal of Science_, 1880. "Burrows and Tracks of
    Invertebrate Animals": _Journal Geological Society of London_,
    1890. "Notes on the Pleistocene of Canada": _Canadian Naturalist_,
    1876. "Air-breathers of the Coal Period ": _Ibid._, 1863.




                 _THE HISTORY OF THE NORTH ATLANTIC._

                      DEDICATED TO THE MEMORY OF

                    PROF. JOHN PHILLIPS, OF OXFORD,

             One of the most able, earnest, and genial of

                          English Geologists;

         and of other Eminent Scientific Men, now passed away,

                         who supported him as

             President of the British Association, at its

                    Meeting in Birmingham, in 1865.


Distribution of Land and Water--Causes of Irregularities of the
Surface Crust and Interior--Position of Continents--Past History of the
Atlantic--Its Relations to Life--Its Future

[Illustration: Map of the North Atlantic, showing depths from 4,000
fathoms upward (after the Challenger Survey).]




CHAPTER IV.

_THE HISTORY OF THE NORTH ATLANTIC._


I had the pleasure of being present at the meeting of the British
Association at Birmingham, in 1865: a meeting attended by an unusually
large number of eminent geologists, under the presidency of my friend
Phillips. I had the further pleasure of being his successor at the
meeting in the same place, in 1886; and the subject of this chapter
is that to which I directed the attention of the Association in my
Presidential address. I fear it is a feeble and imperfect utterance
compared with that which might have been given forth by any of the
great men present in 1865, and who have since left us, could they have
spoken with the added knowledge of the intervening twenty years.

The geological history of the Atlantic appeared to be a suitable
subject for a trans-Atlantic president, and to a Society which had
vindicated its claim to be British in the widest sense by holding a
meeting in Canada, while it was also meditating a visit to Australia--a
visit not yet accomplished, but in which it may now meet with a worthy
daughter in the Australian Association formed since the meeting of
1886. The subject is also one carrying our thoughts very far back in
geological time, and connecting itself with some of the latest and most
important discussions and discoveries in the science of the earth,
furnishing, indeed, too many salient points to be profitably occupied
in a single chapter.

If we imagine an observer contemplating the earth from a convenient
distance in space, and scrutinizing its features as it rolls
before him, we may suppose him to be struck with the fact that
eleven-sixteenths of its surface are covered with water, and that the
land is so unequally distributed that from one point of view he would
see a hemisphere almost exclusively oceanic, while nearly the whole of
the dry land is gathered in the opposite hemisphere. He might observe
that large portions of the great oceanic areas of the Pacific and
Antarctic Oceans are dotted with islands--like a shallow pool with
stones rising above its surface--as if the general depth were small
in comparison with the area. Other portions of these oceans he might
infer, from the colour of the water and the absence of islands, cover
deep depressions in the earth's surface. He might also notice that a
mass or belt of land surrounds each pole, and that the northern ring
sends off to the southward three vast tongues of land and of mountain
chains, terminating respectively in South America, South Africa, and
Australia, towards which feebler and insular processes are given off
by the antarctic continental mass. This, as some geographers have
observed,[21] gives a rudely three-ribbed aspect to the earth, though
two of the ribs are crowded together, and form the Eurasian mass or
double continent, while the third is isolated in the single continent
of America. He might also observe that the northern girdle is cut
across, so that the Atlantic opens by a wide space into the Arctic Sea,
while the Pacific is contracted toward the north, but confluent with
the Antarctic Ocean. The Atlantic is also relatively deeper and less
cumbered with islands than the Pacific, which has the highest ridges
near its shores, constituting what some visitors to the Pacific coast
of America have not inaptly called the "back of the world," while the
wider slopes face the narrower ocean. The Pacific and Atlantic, though
both depressions or flattenings of the earth, are, as we shall find,
different in age, character, and conditions; and the Atlantic, though
the smaller, is the older, and, from the geological point of view, in
some respects, the more important of the two; while, by virtue of its
lower borders and gentler slope, it is, though the smaller basin, the
recipient of the greater rivers, and of a proportionately great amount
of the drainage of the land.[22]

[21] Dana, "Manual of Geology," introductory part. Green, "Vestiges of
a Molten Globe," has summed up these facts.

[22] Mr. Mellard Reade, in two Presidential addresses before the
Geological Society of Liverpool, has illustrated this point and its
geological consequences.

If our imaginary observer had the means of knowing anything of the
rock formations of the continents, he would notice that those bounding
the North Atlantic are, in general, of great age some belonging to
the Laurentian system. On the other hand, he would see that many of
the mountain ranges along the Pacific are comparatively new, and that
modern igneous action occurs in connection with them. Thus he might see
in the Atlantic, though comparatively narrow, a more ancient feature of
the earth's surface; while the Pacific belongs to more modern times.
But he would note, in connection with this, that the oldest rocks of
the great continental masses are mostly toward their northern ends;
and that the borders of the northern ring of land, and certain ridges
extending southward from it, constitute the most ancient and permanent
elevations of the earth's crust, though now greatly surpassed by
mountains of more recent age nearer the equator, so that the continents
of the northern hemisphere seem to have grown progressively from north
to south.

If the attention of our observer were directed to more modern
processes, he might notice that while the antarctic continent freely
discharges its burden of ice to the ocean north of it, the arctic ice
has fewer outlets, and that it mainly discharges itself through the
North Atlantic, where also the great mass of Greenland stands as a huge
condenser and cooler, unexampled elsewhere in the world, throwing
every spring an immense quantity of ice into the North Atlantic, and
more especially into its western part. On the other hand, he might
learn from the driftage of weed and the colour of the water, that the
present great continuous extension and form of the American continent
tend to throw northward a powerful branch of the equatorial current,
which, revolving around the North Atlantic, counteracts the great flow
of ice which otherwise would condemn it to a perpetual winter.

Further, such an observer would not fail to notice that the ridges
which lie along the edges of the oceans and the ebullitions of igneous
matter which proceed, or have proceeded from them, are consequences
of the settling downward of the great oceanic depressions, a settling
ever intensified by their receiving more and more of deposit on their
surfaces; and that this squeezing upward of the borders of these
depressions into folds has been followed or alternated with elevations
and depressions without any such folding, and proceeding from other
causes. On the whole, it would be apparent that these actions are more
vigorous now at the margins of the Pacific area, while the Atlantic is
backed by very old foldings, or by plains and slopes from which it has,
so to speak, dried away without any internal movement. Thus it would
appear that the Pacific is the great centre of earth-movement, while
the Atlantic trench is the more potent regulator of temperature, and
the ocean most likely to be severely affected in this respect by small
changes of its neighbouring land. Last of all, an observer, such as I
have supposed, would see that the oceans are the producers of moisture
and the conveyors of heat to the northern regions of the world, and
that in this respect and in the immense condensation and delivery of
ice at its north end, the Atlantic is by far the more active, though
the smaller of the two.

So much could be learned by an extra-mundane observer; but unless he
had also enjoyed opportunities of studying the rocks of the earth in
detail and close at hand, or had been favoured by some mundane friend
with a perusal of "Lyell's Elements," or "Dana's Manual," he would not
be able to appreciate as we can the changes which the Atlantic has seen
in geological time, and in which it has been a main factor. Nor could
he learn from such superficial observation certain secrets of the deep
sea, which have been unveiled by the sounding lead, the inequalities of
the ocean basin, its few profound depths, like inverted mountains or
table-lands, its vast nearly flat abyssmal floor, and the sudden rise
of this to the hundred fathom line, forming a terrace or shelf around
the sides of the continents. These features, roughly represented in the
map prefixed, he would be unable to perceive.

Before leaving this broad survey, we may make one further remark. An
observer, looking at the earth from without, would notice that the
margins of the Atlantic and the main lines of direction of its mountain
chains are north-east and south-west, and north-west and south-east, as
if some early causes had determined the occurrence of elevations along
great circles of the earth's surface tangent to the polar circles.

We are invited by the preceding general glance at the surface of the
earth to ask certain questions respecting the Atlantic, (1) What has
at first determined its position and form? (2) What changes has it
experienced in the lapse of geological time? (3) What relations have
these changes borne to the development of life on the land and in the
water? (4) What is its probable future?

Before attempting to answer these questions, which I shall not take
up formally in succession, but rather in connection with each other,
it is necessary to state, as briefly as possible, certain general
conclusions respecting the interior of the earth. It is popularly
supposed that we know nothing of this beyond a superficial crust
perhaps averaging 50,000 to 100,000 feet in thickness. It is true we
have no means of exploration in the earth's interior, but the conjoined
labours of physicists have now proceeded sufficiently far to throw
much inferential light on the subject, and to enable us to make some
general affirmations with certainty; and these it is the more necessary
to state distinctly, since they are often treated as mere subjects of
speculation and fruitless discussion.

(1) Since the dawn of geological science, it has been evident that the
crust on which we live must be supported on a plastic or partially
liquid mass of heated rock, approximately uniform in quality under
the whole of its area. This is a legitimate conclusion from the
wide distribution of volcanic phenomena, and from the fact that the
ejections of volcanoes, while locally of various kinds, are similar in
every part of the world. It led to the old idea of a fluid interior of
the earth, but this seems now generally abandoned, and this interior
heated and plastic layer is regarded as merely an under-crust, resting
on a solid nucleus.[23]

[23] I do not propose to express any definite opinion as to this
question, as either conclusion will satisfy the demands of geology. It
would seem, however, that astronomers now admit a slight periodical
deformation of the crust. See Lord Kelvin's Anniversary Address to
Royal Society, 1892.

(2) We have reason to believe, as the result of astronomical
investigations,[24] that, notwithstanding the plasticity or liquidity
of the under-crust, the mass of the earth--its nucleus as we may call
it--is practically solid and of great density and hardness. Thus we
have the apparent paradox of a solid yet fluid earth; solid in its
astronomical relations, liquid or plastic for the purposes of volcanic
action and superficial movements.

[24] Hopkins, Mallet, Lord Kelvin, and Prof. G. H. Darwin maintain
the solidity and rigidity of the earth on astronomical grounds; but
different conclusions have been reached by Fisher, Hennesey, Delaunay,
and Airy. In America, Hunt, Barnard and Crosby, Button, Le Conte and
Wadsworth have discussed these questions. Bonney has suggested that a
mass may be slowly mobile under long-continued pressure, while rigid
with reference to more sudden movements.

(3) The plastic sub-crust is not in a state of dry igneous fusion, but
in that condition of aqueo-igneous or hydrothermic fusion which arises
from the action of heat on moist substances, and which may either
be regarded as a fusion or as a species of solution at a very high
temperature. This we learn from the phenomena of volcanic action, and
from the composition of the volcanic and plutonic rocks, as well as
from such chemical experiments as those of Daubrée, and of Tilden, and
Shenstone.[25] It follows that water or steam, as well as rocky matter,
may be ejected from the under-crust.

[25] _Phil. Trans._, 1884. Also Crosby in _Proc. Boston Soc. Nat.
Hist._, 1883.

(4) The interior sub-crust is not perfectly homogeneous, but may be
roughly divided into two layers or magmas, as they have been called;
an upper, highly silicious or acidic, of low specific gravity and
light-coloured, and corresponding to such kinds of plutonic and
volcanic rocks as granite and trachyte; and a lower, less silicious
or more basic, more dense, and more highly charged with iron, and
corresponding to such igneous rocks as the dolerites, basalts, and
kindred lavas. It is interesting here to note that this conclusion,
elaborated by Durocher and Von Waltershausen, and usually connected
with their names, appears to have been first announced by John
Phillips, in his "Geological Manual," and as a mere common sense
deduction from the observed phenomena of volcanic action and the
probable results of the gradual cooling of the earth. It receives
striking confirmation from the observed succession of acidic and basic
volcanic rocks of all geological periods and in all localities. It
would even seem, from recent spectroscopic investigations of Lockyer,
that there is evidence of a similar succession of magmas in the
heavenly bodies, and the discovery by Nordenskiöld of native iron in
Greenland basalts, affords a probability that the inner magma is in
part metallic, and possibly, that vast masses of unoxidised metals
exist in the central portion of the earth.

(5) Where rents or fissures form in the upper crust, the material of
the lower crust is forced upward by the pressure of the less supported
portions of the former, giving rise to volcanic phenomena either of
an explosive or quiet character, as may be determined by contact with
water. The underlying material may also be carried to the surface by
the agency of heated water, producing those quiet discharges which Hunt
has named crenitic. It is to be observed here that explosive volcanic
phenomena, and the formation of cones, are, as Prestwich has well
remarked, characteristic of an old and thickened crust; quiet ejection
from fissures and hydro-thermal action may have been more common in
earlier periods and with a thinner over-crust This is an important
consideration with reference to those earlier ages referred to in
chapter second.

(6) The contraction of the earth's interior by cooling and by the
emission of material from below the over-crust, has caused this crust
to press downward, and therefore laterally, and so to effect great
bends, folds, and plications; and these, modified subsequently by
surface denudation, and the piling of sediments on portions of the
crust, constitute mountain chains and continental plateaus. As Hall
long ago pointed out,[26] such lines of folding have been produced more
especially where thick sediments had been laid down on the sea-bottom,
and where, in consequence, internal expansion of the crust had occurred
from heating below. Thus we have here another apparent paradox, namely,
that the elevations of the earth's crust occur in the places where the
greatest burden of detritus has been laid down upon it, and where,
consequently, the crust has been softened and depressed. We must
beware, in this connection, of exaggerated notions of the extent of
contraction and of crumpling required to form mountains. Bonney has
well shown, in lectures delivered at the London Institution, that an
amount of contraction, almost inappreciable in comparison with the
diameter of the earth, would be sufficient; and that, as the greatest
mountain chains are less than 1/600th of the earth's radius in height,
they would, on an artificial globe a foot in diameter, be no more
important than the slight inequalities that might result from the
paper gores overlapping each other at the edges. This thinness of the
crushed crust agrees with the deductions of physical science as to
the shallowness of the superficial layer of compression in a cooling
globe. It is perhaps not more than five miles in thickness. A singular
proof of this is seen by the extension of straight cracks filled with
volcanic rock in the Laurentian districts of Canada.[27] The beds of
gneiss and associated rocks are folded and crumpled in a most complex
manner, yet they are crossed by these faults, as a crack in a board
may tear a sheet of paper or a thin veneer glued on it. We thus see
that the crumpled Laurentian crust was very thin, while the uncrushed
sub-crust determined the line of fracture.

[26] Hall (American Association Address, 1857, subsequently
republished, with additions, as "Contributions to the Geological
History of the American Continent"), Mallet, Rogers, Dana, La Conte,
etc.

[27] As, for instance, the great dyke running nearly in a straight line
from near St. Jerome along the Ottawa to Templeton, on the Ottawa, and
beyond, a distance of more than a hundred miles.

(7) The crushing and sliding of the over-crust implied in these
movements raise some serious questions of a physical character. One
of these relates to the rapidity or slowness of such movements,
and the consequent degree of intensity of the heat developed, as a
possible cause of metamorphism of rocks. Another has reference to
the possibility of changes in the equilibrium of the earth itself,
as resulting from local collapse and ridging. These questions in
connection with the present dissociation of the axis of rotation
from the magnetic poles, and with changes of climate, have attracted
some attention,[28] and probably deserve further consideration on the
part of physicists. In so far as geological evidence is concerned, it
would seem that the general association of crumpling with metamorphism
indicates a certain rapidity in the process of mountain-making, and
consequent development of heat; and the arrangement of the older rocks
around the Arctic basin forbids us from assuming any extensive movement
of the axis of rotation, though it does not exclude changes to a
limited extent.

[28] See recent papers of Oldham and Fisher, in _Geological Magazine_,
and _Philosophical Magazine_, July, 1886. Also Péroche, "Revol.
Polaires." Paris, 1886.

(8) It appears from the above that mountains and continental elevations
may be of three kinds, (_a_) They may consist of material thrown out
of volcanic rents, like earth out of a mole burrow. Mountains like
Vesuvius and Ætna are of this kind. (_b_) They may be parts of wide
ridges or chains variously cut and modified by rains and rivers. The
Lebanon and the Catskill Mountains are cases in point, (_c_) They may
be lines of crumpling by lateral pressure. The greatest mountains,
like the Cordillera, the Alps, and the Appalachians are of this kind,
and such mountains may represent lateral pressure occurring at various
times, and whose results have been greatly modified subsequently.

I wish to formulate these principles as distinctly as possible, and as
the result of all the long series of observations, calculations, and
discussions since the time of Werner and Hutton, and in which a vast
number of able physicists and naturalists have borne a part, because
they may be considered as certain deductions from our actual knowledge,
and because they lie at the foundation of a rational physical geology.

We may roughly popularise these deductions by comparing the earth to a
drupe or stone-fruit, such as a plum or peach somewhat dried up. It
has a large and intensely hard stone and kernel, a thin pulp made up
of two layers, an inner, more dense and dark-coloured, and an outer,
less dense and lighter-coloured. These constitute the under-crust. On
the outside it has a thin membrane or over-crust. In the process of
drying it has slightly shrunk, so as to produce ridges and hollows
of the outer crust, and this outer crust has cracked in some places,
allowing portions of the pulp to ooze out--in some of them its lower
dark substance, in others, its upper and lighter material. The analogy
extends no farther, for there is nothing in our withered fruit to
represent the oceans occupying the lower parts of the surface, or the
deposits which they have laid down.

Here a most important feature demands attention. The rain, the streams,
and the sea are constantly cutting down the land and depositing it in
the bed of the waters. Thus weight is taken from the land, and added
to the sea bed. Geological facts, such as the great thickness of the
coal measures, in which we find thousands of feet of sediment, all of
which must have been deposited in shallow water, and the accumulation
of hundreds of feet of superficial material in deltas at the mouth
of great rivers, show that the crust of the earth is so mobile as to
yield downward to every pressure, however slight.[29] It may do this
slowly and gradually, or by jumps from time to time; and this yielding
necessarily tends to squeeze up the edges of the depressed portions
into ridges, and to cause lateral movement and ejection of volcanic
matter at intervals.

[29] Starkie Gardiner, _Nature_, December, 1889.

Keeping in view these general conclusions, let us now turn to their
bearing on the origin and history of the North Atlantic.

Though the Atlantic is a deep ocean, its basin does not constitute so
much a depression of the crust of the earth as a flattening of it, and
this, as recent soundings have shown, with a slight ridge or elevation
along its middle, and banks or terraces fringing the edges, so that its
form is not so much that of a basin as that of a shallow elongated
plate with its middle a little raised. Its true margins are composed
of portions of the over-crust folded, overlapped and crushed, as if by
lateral pressure emanating from the sea itself. We cannot, for example,
look at a geological map of America without perceiving that the
Appalachian ridges, which intervene between the Atlantic and the St.
Lawrence valley, have been driven bodily back by a force acting from
the east, and that they have resisted this pressure only where, as in
the Gulf of St. Lawrence and the Catskill region of New York, they have
been protected by outlying masses of very old rocks, as, for example,
by that of the island of Newfoundland and that of the Adirondack
Mountains. The admirable work begun by my friend and fellow-student,
Professor James Nicol, followed up by Professor Lapworth, and now,
after long controversy, fully confirmed by the recent observations
of the Geological Survey of Scotland, has shown the most intense
action of the same kind on the east side of the ocean in the Scottish
highlands; and the more widely distributed Eozoic and other old rocks
of Scandinavia may be appealed to in further evidence of this.[30]

[30] Address to Geological Section, Brit. Assoc., by Prof. Judd,
Aberdeen Meeting, 1885. According to Rogers, the crumpling of the
Appalachians has reduced a breadth of 158 miles to about 60. Geikie,
Address, Geological Society, 1891-2.

If we now inquire as to the cause of the Atlantic depression, we must
go back to the time when the areas occupied by the Atlantic and its
bounding coasts were parts of the shoreless sea in which the earliest
gneisses or stratified granites of the Laurentian age were being laid
down in vastly extended beds. These ancient crystalline rocks have been
the subject of much discussion and controversy, to which reference has
been made in a previous chapter.

It will be observed, in regard to these theories, that they do not
suppose that the old gneiss is an ordinary sediment, but that all
regard it as formed in exceptional circumstances, these circumstances
being the absence of land and of subaërial decay of rock, and the
presence wholly or principally of the material of the upper surface
of the recently hardened crust. This being granted, the question
arises, Ought we not to combine the several theories as to the origin
of gneiss, and to believe that the cooling crust has hardened in
successive layers from without inward; that at the same time fissures
were locally discharging igneous matter to the surface; that matter
held in suspension in the ocean and matter held in solution by heated
waters rising from beneath the outer crust were mingling their
materials in the deposits of the primitive ocean?[31] It would seem
that the combination of all these agencies may safely be evoked as
causes of the pre-Atlantic deposits. This is the eclectic position I
have maintained in a previous chapter, and which I hold to be in every
way the most probable.

[31] Hunt, _Transactions Royal Society of Canada_, 1885.

Let us suppose, then, the floor of old ocean covered with a flat
pavement of gneiss, or of that material which is now gneiss, the next
question is, How and when did this original bed become converted into
sea and land? Here we have some things certain, others most debatable.
That the cooling mass, especially if it was sending out volumes of
softened rocky material, either in the form of volcanic ejections or
in that of matter dissolved in heated water, and piling this on the
surface, must soon become too small for its shell, is apparent; but
when and where would the collapse, crushing and wrinkling inevitable
from this cause begin? The date is indicated by the lines of old
mountain chains which traverse the Laurentian districts; but the reason
why is less apparent. The more or less unequal cooling, hardening
and conductive power of the outer crust we may readily assume. The
driftage unequally of water-borne detritus to the south-west by the
bottom currents of the sea is another cause, and, as we shall soon see,
most effective. Still another is the greater cooling and hardening of
the crust in the polar regions, and the tendency to collapse of the
equatorial protuberance from the slackening of the earth's rotation.
Besides these, the internal tides of the earth's substance at the
times of solstice would exert an oblique pulling force on the crust,
which might tend to crack it along diagonal lines. From whichever of
these causes, or the combination of the whole, we know that, within
the Laurentian time, folded portions of the earth's crust began to
rise above the general surface, in broad belts running from north-east
to south-west, and from north-west to south-east, where the older
mountains of Eastern America and Western Europe now stand, and that
the subsidence of the oceanic areas, allowed by this crumpling of
the crust, permitted other areas on both sides of the Atlantic to
form limited table-lands. This was the commencement of a process
repeated again and again in subsequent times, and which began in the
middle Laurentian, when for the first time we find beds of quartzite,
limestone, and iron ore, and graphite beds, indicating that there was
already land and water, and that the sea, and perhaps the land, swarmed
with forms of animal and plant life, unknown, for the most part, now.
Independently of the questions as to the animal nature of Eozoon, I
hold that we know, as certainly as we can know anything inferentially,
the existence of these primitive forms of life. If I were to conjecture
what were these early forms of plant and animal life, still unknown to
us by actual specimens, I would suppose that, just as in the Palæozoic,
the acrogens culminated in gigantic and complex forest trees, so in the
Laurentian, the algæ, the lichens, and the mosses grew to dimensions
and assumed complexity of structure unexampled in later times, and
that, in the sea, the humbler forms of Protozoa and Sea Mosses were the
dominant types, but in gigantic and complex forms. The land of this
period was probably limited, for the most part, to high latitudes, and
its aspect, though more rugged and abrupt, and of greater elevation,
must have been of that character which we still see in the Laurentian
hills. The distribution of this ancient land is indicated by the long
lines of old Laurentian rock extending from the Labrador coast and
the north shore of the St. Lawrence, and along the eastern slopes
of the Appalachians in America, and the like rocks of the Hebrides,
the Western Highlands, and the Scandinavian mountains. A small but
interesting remnant is that in the Malvern Hills, so well described by
Holl. It will be well to note here, and to fix on our minds, that these
ancient ridges of Eastern America and Western Europe have been greatly
denuded and wasted since Laurentian times, and that it is along their
eastern sides that the greatest sedimentary accumulations have been
deposited.

From this time dates the introduction of that dominance of existing
causes which forms the basis of uniformitarianism in geology, and which
had to go on with various and great modifications of detail, through
the successive stages of the geological history, till the land and
water of the northern hemisphere attained to their present complex
structure.

So soon as we have a circumpolar belt or patches of Eozoic[32] land and
ridges running southward from it, we enter on new and more complicated
methods of growth of the continents and seas. Portions of the oldest
crystalline rocks, raised out of the protecting water, were now eroded
by atmospheric agents, and especially by the carbonic acid, then
existing in the atmosphere perhaps more abundantly than at present,
under whose influence the hardest of the gneissic rocks gradually
decay. The arctic lands were subjected, in addition, to the powerful
mechanical force of frost and thaw. Thus every shower of rain and
every swollen stream would carry into the sea the products of the
waste of land, sorting them into fine clays and coarser sands; and the
cold currents which cling to the ocean bottom, now determined in their
courses, not merely by the earth's rotation, but also by the lines of
folding on both sides of the Atlantic, would carry south-westward, and
pile up in marginal banks of great thickness the _débris_ produced
from the rapid waste of the land already existing in the Arctic
regions. The Atlantic, opening widely to the north, and having large
rivers pouring into it, was, especially, the ocean characterised, as
time advanced, by the prevalence of these phenomena. Thus, throughout
the geological history it has happened that, while the middle of the
Atlantic has received merely organic deposits of shells of foraminifera
and similar organisms, and this probably only to a small amount, its
margins have had piled upon them beds of detritus of immense thickness.
Professor Hall, of Albany, was the first geologist who pointed out
the vast cosmic importance of these deposits, and that the mountains
of both sides of the Atlantic owe their origin to these great lines
of deposition, along with the fact, afterwards more fully insisted on
by Rogers, that the portions of the crust which received these masses
of _débris_ became thereby weighted down and softened, and were more
liable than other parts to lateral crushing.

[32] Or Archæan, or pre-Cambrian, if these terms are preferred.

Thus, in the later Eozoic and early Palæozoic times, which succeeded
the first foldings of the oldest Laurentian, great ridges were thrown
up, along the edges of which were beds of limestone, and on their
summits and sides, thick masses of ejected igneous rocks. In the bed
of the central Atlantic there are no such accumulations. It must have
been a flat, or slightly ridged, plate of the ancient gneiss, hard and
resisting, though perhaps with a few cracks, through which igneous
matter welled up, as in Iceland and the Azores in more modern times.
In this condition of things we have causes tending to perpetuate and
extend the distinctions of ocean and continent, mountain and plain,
already begun; and of these we may more especially note the continued
subsidence of the areas of greatest marine deposition. This has long
attracted attention, and affords very convincing evidence of the
connection of sedimentary deposit as a cause with the subsidence of the
crust.[33]

[33] Dutton in _Report of U.S. Geological Survey_, 1891. From facts
stated in this report and in my "Acadian Geology," it is apparent
that in the Western States and in the coal fields of Nova Scotia,
shallow-water deposits have been laid down, up to thicknesses of 10,000
to 20,000 feet in connection with continuous subsidence. See also a
paper by Ricketts in the _Geol. Mag._, 1883.

We are indebted to a French physicist, M. Faye, for an important
suggestion on this subject. It is that the sediment accumulated
along the shores of the ocean presented an obstacle to radiation,
and consequently to cooling of the crust, while the ocean floor,
unprotected and unweighted, and constantly bathed with currents of cold
water having great power of convection of heat, would be more rapidly
cooled, and so would become thicker and stronger. This suggestion
is complementary to the theory of Professor Hall, that the areas of
greatest deposit on the margins of the ocean are necessarily those of
greatest folding and consequent elevation. We have thus a hard, thick,
resisting ocean bottom, which, as it settles down toward the interior,
under the influence of gravity, squeezes upwards and folds and plicates
all the soft sediments deposited on its edges. The Atlantic area is
almost an unbroken cake of this kind. The Pacific area has cracked in
many places, allowing the interior fluid matter to exude in volcanic
ejections.

It may be said that all this supposes a permanent continuance of
the ocean basins, whereas many geologists postulate a mid-Atlantic
continent to give the thick masses of detritus found in the older
formations both in Eastern America and Western Europe, and which thin
off in proceeding into the interior of both continents. I prefer, as
already stated, to consider these belts of sediment as the deposits
of northern currents, and derived from arctic land, and that, like
the great banks off the American coast at the present day, which are
being built up by the present arctic current, they had little to do
with any direct drainage from the adjacent shore. We need not deny,
however, that such ridges of land as existed along the Atlantic margins
were contributing their quota of river-borne material, just as on a
still greater scale the Amazon and Mississippi are doing now, and
this especially on the sides toward the present continental plateaus,
though the greater part must have been derived from the wide tracts
of Laurentian land within the Arctic Circle, or near to it. It is
further obvious that the ordinary reasoning respecting the necessity
of continental areas in the present ocean basins would actually
oblige us to suppose that the whole of the oceans and continents
had repeatedly changed places. This consideration opposes enormous
physical difficulties to any theory of alternations of the oceanic and
continental areas, except locally at their margins.

But the permanence of the Atlantic depression does not exclude the idea
of successive submergences of the continental plateaus and marginal
slopes, alternating with periods of elevation, when the ocean retreated
from the continents and contracted its limits. In this respect the
Atlantic of to-day is much smaller than it was in those times when it
spread widely over the continental plains and slopes, and much larger
than it has been in times of continental elevation. This leads us to
the further consideration that, while the ocean beds have been sinking,
other areas have been better supported, and constitute the continental
plateaus; and that it has been at or near the junctions of these
sinking and rising areas that the thickest deposits of detritus, the
most extensive foldings, and the greatest ejections of volcanic matter
have occurred. There has thus been a permanence of the position of
the continents and oceans throughout geological time, but with many
oscillations of these areas, producing submergences and emergences of
the land. In this way we can reconcile the vast vicissitudes of the
continental areas in different geological periods with that continuity
of development from north to south, and from the interiors to the
margins, which is so marked a feature. We have, for this reason, to
formulate another apparent geological paradox, namely, that while, in
one sense, the continental and oceanic areas are permanent, in another,
they have been in continual movement. Nor does this view exclude
extension of the continental borders or of chains of islands beyond
their present limits, at certain periods; and indeed, the general
principle already stated, that subsidence of the ocean bed has produced
elevation of the land, implies in earlier periods a shallower ocean and
many possibilities as to volcanic islands, and low continental margins
creeping out into the sea; while it is also to be noted that there are,
as already stated, bordering shelves, constituting shallows in the
ocean, which at certain periods have emerged as land.

We are thus compelled, as already stated, to believe in the
contemporaneous existence in all geological periods, except perhaps
the earliest of them, of the three distinct conditions of areas on the
surface of the earth, defined in chapter second oceanic areas of deep
sea, continental plateaus and marginal shelves, and lines of plication
and folding.

In the successive geological periods the continental plateaus, when
submerged, owing to their vast extent of warm and shallow sea, have
been the great theatres of the development of marine life and of
the deposition of organic limestones, and when elevated, they have
furnished the abodes of the noblest land faunas and floras. The
mountain belts, especially in the north, have been the refuge and
stronghold of land life in periods of submergence; and the deep
ocean basins have been the perennial abodes of pelagic and abyssal
creatures and the refuge of multitudes of other marine animals and
plants in times of continental elevation. These general facts are full
of importance with reference to the question of the succession of
formations and of life in the geological history of the earth.

So much space has been occupied with these general views, that it would
be impossible to trace the history of the Atlantic in detail through
the ages of the Palæozoic, Mesozoic, and Tertiary. We may, however,
shortly glance at the changes of the three kinds of surface already
referred to. The bed of the ocean seems to have remained, on the whole,
abyssal; but there were probably periods when those shallow reaches of
the Atlantic which stretch across its most northern portion, and partly
separate it from the Arctic basin, presented connecting coasts or
continuous chains of islands sufficient to permit animals and plants to
pass over.[34] At certain periods also there were, not unlikely, groups
of volcanic islands, like the Azores, in the temperate or tropical
Atlantic. More especially might this be the case in that early time
when it was more like the present Pacific; and the line of the great
volcanic belt of the Mediterranean, the mid-Atlantic banks, the Azores
and the West India Islands point to the possibility of such partial
connections. These were stepping stones, so to speak, over which land
organisms might cross, and some of these may be connected with the
fabulous or pre-historic Atlantis.

[34] It would seem, from Geikie's description of the Faroe Islands,
that they may be a remnant of such connecting land, dating from the
Cretaceous or Eocene period.

In the Palæozoic period, the distinctions already referred to, into
continental plateaus, mountain ridges, and ocean depths, were first
developed, and we find, already, great masses of sediment accumulating
on the seaward sides of the old Laurentian ridges, and internal
deposits thinning away from these ridges over the submerged continental
areas, and presenting dissimilar conditions of sedimentation. It would
seem also that, as Hicks has argued for Europe, and Logan and Hall
for America, this Cambrian age was one of slow subsidence of the land
previously elevated, accompanied with or caused by thick deposits of
detritus along the borders of the subsiding shore, which was probably
covered with the decomposing rock arising from long ages of subaërial
waste.

In the coal formation age its characteristic swampy flats stretched
in some places far into the shallower parts of the ocean.[35] In the
Permian, the great plicated mountain margins were fully developed on
both sides of the Atlantic. In the Jurassic, the American continent
probably extended farther to the sea than at present. In the Wealden
age there was much land to the west and north of Great Britain,
and Professor Bonney has directed attention to the evidence of the
existence of this land as far back as the Trias, while Mr. Starkie
Gardiner has insisted on connecting links to the southward, as
evidenced by fossil plants. So late as the Post-glacial, or early human
period, large tracts, now submerged, formed portions of the continents.
On the other hand, the interior plains of America and Europe were often
submerged. Such submergences are indicated by the great limestones
of the Palæozoic, by the chalk and its representative beds in the
Cretaceous, by the Nummulitic formation in the Eocene, and lastly,
by the great Pleistocene submergence, one of the most remarkable of
all, one in which nearly the whole northern hemisphere participated,
and which was probably separated from the present time by only a few
thousands of years.[36] These submergences and elevations were not
always alike on the two sides of the Atlantic. The Salina period of the
Silurian, for example, and the Jurassic, show continental elevation in
America not shared by Europe. The great subsidences of the Cretaceous
and the Eocene were proportionally deeper and wider on the eastern
continent, and this and the direction of the land being from north to
south, cause more ancient forms of life to survive in America. These
elevations and submergences of the plateaus alternated with the periods
of mountain-making plication, which was going on at intervals, at the
close of the Eozoic, at the beginning of the Cambrian, at the close of
the Siluro-Cambrian, in the Permian, and in Europe and Western America
in the Tertiary. The series of changes, however, affecting all these
areas was of a highly complex character in detail.[37]

[35] I have shown the evidence of this in the remnants of Carboniferous
districts once more extensive on the Atlantic coast of Nova Scotia and
Cape Breton ("Acadian Geology").

[36] The recent surveys of the Falls of Niagara coincide with a great
many evidences to which I have elsewhere referred in proving that the
Pleistocene submergence of America and Europe came to an end not more
than ten thousand years ago, and was itself not of very great duration.
Thus in Pleistocene times the land must have been submerged and
re-elevated in a very rapid manner.

[37] "Acadian Geology."

We may also note a fact which I have long ago insisted on,[38] the
regular pulsation of the continental areas, giving us alternations
in each great system of deep-sea and shallow-water beds, so that
the successive groups of formations may be divided into triplets of
shallow-water, deep-water, and shallow-water strata, alternating in
each period. This law of succession applies more particularly to
the formations of the continental plateaus, rather than to those of
the ocean margins, and it shows that, intervening between the great
movements of plication there were subsidences of those plateaus, or
elevations of the sea bottom, which allowed the waters to spread
themselves over all the inland spaces between the great folded mountain
ranges of the Atlantic borders.

[38] "Acadian Geology."

In referring to the ocean basins we should bear in mind that there are
three of these in the northern hemisphere the Arctic, the Pacific, and
the Atlantic. De Ranee has ably summed up the known facts as to Arctic
geology in a series of articles in _Nature_, from which it appears
that this area presents from without inwards a succession of older and
newer formations from the Eozoic to the Tertiary, and that its extent
must have been greater in former periods than at present, while it
must have enjoyed a comparatively warm climate from the Cambrian to
the Pleistocene period. The relations of its deposits and fossils are
closer with those of the Atlantic than with those of the Pacific, as
might be anticipated from its wider opening into the former. Blandford
has recently remarked on the correspondence of the marginal deposits
around the Pacific and Indian oceans,[39] and Dr. Dawson informs me
that this is equally marked in comparison with the west coast of
America, but these marginal areas have not yet gained much on the
ocean. In the North Atlantic, on the other hand, there is a wide belt
of comparatively modern rocks on both sides, more especially toward the
south and on the American side; but while there appears to be a perfect
correspondence on both sides of the Atlantic, and around the Pacific
respectively, there seems to be less parallelism between the deposits
and forms of life of the two oceans, as compared with each other, and
less correspondence in forms of life, especially in modern times.
Still, in the earlier geological ages, as might have been anticipated
from the imperfect development of the continents, the same forms of
life characterise the whole ocean from Australia to Arctic America, and
indicate a grand unity of Pacific and Atlantic life not equalled in
later times,[40] and which speaks of true contemporaneity rather than
of what has been termed homotaxis or mere likeness of orders.

[39] _Journal of Geological Society_, May, 1886. Blandford's statements
respecting the mechanical deposits of the close of the Palæozoic in
the Indian Ocean, whether these are glacial or not, would seem to show
a correspondence with the Permian conglomerates and earth-movements
of the Atlantic area; but since that time the Atlantic has enjoyed
comparative repose. The Pacific seems to have reproduced the conditions
of the Carboniferous in the Cretaceous age, and seems to have been less
affected by the great changes of the Pleistocene.

[40] Daintree and Etheridge, "Queensland Geology," _Journal Geological
Society_, August, 1872; R. Etheridge, Junior, "Australian Fossils,"
_Trans. Phys. Soc. Edin._, 1880.

We may pause here for a moment to notice some of the effects of
Atlantic growth on modern geography. It has given us rugged and broken
shores, composed of old rocks in the north, and newer formations and
softer features toward the south. It has given us marginal mountain
ridges and internal plateaus on both sides of the sea. It has produced
certain curious and by no means accidental correspondences of the
eastern and western sides. Thus the solid basis on which the British
Islands stand may be compared with Newfoundland and Labrador, the
English Channel with the Gulf of St. Lawrence, the Bay of Biscay with
the Bay of Maine, Spain with the projection of the American land at
Cape Hatteras, the Mediterranean with the Gulf of Mexico. The special
conditions of deposition and plication necessary to these results, and
their bearing on the character and productions of the Atlantic basin,
would require a volume for their detailed elucidation.

Thus far our discussion has been limited almost entirely to physical
causes and effects. If we now turn to the life history of the Atlantic,
we are met at the threshold with the question of climate, not as a
thing fixed and immutable, but as changing from age to age in harmony
with geographical mutations, and producing long cosmic summers and
winters of alternate warmth and refrigeration.

We can scarcely doubt that the close connection of the Atlantic and
Arctic oceans is one factor in those remarkable vicissitudes of climate
experienced by the former, and in which the Pacific area has also
shared in connection with the Antarctic Sea. No geological facts are
indeed at first sight more strange and inexplicable than the changes
of climate in the Atlantic area, even in comparatively modern periods.
We know that in the early Tertiary temperate conditions reigned as
far north as the middle of Greenland, and that in the Pleistocene the
Arctic cold advanced until an almost perennial winter prevailed half
way to the equator. It is no wonder that nearly every cause available
in the heavens and the earth has been invoked to account for these
astounding facts. I shall, I trust, be excused if, neglecting most of
these theoretical views, I venture to invite attention, in connection
with this question, chiefly to the old Lyellian doctrine of the
modification of climate by geographical changes. Let us, at least,
consider how much these are able to account for.

The ocean is a great equalizer of extremes of temperature. It does this
by its great capacity for heat, and by its cooling and heating power
when passing from the solid into the liquid and gaseous states, and the
reverse. It also acts by its mobility, its currents serving to convey
heat to great distances, or to cool the air by the movement of cold
icy waters. The land, on the other hand, cools or warms rapidly, and
can transmit its influence to a distance only by the winds, and the
influence so transmitted is rather in the nature of a disturbing than
of an equalizing cause. It follows that any change in the distribution
of land and water must affect climate, more especially if it changes
the character or course of the ocean currents.

Turning to the Atlantic, in this connection we perceive that its
present condition is peculiar and exceptional. On the one hand it is
widely open to the Arctic Sea and the influence of its cold currents,
and on the other it is supplied with a heating apparatus of enormous
power to give a special elevation of temperature, more particularly to
its eastern coasts. The great equatorial current running across from
Africa is on its northern side embayed in the Gulf of Mexico, as in a
great cauldron, and pouring through the mouth of this in the Bahama
channel, forms the gulf stream, which, widening out like a fan, forms
a vast expanse of warm water, from which the prevailing westerly winds
of the North Atlantic waft a constant supply of heated moist air to
the western coasts of Europe, giving them a much more warm and uniform
climate than that which prevails in similar latitudes in Eastern
America, where the cold Arctic currents hug the shore, and bring down
ice from Baffin's Bay. Now all this might be differently arranged. We
shall find that there were times, when the Isthmus of Panama being
broken through, there was no Gulf Stream, and Norway and England
were reduced to the conditions of Greenland and Labrador, and when
refrigeration was still further increased by subsidence of northern
lands affording freer sweep to the Arctic currents. On the other hand,
there were times when the Gulf of Mexico extended much farther north
than at present, and formed an additional surface of warm water to heat
all the interior of America, as well as the Atlantic. Geographical
changes of these kinds, have probably given us the glacial period in
very recent times, and at an earlier era those warm climates which
permitted temperate vegetation to flourish as far north as Greenland.
These are, however, great topics, which must form the subject of other
chapters.

I am old enough to remember the sensation caused by the delightful
revelations of Edward Forbes respecting the zones of animal life in
the sea, and the vast insight which they gave into the significance of
the work on minute organisms previously done by Ehrenberg, Lonsdale
and Williamson, and into the meaning of fossil remains. A little later
the soundings for the Atlantic cable revealed the chalky foraminiferal
ooze of the abyssal ocean. Still more recently, the wealth of facts
disclosed by the _Challenger_ voyage, which naturalists have scarcely
yet had time to digest, have opened up to us new worlds of deep-sea
life.

The bed of the deep Atlantic is covered, for the most part, by a mud
or ooze, largely made up of the _débris_ of foraminifera and other
minute organisms mixed with fine clay. In the North Atlantic the
Norwegian naturalists call this the Biloculina mud. Farther south, the
_Challenger_ naturalists speak of it as Globigerina ooze. In point of
fact it contains different species of foraminiferal shells, Globigerina
and Orbulina being in some localities dominant, and in others, other
species; and these changes are more apparent in the shallower portions
of the ocean.

On the other hand, there are means for disseminating coarse material
over parts of the ocean beds. There are, in the line of the Arctic
current, on the American coast, great sand banks, and off the coast of
Norway, sand constitutes a considerable part of the bottom material.
Soundings and dredgings off Great Britain, and also off the American
coast, have shown that fragments of stone referable to Arctic lands
are abundantly strewn over the bottom, along certain lines, and the
Antarctic continent, otherwise almost unknown, makes its presence
felt to the dredge by the abundant masses of crystalline rock drifted
far from it to the north. These are not altogether new discoveries.
I had inferred, many years ago, from stones taken up by the hooks of
fishermen on the banks of Newfoundland, that rocky material from the
north is dropped on these banks by the heavy ice which drifts over them
every spring, that these are glaciated, and that after they fall to the
bottom sand is drifted over them with sufficient velocity to polish the
stones, and to erode the shelly coverings of Arctic animals attached
to them.[41] If, then, the Atlantic basin were upheaved into land, we
should see beds of sand, gravel and boulders with clay flats and layers
of marl and limestone. According to the _Challenger_ reports, in the
Antarctic seas S. of 64 there is blue mud, with fragments of rock, in
depths of 1,200 to 2,000 fathoms. The stones, some of them glaciated,
were granite, diorite, amphibolite, mica schist, gneiss and quartzite.
This deposit ceases and gives place to Globigerina ooze and red clay
at 46° to 47° S., but even farther north there is sometimes as much as
49 per cent, of crystalline sand. In the Labrador current a block of
syenite, weighing 400 lbs., was taken up from 1,340 fathoms, and in the
Arctic current, 100 miles from land, was a stony deposit, some stones
being glaciated. Among these were smoky quartz, quartzite, limestone,
dolomite, mica schist, and serpentine; also particles of monoclinic and
triclinic felspar, hornblende, augite, magnetite, mica and glauconite,
the latter, no doubt, formed in the sea bottom, the others drifted from
Eozoic and Palæozoic formations to the north.[42]

[41] "Notes on Post-Pliocene of Canada," 1872.

[42] _General Report, "Challenger" Expedition_.

A remarkable fact in this connection is that the great depths of
the sea are as impassable to the majority of marine animals as the
land itself. According to Murray, while twelve of the _Challenger's_
dredgings, taken in depths greater than 2,000 fathoms, gave 92 species,
mostly new to science, a similar number of dredgings in shallower water
near the land, give no less than 1,000 species. Hence arises another
apparent paradox relating to the distribution of organic beings. While
at first sight it might seem that the chances of wide distribution
are exceptionally great for marine species, this is not so. Except in
the case of those which enjoy a period of free locomotion when young,
or are floating and pelagic, the deep ocean sets bounds to their
migrations. On the other hand, the spores of cryptogamic plants may
be carried for vast distances by the wind, and the growth of volcanic
islands may effect connections which, though only temporary, may afford
opportunity for land animals and plants to pass over.

With reference to the transmission of living beings across the
Atlantic, we have before us the remarkable fact that from the Cambrian
age onwards there were, on the two sides of the ocean, many species
of invertebrate animals which were either identical or so closely
allied as to be possibly varietal forms, indicating probably the
shallowness of the ocean in these periods. In like manner, the early
plants of the Upper Silurian, Devonian, and Carboniferous present many
identical species; but this identity is less marked in more modern
times. Even in the latter, however, there are remarkable connections
between the floras of oceanic islands and the continents. Thus the
Bermudas, altogether recent islands, have been stocked by the agency
chiefly of the ocean currents and of birds, with nearly 150 species
of continental plants; and the facts collected by Helmsley as to
the present facilities of transmission, along with the evidence
afforded by older oceanic islands which have been receiving animal and
vegetable colonists for longer periods, go far to show that, time being
given, the sea actually affords facilities for the migration of the
inhabitants of the land, comparable with those of continuous continents.

In so far as plants are concerned, it is to be observed that the early
forests were largely composed of cryptogamous plants, and the spores of
these in modern times have proved capable of transmission from great
distances. In considering this, we cannot fail to conclude, that the
union of simple cryptogamous fructification with arboreal stems of
high complexity, so well illustrated by Dr. Williamson, had a direct
relation to the necessity for a rapid and wide distribution of these
ancient trees. It seems also certain that some spores, as, for example,
those of the Rhizocarps,[43] a type of vegetation abundant in the
Palæozoic, and certain kinds of seeds, as those named _Æthoetesta_
and _Pachytheca_, were fitted for flotation. Further, the periods of
Arctic warmth permitted the passage around the northern belt of many
temperate species of plants, just as now happens with the Arctic flora;
and when these were displaced by colder periods, they marched southward
along both sides of the sea on the mountain chains.

[43] See paper by the author on Palæozoic Rhizocarps, _Chicago Trans._,
1886.

The same remark applies to northern forms of marine invertebrates,
which are much more widely distributed in longitude than those farther
south. The late Mr. Gywn Jeffreys, in one of his latest communications
on this subject, stated that 54 per cent, of the shallow-water mollusks
of New England and Canada are also European, and of the deep-sea forms,
30 out of 35; these last, of course, enjoying greater facilities for
migration than those which have to travel slowly along the shallows of
the coast in order to cross the ocean and settle themselves on both
sides. Many of these animals, like the common mussel and sand clam,
are old settlers which came over in the Pleistocene period, or even
earlier. Others, like the common periwinkle, seem to have been slowly
extending themselves in modern times, perhaps even by the agency of
man. The older immigrants may possibly have taken advantage of lines of
coast now submerged, or of warm periods, when they could creep round
the Arctic shores. Mr. Herbert Carpenter and other naturalists employed
on the _Challenger_ collections have made similar statements respecting
other marine invertebrates, as, for instance, the Echinoderms, of
which the deep-sea crinoids present many common species, and my own
collections prove that many of the shallow-water forms are common.
Dall and Whiteaves[44] have shown that some mollusks and Echinoderms
are common even to the Atlantic and Pacific coasts of North America;
a remarkable fact, testifying at once to the fixity of these species
and to the manner in which they have been able to take advantage of
geographical changes. Some of the species of whelks common to the Gulf
of St. Lawrence and the Pacific are animals which have no special
locomotive powers, even when young, but they are northern forms not
proceeding far south, so that they may have passed through the Arctic
seas. In this connection it is well to remark that many species of
animals have powers of locomotion in youth which they lose when adult,
and that others may have special means of transit. I once found at
Gaspé a specimen of the Pacific species of Coronula, or whale-barnacle,
the _C. reginæ_ of Darwin, attached to a whale taken in the Gulf of
St. Lawrence, and which had possibly succeeded in making that passage
around the north of America which so many navigators have essayed in
vain.[45]

[44] Dall, _Report on Alaska_; Whiteaves, _Trans. R. S. C._

[45] I am informed, however, that the Coronula is found also in the
Biscayan whales.

But it is to be remarked that while many plants and marine
invertebrates are common to the two sides of the Atlantic, it is
different with land animals, and especially vertebrates. I do not know
that any palæozoic insects or land snails or millipedes of Europe and
America are specifically identical, and of the numerous species of
batrachians of the Carboniferous and reptiles of the Mesozoic, all seem
to be distinct on the two sides. The same appears to be the case with
the Tertiary mammals, until in the later stages of that great period we
find such genera as the horse, the camel, and the elephant appearing
on the two sides of the Atlantic; but even then the species seem
different, except in the case of a few northern forms.

Some of the longer-lived mollusks of the Atlantic furnish suggestions
which remarkably illustrate the biological aspect of these questions.
Our familiar friend the oyster is one of these. The first-known oysters
appear in the Carboniferous in Belgium and in the United States of
America. In the Carboniferous and Permian they are few and small, and
they do not culminate till the Cretaceous, in which there are no less
than ninety-one so-called species in America alone; but some of the
largest known species are found in the Eocene. The oyster, though an
inhabitant of shallow water, and very limitedly locomotive when young,
has survived all the changes since the Carboniferous age, and has
spread itself over the whole northern hemisphere,[46] though a warm
water rather than Arctic type.

[46] White, _Report U. S. Geol. Survey_, 1882-3.

I have collected fossil oysters in the Cretaceous clays of the coulées
of Western Canada, in the Lias shales of England, in the Eocene and
the Cretaceous beds of the Alps, of Egypt, of the Red Sea coast, of
Judea, and the heights of Lebanon. Everywhere and in all formations
they present forms which are so variable and yet so similar that one
might suppose all the so-called species to be mere varieties. Did the
oyster originate separately on the two sides of the Atlantic, or did it
cross over so promptly that its appearance seems to be identical on the
two sides? Are all the oysters of a common ancestry, or did the causes,
whatever they were, which introduced the oyster in the Carboniferous
act over again in later periods? Who can tell? This is one of the
cases where causation and development--the two scientific factors
which constitute the basis of what is called evolution--cannot easily
be isolated. I would recommend to those biologists who discuss these
questions to devote themselves to the oyster. This familiar mollusk has
successfully, pursued its course, and has overcome all its enemies,
from the flat-toothed selachians of the Carboniferous to the oyster
dredges of the present day, has varied almost indefinitely, and yet has
continued to be an oyster, unless, indeed, it may at certain portions
of its career have temporarily assumed the guise of a Gryphæa or an
Exogyra. The history of such an animal deserves to be traced with care,
and much curious information respecting it will be found in the report
which I have cited in the note.

But in these respects the oyster, is merely an example of many forms.
Similar considerations apply to all those Pliocene and Pleistocene
mollusks which are found in the raised sea bottoms of Norway and
Scotland, on the top of Moel Tryfaen, in Wales, and at similar great
heights on the hills of America, many of which can be traced back to
early Tertiary times, and can be found to have extended themselves
over all the seas of the northern hemisphere. They apply in like
manner to the ferns, the conifers, and the broad-leaved trees, many
of which we can now trace without specific change to the Eocene and
Cretaceous. They all show that the forms of living things are more
stable than the lands and seas in which they live. If we were to adopt
some of the modern ideas of evolution, we might cut the Gordian knot
by supposing that, as like causes produce like effects, these types
of life have originated more than once in geological time, and need
not be genetically connected with each other. But while evolutionists
repudiate such an application of their doctrine, however natural and
rational, it would seem that nature still more strongly repudiates it,
and will not allow us to assume more than one origin for one species.
Thus the great question of geographical distribution remains in all its
force; and, by still another of our geological paradoxes, mountains
become ephemeral things in comparison with the delicate herbage which
covers them, and seas are in their present extent but of yesterday,
when compared with the minute and feeble organisms that creep on their
sands or swim in their waters.

The question remains: Has the Atlantic achieved its destiny and
finished its course, or are there other changes in store for it in
the future? The earth's crust is now thicker and stronger than ever
before, and its great ribs of crushed and folded rock are more firm and
rigid than in any previous period. The stupendous volcanic phenomena
manifested in Mesozoic and early Tertiary times along the borders
of the Atlantic have apparently died out. These facts are in so far
guarantees of permanence. On the other hand, it is known that movements
of elevation, along with local depression, are in progress in the
Arctic regions, and a great weight of new sediment is being deposited
along the borders of the Atlantic, especially on its western side;
and this is not improbably connected with the earthquake shocks and
slight movements of depression which have occurred in North America.
It is possible that these slight and secular movements may go on
uninterruptedly, or with occasional paroxysmal disturbances, until
considerable changes are produced.

It is possible, on the other hand, that after the long period of
quiescence which has elapsed, there may be a new settlement of the
ocean bed, accompanied with foldings of the crust, especially on the
western side of the Atlantic, and possibly with renewed volcanic
activity on its eastern margin. In either case, a long time relatively
to our limited human chronology may intervene before the occurrence
of any marked change. On the whole, the experience of the past would
lead us to expect movements and eruptive discharges in the Pacific
rather than in the Atlantic area. It is therefore not unlikely that the
Atlantic may remain undisturbed, unless secondarily and indirectly,
until after the Pacific area shall have attained to a greater degree of
quiescence than at present. But this subject is one too much involved
in uncertainty to warrant us in following it farther.

In the meantime the Atlantic is to us a practically permanent ocean,
varying only in its tides, its currents, and its winds, which science
has already reduced to definite laws, so that we can use if we cannot
regulate them. It is ours to take advantage of this precious time of
quietude, and to extend the blessings of science and of our Christian
civilisation from shore to shore, until there shall be no more sea,
not in the sense of that final drying-up of old ocean to which some
physicists look forward, but in the higher sense of its ceasing to be
the emblem of unrest and disturbance, and the cause of isolation.

I must now close this chapter with a short statement of some general
truths which I have had in view in directing attention to the
geological development of the Atlantic. We cannot, I think, consider
the topics to which I have referred without perceiving that the history
of ocean and continent is an example of progressive design, quite as
much as that of living beings. Nor can we fail to see that, while
in some important directions we have penetrated the great secret of
nature, in reference to the general plan and structure of the earth
and its waters, and the changes through which they have passed, we
have still very much to learn, and perhaps quite as much to unlearn,
and that the future holds out to us and to our successors higher,
grander, and clearer conceptions than those to which we have yet
attained. The vastness and the might of ocean and the manner in which
it cherishes the feeblest and most fragile beings, alike speak to us of
Him who holds it in the hollow of His hand, and gave to it of old its
boundaries and its laws; but its teaching ascends to a higher tone when
we consider its origin and history, and the manner in which it has been
made to build up continents and mountain-chains, and, at the same time,
to nourish and sustain the teeming life of sea and land.

  References:--Presidential Address to the British Association for the
    Advancement of Science, Birmingham, 1886. "Geology of Nova Scotia,
    New Brunswick, and Prince Edward Island." Fourth Edition, London,
    1891.




                          _THE DAWN OF LIFE._


                      DEDICATED TO THE MEMORY OF

                         SIR WILLIAM E. LOGAN,

            The unwearied Explorer of the Laurentian Rocks,

                            and the Founder

                                of the

                     Geological Survey of Canada.


What Are the Oldest Rocks, and where?--Conditions of their
Formation--Indications of Life--What its probable Nature

[Illustration: Nature-print of Eozoon, showing laminated, acervuline,
and fragmental portions.

This is printed from an electrotype taken from an etched slab of
Eozoon, and not touched with a graver except to remedy some accidental
flaws in the plate. The diagonal white line marks the course of a
calcite vein.]




CHAPTER V.

_THE DAWN OF LIFE_

Do we know the first animal? Can we name it, explain its structure,
and state its relations to its successors? Can we do this by inference
from the succeeding types of being; and if so, do our anticipations
agree with any actual reality disinterred from the earth's crust? If we
could do this, either by inference or actual discovery, how strange it
would be to know that we had before us even the remains of the first
creature that could feel or will, and could place itself in vital
relation with the great powers of inanimate nature. If we believe in a
Creator, we shall feel it a solemn thing to have access to the first
creature into which He breathed the breath of life. If we hold that all
things have been evolved from collision of dead forces, then the first
molecules of matter which took upon themselves the responsibility of
living, and, aiming at the enjoyment of happiness, subjected themselves
to the dread alternatives of pain and mortality, must surely evoke
from us that filial reverence which we owe to the authors of our own
being; if they do not involuntarily draw forth even a superstitious
adoration. The veneration of the old Egyptian for his sacred animals
would be a comparatively reasonable idolatry, if we could imagine any
of these animals to have been the first that emerged from the domain
of dead matter, and the first link in a reproductive chain of being
that produced all the population of the world. Independently of any
such hypotheses, all students of nature must regard with surpassing
interest the first bright streaks of light that break on the long reign
of primeval night and death, and presage the busy day of teeming animal
existence.

No wonder, then, that geologists have long and earnestly groped in
the rocky archives of the earth in search of some record of this
patriarch of the animal kingdom. But after long and patient research
there still remained a large residuum of the oldest rocks destitute
of all traces of living beings, and designated by the hopeless name
"Azoic,"--the formations destitute of remains of life, the stony records
of a lifeless world. So the matter remained till the Laurentian rocks
of Canada, lying at the base of these old Azoic formations, afforded
forms believed to be of organic origin. The discovery was hailed
with enthusiasm by those who had been prepared by previous study to
receive it. It was regarded with feeble and not very intelligent faith
by many more, and was met with half-concealed or open scepticism by
others. It produced a copious crop of descriptive and controversial
literature, but for the most part technical, and confined to scientific
transactions and periodicals, read by very few except specialists.
Thus, few even of geological and biological students have clear ideas
of the real nature and mode of occurrence of these ancient organisms,
if organisms they are, and of their relations to better known forms of
life; while the crudest and most inaccurate ideas have been current in
lectures and popular books, and even in text-books.

This state of things has long ceased to be desirable in the interests
of science, since the settlement of the questions raised is in the
highest degree important to the history of life. We cannot, it is
true, affirm that Eozoon is in reality the long-sought prototype of
animal existence; but it was for us, at least until recently, the last
organic foothold, on which we can poise ourselves, that we may look
back into the abyss of the infinite past, and forward to the long
and varied progress of life in geological time. Now, however, we
have announcements to be referred to in the sequel of other organisms
discovered in the so-called Archæan rocks; and it is not improbable
that these will rapidly increase. The discussion of its claims has
also raised questions and introduced new points, certain, if properly
entered into, to be fruitful of interesting and valuable thought, and
to form a good introduction to the history of life in connection with
geology.

As we descend in depth and time into the earth's crust, after passing
through nearly all the vast series of strata constituting the monuments
of geological history, we at length reach the Eozoic or Laurentian
rocks,[47] deepest and oldest of all the formations known to the
geologist, and more thoroughly altered or metamorphosed by heat and
heated moisture than any others. These rocks, at one time known as
Azoic, being supposed destitute of all remains of living things, but
now more properly Eozoic, are those in which the first bright streaks
of the dawn of life make their appearance.

[47] Otherwise named "Archæan."

The name Laurentian, given originally to the Canadian development of
these rocks by Sir William Logan, but now applied to them throughout
the world, is derived from a range of hills lying north of the
St. Lawrence valley, which the old French geographers named the
Laurentides. In these hills the harder rocks of this old formation rise
to considerable heights, and form the highlands separating the St.
Lawrence valley from the great plain fronting on Hudson's Bay and the
Arctic Sea. At first sight it may seem strange that rocks so ancient
should anywhere appear at the surface, especially on the tops of
hills; but this is a necessary result of the mode of formation of our
continents. The most ancient sediments deposited in the sea were those
first elevated into land, and first altered and hardened. Upheaved in
the folding of the earth's crust into high and rugged ridges, they have
either remained uncovered with newer sediments, or have had such as
were deposited on them washed away; and being of a hard and resisting
nature, they have remained comparatively unworn when rocks much more
modern have been swept off by denuding agencies.[48]

[48] This implies the permanence of continents in their main features,
a doctrine the writer has maintained for thirty years, and which is
discussed elsewhere.

But the exposure of the old Laurentian skeleton of mother earth is not
confined to the Laurentide Hills, though these have given the formation
its name. The same ancient rocks appear in the Adirondack mountains
of New York, and in the patches which at lower levels protrude from
beneath the newer formations along the American coast from Newfoundland
to Maryland. The older gneisses of Norway, Sweden, and the Hebrides,
of Bavaria and Bohemia, of Egypt, Abyssinia and Arabia, belong to the
same age, and it is not unlikely that similar rocks in many other parts
of the old continent will be found to be of as great antiquity. In no
part of the world, however, are the Laurentian rocks more extensively
distributed or better known than in Canada; and to this as the grandest
and most instructive development of them we may more especially devote
our attention.

The Laurentian rocks, associated with another series only a little
younger, the Huronian, form a great belt of broken and hilly country,
extending from Labrador across the north of Canada to Lake Superior,
and thence bending northward to the Arctic Sea. Everywhere on the lower
St. Lawrence they appear as ranges of billowy rounded ridges on the
north side of the river, and as viewed from the water or the southern
shore, especially when sunset deepens their tints to blue and violet,
they present a grand and massive appearance, which, in the eye of
the geologist, who knows that they have endured the battles and the
storms of time longer than any other mountains, invests them with the
dignity which their mere elevation would fail to give. (Fig. 1.) In the
isolated mass of the Adirondacks, south of the Canadian frontier, they
rise to a still greater elevation, and form an imposing mountain group,
almost equal in height to their somewhat more modern rivals, the White
Mountains, which face them on the opposite side of Lake Champlain.

The grandeur of the old Laurentian ranges is, however, best displayed
where they have been cut across by the great transverse gorge of the
Saguenay, and where the magnificent precipices, known as Capes Trinity
and Eternity, look down from their elevation of 1,500 feet on the
fiord, which at their feet is more than 100 fathoms deep. The name
Eternity applied to such a mass is geologically scarcely a misnomer,
for it dates back to the very dawn of geological time, and is of hoar
antiquity in comparison with such upstart ranges as the Andes and the
Alps. (See Frontispiece.)

On a nearer acquaintance, the Laurentian country appears as a broken
and hilly upland and highland district, clad in its pristine state
with magnificent forests, but affording few attractions to the
agriculturist, except in the valleys, which follow the lines of its
softer beds, while it is a favourite region for the angler, the
hunter, and the lumberman. Many of the Laurentian townships of Canada
are, however, already extensively settled, and the traveller may pass
through a succession of more or less cultivated valleys, bounded by
rocks or wooded hills and crags, and diversified by running streams and
romantic lakes and ponds, constituting a country always picturesque
and often beautiful, and rearing a strong and hardy population. To
the geologist it presents in the main immensely thick beds of gneiss,
bedded diorite and quartzite, and similar crystalline rocks, contorted
in the most remarkable manner, so that if they could be flattened out
they would serve as a skin much too large for mother earth in her
present state, so much has she shrunk and wrinkled since those youthful
days when the Laurentian rocks were her outer covering.

[Illustration: Fig. 1.--Laurentian Hills opposite Kamouraska, Lower St.
Lawrence. The islands in front are Cambro-Silurian.]

[Illustration: Fig. 2.--Section from Petite Nation Seigniory to St.
Jerome (60 miles). After Sir W. E. Logan.

(_a b_) Upper Laurentian. (_c_) Fourth Gneiss. (_d´_) Third Limestone.
(_d_) Third Gneiss. (_e´_) Second Limestone. (_x_) Porphyry. (_y_)
Granite.]

I cannot describe such rocks, but their names, as given in the section,
Fig. 2, will tell something to those who have any knowledge of the
older crystalline materials of the earth's crust. To those who have
not, I would advise a visit to some cliff on the lower St. Lawrence,
or the Hebridean coasts, or the shore of Norway, where the old hard
crystalline and gnarled beds present their sharp edges to the ever
raging sea, and show their endless alternations of various kinds
and colours of strata, often diversified with veins and nests of
crystalline minerals. He who has seen and studied such a section of
Laurentian rock cannot forget it.

The elaborate stratigraphical work of Sir William Logan has proved
that these old crystalline rocks are bedded or stratified, and that
they must have been deposited in succession by some process of aqueous
action. They have, however, through geological ages of vast duration
been subjected to pressure and chemical action, which have, as stated
in a previous chapter, much modified their structure, while it is also
certain that they must have differed originally from the sands, clays
and other materials laid down in the sea in later times.

It is interesting to notice here that the Laurentian rocks thus
interpreted show that the oldest known portions of our continents were
formed in the waters. They are oceanic sediments deposited perhaps when
there was no dry land, or very little, and that little unknown to us,
except in so far as its _débris_ may have entered into the composition
of the Laurentian rocks themselves. Thus the earliest condition of the
earth known to the geologist is one in which old ocean was already
dominant on its surface; and any previous condition when the surface
was heated, and the water constituted an abyss of vapours enveloping
its surface, or any still earlier condition in which the earth was
gaseous or vaporous, is a matter of mere inference, not of actual
observation. The formless and void chaos is a deduction of chemical and
physical principles, not a fact observed by the geologist. Still we
know, from the great dykes and masses of igneous or molten rock which
traverse the Laurentian beds, that even at that early period there
were deep-seated fires beneath the crust; and it is quite possible
that volcanic agencies then manifested themselves, not only with quite
as great intensity, but also in the same manner, as at subsequent
times. It is thus not unlikely that much of the land undergoing
waste in the earlier Laurentian time was of the same nature with
recent volcanic ejections, and that it formed groups of islands in an
otherwise boundless ocean.

However this may be, the distribution and extent of these
pre-Laurentian lands is, and probably ever must be, unknown to us; for
it was only after the Laurentian rocks had been deposited, and after
the shrinkage and deformation of the earth's crust in subsequent times
had bent and contorted them, that the foundations of the continents
were laid. The rude sketch map of America given in Fig. 3 will show
this, and will also show that the old Laurentian mountains mark out the
future form of the American continent.

[Illustration: Fig. 3.--The Laurentian Nucleus of the American
Continent, after Dana.]

Some subsequent writers have, it is true, treated with disbelief
Logan's great discoveries; but no competent geologist who has traced
the regularly bedded limestones and other rocks of his original fields
of investigation could continue to doubt. On this subject I may quote
from my friend Dr. Bonney, one of the most judicious of the builders
who undertake hypothetically to lay the foundation stones of the
earth's crust for our enlightenment in these later days. In an address
delivered at the Bath meeting of the British Association he says:--

"The first deposits on the solidified crust of the earth would
obviously be igneous. As water condensed from the atmosphere on the
cooling surface, aqueous waste or condensation would begin, and
stratified deposits in the ocean would become possible in addition
to detrital volcanic material. But at that time the crust itself, and
even later stratified deposits would often be kept for a considerable
period at a high temperature. Thus, not only rocks of igneous origin
(including volcanic ashes) would predominate in the lowest foundation
stones, but also secondary changes would occur more readily, and even
the sediments or precipitates might be greatly modified. As time went
on, true sediments would predominate over volcanic materials, and these
would be less and less affected by chemical changes, and would more and
more retain their original character. Thus we should expect that as we
retraced the earth's course through 'the corridor of time' we should
arrive at rocks which, though crystalline in structure, were evidently
in great part sedimentary in origin, and should behind them find rocks
of more coarsely crystalline texture and more dubious character, which,
however, probably were in part of a like origin, and should at last
reach coarsely crystalline rocks, in which, while occasional sediments
would be possible, the majority were originally igneous, though
modified at a very early period of their history. This corresponds with
what we find in nature, when we apply, cautiously and tentatively,
the principles of interpretation which guide us in stratigraphical
geology."[49]

[49] "The Foundation Stones of the Earth's Crust," 1888. The extract is
slightly condensed.

This expresses very well the general result of the patient
stratigraphical and chemical labours of Logan and Sterry Hunt, as
applied to the vast areas of old crystalline stratified rocks in
Canada, and which I have had abundant opportunities to verify on the
ground. Under the undoubted Cambrian beds of Canada lies the Huronian,
a formation largely of hardened sands, clays and gravels, now forming
sandstones, slates, and conglomerates, but with great beds of igneous
or volcanic rock, and hardened and altered ash beds. Under this, in
the upper portion of the Laurentian, we have regularly bedded rocks,
quartzites, limestones, and quartzose, and graphitic and ferruginous
gneisses, evidently altered aqueous sediments; but intermixed with
other rocks, as diorites and hornblendic gneisses, which are plainly
of different origin. Lastly, on the bottom of all, we have nothing but
coarse crystalline gneiss, representing perhaps the earliest crust
of a cooling globe. Broadly, and without entering into details or
theoretical views as to the precise causes of formation and alteration
of these rocks, this is the structure of the Archæan or Eozoic system
in Canada; and it corresponds with that of the basement or foundation
stones of our continents in every country that I have been able to
visit, or of which I have trustworthy accounts.

In the lower or fundamental gneiss, and in the igneous beds which
succeed it, we need not look for any indications of living beings; but
so soon as the sea began to deposit sand, mud, limestone, iron ore,
carbon, there would be nothing to exclude the presence of some forms of
marine life; while, as land must have already existed, there would be a
possibility of life on it. This, therefore, we may begin to look for so
soon as we ascend to those beds of the Laurentian in which limestone,
iron ore, and quartzite appear; and it is precisely at this point in
the Laurentian of Canada that indications of life are supposed to have
been found. Certain it is that if we cannot find some sign of life in
the Laurentian or Huronian, we shall have to face as the beginnings of
life the swarms of marine creatures that appear all over the globe at
once, in the early Cambrian age.

Is it likely, then, that such rocks should afford any traces of living
beings, even if any such existed when they were formed? Geologists who
had traced organic remains back to the lowest Cambrian might hope for
such remains, even in the Laurentian; but they long looked in vain
for their actual discovery. Still, as astronomers have suspected the
existence of unknown planets from observing perturbations not accounted
for, and as voyagers have suspected the approach to unknown regions
by the appearance of floating wood or stray land birds, anticipations
of such discoveries have been entertained and expressed from time to
time. Lyell, Dana, and Dr. Sterry Hunt more especially have committed
themselves to such speculations. The reasons assigned may be stated
thus:--

Assuming the Laurentian rocks to be altered sediments, they must, from
their great extent, have been deposited in the ocean; and if there had
been no living creatures in the waters, we have no reason to believe
that they would have consisted of anything more than such sandy and
muddy _débris_ as may be washed away from wasting rocks originally of
igneous origin. But the Laurentian beds contain other materials than
these. No formations of any geological age include thicker or more
extensive limestones. One of the beds measured by the officers of the
Geological Survey is stated to be 1,500 feet in thickness, another is
1,250 feet thick, and a third, 750 feet; making an aggregate of 3,500
feet.[50] These beds may be traced, with more or less interruption,
for hundreds of miles. Whatever the origin of such limestones, it
is plain that they indicate causes equal in extent, and comparable
in power and duration, with those which have produced the greatest
limestones of the later geological periods. Now, in later formations,
limestone is usually an organic rock, accumulated by the slow gathering
from the sea-water, or its plants, of calcareous matter, by corals,
foraminifera, or shell fish, and the deposition of their skeletons,
either entire or in fragments, in the sea bottom. The most friable
chalk and the most crystalline limestones have alike been formed in
this way. We know of no reason why it should be different in the
Laurentian period. When, therefore, we find great and conformable
beds of limestone, such as those described by Sir William Logan in
the Laurentian of Canada, we naturally imagine a quiet sea bottom, in
which multitudes of animals of humble organization were accumulating
limestone in their hard parts, and depositing this in gradually
increasing thickness from age to age. Any attempts to account otherwise
for these thick and greatly extended beds, regularly interstratified
with other deposits, have so far been failures, and have arisen either
from a want of comprehension of the nature and magnitude of the
appearances to be explained, or from the error of mistaking the true
bedded limestones for veins of calcareous spar.

[50] Logan: "Geology of Canada," p. 45.

The Laurentian rocks contain great quantities of carbon, in the form of
graphite or plumbago. This does not occur wholly, or even principally,
in veins or fissures, but in the substance of the limestone and gneiss,
and in regular layers. So abundant is it, that I have estimated the
amount of carbon in one division of the Lower Laurentian of the Ottawa
district at an aggregate thickness of not less than twenty to thirty
feet, an amount comparable with that in the true coal formation itself.
Now we know of no agency existing in present or in past geological
time capable of deoxidizing carbonic acid, and fixing its carbon as
an ingredient in permanent rocks, except vegetable life. Unless,
therefore, we suppose that there existed in the Laurentian age a vast
abundance of vegetation, either in the sea or on the land, we have no
means of explaining the Laurentian graphite.

The Laurentian formation contains great beds of oxide of iron,
sometimes seventy feet in thickness. Here, again, we have an evidence
of organic action; for it is the deoxidizing power of vegetable matter
which has in all the later formations been the efficient cause in
producing bedded deposits of iron. This is the case in modern bog and
lake ores, in the clay ironstones of the coal measures, and apparently,
also, in the great ore beds of the Silurian rocks. May not similar
causes have been at work in the Laurentian period?

Any one of these reasons might, in itself, be held insufficient to
prove so great and, at first sight, unlikely a conclusion as that of
the existence of abundant animal and vegetable life in the Laurentian;
but the concurrence of the whole in a series of deposits unquestionably
marine, forms a chain of evidence so powerful that it might command
belief even if no fragment of any organic and living form or structure
had ever been recognised in these ancient rocks.

Such was the condition of the matter until the existence of supposed
organic remains was announced by Sir W. Logan, at the American
Association for the Advancement of Science, in Springfield, in 1859;
and we may now proceed to narrate the manner of this discovery, and how
it has been followed up.

Before doing so, however, let us visit Eozoon in one of its haunts
among the Laurentian Hills. One of the most noted repositories of
its remains is the great Grenville band of limestone; and one of the
most fruitful localities is at a place called Côte St. Pierre on this
band. Leaving the train at Papineauville, we find ourselves on the
Laurentian rocks, and pass over one of the great bands of gneiss for
about twelve miles, to the village of St. André Avelin. On the road we
see on either hand abrupt rocky ridges, partially clad with forest, and
sometimes showing on their flanks the stratification of the gneiss in
very distinct parallel bands, often contorted, as if the rocks, when
soft, had been wrung as a washerwoman wrings clothes. Between the hills
are little irregular valleys, from which the wheat and oats have just
been reaped, and the tall Indian corn and yellow pumpkins are still
standing in the fields. Where not cultivated, the land is covered with
a rich second growth of young maples, birches, and oaks, among which
still stand the stumps and tall scathed trunks of enormous pines, which
constituted the original forest. Half way we cross the Nation River,
a stream nearly as large as the Tweed, flowing placidly between wooded
banks, which are mirrored in its surface; but in the distance we can
hear the roar of its rapids, dreaded by lumberers in their spring
drivings of logs. Arrived at St. André, we find a wider valley, the
indication of the change to the limestone band, and along this, with
the gneiss hills still in view on either hand, and often encroaching
on the road, we drive for five miles more to Côte St. Pierre. At this
place the lowest depression of the valley is occupied by a little pond,
and, hard by, the limestone, protected by a ridge of gneiss, rises in
an abrupt wooded bank by the roadside, and a little farther forms a
bare white promontory, projecting into the fields.

[Illustration: Fig. 4.--Attitude of Limestone at St. Pierre, (_a_)
Gneiss band in the Limestone, (_b_) Limestone with Eozoon. (_c_)
Diorite and Gneiss.]

The limestone is here highly inclined and much contorted, and in all
the excavations a thickness of about 100 feet of it may be exposed.
It is white and crystalline, varying much, however, in coarseness in
different bands. It is in some layers pure and white; in others it
is traversed by many grey layers of gneissose and other matter, or
by irregular bands and nodules of pyroxene and serpentine, and it
contains subordinate beds of dolomite. In one layer only, and this
but a few feet thick, does the Eozoon occur in abundance in a perfect
state, though fragments and imperfectly preserved specimens abound
in other parts of the bed. It is a great mistake to suppose that it
constitutes whole beds of rock in an uninterrupted mass. Its true mode
of occurrence is best seen on the weathered surfaces of the rock, where
the serpentinous specimens project in irregular patches of various
sizes, sometimes twisted by the contortion of the beds, but often too
small to suffer in this way. On such surfaces the projecting patches
of the fossil exhibit laminæ of serpentine so precisely like the
_Stromatoporæ_ of the Silurian rocks, that any collector would pounce
upon them at once as fossils. In some places these small weathered
specimens can be easily chipped off from the crumbling surface of the
limestone; and it is perhaps to be regretted that they have not been
more extensively shown to palæontologists, with the cut slices which
to many of them are so problematical. One of the original specimens,
brought from the Calumet, and now in the Museum of the Geological
Survey of Canada, was of this kind, and much finer specimens from
Côte St. Pierre are now in that collection and in my own. A very fine
example is represented on the plate facing this chapter, which is taken
from an original photograph. In some of the layers are found other
and more minute vesicular forms, which may be organic, and these,
together with fragmental remains, as ingredients in the limestone, will
be discussed in the sequel. We may merely notice here that the most
abundant layer of Eozoon at this place occurs near the base of the
great limestone band, and that the upper layers, in so far as seen,
are less rich in it. Further, there is no necessary connection between
Eozoon and the occurrence of serpentine, for there are many layers
full of bands and lenticular masses of that mineral without any Eozoon
except occasional fragments, while the fossil is sometimes partially
mineralised with pyroxene, dolomite, or common limestone. The section
in Fig. 4 will serve to show the attitude of the limestone at this
place, while the more general section, Fig. 2, page 101, taken from
Sir William Logan, shows its relation to the other Laurentian rocks.

We may now notice the manner in which the specimens discovered in this
and other places in the Laurentian country came to be regarded as
organic.

It is a trite remark that most discoveries are made, not by one
person, but by the joint exertions of many, and that they have their
preparations made often long before they actually appear. For this
reason I may be excused here for introducing some personal details in
relation to the discovery of Eozoon, and which are indeed necessary in
vindication of its claims. In this case the stable foundations were
laid years before the discovery of Eozoon, by the careful surveys made
by Sir William Logan and his assistants, and the chemical examination
of the rocks and minerals by Dr. Sterry Hunt, which established beyond
all doubt the great age and truly bedded character of the Laurentian
rocks and their probable original nature, and the changes which they
have experienced in the course of geological time. On the other hand,
Dr. Carpenter and others in England were examining the structure of the
shells of the humbler inhabitants of the modern ocean, and the manner
in which the pores of their skeletons become infiltrated with mineral
matter when deposited in the sea bottom. These laborious and apparently
dissimilar branches of scientific inquiry were destined to be united by
a series of happy discoveries, made not fortuitously but by painstaking
and intelligent observers. The discovery of the most ancient fossil
was thus not the chance picking up of a rare and curious specimen. It
was not likely to be found in this way; and if so found, it would have
remained unnoticed and of no scientific value, but for the accumulated
stores of zoological and palæontological knowledge, and the surveys
previously made, whereby the age and distribution of the Laurentian
rocks and the chemical conditions of their deposition and metamorphism
were ascertained.

The first specimens of Eozoon ever procured, in so far as known, were
collected at Burgess, in Ontario, by a veteran Canadian mineralogist,
Dr. Wilson, of Perth, and were sent to Sir William Logan as mineral
specimens. Their chief interest at that time lay in the fact that
certain laminæ of a dark green mineral present in the specimens were
found, on analysis by Dr. Hunt, to be composed of a new hydrous
silicate, allied to serpentine, and which he named loganite. The form
of this mineral was not suspected to be of organic origin. Some years
after, in 1858, other specimens, differently mineralized with the
minerals serpentine and pyroxene, were found by Mr. J. McMullen, an
explorer in the service of the Geological Survey, in the limestone
of the Grand Calumet on the River Ottawa. These seem to have at once
struck Sir W. E. Logan as resembling the Silurian fossils known as
_Stromatopora_, and he showed them to Mr. Billings, the palæontologist
of the survey, and to the writer, with this suggestion, confirming
it with the sagacious consideration that inasmuch as the Ottawa and
Burgess specimens were mineralized by different substances, yet were
alike in form, there was little probability that they were merely
mineral or concretionary. Mr. Billings was naturally unwilling to risk
his reputation in affirming the organic nature of such specimens;
and my own suggestion was that they should be sliced, and examined
microscopically, and that if fossils, as they presented merely
concentric laminæ and no cells, they would probably prove to be
protozoa rather than corals. A few slices were accordingly made, but
no definite structure could be detected. Nevertheless, Sir William
Logan took some of the specimens to the meeting of the American
Association at Springfield, in 1859, and exhibited them as possibly
Laurentian fossils; but the announcement was evidently received with
some incredulity. In 1862 they were exhibited by Sir William to some
geological friends in London, but he remarks that "few seemed disposed
to believe in their organic character, with the exception of my friend,
Professor Ramsay." In 1863 the general Report of the Geological Survey,
summing up its work to that time, was published, under the name of the
"Geology of Canada," and in this, at page 49, will be found two figures
of one of the Calumet specimens, here reproduced, and which, though
unaccompanied with any specific name or technical description, were
referred to as probably Laurentian fossils. (Figs. 5 and 6.)

[Illustration: Fig. 1.--Small specimen of Eozoon, weathered out,
natural size, from a photograph.

Fig. 2.--Canal System of Eozoon injected with serpentine (magnified).

Fig. 3.--Very fine Canals and Tubuli filled with Dolomite (magnified).

(From Micro-photographs.)]

[Illustration: Fig. 5.--Weathered Specimen of Eozoon from the Calumet.
(Collected by Mr. McMullen.)]

[Illustration: Fig. 6.--Cross Section of the Specimen represented in
Fig. 8. The dark parts are the laminæ of calcareous matter converging
to the outer surface.]

About this time Dr. Hunt happened to mention to me, in connection with
a paper on the mineralization of fossils which he was preparing, that
he proposed to notice the mode of preservation of certain fossil woods
and other things with which I was familiar, and that he would show me
the paper in proof, in order that I might give him any suggestions that
occurred to me. On reading it, I observed, among other things, that
he alluded to the supposed Laurentian fossils, under the impression
that the organic part was represented by the serpentine or loganite,
and that the calcareous matter was the filling of the chambers. I took
exception to this, stating that though in the slices I had examined no
structure was apparent, still my impression was that the calcareous
matter was the fossil, and the serpentine or loganite the filling. He
said--"In that case, would it not be well to re-examine the specimens,
and try to discover which view is correct?" He mentioned, at the same
time, that Sir William had recently shown him some new and beautiful
specimens collected by Mr. Lowe, one of the explorers on the staff of
the Survey, from a third locality, at Grenville, on the Ottawa. It
was supposed that these might throw further light on the subject; and
accordingly Dr. Hunt suggested to Sir William to have additional slices
of these new specimens made by Mr. Weston, of the Survey, whose skill
as a preparer of these and other fossils has often done good service to
science. A few days thereafter some slices were sent to me, and were
at once put under the microscope. I was delighted to find in one of
the first specimens examined a beautiful group of tubuli penetrating
one of the calcite layers. Here was evidence, not only that the
calcite layers represented the true skeleton of the fossil, but also
of its affinities with the foraminifera, whose tubulated supplemental
skeleton, as described and figured by Dr. Carpenter, and represented
in specimens in my collection, presented by him, was apparently of the
same type with that preserved in the canals of these ancient fossils.
Fig. 7 is an accurate representation of the group of canals first
detected by me.

[Illustration: Fig. 7.--Group of Canals in the Supplemental Skeleton of
Eozoon. Taken from the specimen in which they were first recognised.
Magnified. (Camera tracing by Mr. H. S. Smith.)]

On showing the structures discovered to Sir William Logan, he entered
into the matter with enthusiasm, and had a great number of slices, as
well as decalcified specimens, prepared, which were placed in my hands
for examination.

Feeling that the discovery was most important, but that it would be
met with determined scepticism by a great many geologists, I was
not content with examining the typical specimens of Eozoon, but had
slices prepared of every variety of Laurentian limestone, of altered
limestones from the Primordial and Silurian, and of serpentine
marbles of all the varieties furnished by our collections. They were
examined with ordinary and polarized light, and with every variety of
illumination. They were also examined as decalcified specimens, after
the carbonate of lime had been removed by acids. An extensive series of
notes and camera tracings were made of all the appearances observed;
and of some of the more important structures beautiful drawings
were executed by the late Mr. H. S. Smith, the then palæontological
draughtsman of the Survey. The result of the whole investigation was a
firm conviction that the structure was organic and foraminiferal, and
that it could be distinguished from any merely mineral or crystalline
forms occurring in these or other limestones.

At this stage of the matter, and after exhibiting to Sir William all
the characteristic appearances, in comparison with such concretionary,
dendritic and crystalline structures as most resembled them, and also
with the structure of recent and fossil Foraminifera, I suggested
that the further prosecution of the matter should be handed over to
Mr. Billings, as palæontologist of the Survey. I was engaged in other
researches, not connected with the Survey or with this particular
department, and I knew that no little labour must be devoted to the
work and to its publication, and that some controversy might be
expected. Mr. Billings, however, with his characteristic caution and
modesty, declined. His hands were full of other work. He had not given
any special attention to the microscopic appearances of Foraminifera or
of mineral substances. It was finally arranged that I should prepare
a description of the fossil, which Sir William would take to London,
along with the more important specimens, and a detailed list stating
all the structures observed in each. Sir William was to submit the
manuscript and specimens to Dr. Carpenter, or, failing him, to Prof.
T. Rupert Jones, in the hope that these eminent authorities would
confirm my conclusions, and bring forward new facts which I might
have overlooked or been ignorant of. Sir William saw both gentlemen,
who gave their testimony in favour of the organic and foraminiferal
character of the specimens; and Dr. Carpenter, in particular, gave much
attention to the subject, and worked out more in detail many of the
finer structures, besides contributing valuable suggestions as to the
probable affinities of the supposed fossil.

Dr. Carpenter thus contributed in a very important manner to the
perfecting of the investigations begun in Canada, and on him fell the
greater part of their illustration and defence,[51] in so far as Great
Britain is concerned.

[51] In _Quarterly Journal of Geological Society_, vol. xxii.; _Proc.
Royal Society_, vol. xv.; _Intellectual Observer_, 1865. _Annals and
Magazine of Natural History_, 1874; and other papers and notices.

The immediate result was a composite paper in the _Proceedings of the
Geological Society_, by Sir W. E. Logan, Dr. Carpenter, Dr. Hunt, and
myself, in which the geology, palæontology and mineralogy of _Eozoon
Canadense_ and its containing rocks were first given to the world.[52]
It cannot be wondered at that when geologists and palæontologists
were thus required to believe in the existence of organic remains in
rocks regarded as altogether Azoic and hopelessly barren of fossils,
and to carry back the dawn of life as far before those Primordial
rocks, which were supposed to contain its first traces, as these are
before the middle period of the earth's life history, some hesitation
should be felt. Further, the accurate appreciation of the evidence
for such a fossil as Eozoon required an amount of knowledge of
minerals, of the more humble types of animals, and of the conditions
of mineralization of organic remains, possessed by few even of
professional geologists. Thus Eozoon has met with some scepticism and
not a little opposition,--though the latter has been weaker than we
might have expected when we consider the startling character of the
facts adduced, and has mostly come from men imperfectly informed.

[52] _Journal Geological Society_, February, 1865.

But what is Eozoon, if really of animal origin? The shortest answer
to this question is, that this ancient fossil is supposed to be the
skeleton of a creature belonging to that simple and humbly organized
group of animals which are known by the name Protozoa. If we take as a
familiar example of these the gelatinous and microscopic creature found
in stagnant ponds, and known as the _Amœba_[53] (Fig. 8), it will form
a convenient starting-point. Viewed under a low power, it appears as
a little patch of jelly, irregular in form, and constantly changing
its aspect as it moves, by the extension of parts of its body into
finger-like processes or pseudopods which serve as extempore limbs.
When moving on the surface of a slip of glass under the microscope,
it seems, as it were, to flow along rather than creep, and its body
appears to be of a semi-fluid consistency. It may be taken as an
example of the least complex forms of animal life known to us, and is
often spoken of by naturalists as if it were merely a little particle
of living and scarcely organized jelly or protoplasm. When minutely
examined, however, it will not be found so simple as it at first sight
appears. Its outer layer is clear and transparent, and more dense than
the inner mass, which seems granular. It has at one end a curious
vesicle which can be seen gradually to expand and become filled with
a clear drop of liquid, and then suddenly to contract and expel the
contained fluid through a series of pores in the adjacent part of
the outer wall. This is the so-called pulsating vesicle, and is an
organ both of circulation and excretion. In another part of the body
may be seen the nucleus, which is a little cell capable, at certain
times, of producing by its division new individuals. Food, when taken
in through the wall of the body, forms little pellets, which become
surrounded by a digestive liquid exuded from the enclosing mass into
rounded cavities or extemporised stomachs. Minute granules are seen
to circulate in the gelatinous interior, and may be substitutes for
blood-cells, and the outer layer of the body is capable of protrusion
in any direction into long processes, which are very mobile, and used
for locomotion and prehension. Further, this creature, though destitute
of most of the parts which we are accustomed to regard as proper to
animals, seems to exercise volition, and to show the same appetites
and passions with animals of higher type. I have watched one of these
animalcules endeavouring to swallow a one-celled plant as long as its
own body; evidently hungry and eager to devour the tempting morsel, it
stretched itself to its full extent, trying to envelope the object of
its desire. It failed again and again; but renewed the attempt, until
at length, convinced of its hopelessness, it flung itself away as if in
disappointment, and made off in search of something more manageable.
With the Amœba are found other types of equally simple Protozoa, but
somewhat differently organized. One of these, _Actinophrys_ (Fig. 9),
has the body globular and unchanging in form, the outer wall of greater
thickness; the pulsating vesicle like a blister on the surface, and the
pseudopods long and thread-like. Its habits are similar to those of the
Amœba, and I introduce it to show the variations of form and structure
possible even among these simple creatures.

[53] The alternating animal, alluding to its change of form.

[Illustration: Fig. 8. Amœba. Fig. 9. Actinophrys.

From original sketches.]

The Amœba and Actinophrys are fresh-water animals, and are destitute
of any shell or covering. But in the sea there exist swarms of similar
creatures, equally simple in organization, but gifted with the power of
secreting around their soft bodies beautiful little shells or crusts of
carbonate of lime, having one orifice, and often in addition multitudes
of microscopic pores through which the soft gelatinous matter can ooze,
and form outside finger-like or thread-like extensions for collecting
food. In some cases the shell consists of a single cavity only, but in
most, after one cell is completed, others are added, forming a series
of cells or chambers communicating with each other, and often arranged
spirally or otherwise in most beautiful and symmetrical forms. Some of
these creatures, usually named Foraminifera, are locomotive, others
sessile and attached. Most of them are microscopic, but some grow by
multiplication of chambers till they are a quarter of an inch or more
in breadth.

The original skeleton or primary cell wall of most of these creatures
is seen under the microscope to be perforated with innumerable pores,
and is extremely thin. When, however, owing to the increased size of
the shell, or other wants of the creature, it is necessary to give
strength, this is done by adding new portions of carbonate of lime to
the outside, and to these Dr. Carpenter has given the appropriate name
of "supplemental skeleton"; and this, when covered by new growths,
becomes what he has termed an "intermediate skeleton." The supplemental
skeleton is also traversed by tubes, but these are often of larger
size than the pores of the cell wall, and of greater length, and
branched in a complicated manner. Thus there are microscopic characters
by which these curious shells can be distinguished from those of
other marine animals; and by applying these characters we learn that
multitudes of creatures of this type have existed in former periods of
the world's history, and that their shells, accumulated in the bottom
of the sea, constitute large portions of many limestones. The manner in
which such accumulation takes place we learn from what is now going on
in the ocean, more especially from the result of the recent deep-sea
dredging expeditions. The Foraminifera are vastly numerous, both near
the surface and at the bottom of the sea, and multiply rapidly; and as
successive generations die, their shells accumulate on the ocean bed,
or are swept by currents into banks, and thus, in process of time,
constitute thick beds of white chalky material, which may eventually
be hardened into limestone. This process is now depositing a great
thickness of white ooze in the bottom of the ocean; and in times past
it has produced such vast thicknesses of calcareous matter as the chalk
and nummulitic limestone of Europe and the orbitoidal limestone of
America. The chalk which alone attains a maximum thickness of 1,000
feet, and, according to Lyell, can be traced across Europe for 1,100
geographical miles, may be said to be entirely composed of shells of
Foraminifera imbedded in a paste of smaller calcareous bodies, the
Coccoliths, which are probably products of marine vegetable life, if
not of some animal organism still simpler than the Foraminifera.

Lastly, while we have in such modern forms as the masses of
Polytrema attached to corals, and the Loftusia of the Eocene and the
carboniferous, large fossil foraminiferal species, there is some reason
to believe that in the earlier geological ages there existed much
larger animals of this grade than are found in our present seas; and
that these, always sessile on the bottom, grew by the addition of
successive chambers, in the same manner with the smaller species.[54]

[54] I refer to some of the Stromatoporæ of the Silurian and the
_Cryptozoon_ of the Cambrian. See note appended to this chapter.

Let us, then, examine the structure of Eozoon, taking a typical
specimen, as we find it in the limestone of Grenville or Petite Nation.
In such specimens the skeleton of the animal is represented by a white
crystalline marble, the cavities of the cells by green serpentine, the
mode of whose introduction we shall have to consider in the sequel.
The lowest layer of serpentine represents the first gelatinous coat
of animal matter which grew upon the bottom, and which, if we could
have seen it before any shell was formed upon its surface, must have
resembled a minute patch of living slime. On this primary layer grew
a delicate calcareous shell, perforated by innumerable minute tubuli,
and resting on the slimy matter of the animal, though supported also
by some perpendicular plates or septa. Upon this again was built up,
in order to strengthen it, a thickening or supplemental skeleton,
more dense, and destitute of fine tubuli, but traversed by branching
canals, through which the soft gelatinous matter could pass for the
nourishment of the skeleton itself, and the extension of pseudopods
beyond it. (Figs. 11, 12.) So was formed the first layer of Eozoon,
which probably was at its beginning only of very small dimensions. On
this the process of growth of successive layers of animal sarcode and
of calcareous skeleton was repeated again and again, till in some cases
even a hundred or more layers were formed (nature-print, Chap. VI.)
As the process went on, however, the vitality of the organism became
exhausted, probably by the deficient nourishment of the central and
lower layers making greater and greater demands on those above, and so
the succeeding layers became thinner, and less supplemental skeleton
was developed. Finally, toward the top, the regular arrangement in
layers was abandoned, and the cells became a mass of rounded chambers,
irregularly piled up in what Dr. Carpenter has termed an "acervuline"
manner, and with very thin walls unprotected by supplemental skeleton.
Then the growth was arrested, and possibly these upper layers gave
off reproductive germs, fitted to float or swim away and to establish
new colonies. We may have such reproductive germs in certain curious
globular bodies, like loose cells, found in connection with Eozoon in
many of the Laurentian limestones.[55] At St. Pierre, on the Ottawa,
these bodies occur on the surface of layers of the limestone in vast
numbers, as if they had been growing separately on the bottom, or had
been drifted over it by currents. They may have served as reproductive
buds or germs to establish new colonies of the species. Such was the
general mode of growth of Eozoon, and we may now consider more in
detail some questions as to its gigantic size, its precise mode of
nutrition, the arrangement of its parts, its relations to more modern
forms, and the effects of its growth in the Laurentian seas.

[55] It would be interesting to compare these bodies with the forms
recently found by Barrois and Cayeux in the "Azoic" quartzite of
Brittany, which should certainly now be called Eozoic.

[Illustration: Fig. 10.--Minute Foraminiferal forms from the Laurentian
of Long Lake. Highly magnified, (_a_) Single cell, showing tubulated
wall. (_b, c_) Portions of same more highly magnified. (_d_) Serpentine
cast of a similar chamber, decalcified, and showing casts of tubuli.]

With respect to the size of Eozoon, this was rivalled by some
succeeding animals of the same humble type in later geological ages;
and, as a whole, foraminiferal animals have been diminishing in
size in the lapse of geological time. This is indeed a fact of so
frequent occurrence that it may almost be regarded as a law of the
introduction of new forms of life, that they assume in their early
history gigantic dimensions, and are afterwards continued by less
magnificent species. The relations of this to external conditions,
in the case of higher animals, are often complex and difficult to
understand; but in organisms so low as Eozoon and its allies, they lie
more on the surface. Such creatures may be regarded as the simplest and
most ready media for the conversion of vegetable matter into animal
tissues, and their functions are almost entirely limited to those
of nutrition. Hence it is likely that they will be able to appear
in the most gigantic forms under such conditions as afford them the
greatest amount of pabulum for the nourishment of their soft parts
and for their skeletons. There is reason to believe, for example,
that the occurrence, both in the chalk and the deep-sea mud, of
immense quantities of the minute bodies known as Coccoliths along with
Foraminifera, is not accidental. The Coccoliths appear to be grains
of calcareous matter formed in minute plants adapted to a deep-sea
habitat; and these, along with the vegetable and animal _débris_
constantly being derived from the death of the living things at the
surface, afford the material both of sarcode and shell. Now if the
Laurentian graphite represents an exuberance of vegetable growth in
those old seas proportionate to the great supplies of carbonic acid
in the atmosphere and in the waters, and if the Eozoic ocean was even
better supplied with salts of lime than those Silurian seas whose vast
limestones bear testimony to their richness in such material, we can
easily imagine that the conditions may have been more favourable to a
creature like Eozoon than those of any other period of geological time.

Growing, as Eozoon did, on the floor of the ocean, and covering wide
patches with more or less irregular masses, it must have thrown up from
its whole surface its pseudopods to seize whatever floating particles
of food the waters carried over it. There is also reason to believe,
from the outline of certain specimens, that it often grew upward
in conical or club-shaped forms, and that the broader patches were
penetrated by large pits or oscula, admitting the sea-water deeply into
the substance of the masses. In this way its growth might be rapid and
continuous; but it does not seem to have possessed the power of growing
indefinitely by new and living layers covering those that had died,
in the manner of some corals. Its life seems to have had a definite
termination, and when that was reached, an entirely new colony had to
be commenced. In this it had more affinity with the Foraminifera, as
we now know them, than with the corals, though practically it had the
same power with the coral polyps of accumulating limestone in the sea
bottom--a power indeed still possessed by its foraminiferal successors.
In the case of coral limestones we know that a large proportion of
these consist not of continuous reefs, but of fragments of coral mixed
with other calcareous organisms, spread usually by waves and currents
in continuous beds over the sea bottom. In like manner we find in the
limestones containing Eozoon, layers of fragmental matter which show
in places the characteristic structures, and which evidently represent
the _débris_ swept from the Eozoic masses and reefs by the action of
the waves. It is with this fragmental matter that the small rounded
organisms already referred to most frequently occur; and while they
may be distinct animals, they may also be the fry of Eozoon, or small
portions of its acervuline upper surface floated off in a living state,
and possibly capable of living independently and of founding new
colonies.

It is only by a somewhat wild poetical licence that Eozoon has been
represented as a "kind of enormous composite animal stretching from the
shores of Labrador to Lake Superior, and thence northward and southward
to an unknown distance, and forming masses 1,500 feet in depth." We
may, it is true, readily believe in the composite nature of masses or
Eozoon, and we see in the corals evidence of the great size to which
composite animals of a higher grade can attain. In the case of Eozoon
we must imagine an ocean floor more uniform and level than that now
existing. On this the organism would establish itself in spots and
patches. These might finally become confluent over large areas, just
as massive corals do. As individual masses attained maturity and died,
their pores would be filled up with limestone or silicious deposits,
and thus could form a solid basis for new generations, and in this way
limestone to an indefinite extent might be produced. Further, wherever
such masses were high enough to be attacked by the breakers, or where
portions of the sea bottom were elevated, the more fragile parts of the
surface would be broken up and scattered widely in beds of fragments
over the bottom of the sea, while here and there beds of mud or sand,
or of volcanic _débris_ would be deposited over the living or dead
organic mass, and would form the layers of gneiss and other schistose
rocks interstratified with the Laurentian limestone. In this way, in
short, Eozoon would perform a function combining that which corals and
Foraminifera perform in the modern seas; forming both reef limestones
and extensive chalky beds, and probably living both in the shallow and
the deeper parts of the ocean. If in connection with this we consider
the rapidity with which the soft, simple, and almost structureless
sarcode of these Protozoa can be built up, and the probability that
they were more abundantly supplied with food, both for nourishing
their soft parts and skeletons, than any similar creatures in later
times, we can readily understand the great volume and extent of the
Laurentian limestones which they aided in producing. I say aided in
producing, because I would not care to commit myself to the doctrine
that the Laurentian limestones are wholly of this origin. There may
have been other limestone builders than Eozoon, and there may have been
limestones formed by plants like the modern Nullipores, or by merely
mineral deposition.

[Illustration: Fig. 11.--Section of a Nummulite, from Eocene Limestone
of Syria. Showing chambers, tubuli, and canals. Compare this and Fig.
12 with Fig. 7 and Nature-print of Eozoon.]

Its relations to modern animals of its type have been very clearly
defined by Dr. Carpenter. In the structure of its proper wall and its
fine parallel perforations, it resembles the _Nummulites_ and their
allies; and the organism may therefore be regarded as an aberrant
member of the Nummuline group, which affords some of the largest and
most widely distributed of the fossil Foraminifera. This resemblance
may be seen in Fig. 11. To the Nummulites it also conforms in its
tendency to form a supplemental or intermediate skeleton with canals,
though the canals themselves in the arrangement more nearly resemble
Calcarina, which is represented in Fig. 12. In its superposition
of many layers, and in its tendency to a heaped up or acervuline
irregular growth it resembles _Polytrema_ and _Tinoporus_, forms of a
different group in so far as shell-structure is concerned. It may thus
be regarded as a composite type, combining peculiarities now observed
in two groups, or it may be regarded as representing one of these in
another series. At the time when Dr. Carpenter stated these affinities,
it might be objected that Foraminifera of these families are in the
main found in the modern and Tertiary periods. Dr. Carpenter has since
shown that the curious oval Foraminifer called _Fusulina_, found in
the coal formation, is allied to both Nummulites and Rotalines; and
Mr. Brady has discovered a true Nummulite in the Lower Carboniferous
of Belgium. I have myself found small Foraminifera in the Silurian and
Cambro-Silurian of Canada. This group being now brought down to the
Palæozoic, we may hope to trace it to the Primordial, and thus to bring
it still nearer to Eozoon in time.

[Illustration: Fig. 12.--Portion of shell of Calcarina. Magnified,
after Carpenter, (_a_) Cells. (_b_) Original cell wall with tubuli.
(_c_) Supplementary skeleton with canals.]

Though Eozoon was probably not the only animal of the Laurentian seas,
yet it was in all likelihood the most conspicuous and important as
a collector of calcareous matter, filling the same place afterwards
occupied by the reef-building corals. Though probably less efficient
than these as a constructor of solid limestones, from its less
permanent and continuous growth, it formed wide floors and patches
on the sea bottom, and when these were broken up, vast quantities of
limestone were formed from their _débris_. It must also be borne in
mind that Eozoon was not everywhere infiltrated with serpentine or
other silicious minerals; quantities of its substance were merely
filled with carbonate of lime, resembling the chamber wall so closely
that it is nearly impossible to make out the difference, and thus is
likely to pass altogether unobserved by collectors, and to baffle
even the microscopist. Although, therefore, the layers which contain
well characterised Eozoon are few and far between, there is reason to
believe that in the composition of the limestones of the Laurentian it
bore no small part, and as these limestones are some of them several
hundred feet in thickness, and extend over vast areas, Eozoon may be
supposed to have been as efficient a world-builder as the Stromatoporæ
of the Silurian and Devonian, the Globigerinæ and their allies in
the chalk, or the Nummulites and Miliolites in the Eocene. It is a
remarkable illustration of the constancy of natural causes and of
the persistence of animal types, that these humble Protozoans, which
began to secrete calcareous matter in the Laurentian period, have been
continuing their work in the ocean through all the geological ages,
and are still busy in accumulating those chalky muds with which recent
dredging operations in the deep sea have made us so familiar. (See Note
appended.)

All this seems sufficiently reasonable, more especially since
no mineralogist has yet succeeded in giving a feasible inorganic
explanation of the combination of canals, laminæ, tubulation and varied
mineral character existing in Eozoon. But then comes the strange fact
of its apparent isolation without companions in highly crystalline
rocks, and with apparently no immediate successors. This has staggered
many, and it certainly, if taken thus baldly, seems in some degree
improbable. Recent discoveries, however, are removing this reproach
from Eozoon. The Laurentian rocks have yielded other varieties, or
perhaps species of the genus, those which I have described as variety
Acervulina, and variety Minor, and still another form, more like a
Stromatopora, which I have provisionally named _E. latior_, from
the breadth and uniformity of its plates.[56] There are also in the
Laurentian limestone cylindrical bodies apparently originally tubular,
and with the sides showing radiating markings in the manner of corals,
or of the curious Cambrian Archæocyathus. Matthew, a most careful
observer, has found in the Laurentian limestone of New Brunswick
certain laminated bodies of cylindrical form, constituting great reefs
in the limestone, and in the slates linear flat objects resembling
Algæ or Graptolites, and spicular structures resembling those of
sponges.[57] Britton has also described from the Laurentian limestone
of New Jersey certain ribbon-like objects of graphite which he regards
as vegetable, and names _Archæophyton Newberryii_.[58] Should these
objects prove to be organic, Eozoon will no longer be alone. Besides
this the peculiar bodies named Cryptozoum by Hall, and which are
intermediate in structure between Eozoon and Loftusia, have now been
found as low as the Lower Cambrian.[59] Barrois has also recently
announced the discovery of forms which he regards as akin to the modern
Radiolaria, creatures of a little higher grade than the Foraminifera,
in the "Archæan" rocks of Brittany.[60] Thus Eozoon is no longer
isolated, but has companions of the same great age with itself. The
progress of discovery is also daily carrying the life of the Cambrian
to lower beds, and thus nearer to the Laurentian. It is not unlikely
that in a few years a pre-Cambrian fauna will force itself on the
attention of the most sceptical geologists.

[56] Notes on Specimens of Eozoon, "Memoirs of Peter Redpath Museum,"
1888.

[57] _Bul. Nat. Hist. New Brunswick, No. IX._, 1890.

[58] _Annals N. Y. Academy of Science_, 1888.

[59] Walcott, Lower Cambrian, 1892.

[60] _Natural Science_, Oct., 1892.

  References:--"Life's Dawn on Earth," London, 1875. (Now out of
    print.) "Specimens of Eozoon Canadense in the Peter Red path
    Museum, Montreal," 1888. (This memoir contains reference to
    previous papers.)


Appended Notes.

1. _Stromatoporæ._ It has been usual of late to regard these as allies
of the modern Millepores and Hydractineæ; but careful study of large
series of specimens has convinced me that some species, notably the
_Stromatocerium_ of the Cambro-Silurian and the _cryptozoum_ of the
Cambrian, cannot be so referred. I hope to establish this in the
future, if time permit.

2. Modern Foraminifera. The discovery by Brady and Lister of
reproductive chamberlets at the margin of the modern _orbitolites_,
tends to connect this with Eozoon. The gigantic foraminiferal species
discovered by Agassiz at the Gallipagos, has points of affinity
with Eozoon; and its arenaceous nature does not affect this, as we
know sandy species in this group closely allied to others that are
calcareous.




                  _WHAT MAY BE LEARNED FROM EOZOON._


                      DEDICATED TO THE MEMORY OF

                       DR. WILLIAM B. CARPENTER,

               Who, among his many Services to Science,

           devoted much Time and Labour to the Investigation

            of Eozoon, and by his Knowledge of Foraminifera

             and unrivalled Power of unravelling difficult

                              Structures

                  did much to Render it intelligible.


The Microscope in Geology--Contributions of the Study of Eozoon to
our Knowledge of the Mode of Preservation of Fossils--Its Teaching
Relatively to the Origin of Life and the Laws of its Introduction and
Progress

[Illustration: Specimen of Eozoon Canadense (Dawson), showing General
Form and Osculiform Tubes. (Reproduced from Photograph.)]




CHAPTER VI.

_WHAT MAY BE LEARNED FROM EOZOON._


The microscope has long been a recognised and valued aid of the
geological observer, and is perhaps now in danger of being somewhat
overrated by enthusiastic specialists. To the present writer its use
is no novelty. When, as a very young geologist, collecting fossil
plants in the coal fields of Nova Scotia, I obtained access to the
then recently published work of Witham on the "Internal Structure of
Fossil Vegetables."[61] Fired by the desire to learn something of
the structure of the blocks of fossil wood in my collection, I at
once procured a microscope of what would now be considered a very
imperfect kind, and proceeded to make attempts to slice and examine my
specimens, and was filled with joy when these old blackened stems for
the first time revealed to me their wonderful structures. At the same
time I extended my studies to every minute form of life that could be
obtained from the sea or fresh waters. A few years later (in 1841),
when a student in Edinburgh, I made the acquaintance of Mr. Sanderson
of that city, who had worked for Nicol and Witham in the preparation of
specimens, and learnt the modes which he had employed. Since that time
I have been accustomed to subject every rock, earth or fossil which
came under my notice to microscopic scrutiny, not as a mere specialist
in that mode of observation, or with the parade of methods and details
now customary, but with the view of obtaining valuable facts bearing
on any investigation I might have in hand. It was this habit which
induced my old friend, Sir William Logan, in 1858 and subsequent years
to ask my aid in the study of the forms believed or suspected to be
organic, which had been discovered in the course of his surveys of the
Laurentian rocks. In one respect this was unfortunate. It occupied
much time, interfered to some extent with other researches, led to
unpleasant controversies. But these evils were more than compensated
by the insight which the study gave into the fact of the persistence
of organic structures in highly crystalline rocks, and to the modes
of ascertaining and profiting, by these obscure remains, while it
has guided and stimulated enquiry and thought as to the origin and
history of life. These benefits entitle the researches and discussions
on Eozoon to be regarded as marking a salient point in the history
of geological discovery, and it is to these principally that I would
attract attention in the present chapter.

[61] Edinburgh, 1833.

Perhaps nothing excites more scepticism as to the animal nature of
Eozoon than the prejudice existing among geologists that no organism
can be preserved in rocks so highly crystalline as those of the
Laurentian series. I call this a prejudice, because any one who makes
the microscopic structure of rocks and fossils a special study, soon
learns that fossils and the rocks containing them may undergo the most
remarkable and complete mechanical and chemical changes without losing
their minute structure, and that limestones, if once fossiliferous,
are hardly ever so much altered as to lose all traces of the organisms
which they contained, while it is a most common occurrence to find
highly crystalline rocks of this kind abounding in fossils preserved as
to their minute structure.

Let us, however, look at the precise conditions under which this takes
place.

When calcareous fossils of irregular surface and porous or cellular
texture, such as Eozoon may have been, or corals were and are, become
imbedded in clay, marl, or other soft sediment, they can be washed
out and recovered in a condition similar to that of recent specimens,
except that their pores or cells, if open, may be filled with the
material of the matrix, or if not so open that they can be thus filled,
they may be more or less incrusted with mineral deposits introduced
by water percolating the mass, or may even be completely filled up in
this way. But if such fossils are contained in hard rocks, they usually
fail, when these are broken, to show their external surfaces, and,
breaking across with the containing rock, they exhibit their internal
structure merely,--and this more or less distinctly, according to the
manner in which their cells or cavities have been filled with mineral
matter. Here the microscope becomes of essential service, especially
when the structures are minute. A fragment of fossil wood which to the
naked eye is nothing but a dark stone, or a coral which is merely a
piece of grey or coloured marble, or a specimen of common crystalline
limestone made up originally of coral fragments, presents, when sliced
and magnified, the most perfect and beautiful structure. In such cases
it will be found that ordinarily the original substance of the fossil
remains in a more or less altered state. Wood may be represented by
dark lines of coaly matter, or coral by its white or transparent
calcareous laminæ; while the material which has been introduced, and
which fills the cavities, may so differ in colour, transparency, or
crystallization, as to act differently on light, and so reveal the
original structure. These fillings are very curious. Sometimes they are
mere earthy or muddy matter which has been washed into the cavities.
Sometimes they are transparent and crystalline. Often they are stained
with oxide of iron or coaly materials. They may consist of carbonate
of lime, silica or silicates, sulphate of baryta, oxides of iron,
carbonate of iron, iron pyrite, or sulphides of copper or lead, all of
which are common materials. They are sometimes so complicated that I
have seen even the minute cells of woody structures, each with several
bands of differently coloured materials deposited in succession, like
the coats of an onyx agate.

A further stage of mineralisation occurs when the substance of the
organism is altogether removed and replaced by foreign matter, either
little by little, or by being entirely dissolved or decomposed,
leaving a cavity to be filled by infiltration. In this state are some
silicified woods, and those corals which have been not filled with
but replaced by silica, and can thus sometimes be obtained entire and
perfect by the solution in an acid of the containing limestone, or by
its removal in weathering. In this state are the beautiful silicified
corals obtained from the corniferous limestone of Lake Erie, which are
so perfectly replaced by flinty matter that when weathered out of the
limestone, or treated with acid till the latter is removed, we find
the coral as perfect as when recent. It may be well to present to the
eye these different stages of fossilization. I have attempted to do
this in Fig. 13, taking a tabulate coral of the genus Favosites for an
example, and supposing the material employed to be calcite and silica.
Precisely the same illustration would apply to a piece of wood, except
that the cell wall would be carbonaceous matter instead of carbonate
of lime. In this figure the dotted parts represent carbonate of lime,
the diagonally shaded parts silica or a silicate. Thus we have in the
natural state the walls of carbonate of lime and the cavities empty
(_a_). When fossilized the cavities may be merely filled with carbonate
of lime, or they may be filled with silica (_b, c_); or the walls
themselves may be replaced by silica, and the cavities may remain
filled with carbonate of lime (_d_); or both the walls and cavities
may be represented by or filled with silica or silicates (_e_). The
ordinary specimens of Eozoon are supposed to be in the third of these
stages, though some exist in the second, and I have reason to believe
that some have reached to the fifth. I have not met with any in the
fourth stage, though this is not uncommon in Silurian and Devonian
fossils. I have further to remark that the reason why wood and the
cells of corals so readily become silicified is that the organic
matter which they contain, becoming oxidized in decay, produces carbon
dioxide, which, by its affinity for alkalies, can decompose soluble
silicates and thus throw down their silica in an insoluble state. Thus
a fragment of decaying wood imbedded in a deposit holding water and
alkaline silicates almost necessarily becomes silicified. It is also
to be remarked that the ordinary specimens of Eozoon have actually not
attained to the extreme degree of mineralization seen in some much more
recent silicified woods and corals, inasmuch as the portion believed to
have been the original calcareous test has not usually been silicified,
but still remains in the state of calcium carbonate.

[Illustration: Fig. 13.--Diagram showing different States of
Fossilization of a cell of a Tabulate Coral, (_a_) Natural condition
walls calcite, cell empty. (_b_) Walls calcite, cell filled with the
same, (_c_) Walls calcite, cell filled with silica or silicate, (_d_)
Walls silicified, cell filled with calcite. (_e_) Walls silicified,
cell filled with silica or silicate.]

With regard, then, to the calcareous organisms with which we have now
more especially to do, when these are embedded in pure limestone and
filled with the same, so that the whole rock, fossils and cavities,
is one in composition, and when metamorphic action has caused the
whole to become crystalline, and has perhaps removed the remains of
carbonaceous matter, it may be very difficult to detect any traces
of structure. But even in this case careful management of light may
reveal some indications. In many instances, however, even where the
limestones have become perfectly crystalline, and the cleavage planes
cut freely across the fossils, these exhibit their forms and minute
structures in great perfection. This is the case in many of the Lower
Silurian limestones of Canada, as I have elsewhere shown.[62] The grey
crystalline Trenton limestone of Montreal, used as a building stone,
is an excellent illustration. To the naked eye it is a grey marble
composed of cleavable crystals; but when examined in thin slices, it
shows its organic fragments in the greatest beauty, and all their
minute parts are perfectly marked out by delicate carbonaceous lines.
The only exception in this limestone is in the case of the crinoids,
in which the cellular structure is filled with transparent calc-spar,
perfectly identical with the original solid matter, so that they appear
solid and homogeneous, but there are examples in which even the minute
meshes of these become' apparent. The specimen represented in Fig. 14
is a mass of Corals, Polyzoa, and Crinoids, and shows these under a
low power, as represented in the figure. The specimen in Fig. 15 shows
the Laurentian Eozoon in a similar state of preservation. It is from a
sketch by Dr. Carpenter, and exhibits the delicate canals partly filled
with calcite or dolomite, as clear and colourless as that of the shell
itself, and distinguishable only by careful management of the light.

[62] _Canadian Naturalist_, 1859: "Microscopic Structure of Canadian
Limestones."

[Illustration: Fig. 14.--Slice of Crystalline Lower Silurian Limestone;
showing Crinoids, Bryozoa, and Corals in fragments.]

[Illustration: Fig. 15.--Walls of Eozoon penetrated with Canals. The
unshaded portions filled with Calcite. (After Carpenter.)]

In the case of recent and fossil Foraminifers, these very frequently
have their chambers filled solid with calcareous matter, and as Dr.
Carpenter well remarks, even well-preserved Tertiary Nummulites in
this state often fail greatly in showing their structures, though in
the same condition they occasionally show these in great perfection.
Among the finest I have seen are specimens from the Mount of Olives,
and Dr. Carpenter mentions as equally good those of the London clay at
Bracklesham. But in no condition do modern Foraminifera, or those of
the Tertiary and Mesozoic rocks appear in greater perfection than when
filled with the hydrous silicate of iron and potash called glauconite
or green earth, a substance now forming in some parts of the ocean, and
which gives, by the abundance of its little bottle-green concretions
the name of "greensand" to formations of the Cretaceous age both in
Europe and America. In some beds of greensand every grain seems,
to have been moulded into the interior of a microscopic shell, and
has retained its form after the frail envelope has been removed. In
some cases the glauconite has not only filled the chambers but has
penetrated the fine tubulation, and when the shell is removed, either
naturally or by the action of an acid, the silicious fillings of the
interior of the tubes project in minute needles or bundles of threads
of marvellous delicacy from the surface of the cast. It is in the
warmer seas, and especially in the bed of the Egean and of the Gulf
Stream, that such specimens are now most usually found.[63] If we ask
why this mineral glauconite should be associated with foraminiferal
shells, the answer is that they are both products of one kind of
locality. The same sea bottoms in which Foraminifera most abound are
also those in which the chemical conditions for the formation of
glauconite exist. Hence, no doubt, the association of this mineral
with the great foraminiferal formation of the chalk. It is indeed by
no means unlikely that the selection by these creatures of the pure
carbonate of lime from the sea water or its minute plants, may be
the means of setting free the silica, iron, and potash, in a state
suitable for their combination. Similar silicates are found associated
with marine limestones, as far back as the Cambro-Silurian age;
and Dr. Sterry Hunt, than whom no one can be a better authority on
chemical geology, has argued on chemical grounds that the occurrence
of serpentine with the remains of Eozoon is an association of the same
character.

[63] Beautiful specimens of Nummulites preserved in this way, from the
Eocene of Kumpfen in Bavaria, have been communicated to me through the
kindness of Dr. Otto Hahn.

However this may be, the infiltration of the pores of Eozoon with
serpentine and other silicates has evidently been one main means of its
preservation. When so infiltrated no metamorphism short of the complete
fusion of the containing rock could obliterate the minutest points
of structure; and that such fusion has not occurred, the preservation
in the Laurentian rocks of the most delicate lamination of the beds
shows conclusively; while, as already stated, it can be shown that the
alteration which has occurred might have taken place at a temperature
far short of that necessary to fuse limestone. Thus has it happened
that these most ancient fossils have been handed down to our time in a
state of preservation comparable, as Dr. Carpenter states, to that of
the best preserved fossil Foraminifera from the more recent formations
that have come under his observation in the course of all his long
experience.

Let us now look more minutely at the nature of the typical specimens
of Eozoon as originally observed and described, and then turn to those
preserved in other ways, or more or less destroyed or defaced. Taking
a polished specimen from Petite Nation, we find the shell represented
by white limestone, and the chambers by light green serpentine. By
acting on the surface with a dilute acid we etch out the calcareous
part, leaving a cast in serpentine of the cavities originally occupied
by the soft animal substance, and when this is done in polished slices,
these may be made to print their own characters on paper, as has
actually been done in the plate prefixed, which is an electrotype from
an etched specimen, and shows both the laminated and acervuline parts
of the fossil. If the process of decalcification has been carefully
executed, we find in the excavated spaces delicate ramifying processes
of opaque serpentine or transparent dolomite, which were originally
imbedded in the calcareous substance, and which are often of extreme
fineness and complexity.[64] (Figs. 18, 19.) These are casts of the
canals which traversed the shell when still inhabited by the animal,
and have subsequently been filled with mineral matter. In evidence
of this we sometimes find in a single canal an outer tubular layer
of serpentine and an inner filling of dolomite, just as vessels of
fossil plants are sometimes filled with successive coats of different
materials. In some well preserved specimens we find the original cell
wall represented by a delicate white film, which under the microscope
shows minute needle-like parallel processes representing its still
finer tubuli. It is evident that to have filled these tubuli, the
serpentine must have been introduced in a state of actual solution,
and must have carried with it no foreign impurities. Consequently
we find that in the chambers themselves the serpentine is pure; and
if we examine it under polarized light, we see that it presents a
singularly curdled or irregularly laminated appearance, as if it had an
imperfectly crystalline structure, and had been deposited in irregular
laminæ, beginning at the sides of the chambers, and filling them toward
the middle, and had afterward been cracked by shrinkage, and the cracks
filled with a second deposit of serpentine.[65] Now, serpentine is a
hydrous silicate of magnesia, and all that we need to suppose is that
in the waters of the Laurentian sea magnesia was present instead of
iron, alumina or potash, and we can understand that the Laurentian
fossil has been petrified by infiltration with serpentine, as more
modern Foraminifera have been with glauconite, which, though it does
not contain magnesia, often has a considerable percentage of alumina.
Further, in specimens of Eozoon from Burgess, the filling mineral is
loganite, a compound of silica, alumina, magnesia and iron with water,
while in other specimens the filling mineral is pyroxene. In like
manner, in certain Silurian limestones from New Brunswick and Wales,
in which the delicate microscopic pores of the skeletons of stalked
starfishes or crinoids have been filled with mineral deposits, so
that when decalcified these are most beautifully represented by their
casts, Dr. Hunt has proved the filling mineral to be[66] intermediate
between serpentine and glauconite. We have, therefore, ample warrant
for adhering to his conclusion that the Laurentian serpentine was
deposited under conditions similar to those of the modern greensand.
Indeed, independently of Eozoon, it is impossible that any geologist
who has studied the manner in which this mineral is associated with
the Laurentian limestones could believe it to have been formed in
any other way. Nor need we be astonished at the fineness of the
infiltration by which these minute tubes, perhaps 1/10000 of an inch
in diameter, are filled with mineral matter. The micro-geologist
well knows how, in more modern deposits, the finest pores of fossils
are filled, and that mineral matter in solution can penetrate the
smallest openings that the microscope can detect. Wherever the fluids
of the living body can penetrate, there also mineral substances can
be carried, and this natural injection, effected under great pressure
and with the advantage of ample time, can surpass any of the feats of
the anatomical manipulator. Fig. 16 represents a microscopic joint of
a Crinoid from the Upper Silurian of New Brunswick, injected with the
hydrous silicate already referred to, and Fig. 17 shows a microscopic
chambered or spiral shell, from a Welsh Silurian limestone, with its
cavities filled with a similar substance.

[64] Very fine specimens can be produced by polishing thin slices, and
then etching them slightly with a very weak acid. (Plate prefixed.)

[65] The same structures may be well seen in thin slices polished, to
be viewed as transparent objects. I may, however, explain that if these
are made roughly, and heated in the process, they may often show only
mineral structures and cleavage planes, whereas, if polished with great
care and slowly, and afterwards cleaned with an acid, they may show the
canals in great perfection.

[66] Silicate of alumina, iron, magnesia, and potash.

[Illustration: Fig. 16.--Joint of a Crinoid, having its Pores injected
with a Hydrous Silicate. Upper Silurian Limestone, Pole Hill, New
Brunswick. Magnified 25 diameters.]

[Illustration: Fig. 17.--Shell from a Silurian Limestone, Wales; its
cavity filled with Hydrous Silicate. Magnified 25 diameters.]

[Illustration: Fig. 18.--Casts of Canals of Eozoon in Serpentine,
decalcified and highly magnified.]

[Illustration: Fig. 19.--Canals of Eozoon. Highly Magnified.]

Taking the specimens preserved by serpentine as typical, we now turn
to certain other and, in some respects, less characteristic specimens,
which are nevertheless very instructive. At the Calumet some of
the masses are partly filled with serpentine and partly with white
pyroxene, an anhydrous silicate of lime and magnesia. The two minerals
can readily be distinguished when viewed with polarized light; and in
some slices I have seen part of a chamber or group of canals filled
with serpentine and part with pyroxene. In this case the pyroxene,
or the materials which now compose it, must have been introduced by
infiltration, as well as the serpentine. This is the more remarkable as
pyroxene is most usually found as an ingredient of igneous rocks; but
Dr. Hunt has shown that in the Laurentian limestones, and also in veins
traversing them, it occurs under conditions which imply its deposition
from water, either cold or warm. Gümbel remarks on this:--"Hunt, in
a very ingenious manner, compares this formation and deposition of
serpentine, pyroxene, and loganite, with that of glauconite, whose
formation has gone on uninterruptedly from the Silurian to the Tertiary
period, and is even now taking place in the depths of the sea; it being
well known that Ehrenberg and others have already shown that many of
the grains of glauconite are casts of the interior of foraminiferal
shells. In the light of this comparison, the notion that the serpentine
and such-like minerals of the primitive limestones have been formed,
in a similar manner, in the chambers of Eozoic Foraminifera, loses any
traces of improbability which it might at first seem to possess."

In many parts of the skeleton of Eozoon, and even in the best
infiltrated serpentine specimens, there are portions of the cell wall
and canal system which have been filled with calcareous spar or with
dolomite, so similar to the skeleton that it can be detected only under
the most favourable lights and with great care (Fig. 15, _supra_). It
is further to be remarked that in all the specimens of true Eozoon,
as well as in many other calcareous fossils preserved in ancient
rocks, the calcareous matter, even when its minute structures are not
preserved, or are obscured, presents a minutely granular or curdled
appearance, arising, no doubt, from the original presence of organic
matter, and not recognised in purely inorganic calcite.

Other specimens of fragmental Eozoon from the Petite Nation localities
have their canals filled with dolomite, which probably penetrated them
after they were broken up and imbedded in the rock. I have ascertained,
with respect to these fragments of Eozoon, that they occur abundantly
in certain layers of the Laurentian limestone, beds of some thickness
being in great part made up of them, and coarse and fine fragments
occur in alternate layers, like the broken corals in some Silurian
limestones.

Finally, on this part of the subject, careful observation of many
specimens of Laurentian limestone which present no trace of Eozoon
when viewed by the naked eye, and no evidence of structure when acted
on with acids, are nevertheless organic, and consist of fragments
of Eozoon, and possibly of other organisms, not infiltrated with
silicates, but only with carbonate of lime, and consequently revealing
only obscure indications of their minute structure. I have satisfied
myself of this by long and patient investigations, which scarcely admit
of any adequate representation, either by words or figures.

Every worker in those applications of the microscope to geological
specimens which have been termed micro-geology, is familiar with the
fact that crystalline forces and mechanical movements of material often
play the most fantastic tricks with fossilized organic matter. In
fossil woods, for example, we often have the tissues disorganized, with
radiating crystallizations of calcite and little spherical concretions
of quartz, or disseminated cubes and grains of pyrite, or little
veins filled with sulphate of barium or other minerals. We need not,
therefore, be surprised to find that in the venerable rocks containing
Eozoon, such things occur in the highly crystalline Laurentian
limestones, and even in some still showing the traces of Eozoon. We
find many disseminated crystals of magnetite, pyrite, spinel, mica and
other minerals, curiously curved prisms of vermicular mica, bundles
of aciculi of tremolite and similar substances, veins of calcite
and crysotile or fibrous serpentine, which often traverse the best
specimens. Where these occur abundantly, we usually find no organic
structures remaining, or if they exist, they are in a very defective
state of preservation. Even in specimens presenting the lamination
of Eozoon to the naked eye, these crystalline actions have often
destroyed the minute structure; and I fear that some microscopists
have been victimized, by having under their consideration only
specimens in which the actual characters had been too much defaced to
be discernible. No mistake can be greater than to suppose that any
and every specimen of Laurentian limestone must contain Eozoon. More
especially have I hitherto failed to detect traces of it in those
carbonaceous or graphitic limestones which are so very abundant in the
Laurentian country. Perhaps where vegetable matter was very plentiful
Eozoon did not thrive, or, on the other hand, the growth of Eozoon
may have diminished the quantity of vegetable matter. It is also to
be observed that much compression and distortion have occurred in the
beds of Laurentian limestone and their contained fossils, and also
that the specimens are often broken by faults, some of which are so
small as to appear only on microscopic examination, and to shift the
plates of the fossil just as if they were beds of rock. This, though
it sometimes produces puzzling appearances, is an evidence that the
fossils were hard and brittle when this faulting took place, and is
consequently an additional proof of their extraneous origin. In some
specimens it would seem that the lower and older part of the fossil
had been wholly converted into serpentine or pyroxene, or had so
nearly experienced this change that only small parts of the calcareous
wall can be recognised. These portions correspond with fossil woods
altogether silicified, not only by the filling of the cells, but
also by the conversion of the walls into silica. I have specimens
which manifestly show the transition from the ordinary condition of
filling with serpentine to one in which the cell walls are represented
obscurely by one shade of this mineral and the cavities by another. In
general, however, it will be gathered from the above explanations that
the specimens of Eozoon fall short in thoroughness of mineralization
of some fossils in much more modern rocks. I have specimens of ancient
sponges whose spicular skeletons, originally silicious, have been
replaced by pyrite or bisulphide of iron, and of Tertiary fossil woods
retaining perfectly their most minute structures, yet entirely replaced
by silica, so that not a particle of the original wood remains.

The above considerations as to mode of preservation of Eozoon concur
with those in the previous chapter in showing its oceanic character,
if really a fossil; but the ocean of the Eozoic period may not have
been so deep as at present, and its waters were probably warm and
well stocked with mineral matters derived from the newly formed land,
or from hot springs in its own bottom. On this point the interesting
investigations of Dr. Hunt with reference to the chemical conditions
of the Silurian seas allow us to suppose that the Laurentian ocean may
have been much more richly stored, more especially with salts of lime
and magnesia, than that of subsequent times. Hence the conditions of
warmth, light, and nutriment required by such gigantic Protozoans would
all be present, and hence, also, no doubt, some of the peculiarities of
their mineralization.

I desire by the above statement of facts to show, on the one hand,
that the study of Eozoon, regarded as probably an ancient form of
marine life, aids us in understanding other ancient fossils, and their
manner of preservation; and on the other hand, that those who deny the
organic origin of Eozoon place us in the position of being unable, in
any rational manner, to account for these forms, so characteristic
of the Laurentian limestones, and set at naught the fair conclusions
deducible from the mode of preservation of fossils in the later
formations. The evidence of organic origin is perhaps not conclusive,
and in the present state of knowledge it is certain to be met with much
scepticism, more especially by certain classes of specialists, whose
grasp of knowledge is not sufficiently wide to cover, on the one hand,
fossilization and metamorphism, and on the other, to understand the
lower forms of life. It may, however, be sufficient to qualify us in
turning our thoughts for a few moments to considerations suggested by
the probable origin of animal life in the seas of the Laurentian period.

Looking down from the elevation of our physiological and mental
superiority, it is difficult to realize the exact conditions in which
life exists in creatures so simple as the Protozoa. There may perhaps
be higher intelligences, that find it equally difficult to realize how
life and reason can manifest themselves in such poor houses of clay
as those we inhabit. But placing ourselves near to these creatures,
and entering, as it were, into sympathy with them, we can understand
something of their powers and feelings. In the first place it is plain
that they can vigorously, if roughly, exercise those mechanical,
chemical, and vegetative powers of life which are characteristic of
the animal. They can seize, swallow, digest, and assimilate food; and,
employing its albuminous parts in nourishing their tissues, can burn
away the rest in processes akin to our respiration, or reject it from
their system. Like us, they can subsist only on food which the plant
has previously produced; for in this world, from the beginning of time,
the plant has been the only organism which could use the solar light
and heat as forces to enable it to turn the dead elements of matter
into living, growing tissues, and into organic compounds capable of
nourishing the animal. Like us, the Protozoa expend the food which
they have assimilated in the production of animal force, and in doing
so cause it to be oxidized, or burnt away, and resolved again into
dead matter. It is true that we have much more complicated apparatus
for performing these functions, but it does not follow that these give
us much real superiority, except relatively to the more difficult
conditions of our existence. The gourmand who enjoys his dinner may
have no more pleasure in the act than the Amœba which swallows a
Diatom; and for all that the man knows of the subsequent processes to
which the food is subjected, his interior might be a mass of jelly,
with extemporised vacuoles, like that of his humble fellow-animal. The
clay is after all the same, and there may be as much difficulty in the
making of a simple organism with varied powers, as a more complex frame
for doing higher work.

In order that we may feel, a complicated apparatus of nerves and brain
cells has to be constructed and set to work; but the Protozoon, without
any distinct brain, is all brain, and its sensation is simply direct.
Thus vision in these creatures is probably performed in a rough way by
any part of their transparent bodies, and taste and smell are no doubt
in the same case. Whether they have any perception of sound as distinct
from the mere vibrations ascertained by touch, we do not know. Here,
also, we are not far removed above the Protozoa, especially those of us
to whom touch, seeing and hearing are direct acts, without any thought
or knowledge of the apparatus employed. We might, so far, as well be
Amœbas. As we rise higher we meet with more differences. Yet it is
evident that our gelatinous fellow being can feel pain, dread danger,
desire possessions, enjoy pleasure, and in a direct unconscious way
entertain many of the appetites and passions that affect ourselves.
The wonder is that with so little of organization it can do so much.
Yet, perhaps, life can manifest itself in a broader and more intense
way where there is little organization, and a highly strung and complex
organism is not so much a necessary condition of a higher life as a
mere means of better adapting it to its present surroundings.

A similar lesson is taught by the complexity of their skeletons. We
speak in a crude, unscientific way of these animals accumulating
calcareous matter, and building up reefs of limestone. We must,
however, bear in mind that they are as dependent on their food for the
materials of their skeletons as we are, and that their crusts grow in
the interior of the sarcode just as our bones do within our bodies. The
provision even for nourishing the interior of the skeleton by tubuli
and canals is in principle similar to that involved in the canals,
cells, and canalicules of bone. The Amœba, of course, knows neither
more nor less of this than the average Englishman. It is altogether
a matter of unconscious growth. The process in the Protozoa strikes
some minds, however, as the more wonderful of the two. It is, says
an eminent modern physiologist, a matter of "profound significance"
that this "particle of jelly [the sarcode of a Foraminifer] is capable
of guiding physical forces in such a manner as to give rise to these
exquisite and almost mathematically arranged structures." Respecting
the structures themselves there is no exaggeration in this. No arch
or dome framed by human skill is more perfect in beauty or in the
realization of mechanical ideas than the tests of some Foraminifera,
and none is so complete and wonderful in its internal structure. The
particle of jelly, however, is a figure of speech. The body of the
humblest Foraminifer is much more than this. It is an organism with
divers parts, and it is endowed with the mysterious forces of life
which in it guide the physical forces, just as they do in building up
phosphate of lime in our bones, or indeed, just as the will of the
architect does in building a palace. The profound significance which
this has, reaches beyond the domain of the physical and vital, even
to the spiritual. It clings to all our conceptions of living things:
"quite as much, for example, to the evolution of an animal with all its
parts from a one-celled germ, as to the connection of brain cells with
the manifestations of intelligence." Viewed in this way, we may share
with the author of the sentence I have quoted his feeling of veneration
in the presence of this great wonder of animal life, "burning, and not
consumed," nay, building up, and that in many and beautiful forms. We
may realize it most of all in the presence of the organism which was
perhaps the first to manifest on our planet these marvellous powers.
We must, however, here also, beware of that credulity which makes too
many thinkers limit their conceptions altogether to physical force in
matters of this kind The merely materialistic physiologist is really in
no better position than the savage who quails before the thunderstorm,
or rejoices in the solar warmth, and seeing no force or power beyond,
fancies himself in the immediate presence of his God. In Eozoon we
must discern not only a mass of jelly but a being endowed with that
higher vital force which surpasses vegetable life, and also physical
and chemical forces; and in this animal energy we must see an emanation
from a Will higher than our own, ruling vitality itself; and this not
merely to the end of constructing the skeleton of a Protozoon, but
of elaborating all the wonderful developments of life that were to
follow in succeeding ages, and with reference to which the production
and growth of this creature were initial steps. It is this mystery of
design which really constitutes the "profound significance" of the
foraminiferal skeleton.

Another phenomenon of animality forced upon our notice by the Protozoa
is that of the conditions of life in animals not individual, as we
are, but aggregative and cumulative in indefinite masses. What, for
instance, the relations to each other of the Polyps, growing together
in a coral mass, or the separate parts of a Sponge, or the separate
lobes of a Foraminifer. In the case of the Polyps we may believe that
there is special sensation in the tentacles and oral opening of each
individual, and that each may experience hunger when in want, or
satisfaction when it is filled with food, and that injuries to one part
of the mass may indirectly affect other parts, but that the nutrition
of the whole mass may be as much unfelt by the individual Polyps as
the processes going on in our own liver are by us. So in the case of a
large Sponge, or Foraminifer, there may be some special sensation in
individual cells, pseudopods, or segments, and the general sensation
may be very limited, while unconscious living powers pervade the
whole. In this matter of aggregation of animals we have thus various
grades. The Foraminifers and Sponges present us with the simplest of
all, and that which most resembles the aggregation of buds in the
plant. The Polyps and complex Bryozoons present a higher and more
specialized type; and though the bilateral symmetry which obtains in
the higher animals is of a different nature, it still at least reminds
us of that multiplication of similar parts which we see in the lower
grades of being. It is worthy of notice here that the lower animals
which show aggregative tendencies present but imperfect indications, or
none at all, of bilateral symmetry. Their bodies, like those of plants,
are for the most part built up around a central axis, or they show
tendencies to spiral modes of growth.

It is this composite sort of life which is connected with the main
geological function of the Foraminifer. While active sensation,
appetite, and enjoyment pervade the pseudopods and external sarcode
of the mass, the hard skeleton common to the whole is growing within;
and in this way the calcareous matter is gradually removed from
the sea water, and built up in solid reefs, or in piles of loose
foraminiferal shells. Thus it is the aggregative or common life,
alike in Foraminifers as in Corals, that tends most powerfully to the
accumulation of calcareous matter; and those creatures whose life is
of this complex character are best suited to be world builders, since
the result of their growth is not merely a cemetery of their osseous
remains, but a huge communistic edifice, to which multitudes of lives
have contributed, and in which successive generations take up their
abode on the remains of their ancestors. This process, so potent in the
progress of the earth's geological history, began, as far as we know,
with Eozoon.

Whether, then, in questioning our proto-foraminifer, we have reference
to the vital functions of its gelatinous sarcode, to the complexity
and beauty of its calcareous test, or to its capacity for effecting
great material results through the union of individuals, we perceive
that we have to do, not with a low condition of those powers which we
designate life, but with their manifestation through the means of a
simple organism; and this in a degree of perfection which we, from our
point of view, would have in the first instance supposed impossible.

If we imagine a world altogether destitute of life, we still might
have geological formations in progress. Not only would volcanoes belch
forth their liquid lavas and their stones and ashes, but the waves and
currents of the ocean and the rains and streams on the land, with the
ceaseless decomposing action of the carbonic acid of the atmosphere,
would be piling up mud, sand, and pebbles in the sea. There might even
be some formation of limestone taking place where springs charged
with bicarbonate of lime were oozing out on the land or the bottom of
the waters. But in such a world all the carbon would be in the state
of carbon dioxide, and all the limestone would either be diffused in
small quantities through various rocks or in limited local beds, or
in solution, perhaps as chloride of calcium, in the sea. Dr. Hunt has
given chemical grounds for supposing that the most ancient seas were
largely supplied with this very soluble salt, instead of the chloride
of sodium, or common salt, which now prevails in the sea water.

Where in such a world would life be introduced? on the land or in the
waters? All scientific probability would say in the latter.[67] The
ocean is now vastly more populous than the land. The waters alone
afford the conditions necessary at once for the most minute and the
grandest organisms, at once for the simplest and for others of the most
complex character. Especially do they afford the best conditions for
those animals which subsist in complex communities, and which aggregate
large quantities of mineral matter in their skeletons. So true is this
that up to the present time all the species of Protozoa and of the
animals most nearly allied to them are aquatic. Even in the waters,
however, plant life, though possibly in very simple forms, must precede
the animal.

[67] A recent writer (Simroth) has, however, undertaken to maintain the
thesis that land life preceded that in the sea. It is unnecessary to
say that he is an evolutionist, influenced by the necessity laid upon
that philosophy to deduce whales, seals, etc., from land animals.

Let humble plants, then, be introduced in the waters, and they would
at once begin to use the solar light for the purpose of decomposing
carbonic acid, and forming carbon compounds which had not before
existed, and which, independently of vegetable life, would never have
existed. At the same time lime and other mineral substances present in
the sea water would be fixed in the tissues of these plants, either
in a minute state of division, as little grains or Coccoliths, or in
more solid masses like those of the Corallines and Nullipores. In this
way a beginning of limestone formation might be made, and quantities
of carbonaceous and bituminous matter, resulting from the decay of
vegetable substances might accumulate on the sea bottom. Now arises
the opportunity for animal life. The plants have collected stores
of organic matter, and their minute germs, along with microscopic
species, are floating everywhere in the sea. The plant has fulfilled
its function as far as the waters are concerned, and now a place is
prepared for the animal. In what form shall it appear? Many of its
higher forms, those which depend upon animal food or on the more
complex plants for subsistence, would obviously be unsuitable. Further,
the sea water is still too much saturated with saline matter to be
fit for the higher animals of the waters. Still further, there may
be a residue of internal heat forbidding coolness, and that solution
of free oxygen which is an essential condition of existence to the
higher forms of life. Something must be found suitable for this saline,
imperfectly oxygenated, tepid sea. Something, too, is wanted that can
aid in introducing conditions more favourable to higher life in the
future. Our experience of the modern world shows us that all these
conditions can be better fulfilled by the Protozoa than by any other
creatures. They can live now equally in those great depths of ocean
where the conditions are most unfavourable to other forms of life,
and in tepid unhealthy pools overstocked with vegetable matter in a
state of putridity. They form a most suitable basis for higher forms
of life. They have remarkable powers of removing mineral matters from
the waters and of fixing them in solid forms. So, in the fitness of
things, a gigantic Foraminifer is just what we need, and after it has
spread itself over the mud and rock of the primeval seas, and built up
extensive reefs therein, other animals may be introduced, capable of
feeding on it, or of sheltering themselves in its stony masses, and
thus we have the appropriate dawn of animal life.

But what are we to say of the cause of this new series of facts, so
wonderfully superimposed upon the merely vegetable and mineral? Must
it remain to us as an act of creation, or was it derived from some
pre-existing matter in which it had been potentially present? Science
fails to inform us, but conjectural "phylogeny" steps in and takes its
place. Haeckel, the prophet of this new philosophy, waves his magic
wand, and simple masses of sarcode spring from inorganic matter, and
form diffused sheets of sea slime, from which are in time separated
distinct amœboid and foraminiferal forms. Experience, however, gives us
no facts whereon to build this supposition, and it remains neither more
nor less scientific or certain than that old fancy of the Egyptians,
which derived animals from the fertile mud of the Nile.

If we fail to learn anything of the origin of Eozoon, and if its life
processes are just as inscrutable as those of higher creatures, we
can at least enquire as to its history in geological time. In this
respect we find, in the first place, that the Protozoa have not had a
monopoly in their profession of accumulators of calcareous rock.

Originated by Eozoon in the old Laurentian time, this process has
been proceeding throughout the geological ages; and while Protozoa,
equally simple with the great prototype of the race, have been and
are continuing its function, and producing new limestones in every
geological period, and so adding to the volume of the successive
formations, new workers of higher grades have been introduced, capable
of enjoying higher forms of animal activity, and equally of labouring
at the great task of continent building; of existing, too, in seas
less rich in mineral substances than those of the Eozoic time, and for
that very reason better suited to higher and more skilled artists. It
is to be observed in connection with this, that as the work of the
Foraminifers has thus been assumed by others, their size and importance
have diminished, and the larger forms of more recent times have some of
them been fain to build up their hard parts of cemented sand instead of
limestone.

When the marvellous results of recent deep-sea dredgings were first
made known, and it was found that chalky foraminiferal earth is yet
accumulating in the Atlantic, with sponges and sea urchins, resembling
in many respects those whose remains exist in the chalk, the fact was
expressed by the statement that we still live in the chalk period.
Thus stated the conclusion is scarcely correct. We do not live in the
chalk period, but the conditions of the chalk period still exist in the
deeper portions of the sea. We may say more than this. To some extent
the conditions of the Laurentian period still exist in the sea, except
in so far as they have been removed by the action of the Foraminifera
and other limestone builders. To those who can realize the enormous
lapse of time involved in the geological history of the earth, this
conveys an impression almost of eternity in the existence of this
oldest of all the families of the animal kingdom.

We are still more deeply impressed with this when we bring into view
the great physical changes which have occurred since the dawn of life.
When we consider that the skeletons of Eozoon contribute to form the
oldest hills of our continents; that they have been sealed up in solid
marble, and that they are associated with hard crystalline rocks
contorted in the most fantastic manner; that these rocks have almost
from the beginning of geological time been undergoing waste to supply
the material of new formations; that they have witnessed innumerable
subsidences and elevations of the continents; and that the greatest
mountain chains of the earth have been built up from the sea since
Eozoon began to exist,--we acquire a most profound impression of the
persistence of the lower forms of animal life, and know that mountains
may be removed and continents swept away and replaced, before the least
of the humble gelatinous Protozoa can finally perish. Life may be a
fleeting thing in the individual, but as handed down through successive
generations of beings, and as a constant animating power in successive
organisms, it appears, like its Creator, eternal.

This leads to another and very serious question. How long did lineal
descendants of Eozoon exist, and do they still exist? We may for the
present consider this question apart from ideas of derivation and
elevation into higher planes of existence. Eozoon as a species, and
even as a genus, may cease to exist with the Eozoic age, and we have
no evidence whatever that any succeeding creatures are its modified
descendants. As far as their structures inform us, they may as much
claim to be original creations as Eozoon itself. Still descendants of
Eozoon may have continued to exist, though we have not yet met with
them. I should not be surprised to hear of a veritable specimen being
some day dredged alive in the Atlantic or the Pacific. It is also
to be observed that in animals so simple as this many varieties may
appear, widely different from the original. In these the general form
and habit of life are the most likely things to change, the minute
structures much less so. We need not, therefore, be surprised to find
its descendants diminishing in size or altering in general form, while
the characters of the fine tubulation and of the canal system would
remain. We need not wonder if any sessile Foraminifer of the Nummuline
group should prove to be a descendant of Eozoon. It would be less
likely that a Sponge or a Foraminifer of the Rotaline type should
originate from it. If one could only secure a succession of deep-sea
limestones with Foraminifers extending all the way from the Laurentian
to the present time, I can imagine nothing more interesting than to
compare the whole series, with the view of ascertaining the limits of
descent with variation, and the points where new forms are introduced.
We have not yet such a series, but it may be obtained; and as these
creatures are eminently cosmopolitan, occurring over vastly wide areas
of sea bottom, and are very variable, they would afford a better test
of theories of derivation than any that can be obtained from the more
locally distributed and less variable animals of higher grade. I was
much struck with this recently, in examining a series of Foraminifera
from the Cretaceous of Manitoba, and comparing them with the varietal
forms of the same species in the interior of Nebraska, 500 miles to the
south, and with those of the English chalk and of the modern seas. In
all these different times and places we had the same species. In all
they existed under so many varietal forms passing into each other, that
in former times every species had been multiplied by naturalists into
several. Yet, in all, the identical varietal forms were repeated with
the most minute markings the same. Here were at once constancy the most
remarkable, and variations the most extensive. If we dwell on the one
to the exclusion of the other, we reach only one-sided conclusions,
imperfect and unsatisfactory. By taking both into connection we can
alone realize the full significance of the facts. We cannot yet obtain
such series for all geological time; but it may even now be worth while
to enquire, What do we know as to any modification in the case of the
primeval Foraminifers, whether with reference to the derivation from
them of other Protozoa or of higher forms of life?

There is no link in geological fact to connect Eozoon with any of the
Mollusks, Radiates, or Crustaceans of the succeeding Cambrian. What
may be discovered in the future we cannot conjecture; but at present
these stand before us as distinct creations. It would of course be more
probable that Eozoon should be the ancestor of some of the Foraminifera
of the Primordial age, but strangely enough it is very dissimilar
from all these, except Cryptozoum and some forms of Stromatopora; and
here, as already stated, the evidence of minute structure fails to
a great extent. Of actual facts, therefore, we have none; and those
evolutionists who have regarded the dawn animal as an evidence in their
favour have been obliged to have recourse to supposition and assumption.

We may imagine Eozoon itself, however, to state its experience as
follows:--"I, Eozoon Canadense, being a creature of low organization
and intelligence, and of practical turn, am no theorist, but have a
lively appreciation of such facts as I am able to perceive. I found
myself growing upon the sea bottom, and know not whence I came. I grew
and flourished for ages, and found no let or hindrance to my expansion,
and abundance of food was always floated to me without my having to go
in search of it. At length a change came. Certain creatures with hard
snouts and jaws began to prey on me. Whence they came I know not; I
cannot think that they came from the germs which I had dispersed so
abundantly throughout the ocean. Unfortunately, just at the same time
lime became a little less abundant in the waters, perhaps because of
the great demands I myself had made, and thus it was not so easy as
before to produce a thick supplemental skeleton for defence. So I had
to give way. I have done my best to avoid extinction; but it is clear
that I must at length be overcome, and must either disappear or subside
into a humbler condition, and that other creatures better provided for
the new conditions of the world must take my place." In such terms we
may suppose that this patriarch of the seas might tell his history, and
mourn his destiny, though he might also congratulate himself on having
in an honest way done his duty and fulfilled his function in the world,
leaving it to other and perhaps wiser creatures to dispute as to his
origin and fate, while perhaps much less perfectly fulfilling the ends
of their own existence.

Thus our dawn animal has positively no story to tell as to its own
introduction or its transmutation into other forms of existence.
It leaves the mystery of creation where it was, but in connection
with the subsequent history of life we can learn from it a little
as to the laws which have governed the succession of animals in
geological time. First, we may learn that the plan of creation has
been progressive, that there has been an advance from the few low and
generalized types of the primæval ocean to the more numerous, higher,
and more specialized types of more recent times. Secondly, we learn
that the lower types, when first introduced, and before they were
subordinated to higher forms of life, existed in some of their grandest
modifications as to form and complexity, and that in succeeding ages,
when higher types were replacing them, they were subjected to decay and
degeneracy. Thirdly, we learn that while the species has a limited term
of existence in geological time, any large type of animal existence,
like that of the Foraminifera or Sponges, for example, once introduced,
continues and finds throughout all the vicissitudes of the earth some
appropriate residence. Fourthly, as to the mode of introduction of new
types, or whether such creatures as Eozoon had any direct connection
with the subsequent introduction of Mollusks, Worms, or Crustaceans, it
is altogether silent, nor can it predict anything as to the order or
manner of their introduction.

Had we been permitted to visit the Laurentian seas, and to study Eozoon
and its contemporary Protozoa when alive, it is plain that we could not
have foreseen or predicted from the consideration of such organisms
the future development of life. No amount of study of the prototypal
Foraminifer could have led us distinctly to the conception of even a
Sponge or a Polyp, much less of any of the higher animals. Why is this?
The answer is that the improvement into such higher types does not
take place by any change of the elementary sarcode, either in those
chemical, mechanical, or vital properties which we can study, but in
the adding to it of new structures. In the Sponge, which is perhaps
the nearest type of all, we have the movable pulsating cilium and true
animal cellular tissue, and along with this the spicular or fibrous
skeleton, these structures leading to an entire change in the mode of
life and subsistence. In the higher types of animals it is the same.
Even in the highest we have white blood corpuscles and germinal matter,
which, in so far as we know, carry on no higher forms of life than
those of an Amœba; but they are now made subordinate to other kinds
of tissues, of great variety and complexity, which never have been
observed to arise out of the growth of any Protozoon. There would be
only a few conceivable inferences which the highest finite intelligence
could deduce as to the development of future and higher animals. He
might infer that the Foraminiferal sarcode, once introduced, might be
the substratum or foundation of other but unknown tissues in the higher
animals, and that the Protozoon type might continue to subsist side
by side with higher forms of living things, as they were successively
introduced. He might also infer that the elevation of the animal
kingdom would take place with reference to those new properties of
sensation and voluntary motion in which the humblest animals diverge
from the life of the plant.

It is important that these points should be clearly before our minds,
because there has been current of late among naturalists a loose way
of writing with reference to them, which seems to have imposed on many
who are not naturalists. It has been said, for example, that such an
organism as Eozoon may include potentially all the structures and
functions of the higher animals, and that it is possible that we might
be able to infer or calculate all these with as much certainty as we
can calculate an eclipse or any other physical phenomenon. Now, there
is not only no foundation in fact for these assertions, but it is, from
our present standpoint, not conceivable that they can ever be realized.
The laws of inorganic matter give no data whence any _à priori_
deductions or calculations could be made as to the structure and
vital forces of the plant. The plant gives no data from which we can
calculate the functions of the animal. The Protozoon gives no data from
which we can calculate the specialties of the Mollusk, the Articulate,
or the Vertebrate. Nor, unhappily, do the present conditions of life of
themselves give us any sure grounds for predicting the new creations
that may be in store for our old planet. Those who think to build a
philosophy and even a religion on such data are mere dreamers, and have
no scientific basis for their dogmas. They are as blind guides as our
primæval Protozoon himself would be in matters whose real solution lies
in the harmony of our own higher and immaterial nature with the Being
who is the Author of all life--the Father "from whom every family in
heaven and earth is named."

  References:--"Life's Dawn on Earth." London, 1885. Specimens of
    Eozoon in the Peter Redpath Museum, Montreal, 1888.




           _THE APPARITION AND SUCCESSION OF ANIMAL FORMS._


                      DEDICATED TO THE MEMORY OF

               THE EMINENT SWISS AND AMERICAN ZOOLOGIST

                            LOUIS AGASSIZ,

         The Founder of the Modern School of American Biology,

                                and of

                           SIR RICHARD OWEN,

                 A Great and Philosophical Naturalist,

       to whose Teaching I and very many Others owe our earliest

               introduction to the Principle of Homology

                        in the Animal Kingdom.


Modern Ideas of Derivation--Development of Animal Forms in
Time--Various Theories of Derivation--History of Organic Types--History
of Organs--Testimony of the Geological Record--Laws of the Succession
Development and Evolution--Evolutionist Theologians

[Illustration: Old Forms of Trilobites, from the Lower Cambrian
  (p. 173 _et seq._)

  _Olenellus Thompsoni_, Emmons.
  _Agnostus vir_, Matthew.
  _Paradoxides regina_, Matthew.]




CHAPTER VII.

_THE APPARITION AND SUCCESSION OF ANIMAL FORMS._


Time was when naturalists were content to take nature as they found
it, without any over-curious inquiries as to the origin of its several
parts, or the changes of which they might be susceptible. Geology
first removed this pleasant state of repose, by showing that all our
present species had a beginning, and were preceded by others, and these
again by others. Geologists were, however, too much occupied with the
facts of the succession to speculate on the ultimate causes of the
appearance and disappearance of species, and it remained for zoologists
and botanists, or as some prefer to call themselves, biologists, to
construct hypotheses or theories to account for the ascertained fact
that successive dynasties of species have succeeded each other in
time. I do not propose in this paper so much to deal with the various
doctrines as to derivation and development now current, as to ask the
question, What do we actually know as to the origin and history of life
on our planet?

This great question, confessedly accompanied with many difficulties and
still waiting for its full solution, has points of intense interest
both for the Geologist and the Biologist. "If," says the great
founder of the uniformitarian School of Geology, "the past duration
of the earth be finite, then the aggregate of geological epochs,
however numerous, must constitute a mere moment of the past, a mere
infinitesimal portion of eternity." Yet to our limited vision, the
origin of life fades away in the almost illimitable depths of past
time, and we are ready to despair of ever reaching, by any process of
discovery, to its first steps of progress. At what time did life begin?
In what form did dead matter first assume or receive those mysterious
functions of growth, reproduction and sensation? Only when we picture
to ourselves an absolutely lifeless world, destitute of any germ of
life or organization, can we realize the magnitude of these questions,
and perceive how necessary it is to limit their scope if we would hope
for any satisfactory answer.

We may here dismiss altogether that form in which these questions
present themselves to the biologist, when he experiments as to the
evolution of living forms from dead liquids or solids attacking the
unsolved problem of spontaneous generation. Nor need we enter on the
vast field of discussion as to modern animals and plants opened up by
Darwin and others. I shall confine myself altogether to that historical
or palæontological aspect in which life presents itself when we study
the fossil remains entombed in the sediments of the earth's crust, and
which will enable me at least to show why some students of fossils
hesitate to give in their adhesion to any of the current notions as to
the origin of species. It will also be desirable to avoid, as far as
possible, the use of the term "evolution," as this has recently been
employed in so many senses, whether of development or causation, as to
have become nearly useless for any scientific purpose; and that when I
speak of creation of species, the term is to be understood not in the
arbitrary sense forced on it by some modern writers, but as indicating
the continuous introduction of new forms of life under definite laws,
but by a power not emanating from within themselves, nor from the
inanimate nature surrounding them.[68]

[68] The terms Derivation, Development and Causation have clear and
definite meanings, and it is preferable, wherever possible, to use one
or other of these.

If we were to follow the guidance of those curious analogies which
present themselves when we consider the growth of the individual
plant or animal from the spore or the ovum, and the development of
vegetable and animal life in geological time--analogies which, however,
it must be borne in mind can have no scientific value whatever,
inasmuch as that similarity of conditions which alone can give force
to reasoning from analogy in matters of science, is wholly wanting--we
should expect to find in the oldest rocks embryonic forms alone, but
of course embryonic forms suited to exist and reproduce themselves
independently.[69]

[69] I may be pardoned for taking an example of the confusion of
thought which this mode of reasoning has introduced into Biology
from a clever article in the _Contemporary_ written by a very able
and much-esteemed biologist. He says: "The morphological distance
between a newly hatched frog's tadpole and the adult frog is almost
as great as that between the adult lancelet and the newly hatched
larvæ of the lamprey." The "morphological distance" truly, but what
of the physiological distance between the young and adult of the same
animal and two adult animals between which is placed the great gulf of
specific and generic diversity which within human experience neither
has been known to pass?

I need not say to palæontologists that this is not what we actually
find in the primordial rocks. I need but to remind them of the early
and remarkable development of such forms as the Trilobites, the
Lingulidæ and the Pteropods, all of them highly complex and specialized
types, and remote from the embryonic stages of the groups to which
they severally belong. In the case of the Trilobites, one need merely
consider the beautiful symmetry of their parts, both transversely and
longitudinally, their division into distinct regions, the necessary
complexity of their muscular and nervous systems, their highly complex
visual organs, the superficial ornamentation and microscopic structure
of their crusts, their advanced position among Crustaceans, indicated
by their strong affinity with the Arachnidans or spiders and scorpions.
(See figures prefixed.)

All these characters give them an aspect far from embryonic, while, as
Barrande has pointed out, this advanced position of the group has its
significance greatly strengthened by the fact that in early primordial
times we have to deal not with one species, but with a vast and highly
differentiated group, embracing forms of many and varied subordinate
types. As we shall see, these and other early animals may be regarded
as of generalized types, but not as embryonic. Here, then, meets us at
the outset the fact that in as far as the great groups of annulose and
molluscous animals are concerned, we can trace these back no farther
than to a period in which they appear already highly advanced, much
specialized and represented by many diverse forms. Either, therefore,
these great groups came in on this high initial plane, or we have
scarcely reached half way back in the life-history of our planet.

We have, here, however, by this one consideration, attained at once to
two great and dominant laws regulating the history of life. First, the
law of continuity, whereby new forms come in successively, throughout
geological time, though, as we shall see, with periods of greater or
less frequency. Secondly, the law of specialization of types, whereby
generalized forms are succeeded by those more special, and this
probably connected with the growing specialization of the inorganic
world. It is this second law which causes the parallelism between the
history of successive species and that of the embryo.

We have already considered the claims which Eozoon and its
contemporaries may urge to recognition, as beginnings of life; but
when we ascend from the Laurentian beds, we find ourselves in a barren
series of conglomerates, sandstones, and other rocks, indicating shore
rather than sea conditions, and remarkably destitute of indications of
life. These are the Huronian beds, and possibly other series associated
with them. They have afforded spicules of sponges, casts of burrows
of worms, obscure forms, which may represent crustaceans or mollusks,
markings of unknown origin, and some laminated forms which may perhaps
represent remains of Eozoon, though their structures are imperfectly
preserved. These are sufficient to show that marine life continued in
some forms, and to encourage the hope that a rich pre-Cambrian fauna
may yet be discovered.

But let us leave for the present the somewhat isolated case of Eozoon,
and the few scattered forms of the Huronian, and go on farther to
the early Cambrian fauna. This is graphically presented to us in
the sections in South Wales, as described by Hicks. Here we find a
nucleus of ancient rocks, supposed to be Laurentian, though in mineral
character more nearly akin to the Huronian, but which have hitherto
afforded no trace of fossils. Resting unconformably on these is a
series of slates and sandstones, regarded as Lower Cambrian, the
Caerfai group of Hicks, and which are the earliest holding organic
remains. The lowest bed which contains indications of life is a red
shale near the base of the series, which holds a few organic remains.
The species are a _Lingulella_, worm burrows and a Trilobite.[70]
Supposing these to be all, it is remarkable that we have no Protozoa
or Corals or Echinoderms, and that the types of Brachiopods and
Crustaceans are of comparatively modern affinities. Passing upward
through 1,000 feet of barren sandstone and shale, we reach a zone in
which many Trilobites of at least five genera are found, along with
Pteropods, Brachiopods and Sponges. Thus it is that life comes in at
the base of the Cambrian in Wales, and it may be regarded as a fair
specimen of the facts as they appear in the earlier fossiliferous beds
succeeding the Laurentian. Taking the first of these groups of fossils,
we may recognise in the worms representatives of those that still
haunt our shores, in the Trilobite a Crustacean or Arachnoid of no
mean grade. The _Lingulellæ_, whether we regard them as molluscoids,
or, with Professor Morse, as singularly specialized worms, represent a
peculiar and distinct type, handed down, through all the vicissitudes
of the geological ages, to the present day. Had the Primordial life
begun with species altogether inscrutable and unexampled in succeeding
ages, this would no doubt have been mysterious; but next to this is
the mystery of the oldest forms of life being also among the newest.
One great fact shines here with the clearness of noon-day. Whatever
the origin of these creatures, they represent families which have
endured till now in the struggle for existence without either elevation
or degradation. Here, again, we may formulate another creative law.
In every great group there are some forms much more capable of long
continuance than others. Lingula among the Brachiopods is a marked
instance.

[70] Probably of the genus Olenellus.

But when, with Hicks, we surmount the mass of barren beds underlying
these remains, which from its unfossiliferous character is probably a
somewhat rapid deposit of Arctic mud, like that which in all geological
time has constituted the rough filling of our continental formations,
and have suddenly sprung upon us many genera of Trilobites, including
the fewest-jointed and most many-jointed, the smallest and the largest
of their race, our astonishment must increase, till we recognise the
fact that we are now in the presence of another great law of creation,
which provides that every new type shall be rapidly extended to the
extreme limits of its power of adaptation.

That this is not merely local is evidenced by the researches of
Matthew and Walcott in the oldest Cambrian of America, where a similar
succession occurs, but with this difference, that in the wider area
presented by the American continent we find a greater variety of
forms of life. Walcott records up to 1892 no less than 67 genera
and 165 species in the oldest Cambrian of America. These include
representatives of the Sponges, Hydroids, Corals, Echinoderms, Worms,
Brachiopods, Bivalve and Univalve Mollusks and Crustaceans, or in
other words, all the leading groups of invertebrate animals that
we find in the sea at present. Of these the dominant group is the
Crustaceans, including Trilobites, numbering one-third of the whole;
and these with the univalve Mollusks and the Brachiopods constitute
the majority, the other groups having comparatively few species. What
a marvellous incoming of life is here! Walcott may well say that on
the theory of gradual development we must suppose that life existed at
a period far before the Cambrian--as far, indeed, as the Cambrian is
before our own time. But this would mean that we know only half of the
history of life; and perhaps it is more reasonable to suppose that when
the conditions became favourable, it came in with a rush.

Before considering the other laws that may be inferred from these
facts, however, let us in imagination transfer ourselves back to the
Primordial age, and suppose that we have in our hands a living specimen
of one of the larger Trilobites, recently taken from the sea, flapping
vigorously its great tail, and full of life and energy; an animal
larger and heavier than the modern king-crab of our shores, furnished
with all the complexity of external parts for which the crustaceans are
so remarkable, and no doubt with instincts and feelings and modes of
action as pronounced as those of its modern allies, and, if Woodward's
views are correct, on a higher plane of rank than the king-crab itself,
inasmuch as it is a composite type connecting Limuli with Isopods,
and even with scorpions. We have obviously here, in the appearance of
this great Crustacean or Arachnoid, a repetition of the facts which
we met with in Eozoon; but how vast the interval between them in
geological time, and in zoological rank! Standing in the presence of
this testimony, I think it is only right to say that we possess no
causal solution of the appearance of these early forms of life; but in
tracing them and their successors upward through the succeeding ages,
we may hope at least to reach some expressions of the laws of their
succession, in possession of which we may return to attack the mystery
of their origin.

First, it must strike every observer that there is a great sameness
of plan throughout the whole history of marine invertebrate life. If
we turn over the pages of an illustrated text-book of geology, or
examine the cases or drawers of a collection of fossils, we shall find
extending through every succeeding formation, representative forms of
Crustaceans, Mollusks, Corals, etc., in such a manner as to indicate
that in each successive period there has been a reproduction of the
same type with modifications; and if the series is not continuous, this
appears to be due rather to abrupt physical changes; since sometimes,
where two formations pass into each other, we find a gradual change in
the fossils by the dropping out and introduction of species one by one.
Thus, in the whole of the great Palæozoic Period, both in its Fauna and
Flora, we have a continuity and similarity of a most marked character.

It is evident that there is presented to us in this similarity of the
forms of successive faunas and floras, a phenomenon which deserves very
careful sifting as to the question of identity or diversity of species.
The data for its comprehension must be obtained by careful study of
the series of closely allied forms occurring in successive formations,
and the great and undisturbed areas of the older rocks in America seem
to give special facilities for this, which should be worked, not in
the direction of constituting new species for every slightly divergent
form, but in striving to group these forms into large specific
types.[71]

[71] The Rynchonellæ of the type of _R. plena_, the Orthids, of
the type of _O. testudinaria_, the Strophomenæ of the types of _S.
alternata_ and _S. Rhomboidalis_, the Atrypæ of the type of _A.
reticularis_, furnish cases in point among the Brachiopods.

There is nothing to preclude the supposition that some of the groups
mentioned in the note are really specific types, with numerous race
modifications. My own provisional conclusion, based on the study of
Palæozoic plants, is that the general law will be found to be the
existence of distinct specific types, independent of each other, but
liable in geological time to a great many modifications, which have
often been regarded as distinct species.[72]

[72] "Geological History of Plants."

While this unity of successive faunæ at first sight presents an
appearance of hereditary succession, it loses much of this character
when we consider the number of new types introduced without apparent
predecessors, the necessity that there should be similarity of type
in successive faunæ on any hypothesis of a continuous plan; and above
all, the fact that the recurrence of representative species or races
in large proportion marks times of decadence rather than of expansion
in the types to which they belong. To turn to another period, this is
very manifest in that singular resemblance which obtains between the
modern mammals of South America and Australia, and their immediate
fossil predecessors--the phenomenon being here manifestly that of
decadence of large and abundant species into a few depauperated
representatives. This will be found to be a very general law, elevation
being accompanied by the apparent abrupt appearance of new types and
decadence by the apparent continuation of old species, or modifications
of them.

This resemblance with difference in successive faunas also connects
itself very directly with the successive elevations and depressions
of our continental plateaus in geological time. Every great Palæozoic
limestone, for example, indicates a depression with succeeding
elevation. On each elevation marine animals were driven back into the
ocean, and on each depression swarmed in over the land, reinforced
by new species, either then introduced, or derived by migration from
other localities. In like manner, on every depression, land plants and
animals were driven in upon insular areas, and on re-elevation, again
spread themselves widely. Now I think it will be found to be a law here
that periods of expansion were eminently those of introduction of new
specific types, and periods of contraction those of extinction, and
also of continuance of old types under new varietal forms.

It must also be noticed that all the leading types of invertebrate
life were early introduced, that change within these was necessarily
limited, and that elevation could take place mainly by the introduction
of the vertebrate orders. So in plants, Cryptogams early attained
their maximum as well as Gymnosperms, and elevation occurred in the
introduction of Phænogams, and this not piecemeal, but as we shall see
in a succeeding chapter, in great force at once.

We may further remark the simultaneous appearance of like types of life
in one and the same geological period, over widely separated regions of
the earth's surface. This strikes us especially in the comparatively
simple and homogeneous life-dynasties of the Palæozoic, when, for
example, we find the same types of Silurian Graptolites, Trilobites and
Brachiopods appearing simultaneously in Australia, America and Europe.
Perhaps in no department is it more impressive than in the introduction
of the Devonian and Carboniferous Ages of that grand cryptogamous
and gymnospermous flora which ranges from Brazil to Spitzbergen, and
from Australia to Scotland, accompanied in all by the same groups of
marine invertebrates. Such facts may depend either on that long life of
specific types which gives them ample time to spread to all possible
habitats, before their extinction, or on some general law whereby the
conditions suitable to similar types of life emerge at one time in all
parts of the world. Both causes may be influential, as the one does
not exclude the other, and there is reason to believe that both are
natural facts. Should it be ultimately proved that species allied and
representative, but distinct in origin, come into being simultaneously
everywhere, we shall arrive at one of the laws of creation, and one
probably connected with the gradual change of the physical conditions
of the world.

Another general truth, obvious from the facts which have been already
collected, is the periodicity of introduction of species. They come
in by bursts or flood tides at particular points of time, while these
great life waves are followed and preceded by times of ebb in which
little that is new is being produced. We labour in our investigation of
this matter under the disadvantage that the modern period is evidently
one of the times of pause in the creative work. Had our time been
that of the early Tertiary or early Mesozoic, our views as to the
question of origin of species might have been very different. It is a
striking fact, in illustration of this, that since the glacial age no
new species of mammal, except, possibly, man himself, can be proved to
have originated on our continents, while a great number of large and
conspicuous forms have disappeared. It is possible that the proximate
or secondary causes of the ebb and flow of life production may be in
part at least physical, but other and more important efficient causes
may be behind these. In any case these undulations in the history of
life are in harmony with much that we see in other departments of
nature.

It results from the above and the immediately preceding statement,
that specific and generic types enter on the stage in great force,
and gradually taper off towards extinction. They should so appear in
the geological diagrams made to illustrate the succession of living
beings. This applies even to those forms of life which come in with
fewest species and under the most humble guise. What a remarkable
swarming, for example, there must have been of Marsupial Mammals in
the early Mesozoic, and in the Coal formation the only known Pulmonate
snails, five or six in number, belong to four generic types, while the
Myriapods and Amphibians alike appear in a crowd of generic forms.

I have already referred to the permanence of species in geological
time. We may now place this in connection with the law of rapid
origination and more or less continuous transmission of varietal forms.
A good illustration will be afforded by a group of species with which
I am very familiar, that which came into our seas at the beginning of
the Glacial age, and still exists. With regard to their permanence, it
can be affirmed that the shells now elevated in Wales to 1,200, and in
Canada to 600 feet above the sea, and which lived before the last great
revolution of our continents a period very remote as compared with
human history--differ in no tittle from their modern successors after
hundreds or thousands of generations. It can also be affirmed that the
more variable species appear under precisely the same varietal forms
then as now, though these varieties have changed much in their local
distribution. The real import of these statements, which might also
be made with regard to other groups, well known to palæontologists,
is of so great significance that it can be realized only after we
have thought of the vast time and numerous changes through which
these humble creatures have survived. I may call in evidence here a
familiar New England animal, the common sand clam, _Mya arenaria_, and
its relative _Mya truncata_, the short sand clam, which now inhabit
together all the northern seas; for the Pacific specimens, from Japan
and California, though differently named, are undoubtedly the same.
_Mya truncata_ appears in Europe in the Coralline Crag, and was
followed by _M. arenaria_ in the Red Crag. Both shells occur in the
Pleistocene of America, and their several varietal forms had already
developed themselves in the Crag, and remain the same to-day; so that
these humble mollusks, littoral in their habits, and subjected to a
great variety of conditions, have continued for a very long period
to construct their shells precisely as at present; while in many
places, as on the Lower St. Lawrence, we find them living together on
the same banks, and yet preserving their distinctness.[73] Nor are
there any indications of a transition between the two species. I might
make similar statements with regard to the Astartes, Buccinums and
Tellinæ of the drift, and could illustrate them by extensive series of
specimens from my own collections.

[73] Paper in _Record of Science_, on Shells at Little Metis.

Another curious illustration is that presented by the Tertiary and
modern faunæ of some oceanic islands far separated from the continents.
In Madeira and Porto Santo, for example, according to Lyell, we have
fifty-six species of land shells in the former, and forty-two in the
latter, only twelve being common to the two, though these islands are
only thirty miles apart. Now in the Pliocene strata of Madeira and
Porto Santo we find thirty-six species in the former, and thirty-five
in the latter, of which only eight per cent, are extinct, and yet
only eight are common to the two islands. Further, there seem to be
no transitional forms connecting the species, and of some of them the
same varieties existed in the Pliocene as now. The main difference
in time is the extinction of some species and the introduction of
others without known connecting links, and the fact that some species,
plentiful in the Pliocene, are rare now, and _vice versâ_. All these
shells differ from those of modern Europe, but some of them are allied
to Miocene species of that continent. Here we have a case of continued
existence of the same forms, and in circumstances which, the more we
think of them, the more do they defy all our existing theories as to
specific origins.

Perhaps some of the most remarkable facts in connection with the
permanence of varietal forms of species are those furnished by that
magnificent flora which burst in all its majesty on the American
continent in the Cretaceous period, and still survives among us, even
in some of its specific types. I say survives; for we have but a
remnant of its forms living, and comparatively little that is new has
probably been added since. The confusion which has obtained as to the
age of this flora, and its mistaken reference to the Miocene Tertiary,
have arisen in part from the fact that this modern flora was in its
earlier times contemporary with Cretaceous animals, and survived the
gradual change from the animal life of the Cretaceous down to that of
the Eocene, and even of the Miocene. In collections of these plants,
from what may be termed beds of transition from the Cretaceous to the
Tertiary, we find many plants of modern species, or so closely related
that they may be mere varietal forms. Some of these will be mentioned
in the next paper, and they show that modern plants, some of them
small and insignificant, others of gigantic size, reach back to a time
when the Mesozoic Dinosaurs were becoming extinct, and the earliest
Placental mammals being introduced. Shall we say that these plants
have propagated themselves unchanged for half a million of years, or
more?[74]

[74] Among these are living species of ferns, one of them our common
"Sensitive Fern," of Eastern America, two species of Hazel still
extant, and Sequoias or giant pines, like those now surviving in
California.

Take from the western Mesozoic a contrasting yet illustrative fact. In
the lowest Cretaceous rocks of Queen Charlotte's Island, Mr. Richardson
and Dr. G. M. Dawson find Ammonites and allied Cephalopods similar
in many respects to those discovered farther south by the California
Survey, and Mr. Whiteaves finds that some of them are apparently
not distinct from species described by the Palæontologists of the
Geological Survey of British India. On both sides of the Pacific these
shells lie entombed in solid rock, and the Pacific rolls between, as
of yore. Yet these species, genera, and even families are all extinct
why, no man can tell, while land plants that must have come in while
the survivors of these Cephalopods still lived, reach down to the
present. How mysterious is all this, and how strongly does it show the
independence in some sense of merely physical agencies on the part of
the manifestations of life!

We have naturally been occupied hitherto with the lower tribes of
animals and with plant life, because these are predominant in the
early ages of the earth. Let us turn now to the history of vertebrate
or back-boned animals, which presents some peculiarities special to
itself. Many years ago Pander[75] described and figured from the
Cambro-Silurian of Russia, a number of minute teeth, some conical and
some comb-like, which he referred to fishes, and to that low form
of the fish type represented by the modern lampreys. Much doubt was
thrown on this determination, more especially as the teeth seemed
to be composed not of bone earth, but of carbonate of lime, and it
was suggested that they may have belonged to marine worms, or to the
lingual ribbons of Gastropod mollusks. Some confirmatory evidence seems
to have been supplied by the discovery of great numbers of similar
forms in the shales of the coal formation of Ohio, by the late Dr.
Newberry. I have had an opportunity to examine these, and find that
they consist of calcium phosphate,[76] or bone earth, and that their
microscopic structure is not dissimilar from that of the teeth of some
of the smaller sharks (Diplodus) found with them. I have therefore
been inclined to believe that there may have already been, even in the
Cambrian or Lower Silurian seas, true fishes, related partly to the
lampreys and partly to sharks; so that the history of the back-boned
animals may have gone nearly as far back as that of their humbler
relations. This conjecture has recently received further support
from the discovery in rocks of Lower Silurian age, in Colorado of a
veritable bone bed, rich in fragmentary remains of fishes. They are
unfortunately so comminuted as to resemble the _débris_ of the food
of some larger animal; but in so far as I can judge from specimens
kindly given to me,[77] they resemble the bony coverings of some of
the familiar fishes of the Devonian. Thus they would indicate, with
Pander's and Rohan's specimens, already two distinct types of fishes as
existing almost as early as the higher invertebrates of the sea.

[75] More recently Rohan has described conical teeth (St. Petersburg
Academy, 1889), but I have not seen his paper.

[76] Analysis of Dr. B. J. Harrington.

[77] By Mr. F. D. Adams and Dr. Walcott.

In the Silurian (Upper Silurian of Murchison) we have undoubted
evidence of the same kind, on both sides of the Atlantic, in teeth and
spines of sharks, and the plates which protected the heads and bodies
of the plate-covered fishes (Placo-ganoids). But it is in the Devonian
that these types appear to culminate, and we have added to them that
remarkable type of "lung fish," as the Germans call them, represented
in our modern world only by the curious and exceptional Burramunda
of Australia, and the mud fishes of Africa and South America,[78]
creatures which show, as do some of the mailed fishes, or ganoids, of
equally great age, the intermediate stages between a swimming bladder
and a lung, and thus approach nearer to the air-breathing animals than
any other fishes.

[78] Ceratodus, Lipidosiren, Protopterus.

Many years ago, in "Acadian Geology," I referred to the probability
that the mailed and lung fishes of the Devonian and Carboniferous
possessed air bladders so constructed as to enable them to breathe air,
as is the case with their modern representatives. In the modern species
this, no doubt, enables them to haunt badly aërated waters, in swamps
and sluggish streams, and in some cases even to survive when the water
in which they live is dried up. In the Carboniferous and Devonian it
may have served a similar purpose, fitting them to inhabit the lagoons
and creeks of the coal swamps, the water of which must often have
been badly aërated. It makes against this that some sharks followed
them into these waters, and the modern sharks have no swim-bladders.
Possibly, however, the sharks habitually haunted the open sea, and only
made occasional raids on the dangerous waters tenanted by the ganoids.
It is also true that only certain genera of sharks are found to be
represented in the carbonaceous shales, and they may have differed
in this respect from the ordinary forms of the order. It has been
suggested that only a small change would be necessary to enable some
of these lung fishes to become Batrachians, and no doubt this is the
nearest approach of the fish to the reptile; but we have not yet found
connecting links sufficient to bridge over the whole distance.

[Illustration: Two Primitive Vertebrates, _Palæospondylus_
(enlarged) and _Pterichthys_ (reduced), (After Woodward, with some
modifications.)]

The plate-bearing ganoids of the Silurian and Devonian, at one time
supposed to be allied to Crustaceans, but whose dignity as "Forerunners
of the back-boned animals" is now generally admitted,[79] are clearly
true fishes, and of somewhat high rank, their strange bony armour being
evidently a special protection against the attacks of contemporary
sharks and gigantic crustaceans; and if we may judge by the Colorado
specimens, their existence dates back almost to the close of the
Cambrian, and they were probably contemporary with small sharks; while
as early as the Silurian and Devonian, if we regard the scaly ganoids
as a distinct type, we have already four types of fishes, and these
akin to those which in modern time we must regard as the highest of
their class.

[79] A. Smith Woodward, "Natural Science," 1892, and _Annals and Maga.
Nat. Hist._, October, 1890. This able naturalist, in introducing his
subject, remarks, from the point of view of an evolutionist:--"Whether
some form of 'worm' gave origin to the forerunners of the great
back-boned race, or whether a primeval relative of the King-crab
turned upside down and rearranged limbs and head these are questions
still admitting of endless discussion, no doubt fruitless in their
main object, but desirable from the new lines of investigation they
continually suggest."

One very little fish of the Devonian, of which specimens have been
kindly sent me by a friend in Scotland,[80] the Palæospondylus of
Traquair, may raise still higher hopes for the early vertebrates. It is
a little creature, an inch to two inches in length, destitute or nearly
destitute of bony covering, having a head which suggests the presence
of external gills, large eyes, and even elongated nasal bones,[81] a
long vertebral column composed of separate bony rings, more than fifty
in number, with possible indications of ribs in front and distinct
neural and haemal processes behind. One cannot look at it without the
suggestion occurring of some of the smaller snake-like Batrachians of
the Carboniferous and Permian; and I should not be surprised if it
should come to be regarded either as a forerunner of the Batrachians or
as a primitive tadpole.

[80] James Reed, Esq., of Allan House, Blairgowrie.

[81] I am aware that Woodward regards these parts differently.

However this may be, the upper part of the Devonian, though rich in
fishes and plants, has afforded no higher vertebrates than its lower
parts, and in the lowest Carboniferous beds we suddenly find ourselves
in the presence of Batrachians with well-developed limbs and characters
which ally them to the Lizards. True lizard-like reptiles appear in
the Permian, and then we enter on that marvellous reign of reptiles,
in which this class assumed so many great and remarkable forms, and
asserted itself in a manner of which the now degraded reptilian class
can afford no conception.

The mammals and birds make their first appearance quietly in small and
humble forms in the reign of reptiles, in which there was little place
left for them by the latter; but the mammals burst upon us in all their
number and magnitude in the Eocene and Miocene, in which quadrupedal
mammalian life may be said to have culminated in grandeur, variety, and
geographical distribution; far excelling in these respects the time in
which we live.

The development in time of the back-boned animals thus stands in
some degree by itself; but it illustrates the same laws of early
generalised types, and sudden and wide introduction of new forms, which
we have seen in the case of the invertebrates and the plants.

Such facts as those to which I have referred, and many others, which
want of space prevents me from noticing, are in one respect eminently
unsatisfactory, for they show us how difficult must be any attempts
to explain the origin and succession of life. For this reason they
are quietly put aside or explained away in most of the current
hypotheses on the subject. But we must, as men of science, face these
difficulties, and be content to search for facts and laws, even if they
should prove fatal to preconceived views.

A group of new laws, indeed, here breaks upon us. (1) The great
vitality and rapid extension and variation of new specific types. (2)
The law of spontaneous decay and mortality of species in time. (3) The
law of periodicity and of simultaneous appearance of many allied forms.
(4) The abrupt entrance and slow decay of groups of species. (5) The
extremely long duration of some species in time. (6) The grand march of
new forms landwards, and upwards in rank. Such general truths deeply
impress us at least with the conclusion that we are tracing, not a
fortuitous succession, but the action of power working by law.

I have thus far said nothing of the bearing of the prevalent ideas of
descent with modification on this wonderful procession of life. None
of these, of course, can be expected to take us back to the origin of
living beings; but they also fail to explain why so vast numbers of
highly organized species struggle into existence simultaneously in one
age and disappear in another, why no continuous chain of succession in
time can be found gradually blending species into each other, and why,
in the natural succession of things, degradation under the influence
of external conditions and final extinction seem to be laws of organic
existence. It is useless here to appeal to the imperfection of the
record, or to the movements or migrations of species. The record is
now, in many important parts, too complete, and the simultaneousness
of the entrance of the faunas and floras too certainly established,
and moving species from place to place only evades the difficulty. The
truth is that such hypotheses are at present premature, and that we
require to have larger collections of facts. Independently of this,
however, it appears to me that from a philosophical point of view it
is extremely probable that all theories of evolution, as at present
applied to life, are fundamentally defective in being too partial in
their character; and perhaps I cannot better group the remainder of the
facts to which I wish to refer than by using them to illustrate this
feature of most of our attempts at generalization on this subject.

First, then, these hypotheses are too partial, in their tendency to
refer numerous and complex phenomena to one cause, or to a few causes
only, when all trustworthy analogy would indicate that they must result
from many concurrent forces and determinations of force. We have all,
no doubt, read those ingenious, not to say amusing, speculations in
which some entomologists and botanists have indulged with reference to
the mutual relations of flowers and suctorial insects. Geologically
the facts oblige us to begin with Cryptogamous plants and chewing
insects, and out of the desire of insects for non-existent honey,
and the adaptations of plants to the requirements of non-existent
suctorial apparatus, we have to evolve the marvellous complexity of
floral form and colouring, and the exquisitely delicate apparatus
of the mouths of haustellate insects. Now, when it is borne in mind
that this theory implies a mental confusion on our part precisely
similar to that which, in the department of mechanics, actuates the
seekers for perpetual motion, that we have not the smallest tittle of
evidence that the changes required have actually occurred in any one
case, and that the thousands of other structures and relations of the
plant and the insect have to be worked out by a series of concurrent
developments so complex and absolutely incalculable in the aggregate,
that the cycles and epicycles of the Ptolemaic astronomy were child's
play in comparison, we need not wonder that the common sense of mankind
revolts against such fancies, and that we are accused of attempting to
construct the universe by methods that would baffle Omnipotence itself,
because they are simply absurd. In this aspect of them, indeed, such
speculations are necessarily futile, because no mind can grasp all the
complexities of even any one case, and it is useless to follow out an
imaginary line of development which unexplained facts must contradict
at every step. This is also, no doubt, the reason why all recent
attempts at constructing "Phylogenies" are so changeable, and why no
two experts can agree about almost any of them.

A second aspect in which such speculations are too partial, is in
the unwarranted use which they make of analogy. It is not unusual to
find such analogies as that between the embryonic development of the
individual animal and the succession of animals in geological time
placed on a level with that reasoning from analogy by which geologists
apply modern causes to explain geological formations. No claim could
be more unfounded. When the geologist studies ancient limestones built
up of the remains of corals, and then applies the phenomena of modern
coral reefs to explain their origin, he brings the latter to bear
on the former by an analogy which includes not merely the apparent
results, but the causes at work, and the conditions of their action,
and it is on this that the validity of his comparison depends, in so
far as it relates to similarity of mode of formation. But when we
compare the development of an animal from an embryo cell with the
progress of animals in time, though we have a curious analogy as to the
steps of the process, the conditions and causes at work are known to
be altogether dissimilar, and therefore we have no evidence whatever
as to identity of cause, and our reasoning becomes at once the most
transparent of fallacies. Further, we have no right here to overlook
the fact that the conditions of the embryo are determined by those of
a previous adult, and that no sooner does this hereditary potentiality
produce a new adult animal, than the terrible external agencies of the
physical world, in presence of which all life exists, begin to tell on
the organism, and after a struggle of longer or shorter duration it
succumbs to death, and its substance returns into inorganic nature, a
law from which even the longer life of the species does not seem to
exempt it. All this is so plain and manifest that it is extraordinary
that evolutionists will continue to use such partial and imperfect
arguments. Another illustration may be taken from that application
of the doctrine of natural selection to explain the introduction of
species in geological time, which is so elaborately discussed by Sir
C. Lyell in the last edition of his "Principles of Geology." The great
geologist evidently leans strongly to the theory, and claims for it
the "highest degree of probability," yet he perceives that there is a
serious gap in it; since no modern fact has ever proved the origin of a
new species by modification. Such a gap, if it existed in those grand
analogies by which he explained geological formations through modern
causes, would be admitted to be fatal.

A third illustration of the partial character of these hypotheses may
be taken from the use made of the theory deduced from modern physical
discoveries, that life must be merely a product of the continuous
operation of physical laws. The assumption for it is nothing more
that the phenomena of life are produced merely by some arrangement
of physical forces, even if it be admitted to be true, gives only a
partial explanation of the possible origin of life. It does not account
for the fact that life, as a force, or combination of forces, is set in
antagonism to all other forces. It does not account for the marvellous
connection of life with organization. It does not account for the
determination and arrangement of forces implied in life. A very simple
illustration may make this plain. If the problem to be solved were the
origin of the mariner's compass, one might assert that it is wholly a
physical arrangement, both as to matter and force. Another might assert
that it involves mind and intelligence in addition. In some sense
both would be right. The properties of magnetic force and of iron or
steel are purely physical, and it might even be within the bounds of
possibility that somewhere in the universe a mass of natural lodestone
may have been so balanced as to swing in harmony with the earth's
magnetism. Yet we would surely be regarded as very credulous if we
could be induced to believe that the mariner's compass has originated
in that way. This argument applies with a thousandfold greater force to
the origin of life, which involves even in its simplest forms so many
more adjustments of force and so much more complex machinery.

Fourthly, these hypotheses are partial, inasmuch as they fail to
account for the vastly varied and correlated interdependencies of
natural things and forces, and for the unity of plan which pervades the
whole. These can be explained only by taking into the account another
element from without. Even when it professes to admit the existence
of a God, the evolutionist reasoning of our day contents itself
altogether with the physical or visible universe, and leaves entirely
out of sight the power of the unseen and spiritual, as if this were
something with which science has nothing to do, but which belongs only
to imagination or sentiment. So much has this been the case, that when
recently a few physicists and naturalists have referred to the "Unseen
Universe," they have seemed to be teaching new and startling truths,
though only reviving some of the oldest and most permanent ideas of
our race. From the dawn of human thought it has been the conclusion
alike of philosophers, theologians, and the common sense of mankind,
that the seen can be explained only by reference to the unseen, and
that any merely physical theory of the world is necessarily partial.
This, too, is the position of our sacred Scriptures, and is broadly
stated in their opening verse, and indeed it lies alike at the basis
of all true religion and all sound philosophy, for it must necessarily
be that "the things that are seen are temporal, the things that are
unseen, eternal." With reference to the primal aggregation of energy in
the visible universe, with reference to the introduction of life, with
reference to the soul of man, with reference to the heavenly gifts of
genius and prophecy, with reference to the introduction of the Saviour
Himself into the world, and with reference to the spiritual gifts and
graces of God's people, all these spring, not from sporadic acts of
intervention, but from the continuous action of God and the unseen
world; and this, we must never forget, is the true ideal of creation in
Scripture and in sound theology. Only in such exceptional and little
influential philosophies as that of Democritus, and in the speculations
of a few men carried off their balance by the brilliant physical
discoveries of our age, has this necessarily partial and imperfect view
been adopted. Never, indeed, was its imperfection more clear than in
the light of modern science.

Geology, by tracing back all present things to their origin, was the
first science to establish on a basis of observed facts the necessity
of a beginning and end of the world. But even physical science now
teaches us that the visible universe is a vast machine for the
dissipation of energy; that the processes going on in it must have had
a beginning in time, and that all things tend to a final and helpless
equilibrium. This necessity implies an unseen power, an invisible
universe, in which the visible universe must have originated, and to
which its energy is ever returning. The hiatus between the seen and the
unseen may be bridged over by the conceptions of atomic vortices of
force, and by the universal and continuous ether; but whether or not,
it has become clear that the conception of the unseen, as existing,
has become necessary to our belief in the possible existence of the
physical universe itself, even without taking life into account.

It is in the domain of life, however, that this necessity becomes most
apparent; and it is in the plant that we first clearly perceive a
visible testimony to that unseen which is the counterpart of the seen.
Life in the plant opposes the outward rush of force in our system,
arrests a part of it on its way, fixes it as potential energy, and
thus, forming a mere eddy, so to speak, in the process of dissipation
of energy, it accumulates that on which animal life and man himself may
subsist, and assert for a time supremacy over the seen and temporal on
behalf of the unseen and eternal. I say, for a time, because life is,
in the visible universe, as at present constituted, but a temporary
exception, introduced from that unseen world where it is no longer
the exception but the eternal rule. In a still higher sense, then,
than that in which matter and force testify to a Creator, organization
and life, whether in the plant, the animal, or man, bear the same
testimony, and exist as outposts put forth in the succession of ages
from that higher heaven that surrounds the visible universe. In them,
too, Almighty power is no doubt conditioned or limited by law; yet they
bear more distinctly upon them the impress of their Maker, and, while
all explanations of the physical universe which refuse to recognise its
spiritual and unseen origin must necessarily be partial and in the end
incomprehensible, this destiny falls more quickly and surely on the
attempt to account for life and its succession on merely materialistic
principles.

Here again, however, we must bear in mind that creation, as maintained
against such materialistic evolution, whether by theology, philosophy,
or Holy Scripture, is necessarily a continuous, nay, an eternal,
influence, not an intervention of disconnected acts. It is the true
continuity, which includes and binds together all other continuity.

It is here that natural science meets with theology, not as an
antagonist, but as a friend and ally in its time of greatest need;
and I must here record my belief that neither men of science nor
theologians have a right to separate what God in Holy Scripture has
joined together, or to build up a wall between nature and religion, and
write upon it, "no thoroughfare." The science that does this must be
impotent to explain nature, and without hold on the higher sentiments
of man. The theology that does this must sink into mere superstition.

In conclusion, can we formulate a few of the general laws, or perhaps I
had better call them the general conclusions, respecting life, in which
all Palæontologists may agree. Perhaps it is not possible to do this at
present satisfactorily, but the attempt may do no harm. We may, then, I
think, make the following affirmations:--

1. The existence of life and organization on the earth is not eternal,
or even coeval with the beginning of the physical universe, but may
possibly date from Laurentian or immediately pre-Laurentian ages.

2. The introduction of new species of animals and plants has been a
continuous process, not necessarily in the sense of derivation of
one species from another, but in the higher sense of the continued
operation of the cause or causes which introduced life at first. This,
as already stated, I take to be the true theological or Scriptural as
well as scientific idea of what we ordinarily and somewhat loosely term
creation.

3. Though thus continuous, the process has not been uniform; but
periods of rapid production of species have alternated with others in
which many disappeared and few were introduced. This may have been an
effect of physical cycles reacting on the progress of life.

4. Species, like individuals, have greater energy and vitality in
their younger stages, and rapidly assume all their varietal forms, and
extend themselves as widely as external circumstances will permit. Like
individuals also, they have their periods of old age and decay, though
the life of some species has been of enormous duration in comparison
with that of others; the difference appearing to be connected with
degrees of adaptation to different conditions of life.

5. Many allied species, constituting groups of animals and plants, have
made their appearance at once in various parts of the earth, and these
groups have obeyed the same laws with the individual and the species in
culminating rapidly, and then slowly diminishing, though a large group
once introduced has rarely disappeared altogether.

6. Groups of species, as genera and orders, do not usually begin with
their highest or lowest forms, but with intermediate and generalized
types, and they show a capacity for both elevation and degradation in
their subsequent history.

7. The history of life presents a progress from the lower to the
higher, and from the simpler to the more complex, and from the more
generalized to the more specialized. In this progress new types are
introduced, and take the place of the older ones, which sink to a
relatively subordinate place, and become thus degraded. But the
physical and organic changes have been so correlated and adjusted
that life has not only always maintained its existence, but has been
enabled to assume more complex forms, and thus older forms have been
made to prepare the way for newer, so that there has been, on the
whole, a steady elevation culminating in man himself. Elevation and
specialization have, however, been secured at the expense of vital
energy and range of adaptation, until the new element of a rational and
inventive nature was introduced only in the case of man.

8. In regard to the larger and more distinct types, we cannot find
evidence that they have, in their introduction, been preceded by
similar forms connecting them with previous groups; but there is reason
to believe that many supposed representative species in successive
formations are really only races or varieties.

9. In so far as we can trace their history, specific types are
permanent in their characters from their introduction to their
extinction, and their earlier varietal forms are similar to their later
ones.

10. Palæontology furnishes no direct evidence, perhaps never can
furnish any, as to the actual transformation of one species into
another, or as to the actual circumstances of creation of a species;
but the drift of its testimony is to show that species come in _per
saltum_, rather than by any slow and gradual process.

11. The origin and history of life cannot, any more than the origin
and determination of matter and force, be explained on purely material
grounds, but involve the consideration of power referable to the unseen
and spiritual world.

Different minds may state these principles in different ways, but I
believe that in so far as palæontology is concerned, in substance they
must hold good, at least as steps to higher truths. And now allow me
to say that we should be thankful that it is given to us to deal with
so great questions, and that in doing so, deep humiliation, earnest
seeking for truth, patient collection of all facts, self-denying
abstinence from hasty generalizations, forbearance and generous
estimation with regard to our fellow labourers, and reliance on that
Divine Spirit which has breathed into us our intelligent life, and is
the source of all true wisdom, are the qualities which best become us.

But while the principles noted above may be said to be known laws of
the apparition of new forms of life, they do not reach to the secondary
efficient causes of the introduction of new species. What these may
ultimately prove to be, to what extent they can be known by us, and to
what extent they may include processes of derivation, it is impossible
now to say. At present we must recognise in the prevailing theories on
the subject merely the natural tendency of the human mind to grasp the
whole mass of the unknown under some grand general hypothesis, which,
though perhaps little else than a figure of speech, satisfies for the
moment. We are dealing with the origin of species precisely as the
alchemists did with chemistry, and as the Plutonists and Neptunists
did with geology; but the hypotheses of to-day may be the parents
of investigations which will become real science to-morrow. In the
meantime it is safe to affirm that whatever amount of truth there may
be in the several hypotheses which have engaged our attention, there is
a creative force above and beyond them, and to the threshold of which
we shall inevitably be brought, after all their capabilities have been
exhausted by rigid investigation of facts. It is also consolatory to
know that species, in so far as the Modern period, or any one past
geological period may be concerned, are so fixed that for all practical
purposes they may be regarded as unchanging. They are to us what the
planets in their orbits are to the astronomer, and speculations as
to the origin of species are merely our nebular hypotheses as to the
possible origin of worlds and systems.

  References:--Address as Vice-President of American Association at
    Detroit, 1875. "The Chain of Life in Geological Time," London,
    1879. Addresses to Natural History Society of Montreal, published
    in _Canadian Naturalist_, "Apparition of Animal Forms," _Princeton
    Review_.




                _THE GENESIS AND MIGRATIONS OF PLANTS._


                      DEDICATED TO THE MEMORY OF

                           DR. OSWALD HEER,

          The Able and Successful Student of the later Floras

                      of the Northern Hemisphere.


Geological Periods as Related to Plants--Arctic Origin of Floras--The
Devonian Flora--Arctic Climates of the Past--History of Some Modern
Forms--Laws of the Succession

[Illustration: Vegetation of the Middle Devonian or Erian, restored
from actual specimens (p. 202).]




CHAPTER VIII.

_THE GENESIS AND MIGRATIONS OF PLANTS._


If, for convenience of reference, we divide the whole history of the
earth, from the time when a solid crust first formed on its surface and
began to be ridged up into islands or mountains in the primeval ocean,
into four great periods, we shall find that each can be characterized
by some features in relation to the world of plants.

That Archean age, in which the oldest known beds of rocks were
produced--rocks now greatly crumpled by the first movements of the
thin crust, and hardened and altered by heat and pressure has, it is
true, little to tell us. But, as elsewhere stated, even it has beds of
Carbon in the form of Graphite--veritable altered coal seams--which the
analogy of later formations would lead us to believe must have been
accumulated by the growth of plants. This growth is indeed the only
known cause capable of producing such effects. If we should ever be
fortunate enough to find beds of the Laurentian series in an unaltered
state, we may hope to know something of this old flora. Nor need we be
surprised if it should prove of higher grade and more noble development
than we should at first sight anticipate. If there ever was a time when
vegetation alone possessed the earth, and when there were no animals to
devour or destroy it, we might expect to find it in its first and best
estate, perhaps not comparable in variety and complexity of parts with
the flora of the modern world, but grand in its luxuriance and majesty.
Of such discoveries, however, we have no certain indication at present.

If such a primeval flora as that above indicated ever existed, it must
have perished utterly before the incoming of the next great age of
the world--that known as the Palæozoic, whose rocks are surpassingly
rich in the remains of animals, especially those of the lower or
invertebrate classes and those that inhabit the waters.

In the oldest Palæozoic rocks we find no plants certainly terrestrial,
but abundance of Algæ or seaweeds, and some gigantic members of the
vegetable kingdom which seem to have been trees, with structures
more akin to those of aquatic than to those of land plants.[82] At a
somewhat early stage, however, in the rocks of this period, we discover
a few undoubted land plants.[83] These seem to be allied to the modern
Club mosses and to their humble relations, the pillworts[84] and other
small plants of similar structure found in ponds and swamps. Some of
them, indeed, appear to be intermediate between these groups. All
these plants are Cryptogams, or destitute of true flowers, but do not
belong to the lowest forms of that type. Thus, so far as we know, plant
life on the land began possibly with certain large trees of algoid
structures, and more certainly with the club mosses and pillworts and
their allies, and these last in the form of species not tree-like in
dimensions, but of very moderate size. The structures of these plants
are already sufficiently well known to inform us that the plan and
functions of the root, stem and leaf, and of spores and spore case
were set up; and that the structures and functions of vegetable cells,
fibres and some kinds of vessels were perfected, and all the apparatus
introduced necessary for the fertilization and reproduction of plants
of some degree of complexity. At the same time, the peculiar structures
of the higher Algæ were brought to a pitch of perfection not surpassed
if equalled in modern times, and which may have enabled plants so
constructed to exist even on the land.

[82] Nematophyton, etc. See "Geological History of Plants."

[83] Psilophyton, Protannularia, etc.

[84] Rhizocarpeæ.

From these beginnings in the early Palæozoic, the progress of the
vegetable kingdom went on, until, in the later parts of that great
period, the Devonian and Carboniferous eras, it culminated in those
magnificent forests which have left so many interesting remains, and
which accumulated the materials of our great beds of coal. In these the
families of the Club mosses, the Ferns and the Mare's-tails attained
to a perfection in structure and size altogether unexampled in the
modern world, and may be said to have overspread the earth almost to
the exclusion of other trees. Here, however, two new families come in
of higher grade, and leading the way to the flowering plants. These are
the Pines and their allies and the Cycads, and certain intermediate
forms, neither Pines nor Cycads, but allied to both.[85] This wonderful
flora, which we have now the materials to reproduce in imagination
almost in its entirety, decays and passes away in the Permian system,
the last portion of the Palæozoic, and in entering into the third great
period of the earth's history--the Mesozoic, we again find an almost
entire change of vegetation. Here, however, we are able to understand
something of the reasons of this. The Palæozoic floras seem to have
originated in the North, and propagated themselves southward till they
replenished the earth, and they were favoured by the existence at
that time of vast swampy flats extending over great areas of the yet
imperfectly elaborated continents. The Mesozoic floras, on the other
hand, seem to have been of Southern or equatorial origin, and to have
followed up the older vegetation as it decayed and disappeared, or
retreated in its old age to its northern home. There is, of course,
much in all this that we do not understand, but the general fact seems
certain.

[85] _Cordaites_, etc. As I have elsewhere shown, these are distinct
sub-floras in the Lower, Middle and Upper Devonian, and in the Lower,
Middle and Upper Carboniferous and Permian, sufficiently different to
allow these periods to be determined by the evidence of these fossil
plants. Reports prepared for Geological Survey of Canada.

The early Mesozoic is altogether peculiar. It shows a vast predominance
of Cycads, Pines and Ferns, to the exclusion both of the gigantic
Cryptogams of the Palæozoic and of the ordinary exogenous trees of the
modern time. It has a strange, weird aspect, and more resembles that of
some warm islands of the southern hemisphere at present, than anything
else known to us. It is as if the flora of some southern island had
migrated and invaded all parts of the world. The geographical and
climated conditions which permitted this must have been of a character
different from those both of earlier and later times.

As we approach to the termination of the Mesozoic, which, in regard
to animal life, is the age of reptiles, a new and strange development
meets us. We find beds filled with leaves of broad-leaved plants
similar to those of our modern woods, and in most cases apparently
belonging to the same genera with plants now living, and this new
type of vegetation persists to the present, though with marked
differences of species in successive eras, as in the Middle and Upper
Cretaceous, and the Lower, Middle and Upper Kainozoic, or Tertiary.
It is noteworthy that while this new vegetation not only altogether
supersedes the great Cryptogamous forests of the Palæozoic, but
replaces the Cycads of the immediately preceding eras, the Pines retain
all their prominence and grandeur, and even seem to excel in number of
species, in breadth of dispersion, and in magnitude of growth their
successors in the present world.

While in the latter Cretaceous and Early Tertiary, the northern
hemisphere at least seems to have enjoyed an exceptionally warm
climate, the later Tertiary introduces that period of cold known as
the Glacial age. While there is no doubt that the intensity of this
glaciation has been greatly exaggerated by extreme glacialists, and
while it is certain that some vegetation, and this not altogether of
Arctic types, continued to exist throughout this period, even in the
now temperate regions of our continents, it is evident that a great
reduction of the exuberance of the flora occurred by the removal of
many species, and that the present flora of the northern hemisphere is
inferior in variety and magnificence to that of the Middle Tertiary,
just as it is found that the Mammalian fauna of our continents has
since that time been reduced both in the number and magnitude of its
species.

If the reader has followed this general sketch, he will be prepared to
appreciate some examples of a more detailed character relating to the
floras of different periods, and some discussions of general points
relating to the genesis and vicissitudes of the vegetable kingdom.

The origination of the more important floras which have occupied
the northern hemisphere in geological times, not, as one might at
first sight suppose, in the sunny climates of the South, but under
the arctic skies, is a fact long known or suspected. It is proved by
the occurrence of fossil plants in Greenland, in Spitzbergen, and in
Grinnell Land, under circumstances which show that these were their
primal homes. The fact bristles with physical difficulties, yet is
fertile of the most interesting theoretical deductions, to reach which
we may well be content to wade through some intricate questions. Though
not at all a new fact, its full significance seems only recently to
have dawned on the minds of geologists, and within recent years it
has produced a number of memoirs and addresses to learned societies,
besides many less formal notices.[86]

[86] Saporata, "Ancienne Vegetation Polaire"; Hooker, Presidential
Address to Royal Society, 1878; Thistleton Dyer, "Lecture on Plant
Distribution "; Mr. Starkie Gardner, Letters in _Nature_, 1878, etc.
The basis of most of these brochures is to be found in Heer's "Flora
Fossilis Arctica."

The earliest suggestion on this subject known to the writer is that of
my old and dear friend, Professor Asa Gray, in 1867, with reference to
the probable northern source of the related floras of North America
and Eastern Asia. With the aid of new facts disclosed by Heer and
Lesquereux, Gray returned to the subject in 1872, and more fully
developed this conclusion with reference to the Tertiary floras,[87]
and still later he further discussed these questions in an able lecture
on "Forest Geography and Archæology."[88] In this he puts the case so
well and tersely that I may quote the following sentences as a text for
what follows:--

[87] Address to American Association.

[88] _American Journal of Science_, xvi., 1878.

"I can only say, at large, that the same species (of Tertiary fossil
plants) have been found all round the world; that the richest and
most extensive finds are in Greenland; that they comprise most of
the sorts which I have spoken of, as American trees which once lived
in Europe--Magnolias, Sassafras, Hickories, Gum-trees, our identical
Southern Cypress (for all we can see of difference), and especially
_Sequoias_, not only the two which obviously answer to the two Big-trees
now peculiar to California, but several others; that they equally
comprise trees now peculiar to Japan and China--three kinds of
Gingko-trees, for instance, one of them not evidently distinguishable
from the Japan species which alone survives; that we have evidence, not
merely of Pines and Maples, Poplars, Birches, Lindens, and whatever
else characterize the temperate-zone forests of our era, but also of
particular species of these, so like those of our own time and country,
that we may fairly reckon them as the ancestors of several of ours.
Long genealogies always deal more or less in conjecture; but we appear
to be within the limits of scientific inference when we announce that
our existing temperate trees came from the north, and within the bounds
of high probability when we claim not a few of them as the originals
of present species. Remains of the same plants have been found fossil
in our temperate region, as well as in Europe."

Between 1860 and 1870 the writer was engaged in working out all that
could be learned of the Devonian plants of Eastern America, the oldest
known flora of any richness, and which consists almost exclusively of
gigantic, and to us grotesque, representatives of the Club mosses,
Ferns, and Mare's-tails, with some trees allied to the Cycads and
Pines. In this pursuit nearly all the more important localities were
visited, and access was had to the large collections of Professor Hall
and Professor Newberry in New York and Ohio, as well as to those of
the Geological Survey of Canada, and to those made in the remarkable
plant-bearing beds of St. John, New Brunswick, by Messrs. Matthew
and Hartt. In the progress of these researches, which developed an
unexpectedly rich assemblage of species, the northern origin of this
old flora seemed to be established by its earlier culmination in the
north-east, in connection with the growth of the American land to the
southward, which took place after the great Upper Silurian subsidence,
by elevations which began in the north, while those portions of the
continent to the south-west still remained under the sea.

When, in 1870, the labours of those ten years were brought before the
Royal Society of London, in the Bakerian Lecture of that year, and in a
memoir illustrating no less than one hundred and twenty-five species of
plants older than the great Carboniferous system, these deductions were
stated in connection with the conclusions of Hall, Logan, and Dana,
as to the distributions of sediment along the north-east side of the
American continent, and the anticipation was hazarded that the oldest
Palæozoic floras would be discovered to the north of Newfoundland.
Mention was also made of the apparent earlier and more copious birth of
the Devonian flora in America than in Europe, a fact which is itself
connected with the greater northward extension of this continent.

Unfortunately the memoir containing these results was not published by
the Royal Society, and its publication was secured in a less perfect
form only in the reports of the Geological Survey of Canada. The part
of the memoir relating to Canadian fossil plants, with a portion of the
theoretical deductions, was published in a report issued in 1871.[89]
In this report the following language was used:--

[89] "Fossil Plants of the Devonian and Upper Silurian Formations of
Canada," pp. 92, twenty plates. Montreal, 1871.

"In Eastern America, from the Carboniferous period onward, the centre
of plant distribution has been the Appalachian chain. From this the
plants and sediments extended westward in times of elevation, and
to this they receded in times of depression. But this centre was
non-existent before the Devonian period, and the centre of this must
have been to the north-east, whence the great mass of older Appalachian
sediment was derived. In the Carboniferous period there was also an
eastward distribution from the Appalachians, and links of connection
in the Atlantic bed between the floras of Europe and America. In the
Devonian such connection can have been only far to the north-east. It
is therefore in Newfoundland, Labrador, and Greenland that we are to
look for the oldest American flora, and in like manner on the border of
the old Scandinavian nucleus for that of Europe."

"Again, it must have been the wide extension of the sea of the
Corniferous limestone that gave the last blow to the remaining flora of
the Lower Devonian: and the re-elevation in the middle of that epoch
brought in the Appalachian ridges as a new centre, and established
a connection with Europe which introduced the Upper Devonian and
Carboniferous floras. Lastly, from the comparative richness of the
later Erian[90] flora in Eastern America, especially in the St. John
beds, it might be a fair inference that the north-eastern end of the
Appalachian ridge was the original birthplace or centre of creation of
what we may call the later Palæozoic flora, or a large part of that
flora."

[90] The term Erian is used as synonymous with Devonian, and probably
should be preferred to it, as pointing to the best development of this
formation known, which is on the shores of Lake Erie.

When my paper was written I had not seen the account published by the
able Swiss palæobotanist Heer, of the remarkable Devonian flora of Bear
Island, near Spitzbergen.[91] From want of acquaintance with the older
floras of America and Western Europe, Heer fell into the unfortunate
error of regarding the Bear Island plants as Lower Carboniferous, a
mistake which his great authority has tended to perpetuate, and which
has even led to the still graver error of some European geologists, who
do not hesitate to regard as Carboniferous the fossil plants of the
American deposits from the Hamilton to the Chemung groups inclusive,
though these belong to formations underlying the oldest Carboniferous,
and characterized by animal remains of unquestioned Devonian age. In
1872 I addressed a note to the Geological Society of London on the
subject of the so-called "Ursa stage" of Heer, showing that though it
contained some forms not known at so early a date in temperate Europe,
it was clearly Devonian when tested by North American standards; but
that in this high latitude, in which, for reasons stated in the report
above referred to, I believed the Devonian plants to have originated,
there might be an intermixture of the two floras. But such a mixed
group should in that latitude be referred to a lower horizon than if
found in temperate regions.

[91] Trans. Swedish Academy, 1871, _Journal London Geological Society_,
vol. xxvlii.

Between 1870 and 1873 my attention was turned to the two sub-floras
intermediate between those of the Devonian and the coal formation, the
floras of the Lower Carboniferous (Sub-carboniferous of some American
geologists) and the Millstone Grit, and in a report upon these[92]
similar deductions were expressed. It was stated that in Newfoundland
and Northern Cape Breton the coal formation species come in at an
early part of that period, and as we proceed southward they belong to
progressively newer portions of the Carboniferous system. The same fact
is observed in the coal beds of Scotland, as compared with those of
England, and it indicates that the coal formation flora, like that of
the Devonian, spread itself from the north, and this accords with the
somewhat extensive occurrence of Lower Carboniferous rocks and fossils
in the Parry Islands and elsewhere in the Arctic regions.[93]

[92] "Fossil Plants of Lower Carboniferous and Millstone Grit
Formations of Canada," pp. 47, 10 plates. Montreal, 1873.

[93] G. M. Dawson, "Report on Arctic Regions of Canada."

Passing over the comparatively poor flora of the earlier Mesozoic,
consisting largely of cycads, pines, and ferns, which, as we have
seen, is probably of southern origin, and is as yet little known in
the arctic, though represented, according to Heer, by the supposed
Jurassic flora of Cape Boheman, we find, especially at Komé and Atané
in Greenland, an interesting occurrence of those earliest precursors
of the truly modern forms of plants which appear in the Cretaceous,
the period of the English chalk, and of the New Jersey greensands.
There are two plant groups of this age in Greenland, one, that of
Komé consists almost entirely of ferns, cycads, and pines, and is
of decidedly Mesozoic aspect. This was regarded by Heer as Lower
Cretaceous. The other, that of Atané, holds remains of many modern
temperate genera, as _Populus_, _Myrica_, _Ficus_, _Sassafras_, and
_Magnolia_. This he regards as Middle Cretaceous. Above this is
the Patoot series, with many exogenous trees of modern genera, and
representing the Upper Cretaceous. Resting upon these Upper Cretaceous
beds, without the intervention of any other formation,[94] are beds
rich in plants of much more modern appearance, and referred by Heer
to the Miocene period, a reference which appeared at the time to be
warranted by comparison with the Tertiary plants of Europe, but, as
we shall see, not with those of America. Still farther north this
so-called Miocene assemblage of plants appears in Spitzbergen and
Grinnell Land; but there, owing to the predominance of trees allied
to the spruces, it has a decidedly more boreal character than in
Greenland, as might be anticipated from its nearer approach to the
pole.[95]

[94] Nordenskiöld, Expedition to Greenland, _Geological Magazine_, 1872.

[95] Yet even here the Bald Cypress (_Taxodium distichum_), or a tree
nearly allied to it, is found, though this species is now limited to
the Southern States. Fielden and De Ranee, _Journal of Geological
Society_, 1878.

If now we turn to the Cretaceous and Tertiary floras of Western
America, as described by Lesquereux, Newberry, and Ward, we find in
the lowest Cretaceous rocks known there until very recently--those
of the Dakota group, which may be in the lower part of the Middle
Cretaceous--a series of plants[96] essentially similar to those of
the Middle Cretaceous of Greenland. To these I have been able to add,
through the researches of Mr. Richardson and Dr. G. M. Dawson, a
still earlier flora, that of the Kootanie and Queen Charlotte Island
formations, as old as the Gault and Wealden. It wants the broad-leaved
plants of the Dakota, and consists mainly of pines, cycads, and
ferns; and only in its upper part contains a few forerunners of
the exogens.[97] These plants occur in beds indicating shallow sea
conditions as prevalent in the interior of America, causing, no
doubt, a warm climate in the north. Overlying this plant-bearing
formation we have an oceanic limestone (the Niobrara), corresponding
in many respects to the European chalk, and containing similar
microscopic organisms. This extends far north into the British
territory,[98] indicating farther subsidence and the prevalence of a
vast Mediterranean Sea, filled with warm water from the equatorial
currents, and not invaded by cold waters from the north. This is
succeeded by Upper Cretaceous deposits of clay and sandstone, with
marine remains, though very sparsely distributed; and these show that
further subsidence or denudation in the north had opened a way for the
arctic currents, producing a fall of temperature at the close of the
Cretaceous, and partially filling up the Mediterranean of that period.

[96] Lesquereux, Report on Cretaceous Flora. The reader not interested
in American details may pass over to the middle of page 213.

[97] This flora has since been described in Virginia and Maryland by
Fontaine, and has been recognised in Montana by Newberry.

[98] G. M. Dawson, Report on Forty-ninth Parallel.

Of the flora of the Middle and Upper Cretaceous periods, which must
have been very long, we know something in the interior regions through
the plants of Dunvegan and Peace River;[99] and on the coast of British
Columbia we have the remarkable Cretaceous coal field of Vancouver's
Island, which holds the remains of plants of modern genera, including
species of fan palm, ginkgo, evergreen oak, tulip tree, and other forms
proper to a warm temperature or subtropical climate. They probably
indicate a warmer climate as then prevalent on the Pacific coast
than in the interior, and in this respect correspond with a meagre
transition flora, intermediate between the Cretaceous and Eocene or
earliest Tertiary of the interior regions, and named by Lesquereux the
Lower Lignitic.

[99] _Trans. Royal Society of Canada._

Immediately above these Upper Cretaceous beds we have the great
Lignite Tertiary of the west--the Laramie group of recent American
reports[100]--abounding in fossil plants, proper to a temperate
climate, at one time regarded as Miocene, but now known to be Lower
Eocene.[101] These beds, with their characteristic plants, have been
traced into the British territory north of the forty-ninth parallel,
and it has been shown that their fossils are identical with those of
the McKenzie River Valley, described by Heer as Miocene, and probably
also with those of Alaska, referred to the same age.[102] Now this
truly Eocene flora of the temperate and northern parts of America has
so many species in common with that called Miocene in Greenland, that
its identity can scarcely be doubted. These facts have led me to doubt
the Miocene age of the upper plant-bearing beds of Greenland, and more
recently Mr. J. Starkie Gardner has shown from comparison with the
Eocene flora of England and other considerations, that they are really
of that earlier date.[103]

[100] Ward, Repts. and Bulletins Am. Geol. Survey.

[101] Lesquereux's Tertiary Flora; White and Ward on the Laramie Group;
Stevenson, Geological Relations of Lignitic Groups, _Am. Phil. Soc._,
June, 1875.

[102] G. M. Dawson, Report on the Geology of the Forty-ninth Parallel,
1875, where full details on these points may be found.

[103] _Nature_, Dec. 12th, 1878; Publications Palæontographical
Society; Reports to British Association. It seems certain that the
so-called Miocene of Bovey Tracey in Devon, and of Mull in Scotland, is
really Eocene. The Tertiary plant-bearing beds of Greenland are said by
Nathorst to rest unconformably on the Cretaceous, and are characterized
by _M'Clintockia_ and other forms known in the Eocene of Great Britain
and Ireland.

In looking at these details, we might perhaps suppose that no
conditions of climate could permit the vegetation of the neighbourhood
of Disco in Greenland to be identical with that of Colorado and
Missouri, at a time when little difference of level existed in the two
regions. Either the southern flora migrated north in consequence of a
greater amelioration of climate, or the northern flora moved southward
as the climate became colder. The same argument, as Gardner has ably
shown, applies to the similarity of the Tertiary plants of temperate
Europe to those of Greenland. If Greenland required a temperature of
about 50°, as Heer calculates, to maintain its "Miocene" flora, the
temperature of England must have been at least 70°, and that of the
south-western States still warmer. It is to be observed, however, that
the geographical arrangements of the American land in Cretaceous and
early Eocene times, included the existence of a great inland sea of
warm water extending at some periods as far north as the latitude of
55°, and that this must have tended to much equality of climatical
conditions.

We cannot certainly affirm anything respecting the origin and
migrations of these floras, but there are some probabilities which
deserve attention. The ferns and cycads of the so-called Lower
Cretaceous of Greenland are nothing but a continuation of the previous
Jurassic flora. Now this was established at an equally early date in
the Queen Charlotte Islands,[104] and still earlier in Virginia.[105]
The presumption is, therefore, that it came from the south. It has
indeed the facies of a southern hemisphere and insular flora; and
probably spread itself northward as far as Greenland at a time when
the American land was long, narrow, and warm, and when the ocean
currents were carrying tepid water far toward the arctic regions. The
flora which succeeds this in the sections at Atané and Patoot has no
special affinities with the southern hemisphere, and is of a warm
temperate and continental character. It is very similar in its general
aspect to that of the Dakota group farther to the south, and this is
probably Middle Cretaceous. This flora must have originated either
somewhere in temperate America, or within the arctic circle, and it
must have replaced the older one by virtue of increasing subsidence
and gradual change of climate. It must therefore have been connected
with the depression of the land which took place in the course of the
Cretaceous. During this movement it spread over all Western America,
and as the land again arose from the sea of the Niobrara chalk, it
assumed an aspect more suited to a cool climate, or moved southward,
and finally abandoned the Arctic regions, perhaps continuing to exist
on the Pacific coast, and in sheltered places in the north, till the
warm inland seas of the Upper Cretaceous had given place to the wide
plains and land-locked brackish seas or fresh-water lakes of the
Laramie period (Eocene). Thus the true Upper Cretaceous marks in the
interior a cooler period intervening between the Middle Cretaceous and
the Lower Eocene floras of Greenland.

[104] Reports Geological Survey of Canada.

[105] Fontaine has well described the Mesozoic flora of Virginia,
_American Journal of Science_, January, 1879.

This latter established itself in Greenland, and probably all around
the Arctic circle, in the mild period of the earliest Eocene, and
as the climate of the northern hemisphere became gradually reduced
from that time till the end of the Pliocene, it marched on over both
continents to the southward, chased behind by the modern arctic flora,
and eventually by the frost and snow of the Glacial age. This history
may admit of correction in details; but, so far as present knowledge
extends, it is in the main not far from the truth.

Perhaps the first great question which it raises is that as to the
causes of the alternations of warm and cold climates in the north,
apparently demanded by the vicissitudes of the vegetable kingdom. Here
we may set aside the idea that in former times plants were suited to
endure greater cold than at present. It is true that some of the fossil
Greenland plants are of unknown genera, and many are new species to us;
but we are on the whole safe in affirming that they must have required
conditions similar to those necessary to their modern representatives,
except within such limits as we now find to hold in similar cases among
existing plants. Still we know that at the present time many species
found in the equable climate of England will not live in Canada,
though species to all appearance similar in structure are natives of
the latter. There is also some reason to suppose that species, when
new, may have greater hardiness and adaptability than when in old age,
and verging toward extinction. In any case, these facts can account
for but a small part of the phenomena, which require to be explained
by physical changes affecting the earth as a whole, or at least the
northern hemisphere. Many theoretical views have been suggested on this
subject, which will be found discussed elsewhere, and perhaps the most
practical way to deal with them here will be to refer to the actual
conditions known to have prevailed in connection with the introduction
and distribution of the principal floras which have succeeded each
other in geological history.

If we can assume that all the carbon now sealed up in limestones and in
coal was originally floating in the atmosphere as carbon dioxide, then
we would have a cause which might seriously have affected the earlier
land floras--that, for instance, which may have existed in the Eozoic
age, and those well known to us in the Palæozoic. Such an excess of
carbonic acid would have required some difference of constitution in
the plants themselves; it would have afforded them a super-abundance
of wood-forming nutriment, and it would have acted as an obstacle to
the radiation of heat from the earth, almost equal to the glass roof
of a greenhouse, thus constituting a great corrective of changes of
temperature. Under such circumstances we might expect a peculiar and
exuberant vegetation in the earlier geological ages, though this would
not apply to the later in any appreciable degree. In addition to this
we know that the geographical arrangements of our continents were
suited to the production of a great uniformity of climate. Taking the
American continent as the simpler, we know that in this period there
existed in the interior plateau between the rudimentary eastern and
western mountains a great inland sea, so sheltered from the north
that its waters contained hundreds of species of corals, growing with
a luxuriance unsurpassed in the modern tropics. On the shores and
islands of such a sea we do not wonder that there should have been
tree-ferns and gigantic lycopods. In the succeeding Carboniferous,
vast areas, both on the margins and in the interior of the continent,
were occupied with swampy flats and lagoons, the atmosphere of which
must have been loaded with vapour, and rich in compounds of carbon,
though the temperature may have been lower than in the Devonian. There
still remained, however, more especially in the west, a remnant of
the old inland sea, which must have greatly aided in carrying a warm
temperature to the north.

If now we pass to the succeeding Jurassic age, we find a more meagre
and less widely distributed flora, corresponding to less favourable
geographical and climatal conditions, while in the Cretaceous and
Eocene ages a return to the old condition of a warm Mediterranean in
continuation of the Gulf of Mexico gave those facilities for vegetable
growth, which carried plants of the temperate zone as far north as
Greenland.

It thus appears that those changes of physical geography and of the
ocean currents to which reference is so often made in these papers,
apply to the question of the distribution of plants in geological time.

These same causes may help us to deal with the peculiarities of the
great Glacial age, which may have been rendered exceptionally severe
by the combination of several of the continental and oceanic causes of
refrigeration. We must not imagine, however, that the views of those
extreme glacialists, who suppose continental ice caps reaching half way
to the equator, are borne out by facts. In truth, the ice accumulating
round the pole must have been surrounded by water, and there must
have been tree-clad islands in the midst of the icy seas, even in the
time of greatest refrigeration. This is proved by the fact that in
the lower Leda clay of Eastern Canada, which belongs to the time of
greatest submergence, and whose fossil shells show sea water almost at
the freezing point, there are leaves of poplars and other plants which
must have been drifted from neighbouring shores. Similar remains occur
in clays of similar origin in the basin of the great lakes and in the
West, and are not Arctic plants, but members of the North Temperate
flora.[106] These have been called "interglacial," but there is no
evidence to prove that they are not truly glacial. Thus, while the
arctic flora must have continued to exist within the Arctic circle in
the Glacial age, we have evidence that those of the cold temperate and
subarctic zones continued to exist pretty far north. At the same time
the warm temperate flora would be driven to the south, except where
sustained in insular spots warmed by the equatorial currents. It would
return northward on the re-elevation of the land and the return of
warmth.

[106] Pleistocene Plants of Canada, Dawson and Penhallow, _Bull, Geol.
Socy._, America, 1890. In Europe the Arctic flora extended, relatively
to present climate, farther south.

If, however, our modern flora is thus one that has returned from the
south, this would account for its poverty in species as compared with
those of the early Tertiary. Groups of plants descending from the north
have been rich and varied. Returning from the south they are like the
shattered remains of a beaten army. This, at least, has been the case
with such retreating floras as those of the Lower Carboniferous, the
Permian, and the Jurassic, and possibly that of the Lower Eocene of
Europe.

The question of the supply of light to an Arctic flora is much less
difficult than some have imagined. The long summer day is in this
respect a good substitute for a longer season of growth, while a
copious covering of winter snow not only protects evergreen plants from
those sudden alternations of temperature which are more destructive
than intense frost, and prevents the frost from penetrating to their
roots, but by the ammonia which it absorbs preserves their greenness.
According to Dr. Brown, the Danish ladies of Disco long ago solved
this problem.[107] He informs us that they cultivate in their houses
most of our garden flowers, as roses, fuchsias, and geraniums, showing
that it is merely warmth, and not light that is required to enable a
subtropical flora to thrive in Greenland. Even in Canada, which has a
flora richer in some respects than that of temperate Europe, growth is
effectually arrested by cold for nearly six months, and though there is
ample sunlight there is no vegetation. It is indeed not impossible that
in the plans of the Creator the continuous summer sun of the Arctic
regions may have been made the means for the introduction, or at least
for the rapid growth and multiplication, of new and more varied types
of plants. It is a matter of familiar observation in Canada that our
hardy garden flowers attain to a greater luxuriance and intensity of
colour in those more northern latitudes where they have the advantage
of long and sunny summer days.

[107] _Florula Discoana_, Botanical Society of Edinburgh, 1868.

Much, of course, remains to be known of the history of the old floras
whose fortunes I have endeavoured to sketch, and which seem to have
been driven like shuttlecocks from north to south, and from south to
north, especially on the American continent, whose meridional extension
seems to have given a field specially suited for such operations.

This great stretch of the western continent from north to south is also
connected with the interesting fact that, when new floras are entering
from the Arctic regions, they appear earlier in America than in Europe;
and that in times when the old floras are retreating from the south,
old genera and species linger longer in America. Thus, in the Devonian
and Cretaceous new forms of those periods appear in America long before
they are recognised in Europe, and in the modern epoch forms that
would be regarded in Europe as Miocene still exist. Much confusion in
reasoning as to the geological ages of the fossil flora has arisen from
want of attention to this circumstance.

What we have learned respecting this wonderful history has served
strangely to change some of our preconceived ideas. We must now be
prepared to admit that an Eden might exist even in Spitsbergen, that
there are possibilities in this old earth of ours which its present
condition does not reveal to us; that the present state of the world is
by no means the best possible in relation to climate and vegetation;
that there have been and might be again conditions which could convert
the ice-clad Arctic regions into blooming paradises, and which, at
the same time, would moderate the fervent heat of the tropics. We are
accustomed to say that nothing is impossible with God; but how little
have we known of the gigantic possibilities which lie hidden under some
of the most common of His natural laws.

Yet these facts have been made the occasion of speculations as to
the spontaneous development of plants without any direct creative
intervention. It would, from this point of view, be a nice question
to calculate how many revolutions of climate would suffice to evolve
the first land plant; what are the chances that such plant would be so
dealt with by physical changes as to be preserved and nursed into a
meagre flora like that of the Upper Silurian or the Jurassic; how many
transportations to Greenland would suffice to promote such meagre flora
into the rich and abundant forests of the Upper Cretaceous, and to
people the earth with the exuberant vegetation of the early Tertiary.
Such problems we may never be able to solve. Probably they admit of no
solution, unless we invoke the action of a creative mind, operating
through long ages, and correlating with boundless power and wisdom
all the energies inherent in inorganic and organic nature. Even then
we shall perhaps be able to comprehend only the means by which, after
specific types have been created, they may, by the culture of their
Maker, be "sported" into new varieties or sub-species, and thus fitted
to exist under different conditions, or to occupy higher places in the
economy of nature.

Before venturing on such extreme speculations as some now current on
questions of this kind, we would require to know the successive extinct
floras as perfectly as those of the modern world, and to be able to
ascertain to what extent each species can change, either spontaneously
or under the influence of struggle for existence, or expansion under
favourable conditions, and under Arctic semi-annual days and nights, or
the shorter days of the tropics. Such knowledge, if ever acquired, it
may take ages of investigation to accumulate. In any case the subject
of this paper indicates one hopeful line of study with the object of
arriving at some comprehension of the laws of creation.

While the facts above slightly sketched impress us with the grand
progress of the vegetable kingdom in geological time, they equally show
the persistence of vegetable forms as compared with that of the dead
continental masses and the decay of some forms of life in favour of the
introduction of others.

When we find in the glacial beds the leaves of trees still living in
North America and Europe, and consider the vicissitudes of elevation
and submergence of the land, and of Arctic and temperate climates
which have occurred, we are struck with the persistence of the weak
things of life, as compared with the changeableness of rocks and
mountains. A superficial observer might think the fern or the moss
of a granite hill a frail and temporary thing as compared with solid
and apparently everlasting rock. But just the reverse is the case.
The plant is usually older than the mountain. But the glacial age
is a very recent thing. We have facts older than this. As hinted in
a previous paper, in the Laramie clays associated with the Lignite
beds of North-western Canada--beds of Lower Eocene or early Tertiary
age--which were deposited before the Rocky Mountains or the Himalayas
had reared their great peaks and ridges, and at a time when the whole
geography of the northern hemisphere was different from what it is
at present--are remains of very frail and delicate plants which still
live. I have shown that in these clays there exist, side by side, the
Sensitive Fern, _Onoclea sensibilis_, and one of the delicate rock
ferns, _Davallia tenuifolia_.[108] The first is still very abundant
all over North America. The second has ceased to exist in North
America, but still survives in the valleys of the Himalayas. These two
little plants, once probably very widely diffused over the northern
hemisphere, have continued to exist through the millenniums separating
the Cretaceous from the present time, and in which the greater part
of our continent was again and again under the sea, in which great
mountain chains have been rolled up and sculptured into their present
forms, and in which giant forms, both of animal and plant life, have
begun, culminated and passed away. Truly God hath chosen the weak
things of the world to confound those that are strong.

[108] Report on 49th Parallel, 1875.

Other plants equally illustrate the decadence of important types of
vegetable life. In the beautiful family of the Magnolias there exists
in America a most remarkable and elegant tree, whose trunk attains
sometimes a diameter of 7 feet and a height of 80 or 90 feet. Its
broad deep green leaves are singularly truncate at the end, as if
artificially cut off, and in spring it puts forth a wealth of large and
brilliant orange and yellow flowers, from which it obtains the name of
Tulip tree. It is the _Liriodendron tulipifera_ of botanists, and the
sole species of its genus. This Tulip tree has a history. All through
the Tertiary beds we find leaves referable to the genus, and belonging
not to one species only, but to several, and as we go back into the
Cretaceous, the species seem to become more numerous. Many of them
have smaller leaves than the modern species, others larger, and some
have forms even more quaint than that of the existing Tulip tree. The
oldest that I have seen in Canada is one from the Upper Cretaceous of
Port McNeil in the north of Vancouver Island, which is as large as that
of the modern species, and very similar in form. Thus this beautiful
vegetable type culminated long geological ages ago, and was represented
by many species, no doubt occupying a prominent place in the forests of
the northern hemisphere. To-day only a single species exists, in our
warmer regions, to keep up the memory of this almost perished genus;
but that species is one of our most beautiful trees.

The history of the Sequoias or giant Cypresses, of which two species
now exist in limited areas in California, is still more striking.
These giant trees, monsters of the vegetable kingdom, are, strange to
say, very limited in their geographical range. The greater of the two,
_Sequoia gigantea_, the giant tree _par excellence_, seems limited to a
few groves in California. At first sight this strikes us as anomalous,
especially as we find that the tree will grow somewhat widely both
in Europe and America when its seeds are sown in suitable soil. The
mystery is solved when we learn that the two existing species are but
survivors of a genus once diffused over the whole northern hemisphere,
and represented by many species, constituting, in the Later Cretaceous
and Eocene ages, vast and dark forests extending over enormous areas
of our continents, and forming much of the material of the thick and
widely distributed Lignite beds of North-western America. Thus the
genus has had its time of expansion and prevalence, and is now probably
verging on extinction, not because there are not suitable habitats, but
either because it is now old and moribund, or because other and newer
forms have now a preference in the existing conditions of existence.

The Plane trees, the Sassafras, the curious Ginkgo tree or fern-leaved
yew of Japan, are cases of similar decadence of genera once represented
by many species, while other trees, like the Willows and Poplars, the
Maples, the Birches, the Oaks and the Pines, though of old date, are
still as abundant as they ever were, and some genera would seem even
to have increased in number of species, though on the whole the flora
of our modern woods is much less rich than those of the Miocene and
Eocene, or even than that of the Later Cretaceous. The early Tertiary
periods were, as we know, times of exuberant and gigantic animal life
on the land, and it is in connection with this that the vegetable
world seems to have attained its greatest variety and luxuriance. Even
that early post-glacial age in which primitive man seems first to have
spread himself over our continents was one richer both in animal and
plant life than the present. The geographical changes which closed
this period and inaugurated the modern era seem to have reduced not
only the area of the continents but the variety of land life in a very
remarkable manner. Thus our last lesson from the genesis and migrations
of plants is the humbling one that the present world is by no means the
best possible in so far as richness of vegetable and animal life is
concerned.

Reference has been made to the utility of fossil plants as evidence
of climate; but the subject deserves more detailed notice. I have
often pondered on the nature of the climate evidenced by the floras of
the Devonian and Carboniferous; but the problem is a difficult one,
not only because of the peculiar character of the plants themselves,
so unlike those of our time, but because of the probably different
meteorological conditions of the period. It is easy to see that a
flora of tree-ferns, great lycopods and pines is more akin to that of
oceanic islands in warm latitudes than anything else that we know.
But the Devonian and Carboniferous plants did not flourish in oceanic
islands, but for the most part on continental areas of considerable
dimensions, though probably more flat and less elevated than those
of the present day. They also grew, from Arctic latitudes, almost,
if not altogether, to the equator; and though there are generic
differences in the plants of these periods in the southern hemisphere,
yet these do not affect the general facies. There are, for example,
characteristic Lepidodendroids in the Devonian and Carboniferous of
Brazil, Australia, and South Africa. If now we consider the plants a
little more in detail, coniferous and taxine trees grow now in very
different latitudes and climates. There is therefore nothing so very
remarkable in their occurrence. The great group of Cordaites may have
been equally hardy; but it is noteworthy that their geographical
distribution is more limited. In Europe, for example, they are more
characteristic in France than in Great Britain. Ferns and Lycopods and
Mare's-tails are also cosmopolitan, but the larger species belong to
the warmer climates, and nowhere at present do they become so woody and
so complex in structure as they were in the older geological periods.
At the present day, however, they love moisture rather than aridity,
and uniformity of temperature rather than extreme light and heat. The
natural inference would be that in these older periods geographical
and other conditions must have conspired to produce a uniform and
moist climate over a large portion of the continents. The geographical
conditions of the Carboniferous age, and the distribution of animal
life on the sea and land, confirm the conclusion based on the flora.
Further, if, as seems probable, there was a larger proportion of carbon
dioxide in the atmosphere than at present, this would not only directly
affect the growth of plants, but would impede radiation, and so prevent
escape of heat by that means, while the moisture exhaled from inland
seas and lagoons and vastly extended swamps, would tend in the same
direction.

It would, however, be a mistake to infer that there were not local
differences of climate. I have elsewhere[109] advocated the theory
that the great ridge of boulders, the New Glasgow conglomerate, which
forms one margin of the coal field of Picton, in Nova Scotia, is an
ice-formed ridge separating the area of accumulation of the great
thirty-six feet seam from an outer area in which aqueous conditions
prevailed, and little coal was formed. In this case, an ice-laden
sea, carrying boulders on its floes and fields of ice, must have been
a few miles distant from forests of Lepidodendra, Cordaites, and
Sigillariæ, and the climate must have been anything but warm, at least
at certain seasons. Nor have we a right to infer that the growth of
the coal-plants was rapid. Stems, with woody axes and a thick bark,
containing much fibrous and thick-walled cellular tissue, are not to
be compared with modern succulent plants, especially when we consider
the sparse and rigid foliage of many of them. Our conclusion should,
therefore, be that geographical conditions and the abundance of
carbon dioxide in the atmosphere favoured a moist climate and uniform
temperature, and that the flora was suited to these conditions.

[109] "Acadian Geology," Carboniferous of Picton.

As to the early Mesozoic flora, I have already suggested that it must
have been an invader from the south, for which the intervening Permian
age had made way by destroying the Palæozoic flora. This was probably
effected by great earth-movements changing geographical conditions.
But in the Mesozoic the old conditions to some extent returned, and
the Carboniferous plants being extinct, their places were taken by
pines, lycopods, and ferns, whose previous home had been in the insular
regions of the tropics, and which, as climatal conditions improved,
pushed their way to the Arctic circle. But, being derivatives of warm
regions, their vitality and capacity for variation were not great,
and they only locally and in favourable conditions became great coal
producers. The new flora of the Later Cretaceous and the Tertiary, as
previously stated, originated in the Arctic, and marched southward.

These newer Cretaceous plants presented from the first the generic
aspects of modern vegetation, and so enable us much better to gauge
their climatal conditions. In general, they do not indicate tropical
heat in the far north, but only that of the warm temperate zone; but
this in some portions of the period certainly extends to the middle of
Greenland, unless, without any evidence, we suppose that the Cretaceous
and lower Tertiary plants differed in hardiness of constitution from
their modern representatives. They prove, however, considerable
oscillations of climate. Gardner, Nathorst and Reid have shown this in
Europe, and that it extends from the almost tropical flora of the lower
Eocene to the Arctic flora of the Pleistocene. In America, owing, as
Grey has suggested, to its great north and south extension, the changes
were more regular and gradual. In the warmer periods of the Cretaceous,
the flora as far north as 55° was similar to that of Georgia and
Northern Florida at the present day, while in the cooler period of the
Laramie (Lower Eocene, or more probably Paleocene) it was not unlike
that of the Middle States. In the Pleistocene, the flora indicates a
boreal temperature in the Glacial age. Thus there are no very extreme
contrasts, but the evident fact of a warm temperate or subtropical
climate extending very far north at the same times when Greenland had
a temperate climate. As I have elsewhere shown,[110] discoveries in
various parts of North America are beginning to indicate the precise
geographical conditions accompanying the warmer and colder climates.

[110] Trans. Royal Society of Canada, 1890-1.

It would be wrong to leave this subject without noticing that
remarkable feature in the southward movement of the later floras,
to which I believe Prof. Gray was the first to direct attention. In
those periods when a warm climate prevailed in the Arctic regions,
the temperate flora must have been, like the modern Arctic flora,
circumpolar. When obliged to migrate to the south, it had to follow the
lines of the continents, and so to divide into separate belts. Three of
these at present are the floras of Western Europe, Eastern Asia, and
Eastern America, all of which have many representative species. They
are separated by oceans and by belts of land occupied by plants which
have not been obliged to migrate. Thus, while the flora of the Eastern
United States resembles that of China and Japan, that of California
and Oregon is distinct from both, and represents a belt of old species
retained in place by the continued warmth of the Pacific shore, and the
continuous extension of the American continent to the south affording
them means of retreat in the Glacial age. Were the plants of China
and Eastern America enabled to return to the Arctic, they would then
reunite into one flora. Gray compares the process of their separation
to the kind of selection which might be made by a botanical distributor
who had the whole collection placed in his hands, with instructions
to give one species of each genus to Europe, to Eastern Asia, and to
Eastern America; and if there was only one species in a genus, or if
one remained over, this was to be thrown into one of the regions, with
a certain preference in favour of America and Asia. This remarkable
kind of geographical selection opens a wide field not only for thought,
but for experiment on the actual relationship of the representative
species. There is a similar field for comparison between the trees
of Georgia in latitude 30° to 35°, and the same species or their
representatives as they existed in Cretaceous times in the latitudes of
50° and 60°. The two floras, as I know from actual comparison, are very
similar.

One word may be said here as to use of fossil plants in determining
geological time. In this I need only point to the fact of my
having defined in Canada three Devonian floras, a Lower, Middle,
and Upper, and that Mr. Whiteaves, in his independent study of the
fossil fishes, has vindicated my conclusions. There are also in Nova
Scotia three distinctive sub-floras of the Lower, Middle, and Upper
Carboniferous.[111] I have verified these for the Devonian and
Carboniferous of the United States, and to some extent also for those
of Europe. To the same effect is the recognition of the Kootanie or
Lower Cretaceous, the Middle Cretaceous, Upper Cretaceous, Laramie and
Miocene in Western Canada. These have in all cases corresponded with
the indications of animal fossils[112] and of stratigraphy. Fossil
plants have been less studied in this connection than fossil animals,
but I have no hesitation in affirming that, with reference to the
broader changes of the earth's surface, any competent palæobotanist is
perfectly safe in trusting to the evidence of vegetable fossils.

[111] _Transactions Royal Society of Canada_, 1883 to 1891.

[112] Reports on Fossil Plants of the Devonian and Lower Carboniferous.

It may be objected that such evidence will be affected by the
migrations of plants, so that we cannot be certain that identical
species flourished in Greenland and in temperate America at the same
time. If such species originated in Greenland and migrated southward,
the specimens found at the south may be much newer than those in the
north. This, no doubt, is locally true, but the migrations of plants,
though slow, occupy less time than that of a great geological period.
It may also be objected that the flora of swamps, plains, and mountain
tops would differ at any one period. This also is true, but the same
difficulty applies to animals of the deep sea, the shore, and the land;
and these diversities of station have always to be taken into account
by the palæontologist.

  References:--Report on the Erian or Devonian Plants of Canada,
    Montreal, 1871. Article in Princeton Review on Genesis and
    Migrations of Plants. "The Geological History of Plants," London
    and New York, 1888 and 1892. Papers on Fossil Plants of Western
    Canada, 1883, and following volumes of Transactions of Royal
    Society of Canada.

  Note.--Since writing the above, I have obtained access to Dall and
    Harris' "Neocene Correlation Papers," which throw some additional
    light on the Cretaceous and Eocene Floras of Alaska, which, from
    its high northern latitude, affords a good parallel to Greenland.
    It would appear that plant-beds occur in that territory at two
    horizons. One of these (Cape Beaufort), according to Lesquereux and
    Ward, holds species of Neocomian Age, and apparently equivalent to
    the Kootanie of British Columbia and the Komé of Greenland. The
    other, which occurs at several localities (Elukak, Port Graham,
    etc.), has a flora evidently of Laramie (Eocene) age, equivalent to
    the "Miocene" of Heer and Lesquereux, and to the Lignite Tertiary
    of Canada. The plants are accompanied by lignite, and evidently
    _in situ_, and clearly prove harmony with Greenland and British
    Columbia in two of the periods of high Arctic temperature indicated
    above.




                         _THE GROWTH OF COAL._


                      DEDICATED TO THE MEMORY OF

                             DR. SCHIMPER,

                             OF STRASBURG,

            The Author of "La Flore du Monde Primitif," and

              many other Contributions to Fossil Botany,

                                and of

                          DR. H. R. GOEPPERT,

          whose Essay on the Structure and Formation of Coal

               was One of my first Guides in its Study.


Questions of Growth and Driftage--Testimony of a Block of Coal under
the Microscope--Different Kinds of Coal--Conditions Necessary to
Accumulation in Situ--Coal Beds and their Accompaniments--Underclays
and Roofs--Vegetable Remains--History of Coal Groups--Summary
of Evidence--Subsidence of Coal Areas--Stigmaria and other Coal
Plants--Later Coal Accumulations--The Story and Uses of Coal

[Illustration: Part of a Coal Group, at the South Joggins, with
underclays and erect trees and Calamites (p. 238).]




CHAPTER IX.

_THE GROWTH OF COAL._


My early boyhood was spent on the Coal formation rocks and in the
vicinity of collieries; and among my first natural history collections,
in a childish museum of many kinds of objects, were some impressions of
fern leaves from the shales of the coal series. It came to pass in this
way that the Carboniferous rocks were those which I first studied as an
embryo geologist, and much of my later work has consisted in collecting
and determining the plants of that ancient period, and in studying
microscopic sections of coals and fossil woods accompanying them. For
this reason, and because I have published so much on this subject, my
first decision was to leave it out of these Salient Points: but on
second thoughts it seemed that this might be regarded as a dereliction
of duty; more especially as some of the conclusions supposed to be the
best established on this subject have recently been called in question.

Had I been writing a few years ago, I might have referred to the mode
of formation of coal as one of the things most surely settled and
understood. The labours of many eminent geologists, microscopists and
chemists in the old and the new worlds had shown that coal nearly
always rests upon old soil-surfaces penetrated with roots, and that
coal beds have in their roofs erect trees, the remains of the last
forests that grew upon them. Logan and the writer have illustrated
this in the case of the series of more than eighty successive coal
beds exposed at the South Joggins, and of the great thirty feet seam
of the Picton coal series, whose innumerable laminæ have all been
subjected to careful scrutiny, and have shown unequivocal evidence of
land surfaces accompanying the deposition of the coal. Microscopical
examination has proved that these coals are composed of the materials
of the same trees whose roots are found in the underclays, and their
stems and leaves in the roof shales; that much of the material of the
coal has been partially subjected to subaërial decay at the time of its
accumulation; and that in this, ordinary coal differs from bituminous
shale, earthy bitumen and some kinds of cannel, which have been formed
under water; that the matter remaining as coal consists almost entirely
of epidermal tissues, which being suberose or corky in character are
highly carbonaceous, very durable and impermeable by water, and are,
hence, the best fitted for the production of pure coal; and finally,
that the vegetation and the climatal and geographical features of
the coal period were eminently fitted to produce in the vast swamps
of that period precisely the effects observed. All these points and
many others have been thoroughly worked out for both European and
American coal fields, and seemed to leave no doubt on the subject. But
several years ago certain microscopists observed in slices of coal,
thin layers full of spore cases, a not unusual circumstance, since
these were shed in vast abundance by the trees of the coal forests,
and because they contain suberose matter of the same character with
epidermal tissues generally. Immediately we were informed that all coal
consists of spores, and this being at once accepted by the unthinking,
the results of the labours of many years are thrown aside in favour of
this crude and partial theory. A little later, a German microscopist
has thought proper to describe coal as made up of minute algæ, and
tries to reconcile this view with the appearances, devising at the same
time a new and formidable nomenclature of generic and specific names,
which would seem largely to represent mere fragments of tissues.
Still later, some local facts in a French coal field have induced an
eminent observer of that country to revive the drift theory of coal,
in opposition to that of growth _in situ_. Views of this kind have
also recently been advanced in England by some of those younger men
who would earn distinction rather by overthrowing the work of their
seniors than by building on it. These writers base their conclusions
on a few exceptional facts, as the occasional occurrence of seams of
coal without distinct underlays, and the occurrence of clay partings
showing aquatic conditions in the substance of thick coals; and they
fail to discern the broader facts which these exceptions confirm. Let
us consider shortly the essential nature of coal, and some of the
conditions necessary to its formation.

A block of the useful mineral which is so important an element in
national wealth, and so essential to the comfort of our winter homes,
may tell us much as to its history if properly interrogated, and what
we cannot learn from it alone we may be taught by studying it in the
mine whence it is obtained, and in the cliffs and cuttings where the
edges of the coaly beds and their accompaniments are exposed.

Our block of coal, if anthracite, is almost pure carbon. If bituminous
coal, it contains also a certain amount of hydrogen, which in
combination with carbon enables it to yield gas and coal tar, and which
causes it to burn with flame. If, again, we examine some of the more
imperfect and more recent coals, the brown coals, so called, we shall
find that in composition and texture they are intermediate between
coal proper and hardened or compressed peat. Now such coaly rocks can,
under the present constitution of nature, be produced only in one way,
namely, by the accumulation of vegetable matter, for vegetation alone
has the power of decomposing the carbonic acid of the atmosphere, and
accumulating it as carbon. This we see in modern times in the vegetable
soil, in peaty beds, and in vegetable muck accumulated in ponds and
similar places. Such vegetable matter, once accumulated, requires only
pressure and the changes which come of its own slow putrefaction to be
converted into coal.

But in order that it may accumulate at all, certain conditions are
necessary. The first of these includes the climatal and organic
arrangements necessary for abundant vegetable growth. The second is the
facility for the preservation of the vegetable matter, without decay or
intermixture with earthy substances; and this, for a long time, till
a great thickness of it accumulates. The third is its covering up by
other deposits, so as to be compressed and excluded from air. It is
evident that when we have to consider the formation of a bed of coal
several feet in thickness, and spread, perhaps, over hundreds of square
miles, many things must conduce to such a result, and the wonder is
perhaps rather that such conditions should ever have been effectively
combined. Yet this has occurred at different periods of geological
history and in many places, and in some localities it has been so
repeated as to produce many beds of coal in succession.

Let us now question our block of coal as to its origin, supposing it
to be a piece of ordinary bituminous coal, or still better, a specimen
of one of the impure somewhat shaly coals which one sometimes finds
accidentally in the coal bin. In looking at the edge of our specimen
we observe that it has a "reed" or grain, which corresponds with the
lamination or bedding of the seam of coal from which it came. Looking
at this carefully, we shall see that there are many thin layers of
bright shining coal, and the more of these usually the better the
coal. These layers, in tracing them along, we observe often to thin
out and disappear. They are not very continuous. If our specimen
is an impure coal, we will find that it readily splits along the
surfaces of these layers, and that when so split, we can see that each
layer of shining coal has certain markings, perhaps the flattened
ribs and scars of Sigillaria or other coal-formation trees on its
surface. In other words, the layers of fine coal are usually flattened
trunks and branches of trees, or perhaps rather of the imperishable
and impermeable bark of such trees, the wood having perished. A few
very thin layers of shining coal we may also find to consist of the
large-ribbed leaves of the plant known as Cordaites. This kind of coaly
matter then usually represents trunks of trees which in a prostrate and
flattened state may constitute more than half of the bulk of ordinary
coal-formation coal. Under the microscope this variety of coal shows
little structure, and this usually the thickened cells of cortical
tissue. Intervening between these layers we perceive lamina?, more
or less thick and continuous, of what we may call dull coal, black
but not shining; resembling, in fact, the appearance of cannel coal.
If we split the coal along one side of these layers, and examine it
in a strong light, we may see shreds of leaf stalks and occasionally
even of fern leaves, or skeletons of these, showing the veins, and
many flattened disc-like bodies, spore cases and macrospores, shed by
the plants which make up the coal. These layers represent what may be
called compressed vegetable mould or muck, and this is by no means a
small constituent of many coals. This portion of the coal is the most
curious and interesting in microscopic slices, showing a great variety
of tissues and many spores and spore cases. Lastly, we find on the
surface of the coal, when split parallel to the bedding, a quantity
of soft shining fibrous material, known as mineral charcoal or mother
coal, which in some varieties of the mineral is very abundant, in
others much more rare. This is usually too soft and incoherent to be
polished in thin slices for the microscope; but if boiled for a length
of time in nitric acid, so as to separate all the mineral matter
contained in it, the fibres sometimes become beautifully translucent
and reveal the tissues of the wood of various kinds of Carboniferous
trees, more especially of Calamites, Cordaites and Sigillariæ. Fibres
of mineral charcoal prepared in this way are often very beautiful
microscopic objects under high powers; and this material of the coal
is nothing else than little blocks of rotten wood and fibrous bark,
broken up and scattered over the surface of the forming coal bed. All
these materials, it must be observed, have been so compressed that the
fragments of decayed wood have been flattened into films, the vegetable
mould consolidated into a stony mass, and trunks of great trees
converted by enormous pressure into laminæ of shining coal, a tenth of
an inch in thickness, so that the whole material has been reduced to
perhaps one-hundredth of its original volume.

Restoring the mass in imagination to its original state, what do we
find? A congeries of prostate trunks with their interstices filled with
vegetable muck or mould, and occasional surfaces where rotten wood,
disintegrated into fragments, was washed about in local floods or rain
storms, and thus thrown over the surface. Lyell seems very nearly to
have hit the mark when he regarded the conditions of the great dismal
swamp of Virginia as representing those of a nascent coal field. We
have only to realize in the coal period the existence of a dense
vegetation very different from that of modern Virginia, of a humid and
mild climate, and of a vast extension of low swampy plains, to restore
the exact conditions of the coal swamps.

But how does this correspond with the facts observed in mines and
sections? To the late Sir William Logan is due the merit of observing
that in South Wales the underclays or beds of indurated clay and earth
underlying the coal seams are usually filled with the long cylindrical
rootlets and branching roots of a curious plant, very common in the
coal formation, the Stigmaria. He afterwards showed that the same fact
occurs in the very numerous coal beds exposed in the fine section cut
by the tides of the Bay of Fundy, in the coal rocks of Nova Scotia. In
that district I have myself followed up his observations, examining
in detail every one of eighty-one Coal Groups, as I have called them,
each consisting of at least one bed of coal, large or small, with
its accompaniments, and in many cases of several small seams with
intervening clays or shales.[113] In nearly every case the Stigmaria
"underclay" is distinctly recognisable, and often in a single coal
group there are several small seams separated by underclays with roots
and rootlets. These underclays are veritable fossil soils; sometimes
bleached clays or sands, like the subsoils of modern swamps; sometimes
loamy or sandy, or of the nature of hardened vegetable mould. They
rarely contain any remains of aquatic animals, or of animals of any
kind, but are filled with stigmaria roots and rootlets, and sometimes
hold a few prostrate stems of trees.[114] While the underclay is thus
a fossil soil, the roof or bed above the coal, usually of a shaly
character, is full of remains of leaves and stems and fruits, and often
holds erect stumps, the remains of the last trees that grew in the
swamp before it was finally covered up.

[113] For details see _Journal Geol. Society of London_, 1865; and
"Acadian Geology," last edition, 1891.

[114] At the South Joggins, in two or three cases, beds of bituminous
shale full of Naiadites and Cyprids have by elevation and drying become
fit for the growth of trees with stigmaria roots; but this is quite
exceptional, no doubt arising from the accidental draining of lakes or
lagoons on their elevation above the sea level.

Some of the thinnest coals, and some beds so thin and impure that they
can scarcely be called coals at all, are the most instructive. Witness
the following from my section of the South Joggins.

Coal Group 1, of Division 3, is the highest of the series. Its section
is as follows:--

  "Grey argillaceous shale.
   Coal, 1 inch.
   Grey argillaceous underclay, Stigmaria.

"The roof holds abundance of fern leaves (_Alethopteris lonchitica_).
The coal is coarse and earthy, with much epidermal and bast tissue,
spore cases, etc., vascular bundles of ferns and impressions of bark
of Sigillaria and leaves of Cordaites. It may be considered as a
compressed vegetable soil resting on a subsoil full of rootlets of
Stigmaria." In this case the coal is an inch in thickness, but there
are many beds where the coal is a mere film, and supports great
erect stems of Sigillaria, sending downward their roots in the form
of branching Stigmariæ into the underclay, thus proving that the
Stigmariæ of the underclays are the roots of the Sigillariæ of the
coals and their roofs.

Here is another example which may be called a coal group, and is No. 11
of the same division:

  "Grey argillaceous shale, erect Calamites.
   Coal, 1 inch.
   Grey argillaceous underclay, Stigmaria, 1 ft. 6 in.
   Coal, 2 inches.
   Grey argillaceous underclay, Stigmaria, 4 in.
   Coal, 1 inch.
   Grey argillaceous underclay, Stigmaria.

"This is an alternation of thin, coarse coals with fossil soils. The
roof shale contains erect Calamites, which seem to have been the last
vegetation which grew on the surface of the upper coal."

Such facts, with many minor varieties, extend through the whole
eighty-one coal groups of this remarkable section, as any one may see
by referring to the paper and work cited in the preceding note. It
is possibly because in most coal fields the smaller and commercially
useless beds are so little open to observation, that so crude ideas
derived merely from imperfect access to the beds that are worked exist
among geologists. The following summary of facts may perhaps serve to
place the evidence as to the mode of accumulation of coal fairly before
the reader:--

(1) The occurrence of Stigmaria under nearly every bed of coal proves,
beyond question, that the material was accumulated by growth _in situ_,
while the character of the sediments intervening between the beds of
coal proves with equal certainty the abundant transport of mud and sand
by water. In other words, conditions similar to those of the swampy
deltas of great rivers, or the swampy flats of the interiors of great
continents, are implied.

(2) The true coal consists principally of the flattened bark of
sigillaroid and other trees, intermixed with leaves of ferns and
_Cordaites_, and other herbaceous _débris_, including vast numbers of
spores and spore cases, and with fragments of decayed wood constituting
"mineral charcoal," all their materials having manifestly alike grown
and accumulated where we find them.

(3) The microscopical structure and chemical composition of the beds
of cannel coal and earthy bitumen, and of the more highly bituminous
and carbonaceous shales, show them to have been of the nature of the
fine vegetable mud which accumulates in the ponds and shallow lakes
of modern swamps. These beds are always distinct from true subaërial
coal. When such fine vegetable sediment is mixed, as is often the
case, with mud, it becomes similar to the bituminous limestone and
calcareo-bituminous shales of the coal measures.

(4) A few of the underclays which support beds of coal are of the
nature of the vegetable mud above referred to; but the greater part are
argillo-arenaceous in composition, with little vegetable matter, and
bleached by the drainage from them of water containing the products
of vegetable decay. They are, in short, loamy or clay soils in the
chemical condition in which we find such soils under modern bogs,
and must have been sufficiently above water to admit of drainage.
The absence, or small quantity of sulphides, and the occurrence of
carbonate of iron in connection with them, prove that when they
existed as soils, rain water, and not sea water, percolated them.

(5) The coal and the fossil trees present many evidences of subaërial
conditions. Most of the erect and prostrate trees had become hollow
shells of bark before they were finally imbedded, and their wood had
broken into cubical pieces of mineral charcoal. Land snails and galley
worms (_Xylobius_) crept into them, and they became dens or traps for
reptiles. Large quantities of mineral charcoal occur on the surfaces of
all the larger beds of coal. None of these appearances could have been
produced by subaqueous action.

(6) Though the roots of _Sigillaria_ bear some resemblance to the
rhizomes of certain aquatic plants, yet structurally they have much
resemblance to the roots of Cycads, which the stems also resemble.
Further, the _Sigillariæ_ grew on the same soils which supported
conifers, _Lepidodendra_, _Cordaites_, and ferns, plants which could
not have grown in water. Again, with the exception, perhaps, of some
_Pinnulariæ_ and _Asterophyllites_, and Rhizocarpean spores, there is
a remarkable absence from the coal measures of any form of properly
aquatic vegetation.

(7) The occasional occurrence of marine or brackish-water animals in
the roofs of coal beds, or even in the coal itself, affords no evidence
of subaqueous accumulation, since the same thing occurs in the case of
modern submarine forests. Such facts merely imply that portions of the
areas of coal accumulation were liable to inundation of a character so
temporary as not finally to close the process, as happened when at last
a roof shale was deposited by water over the coal. Cannel coals and
bituminous shales holding mussel-like shells, fish scales, etc., imply
the existence sometimes for long periods of ponds, lakes or lagoons
in the coal swamps, but ordinary coal did not accumulate in these. It
is in the cannels and similar subaqueous coals that the macrospores
which I attribute in great part to aquatic plants, allied to modern
Salvinia, etc., are chiefly found.[115]

[115] "Geological History of Plants," _Bulletin Chicago Academy of
Sciences_, 1886.

For these and other reasons, some of which are more fully stated in the
papers referred to, while I admit that the areas of coal accumulation
were frequently submerged, I must maintain that the true coal is a
subaërial accumulation by vegetable growth on soils wet and swampy,
it is true, but not submerged. I would add the further consideration,
already urged elsewhere, that in the case of the fossil forests
associated with the coal, the conditions of submergence and silting-up
which have preserved the trees as fossils, must have been precisely
those which were fatal to their existence as living plants, a fact
sufficiently evident to us in the case of modern submarine forests, but
often overlooked by the framers of theories of the accumulation of coal.

It seems strange that the occasional inequalities of the floors of
the coal beds, the sand or gravel ridges which traverse them, the
channels cut through the coal, the occurrence of patches of sand, and
the insertion of wedges of such material splitting the beds, have been
regarded by some able geologists as evidences of the aqueous origin of
coal. In truth, these appearances are of constant occurrence in modern
swamps and marshes, more especially near their margins, or where they
are exposed to the effects of ocean storms or river inundations. The
lamination of the coal has also been adduced as a proof of aqueous
deposition; but the microscope shows, as I have elsewhere pointed out,
that this is entirely different from aqueous lamination, and depends
on the superposition of successive generations of more or less decayed
trunks of trees and beds of leaves. The lamination in the truly aqueous
cannels and carbonaceous shales is of a very different character.

It is scarcely necessary to remark that in the above summary I have
had reference principally to my own observations in the coal formation
of Nova Scotia; but similar facts have been detailed by many other
observers in other districts.[116]

[116] Especially Brongniart, Goeppert, Hawkshaw, Lyell, Logan, De la
Boche, Beaumont, Binney, Rogers, Lesquereux, Williamson, Grand' Eury.

A curious point in connection with the origin of coal is the question
how could vegetable matter be accumulated in such a pure condition?
There is less difficulty in regard to this if we consider the coal
as a swamp accumulation _in situ_. It is in this way that the purest
vegetable accumulations take place at present, whereas in lakes and at
the mouths of rivers vegetable matter is always mixed up with mud. Coal
swamps, however, must have been liable to submergences or to temporary
inundations, and it is no doubt to these that we have to attribute
the partings of argillaceous matter often found in coal beds, as well
as the occasional gulches cut into the coal and filled with sand and
lenticular masses of earthy matter. To a similar cause we must also
attribute the association of cannel with ordinary coal. The cannel is
really a pulpy, macerate mass of vegetable matter accumulated in still
water, surrounded and perhaps filled with growing aquatic herbage.
Hence it is in such beds that we find the greatest accumulations of
macrospores, derived, probably, in great part from aquatic plants.
Buckland long ago compared the matter of cannel to the semi-fluid
discharge of a bursting bog, and Alex. Agassiz has more recently shown
that in times of flood the vegetable muck of the Everglades of Florida
flows out in thick inky streams, and may form large beds of vegetable
matter having the character of the materials of cannel. It is evident
that in swamps of so great extent as those of the coal formation, there
must have been shallow lakes and ponds, and wide sluggish streams,
forming areas for the accumulation of vegetable _débris_ and this
readily accounts for the association of ordinary beds of coal with
those of cannel, and with bituminous shales or earthy bitumen, as well
as for the occurrence of scales of fish and other aquatic animals in
such beds. Lyell's interesting observation of the submerged areas at
New Madrid, keeping free of Mississippi mud, because fringed with a
filter of cane-brake, shows that the areas of coal accumulation might
often be inundated without earthy deposit, if, as seems probable, they
were fringed with dense brakes of calamites, sheltering them from the
influx of muddy water. It seems also certain that the water of the coal
areas would be brown and laden with imperfect vegetable acids, like
that of modern bogs, and such water has usually little tendency to
deposit any mineral matter, even in the pores of vegetable fragments.
The only exception to this is one which also occurs in modern swamps,
namely, the tendency to deposit iron, either as carbonate (Clay
Ironstone), or sulphide (Iron Pyrite), both of which are products of
modern bogs, and equally characteristic of the coal swamps.

Where great accumulations of sediment are going on, as at the mouths
of modern rivers, there is a tendency to subsidence of the area of
the deposit, owing to its weight. This applies, perhaps, to a greater
extent to coal areas. Thus the area of a coal swamp would ultimately
sink so low as to be overflowed, and a roof shale would be deposited to
bury up the bed of coal, and transmit it to future ages, chemically,
and mechanically changed by pressure and by that slow decomposition
which gradually converts vegetable matter into carbon and hydrocarbons.
The long continuance and great extent of these alternations of growth
and subsidence is perhaps the most extraordinary fact of all. At the
South Joggins, if we include the surfaces having erect trees with those
having beds of coal, the process of growth of a forest or bog, and
its burial by subsidence and deposition must have been repeated about
a hundred times before the final burial of the whole under the thick
sandstones of the Upper Carboniferous and Permian.

Mention has been made of Sigillaria and other trees of the coal
formation period. These trees and others allied to them, of which there
were many kinds, may be likened to gigantic club mosses, which they
resembled in fruit and foliage, though vastly more complex in structure
of stem and branch. Some of them, perhaps, were of much higher rank
than any of the modern plants most nearly allied to them. One of their
most remarkable features was that of their roots--those Stigmariæ, to
which so frequent reference has been made. They differed from modern
roots, not only in some points of structure, but in their regular
bifurcation, and in having huge root fibres articulated to the roots,
and arranged in a regular spiral manner, like leaves. They radiate
regularly from a single stem, and do not seem to have sent up buds or
secondary stems. They thus differed from the botanical definition of a
root, and also from that of a rhizoma, or root stock; being, in short,
a primitive and generalized contrivance, suited to trees themselves
primitive and generalized, and to special and peculiar circumstances
of growth. Some botanists have imagined that they were aquatic plants,
growing at the bottom of lakes, but their mode of occurrence negatives
this. I have elsewhere stated this as follows:--[117]

[117] _Natural Science_, May, 1892.

"It is quite certain that Stigmariæ are not 'rhizomes which floated
in water, or spread themselves out on the surface of mud.' Whether
rhizomes or not, they grew in the soil, or in the upper layers of peaty
deposits since changed into coal. The late Richard Brown and the writer
have shown that they grew in the underclays or fossil soils, and that
their rootlets radiated in these soils in all directions.[118] In one
of my papers I have figured a Stigmarian root penetrating through an
erect _Sigillaria_, and Logan, in his Report of 1845, had already
figured a similar example. The penetration of decaying stems by the
rootlets of _Stigmaria_ is a fact well known to all who have studied
slices of Carboniferous plants,[119] while _Stigmariæ_ are often found
creeping inside the bark of erect and prostrate trunks. Besides this,
as I have shown in 'Acadian Geology,' in the section of 5,000 feet
of coal measures at the South Joggins (including eighty-one distinct
coal groups, and a larger number of soils with _Stigmaria_, or erect
trees), _Sigillaria_ and _Stigmaria_ occur together, and the latter
nearly always either in argillaceous soils, or sands hardened into
'Gannister,' which are often filled with roots or rootlets, or on the
surfaces of coal beds. On the other hand, the numerous bituminous
limestones, and calcareous and other shales holding remains of fishes,
crustaceans, and bivalve shells do not contain Stigmaria _in situ_--the
only exceptions being two beds of bituminous limestone, the upper
parts of which have been converted into underclays. This section, and
that of North Sydney--two of the most complete and instructive in
the world--have afforded conclusive proof of this mode of growth of
_Sigillaria_ and _Stigmaria_.

[118] _Quart. Journ. Geol. Soc._, vol. ii. p. 394 (1846); _Ibid._, vol.
iv. p. 47 (1847); _Ibid._, vol. v. p. 355 (1849); _Ibid._, vol. v. pp.
23, 30.

[119] Williamson has noticed this in his excellent Memoirs in the
_Phil. Trans._

"The objection to calling the Stigmariæ roots and their processes
rootlets, appears to me a finical application of modern botanical
usages to times for which they do not hold. We might equally object
to the application of the term roots to those which spring from the
earthed-up stems of Calamites, radiating as they do from nodes which,
in the air, would produce branchlets. Grand' Eury's figures show
abundant instances of this. We might also object to the exogenous stems
described by Williamson, which belong to cryptogamous plants; and,
unlike anything modern, are made up exclusively of scalariform tissue.
If the articulation and regular arrangement of those gigantic root
hairs, the rootlets, or 'leaves' of _Stigmaria_, are to be regarded
as depriving them of the name which clearly describes their function,
we may call them underground branches, though, by so doing, we set at
nought both their function and their mode of growth."

Dr. Williamson, in a recent paper, expresses the same view in the
following terms[120]:--"At that period (the Carboniferous age) no
Angiosperms existed on the earth, and even the Gymnosperms were very
far from reaching their modern development. Under these circumstances
the Cryptogams chiefly became the giant forest trees of that remote
age. To become such, they required an organization very different in
some respects from that of their degraded living representatives. Hence
we must not appeal to these degenerate types for illustrations and
explanations of structures no longer existing. Still less must we turn
to what we find in the Angiosperms, that wholly distinct race which has
taken the place of the primæval Cryptogams in our woods. The primeval
giants of the swampy forests had doubtless a morphology assigned to
them, adapted to the physical conditions by which they were surrounded;
but if even their dwarfed and otherwise modified descendants fail to
throw light upon morphological details once so common, still less must
we expect to obtain that light from the living and wholly different
flowering plants."

[120] _Natural Science_, July, 1892.

With the remarkable trees above referred to, there coëxisted a vast
multitude of ferns, some arborescent, others herbaceous, tall,
reed-like plants, the Calamites, allied to modern Mare's-tails, a
very remarkable family of plants allied to modern Cycads and Pines;
the Cordaites, which seem to have grown plentifully in certain parts
of the coal areas--probably the drier parts, so that their remains
sometimes constitute the greater part of small seams of coal. There
were also true pine-like trees, though these would seem to have grown
most abundantly on the higher levels. Nor was strictly aquatic
vegetation wanting. We find, both in the preceding Devonian and the
Carboniferous, that the little aquatic plants now known as Rhizocarps,
and structurally allied to the Ferns--such plants as the floating
Salvinia, and the Pillworts of our swamps, were vastly abundant, and
they may have filled and choked up with their exuberant growth many of
the lakes and slow streams of the period, furnishing layers of cannel
and "macrospore" coal, and earthly bitumen or Torbanite.

We have hitherto confined our attention to the great Carboniferous
period, so called, as emphatically the age of coal; but this mineral,
and allied forms of carbon, were produced both before and after. Even
in that old Laurentian age, which includes the oldest rocks that we
know, formed when the first land had just risen out of the waters,
there are thick beds of graphite, or plumbago, chemically the same with
anthracite coal, and which must have been produced by the agency of
plants, whether terrestrial or aquatic. We may suppose that the plants
of this remote age were of very humble type as much lower than those
of the coal formation as these are lower than those of the present
day; but if so, then, on the analogy of the Carboniferous, they would
be high and complex representatives of those low types. But there is
another and more startling possibility; that the Laurentian may have
been a period when vegetable life culminated on the earth, and existed
in its most complete and grandest forms in advance of the time when
it was brought into subordination to the higher life of the animal.
In the meantime, the Laurentian rocks are in a state of so extreme
metamorphism that they have afforded no certain indication of the forms
or structures of the vegetation of the period.

We find indications of plant life through all the Palæozoic groups
succeeding the Laurentian; but it is not till we reach the Devonian,
the system immediately preceding the Carboniferous, that we find
an abundance of forms not essentially different from those of the
Carboniferous, though similar in details. Only a few and very small
beds of coal were accumulated in this age; but there was an immense
abundance of bituminous shale enriched with the macrospores of
Rhizocarps. The Ohio black shale, which is said to extend its outcrop
across that state with a breadth of ten to twenty miles, and a
thickness of 550 feet, is filled with macrospores of Protosalvinia, as
is its continuation in Canada.

Above the great coal formation the Permian and Jurassic contain beds
of coal, though of limited extent, and formed in the case of the two
latter of very different plants from those of the Carboniferous. In
the Cretaceous and Tertiary ages, after the abundant introduction
of species of forest trees still living, coal making seems to have
obtained a new impulse, so that in China and the western part of
America there are coals of great extent and value, all made of plants
of genera still existing. In the Cretaceous coal of Vancouver Island
there are remains of such modern trees as the Poplars, Magnolias,
Palmettos, Sequoias, and a great variety of other genera still living
in America. Out of the remains of these, under favouring conditions,
quite as good coal as that of the coal formation has been made,
although the plants are so different. There is, indeed, reason to
believe that those now rare trees, the Sequoias, represented at the
present time only by the big trees of California, and their companion,
the redwood, were then spread universally over the northern hemisphere,
and formed dense forests on swampy flats which led to the accumulation
of coal beds in which the trunks and leaves of the Sequoias formed
main ingredients, so that Sequoia and its allies in this later age
take the place of the Sigillariæ of the coal formation. Last of all,
coal accumulation is still going on in the Everglades of Florida,
the dismal swamp of Virginia, and the peat-bogs of the more northern
regions. So the vegetable kingdom has, throughout its long history,
been continually depriving the atmosphere of its carbon dioxide, and
accumulating this in beds of coal. In the earlier ages indeed, this
would seem to us to have been its main use.

To the modern naturalist, vegetable life, with regard to its uses,
is the great accumulator of pabulum for the sustenance of the higher
forms of vital energy manifested in the animal. In the Palæozoic this
consideration sinks in importance. In the Coal period we know few land
animals, and these not vegetable feeders, with the exception of some
insects, millipedes, and snails. But the Carboniferous forests did not
live in vain, if their only use was to store up the light and heat of
those old summers in the form of coal, and to remove the excess of
carbonic acid from the atmosphere. In the Devonian period even these
utilities fail, for coal does not seem to have been accumulated to
any great extent, though the abundant petroleum of the Devonian is,
no doubt, due to the agency of aquatic vegetation. In addition to
scorpions, a few insects are the only known tenants of the Devonian
land, and these are of kinds whose lame probably lived in water, and
were not dependent on land plants. We may have much yet to learn of the
animal life of the Devonian; but for the present, the great plan of
vegetable nature goes beyond our measures of utility; and there remains
only what is perhaps the most wonderful and suggestive correlation
of all, namely, that our minds are able to trace in these perished
organisms structures similar to those of modern plants, and thus to
reproduce in imagination the forms and habits of growth of living
things which so long preceded us on the earth.

In another way Huxley has put the utilitarian aspect of the case so
admirably, that I cannot refrain from quoting his clever apotheosis of
nature in connection with the production of coal.

"Nature is never in a hurry, and seems to have had always before her
eyes the adage, 'Keep a thing long enough, and you will find a use for
it.' She has kept her beds of coal for millions of years without being
able to find a use for them; she has sent them beneath the sea, and the
sea beasts could make nothing of them; she had raised them up into dry
land, and laid the black veins bare, and still for ages and ages there
was no living thing on the face of the earth that could see any sort
of value in them; and it was only the other day, so to speak, that she
turned a new creature out of her workshop, who, by degrees, acquired
sufficient wits to make a fire, and then to discover that the black
rock would burn.

"I suppose that nineteen hundred years ago, when Julius Cæsar was good
enough to deal with Britain as we have dealt with New Zealand, the
primæval Briton, blue with cold and woad, may have known that the
strange black stone which he found here and there in his wanderings
would burn, and so help to warm his body and cook his food. Saxon,
Dane, and Norman swarmed into the land. The English people grew into a
powerful nation; and Nature still waited for a return for the capital
she had invested in ancient club mosses. The eighteenth century
arrived, and with it James Watt. The brain of that man was the spore
out of which was developed the steam engine, and all the prodigious
trees and branches of modern industry which have grown out of this. But
coal is as much an essential of this growth and development as carbonic
acid is of a club moss. Wanting the coal, we could not have smelted
the iron needed to make our engines; nor have worked our engines
when we got them. But take away the engines, and the great towns of
Yorkshire and Lancashire vanish like a dream. Manufactures give place
to agriculture and pasture, and not ten men could live where now ten
thousand are amply supported.

"Thus all this abundant wealth of money and of vivid life is Nature's
investment in club mosses and the like so long ago. But what becomes
of the coal which is burnt in yielding the interest? Heat comes out
of it, light comes out of it, and if we could gather together all that
goes up the chimney, and all that remains in the grate of a thoroughly
burnt coal fire, we should find ourselves in possession of a quantity
of carbonic acid, water, ammonia, and mineral matters exactly equal in
weight to the coal. But these are the very matters with which Nature
supplied the club mosses which made coal. She is paid back principal
and interest at the same time; and she straightway invests the carbonic
acid, the water, and the ammonia in new forms of life, feeding with
them the plants that now live. Thrifty Nature, surely! no prodigal, but
the most notable of housekeepers."[121]

[121] _Contemporary Review_, 1871.

All this is true and well told; but who is "Nature," this goddess who,
since the far-distant Carboniferous age, has been planning for man? Is
this not another name for that Almighty Maker who foresaw and arranged
all things for His people "before the foundation of the world."

  References:--On Structures in Coal, _Journal Geological Society
    of London_, xv., 1853. Contains results of microscopic study of
    Nova Scotia coals. Conditions of Accumulation of Coal, _Ibid._,
    xxii., 1866. Contains South Joggins section. Spore-cases in Coal,
    _Am. Journal of Science_, 3rd series, vol. I, 1871. Rhizocarps in
    the Devonian, _Bulletin Chicago Academy_, vol. I, 1886. "Acadian
    Geology and Supplement," 3rd edition, 1891, Cumberland Coal Field.
    "Geological History of Plants," chap, iv., London and New York, 2nd
    edition, 1892.




                      _THE OLDEST AIR-BREATHERS._


                      DEDICATED TO THE MEMORY OF

                 MY FRIEND AND EARLY PATRON AND GUIDE

                          SIR CHARLES LYELL,

                  To whom we are Indebted for so much

              of the Scientific Basis of Modern Geology.


Earliest Discoveries--Footprints of Batrachians--Labyrinthodents
of the Carboniferous--Microsauria of the Carboniferous--Other
Types--Discoveries in Erect Trees--Invertebrate Air-breathers, Land
Snails, Millipedes, Insects, Spiders And Scorpions--General Conclusions

[Illustration: Remains of Hylonomus Lyelli, Dawson, 1859. Coal
Measures, South Joggins; Nova Scotia.

Photograph of Type specimen somewhat enlarged, _Geol. Magazine_, 1891
(p. 279). (1) Cranial bones and mandibles; (1_a_) Sternal and shoulder
bones; (2) Mandible; (3) Humerus, ribs and vertebræ; (4) Hind limb; (5)
Pelvis; (6) Caudal vertebræ.]




CHAPTER X.

_THE OLDEST AIR-BREATHERS._


Animal life had its beginning in the waters, and to this day the waters
are the chief habitat of animals, especially of the lower forms. If
we divide the animal kingdom into great leading types, the lowest of
these groups, the Protozoa, includes only aquatic forms; the next,
that of the coral animals and their allies, is also aquatic. So are
all the species of the Sea Urchins and Star Fishes. Of the remaining
groups, the Mollusks, the Crustaceans, and the Worms are dominantly
aquatic, only a small proportion being air-breathers. It is only in
the two remaining groups, including the Insects and Spiders on the one
hand, and the Vertebrate animals on the other, that we have terrestrial
species in large proportion.

The same fact appears in geological time. The periods represented by
the older Palæozoic rocks have been termed ages of invertebrates,
and they might also be termed ages of aquatic animals. It is only
gradually, and as it were with difficulty, that animals living in the
less congenial element of air are introduced--at first a few scorpions
and insects, later, land snails and amphibian reptiles, later still,
the higher reptiles and the birds, and last of all the higher mammalia.

We need not wonder at this, for the conditions of life with reference
to support, locomotion, and vicissitudes of temperature are more
complex and difficult in air, and require more complicated and perfect
machinery for their maintenance. Thus it was that probably half of the
whole history of our earth had passed away before the land became
the abode of any large number and variety of animals; while it was
only about the same time that the development of the vegetable kingdom
became so complete as to afford food and shelter for air-breathers.

It is also worthy of note that it is only in comparatively recent times
that we have been able to discover the oldest air-breathing animals,
and geologists long believed that the time when animals had existed on
the land was even shorter than it had actually been. This arose in part
from the infrequency and rarity of preservation of the remains of the
earliest creatures of this kind, and perhaps partly from the fact that
collectors were not looking for them.

That there was dry land, even in the Cambro-Silurian period, we know,
and can even trace its former shores. In Canada our old Laurentian
coast extends for more than a thousand miles, from Labrador to Lake
Superior, marking the southern border of the nucleus of the American
continent in the Cambrian and Cambro-Silurian periods. Along a great
part of this ancient coast we have the sand flats of the Potsdam
Sandstone, affording very favourable conditions for the imbedding of
land animals, did these exist; still, notwithstanding the zealous
explorations of the Geological Survey, and of many amateurs, no trace
of an air-breather has been found. I have myself followed the oldest
Palæozoic beds up to their ancient limits in some localities, and
collected the shells which the waves had dashed on the beach, and have
seen under the Cambro-Silurian beds the old pre-Cambrian rocks pitted
and indented with weather marks, showing that this shore was then
gradually subsiding; yet the record of the rocks was totally silent
as to the animals that may have trod the shore, or the trees that may
have waved over it. All that can be said is that the sun shone, the
rain fell, and the wind blew as it does now, and that the sea abounded
in living creatures. The eyes of Trilobites, the weathered Laurentian
rocks, the wind ripples in the Potsdam sandstone, the rich fossils
of the limestones, testify to these things. The existence of such
conditions would lead us to hope that land animals may yet be found in
these older formations. On the other hand, the gradual failure of one
form of life after another, as we descend in the geological series, and
the rarity of fishes and land plants in the Silurian rocks and their
absence from the Cambrian, might induce us to believe that we have here
reached the beginning of animal life, and have left far behind us those
forms that inhabit the land.

Even in the Carboniferous period, though land plants abound,
air-breathers are not numerous, and most of them have only been
recently recognised. We know, however, with certainty that the dark and
luxuriant forests of the coal period were not destitute of animal life.
Reptiles[122] crept under their shade, land snails and millipedes fed
on the rank leaves and decaying vegetable matter, and insects flitted
through the air of the sunnier spots. Great interest attaches to these
creatures; perhaps the first-born species in some of their respective
types, and certainly belonging to one of the oldest land faunas, and
presenting prototypes of future forms equally interesting to the
geologist and the zoologist.

[122] I shall use the term reptile here in its broad, popular sense, as
including Batrachians as well as reptiles proper.

It has happened to the writer of these pages to have had some share in
the finding of several of these ancient animals. The coal formation of
Nova Scotia, so full in its development, so rich in fossil remains, and
so well exposed in coast cliffs, has afforded admirable opportunities
for such discoveries, which have been so far improved that at least
twenty-five out of the not very large number of known Carboniferous
land animals have been obtained from it.[123] The descriptions of
these creatures, found at various times and at various places, are
scattered through papers ranging in date from 1844 to 1891,[124]
and are too fragmentary to give complete information respecting the
structures of the animals, and their conditions of existence.

[123] It appears that about a hundred species of Carboniferous reptiles
have been recognised on the continent of Europe, in Great Britain, and
in the United States. They belong to a number of distinct types, all,
however, being of batrachian affinities.

[124] Papers by Lyell, Owen, and the author, in the _Journal of the
Geological Society of London_, i. ii. ix. x. xi. xvi. xvii. xviii.;
"Acadian Geology," by the author; Papers in _Trans. Royal Society of
London_, _Am. Jl. of Science_, and _Geological Magazine_.


Footprints.

It has often happened to geologists, as to other explorers of
new regions, that footprints on the sand have guided them to the
inhabitants of unknown lands, and such footprints, proverbially
perishable, may be so preserved by being filled up with matter
deposited in them as to endure for ever. This we may see to-day in
the tracks of sandpipers and marks of rain-drops preserved in the
layers of alluvial mud deposited by the tides of the Bay of Fundy, and
which, if baked or hardened by pressure, might become imperishable,
like the inscriptions of the old Chaldeans on their tablets of baked
clay. The first trace ever observed of reptiles in the Carboniferous
system consisted of a series of small but well-marked footprints found
by Sir W. E. Logan, in 1841, in the lower coal measures of Horton
Bluff, in Nova Scotia; and as the authors of most of our general
works on geology have hitherto, in so far as I am aware, failed to do
justice to this discovery, I shall notice it here in detail. In the
year above mentioned, Sir William, then Mr. Logan, examined the coal
fields of Pennsylvania and Nova Scotia, with the view of studying
their structure, and extending the application of the discoveries
as to beds with roots, or Stigmaria underclays, which he had made
in the Welsh coal fields. On his return to England he read a paper
on these subjects before the Geological Society of London, in which
he noticed the subject of reptilian footprints at Horton Bluff. The
specimen was exhibited at the meeting of the Society, and was, I
believe, admitted, on the high authority of Prof. Owen, to be probably
reptilian. Unfortunately Sir William's paper appeared only in abstract
in the Transactions; and in this abstract, though the footprints are
mentioned, no opinion is expressed as to their nature. Sir William's
own opinion is thus stated in a letter to me, dated June, 1843, when
he was on his way to Canada, to commence the survey which has since
developed so astonishing a mass of geological facts.

[Illustration: Footprints of _Hylopus Logani_, Dawson, Lower
Carboniferous, Nova Scotia.

Natural size and reduced.

These footprints were the first indications of Carboniferous land
vertebrates ever observed; they were probably made by a Microsaurian
and one of the earliest species of this type. They show a remarkable
length of stride and development of limb.]

"Among the specimens which I carried from Horton Bluff, one is of very
high interest. It exhibits the footprints of some reptilian animal.
Owen has no doubt of the marks being genuine footprints. The rocks of
Horton Bluff are below the gypsum of that neighbourhood; so that the
specimen in question (if Lyell's views are correct[125]) comes from the
very bottom of the coal series, or at any rate very low down in it, and
demonstrates the existence of reptiles at an earlier epoch than has
hitherto been determined; none having been previously found below the
magnesian limestone, or, to give it Murchison's new name, the 'Permian
era.'"

[125] Sir Charles Lyell had then just read a paper announcing his
discovery that the gypsiferous system of Nova Scotia is Lower
Carboniferous, in which he mentions the footprints referred to, as
being reptilian.

This extract is of interest, not merely as an item of evidence in
relation to the matter now in hand, but as a mark in the progress of
geological investigation. For the reasons above stated, the important
discovery thus made in 1841, and published in 1842, was overlooked; and
the discovery of reptilian bones by Von Dechen, at Saarbruck, in 1844,
and that of footprints by Dr. King in the same year, in Pennsylvania,
have been uniformly referred to as the first observations of this
kind. Insects and Arachnidans, it may be observed, had previously been
discovered in the coal formation in Europe.

The original specimen of these footprints is still in the collection
of the Geological Survey of Canada, and a cast which Logan kindly
presented to me is exhibited in the Peter Redpath Museum of McGill
University. It is a slab of dark-coloured sandstone, glazed with fine
clay on the surface; and having a series of seven footprints in two
rows, distant about three inches; the distance of the impressions in
each row being three or four inches, and the individual impressions
about one inch in length. They seem to have been made by the points of
the toes, which must have been armed with strong and apparently blunt
claws, and appear as if either the surface had been somewhat firm,
or the body of the animal had been partly water-borne. In one place
only is there a distinct mark of the whole foot, as if the animal
had exerted an unusual pressure in turning or stopping suddenly. One
pair of feet--the fore feet, I presume--appear to have had four toes
touching the ground; the other pair show only three or four, and it
is to be observed that the outer toe, as in the larger footprints
discovered by Dr. King, projects in the manner of a thumb, as in the
cheirotherian tracks of the Trias. At a later date another series of
footprints, possibly of the same animal, was obtained at the same
place by Prof. Elder, and is now in the Peter Redpath Museum. Each
foot in this shows five toes, and it is remarkable that the animal was
digitigrade and took a long step for its size, indicating a somewhat
high grade of quadrupedal organization. No mark of the tail or belly
appears. The impressions are such as may have been made by animals
similar to some of those to be described in the sequel.

Shortly afterward, Dr. Harding, of Windsor, when examining a cargo of
sandstone which had been landed at that place from Parrsboro', found
on one of the slabs a very distinct series of footprints, each with
four toes, and a trace of the fifth. Dr. Harding's specimen is now
in the museum of King's College, Windsor. Its impressions are more
distinct, but not very different otherwise from those above described,
as found at Horton Bluff. The rocks at that place are probably of
nearly the same age with those of Parrsboro'. I afterward examined the
place from which this slab had been quarried, and satisfied myself
that the beds are Carboniferous, and probably Lower Carboniferous.
They were ripple-marked and sun-cracked, and I thought I could detect
some footprints, though more obscure than those in Dr. Harding's slab.
Similar footprints are also stated to have been found by Dr. Gesner, at
Parrsboro'. All of these were from the lowest beds of the Carboniferous
system.

I have since observed several instances of such impressions at the
Joggins, at Horton, and near Windsor, showing that they are by no means
rare, and that reptilian animals existed in no inconsiderable numbers
throughout the coal field of Nova Scotia, and from the beginning to the
end of the Carboniferous period. Most of these, when well preserved,
shew five toes both on the anterior and posterior limb. On comparing
these earlier Carboniferous footprints with one another, it will be
observed that they are of similar general character, and may have been
made by one kind of animal, which must have had the fore and hind feet
nearly of equal size, and a digitigrade mode of walking. Footprints of
similar form are found in the coal formation, as well as others of much
larger size. The latter are of two kinds. One of these shows short hind
feet of digitigrade character and a long stride, in this resembling the
smaller footprints of the Lower Carboniferous, which are remarkable
for the length of limb which they indicate by the distance between the
footprints. The other kind shows long hind feet, as if the whole heel
were brought down to the ground in a plantigrade manner. These have
also the outer toe separated from the others, and sometimes provided
with a long claw. The fore foot is sometimes smaller than the hind
foot, and differently formed.[126] In these respects they resemble the
great Labyrinthodont Batrachians of the subsequent Trias. Their stride
also is comparatively short, and the rows of impressions wide apart, as
if the body of the animal had been broad, and its limbs short.

[126] Fine slabs of these footprints have been presented by Mr.
Sandford Fleming to the Geological Survey of Canada.

We have thus two types of quadrupedal footprints, to the first of
which I have given the name Hylopus, and have restricted the term
Sauropus,[127] to the second. The first apparently belongs to the
usually small reptiles of the group _Microsauria_, which had a
well-marked lizard-like form, with well-developed limbs, and perhaps
also to some of the smaller Labyrinthodonts, the second to the group
of _Labyrinthodontia_, which were often of large size and with stout
and short limbs and plantigrade hind feet. There are also some small
and uncertain tracks, which may have been made by newt-like animals
with short feet, and a singular trail of large size, and with a row
of impressions at each side (Diplichnites),[128] which, if made by a
vertebrate animal, would seem to indicate that serpentiform shape which
we know belonged to some Carboniferous Batrachians.

[127] Given by King.

[128] Impressions and Footprints of Animals, _Am. Jour. Sci._, 1873.

The bones of these animals, however, hitherto found in Nova Scotia, may
all have belonged to the two groups first named, the Labyrinthodontia
and Microsauria, and I shall proceed to give some examples of each of
these.

In leaving the footprints, I may merely mention that the animals
which produced them may, in certain circumstances, have left distinct
impressions only of three or four toes, when they actually possessed
five, while in other circumstances all may have left marks; and that,
when wading in deep mud, their footprints were altogether different
from those made on hard sand or clay. In some instances the impressions
may have been made by animals wading or swimming in water, while in
others the rain marks and sun cracks afford evidence that the surface
was a subaërial one. They are chiefly interesting as indicating the
wide diffusion and abundance of the creatures producing them, and that
they haunted tidal flats and muddy shores, perhaps emerging from the
water that they might bask in the sun, or possibly searching for food
among the rejectamenta of the sea, or of lagunes and estuaries.


The Labyrinthodonts of the Coal Period, Baphetes Planiceps and
Dendrerpeton Acadianum.

In the summer of 1851 I had occasion to spend a day at the Albion Mines
in the eastern part of Nova Scotia, and on arriving at the railway
station in the afternoon, found myself somewhat too early for the
train. By way of improving the time thus left on my hands, I betook
myself to the examination of a large pile of rubbish, consisting of
shale and ironstone from one of the pits, and in which I had previously
found scales and teeth of fishes. In the blocks of hard carbonaceous
shale and earthy coal, of which the pile chiefly consisted, scales,
teeth and coprolites often appeared on the weathered ends and surfaces
as whitish spots. In looking for these, I observed one of much greater
size than usual on the edge of a block, and on splitting it open, found
a large flattened skull, about six inches broad, the cranial bones of
which remained entire on one side of the mass, while the palate and
teeth, in several fragments, came away with the other half. Carefully
trimming the larger specimen, and gathering all the smaller fragments,
I packed them up as safely as possible, and returned from my little
excursion much richer than I had hoped.

The specimen, on further examination, proved somewhat puzzling. I
supposed it to be, most probably, the head of a large ganoid fish;
but it seemed different from anything of this kind with which I could
compare it; and at a distance from comparative anatomists, and without
sufficient means of determination, I dared not refer it to anything
higher in the animal scale. Hoping for further light, I packed it
up with some other specimens, and sent it to the Secretary of the
Geological Society of London, with an explanatory note as to its
geological position, and requesting that it might be submitted to some
one versed in such fossils. For a year or two, however, it remained as
quietly in the Society's collection as if in its original bed in the
coal mine, until attention having been attracted to such remains by the
discoveries made by Sir Charles Lyell and myself in 1852, at the South
Joggins, and published in 1853,[129] the Secretary or President of the
Society re-discovered the specimen, and handed it to Sir Richard Owen,
by whom it was described in December, 1853,[130] under the name of
_Baphetes planiceps_, which may be interpreted the "flat-headed diving
animal," in allusion to the flatness of the creature's skull, and the
possibility that it may have been in the habit of diving.

[129] _Journal of Geological Society of London_, vol. ix.

[130] _Journal of Geological Society_, vol. x.; and additional notes,
vol. xi.

The parts preserved in my specimen are the bones of the anterior and
upper part of the skull in one fragment, and the teeth and palatal
bones in others. These parts were carefully examined and described by
Owen, and the details will be found in his papers referred to in the
note. We may merely observe here that the form and arrangement of the
bones showed batrachian affinities, that the surface of the cranium was
sculptured in the manner of the group of Labyrinthodonts, and that the
teeth possessed the peculiar and complicated plication of the ivory and
enamel seen in creatures of this type. The whole of these characters
are regarded as allying the animal with the great crocodilian frogs
of the Trias of Europe, first known as _Cheirotherians_, owing to the
remarkable hand-like impressions of their feet, and afterwards as
_Labyrinthodonts_, from the beautifully complicated convolutions of the
ivory of their teeth.

Unfortunately the original specimen exhibited only the head, and after
much and frequent subsequent searching, the only other bones found are
a scapula, or shoulder bone, and one of the surface scales which served
for protection, and which indicate at least that the creature possessed
walking limbs and was armed with bony scales sculptured in the same
manner with the skull bones.

Of the general form and dimensions of _Baphetes_, the facts at present
known do not enable us to say much. Its formidable teeth and strong
maxillary bones show that it must have devoured animals of considerable
size, probably the fishes whose remains are found with it, or the
smaller reptiles of the coal. It must, in short, have been crocodilian,
rather than frog-like, in its mode of life; but whether, like the
Labyrinthodonts, it had strong limbs and a short body, or like the
crocodiles, an elongated form and a powerful natatory tail, the remains
do not decide. One of the limbs or a vertebra of the tail would settle
this question, but neither has as yet been found. That there were large
animals of the labyrinthodontal form in the coal period is proved by
the footprints discovered by Dr. King in Pennsylvania, which may have
been produced by an animal of the type of _Baphetes_, as well as by
those of _Sauropus unguifer_ from the Carboniferous of Nova Scotia,
and which would very well suit an animal of this size and probable
form. On the other hand, that there were large swimming reptiles seems
established by the discovery of the vertebræ of _Eosaurus Acadianus_,
at the Joggins, by Marsh.[131] The locomotion of _Baphetes_ must have
been vigorous and rapid, but it may have been effected both on land and
in water, and either by feet or tail, or both. A jawbone found at the
Joggins in Nova Scotia, and to which I have attached the name _Baphetes
minor_, may have belonged to a second species. Great Batrachians allied
to Baphetes, but different specifically or generically, have since been
found in the coal formations of Great Britain, the continent of Europe
and the United States.

[131] _Silliman's Journal_, 1859.

With the nature of the habitat of this formidable creature we are
better acquainted. The area of the Albion Mines coal field was
somewhat exceptional in its character. It seems to have been a bay or
indentation in the Silurian land, separated from the remainder of the
coal field by a high shingle beach, now a bed of conglomerate. Owing
to this circumstance, while in the other portions of the Nova Scotia
coal field the beds of coal are thin, and alternate with sandstones
and shales, at the Albion Mines a vast thickness of almost unmixed
vegetable matter has been deposited, constituting the "main seam" of
thirty-eight feet thick, and the "deep seam," twenty-four feet thick,
as well as still thicker beds of highly carbonaceous shale. But, though
the area of the Albion coal measures was thus separated, and preserved
from marine incursions, it must have been often submerged, and probably
had connection with the sea, through rivers or channels cutting the
enclosing beach. Hence beds of earthy matter occur in it, containing
remains of large fishes. One of the most important of these is that
known as the "Holing stone," a band of black highly carbonaceous shale,
coaly matter, and clay ironstone, occurring in the main seam, about
five feet below its roof, and varying in thickness from two inches to
nearly two feet. It was from this band that the rubbish heap in which I
found the skull of _Baphetes planiceps_ was derived. It is a laminated
bed, sometimes hard and containing much ironstone, in other places soft
and shaly, but always black and carbonaceous, and often with layers
of coarse coal, though with few fossil plants retaining their forms.
It contains large round flat scales and flattened curved teeth, which
I attribute to a fish of the genus _Rhizodus_, resembling, if not
identical with, _R. lancifer_, Newberry. With these are double-pointed
shark-like teeth, and long cylindrical spines of a species of _Diplodus_,
which I have named _D. acinaces.[132]_ There are also shells of the
minute _Spirorbis_, so common in the coal measures of other parts of
Nova Scotia, and abundance of fragments of coprolitic matter, or fossil
excrement, sometimes containing bones and scales of fishes.

[132] "Supplement to Acadian Geology," pp. 43 and 50. These fishes are
now known under the generic name Leptacanthus.

It is evident that the "Holing stone" indicates one of those periods
in which the Albion coal area, or a large part of it, was under
water, probably fresh or brackish, as there are no properly marine
shells in this, or any of the other beds of this coal series. We may
then imagine a large lake or lagune, loaded with trunks of trees and
decaying vegetable matter, having in its shallow parts, and along
its sides, dense brakes of _Calamites_, and forests of _Sigillaria_,
_Lepidodendron_, and other trees of the period, extending far on every
side as damp pestilential swamps. In such a habitat, uninviting to
us, but no doubt suited to _Baphetes_, that creature crawled through
swamps and thickets, wallowed in flats of black mud, or swam and dived
in search of its finny prey. It was, in so far as we know, the monarch
of these swamps, though there is, as already stated, evidence of the
existence of similar creatures of this type quite as large in other
parts of the Nova Scotia coal field. We must now notice a smaller
animal belonging to the same family of Labyrinthodonts.

The geology of Nova Scotia is largely indebted to the world-embracing
labours of Sir Charles Lyell. Though much had previously been done
by others, his personal explorations in 1842, and his paper on the
gypsiferous formation, published in the following year, first gave
form and shape to some of the more difficult features of the geology
of the country, and brought it into relation with that of other parts
of the world. In geological investigation, as in many other things,
patient plodding may accumulate large stores of fact, but the magic
wand of genius is required to bring out the true value and significance
of these stores of knowledge. It is scarcely too much to say that the
exploration of a few weeks, and subsequent study of the subject by Sir
Charles, with the impulse and guidance given to the labours of others,
did as much for Nova Scotia as might have been effected by years of
laborious work under less competent heads.

Sir Charles naturally continued to take an interest in the geology of
Nova Scotia, and to entertain a desire to explore more fully some of
those magnificent coast sections which he had but hastily examined;
and when, in 1851, he had occasion to revisit the United States, he
made an appointment with the writer of these pages to spend a few
days in renewed explorations of the cliffs of the South Joggins. The
object specially in view was the thorough examination of the beds of
the true coal measures, with reference to their contained fossils, and
the conditions of accumulation of the coal; and the results were given
to the world in a joint paper on "The remains of a reptile and a land
shell discovered in the interior of an erect tree in the coal measures
of Nova Scotia," and in the writer's paper on the "Coal Measures of
the South Joggins";[133] while other important investigations grew out
of the following up of these researches, and much matter in relation
to the vegetable fossils still remains to be worked up. It is with the
more striking fact of the discovery of the remains of a reptile in the
coal measures that we have now to do.

[133] _Journal of the Geological Society of London_, vols. ix. and x.;
and "Acadian Geology."

The South Joggins Section is, among other things, remarkable for the
number of beds which contain remains of erect trees imbedded _in situ_:
these trees are for the most part Sigillariæ, those great-ribbed
pillar-like trees which seem to have been so characteristic of the
forests of the coal formation flats and swamps, and so important
contributors to the formation of coal. They vary in diameter from six
inches to five feet. They have grown on underclays and wet soils,
similar to those on which the coal was accumulated; and these having
been submerged or buried by mud carried down by inundations, the trees,
killed by the accumulations around their stems, have decayed, and their
tops being broken off at the level of the mud or sand, the cylindrical
cavities left open by the disappearance of the wood, and preserved in
their form by the greater durability of the bark, have been filled with
sand and clay. This, now hardened into stone, constitutes pillar-like
casts of the trees, which may often be seen exposed in the cliffs,
and which, as these waste away, fall upon the beach. The sandstones
enveloping these pillared trunks of the ancient Sigillariæ of the coal,
are laminated or bedded, and the laminæ, when exposed, split apart with
the weather, so that the trees themselves become broken across; this
being often aided by the arrangement of the matter within the trunks,
in layers more or less corresponding to those without. Thus one of
these fossil trees usually falls to the beach in a series of discs,
somewhat resembling the grindstones which are extensively manufactured
on the coast. The surfaces of these fragments often exhibit remains
of plants which have been washed into the hollow trunks, and have
been imbedded there; and in our explorations of the shore, we always
carefully scrutinized such specimens, both with the view of observing
whether they retained the superficial markings of Sigillariæ, and with
reference to the fossils contained in them. It was while examining a
pile of these "fossil grindstones" that we were surprised by finding
on one of them what seemed to be fragments of bone. On careful search
other bones appeared, and they had the aspect, not of remains of
fishes, of which many species are found fossil in these coal measures,
but rather of limb bones of a quadruped. The fallen pieces of the tree
were carefully broken up, and other bones disengaged, and at length a
jaw with teeth made its appearance. We felt quite confident, from the
first, that these bones were reptilian; and the whole, being carefully
packed and labelled, were taken by Sir Charles to the United States,
and submitted to Prof. J. Wyman of Cambridge; who recognised their
reptilian character, and prepared descriptive notes of the principal
bones, which appeared to have belonged to two species. He also observed
among the fragments an object of different character, apparently a
shell; which was recognised by Dr. Gould of Boston, and afterward by
M. Deshayes, as probably a land-snail, and has since been named _Pupa
vetusta_.

The specimens were subsequently taken to London and reexamined by
Prof. Owen, who confirmed Wyman's inferences, added other characters
to the description, and named the larger and better preserved species
_Dendrerpeton Acadianum_, in allusion to its discovery in the interior
of a tree, and to its native country of Acadia or Nova Scotia. It is
necessary to state in explanation of the fragmentary character of the
remains obtained, that in the decay of the animals imbedded in the
erect trees at the Joggins, their skeletons have become disarticulated,
and the portions scattered, either by falling into the interstices
of the vegetable fragments in the bottom of the hollow trunks, or by
the water with which these may have sometimes been partly filled. We
thus usually obtain only separate bones; and though all of these are
no doubt present in each case, it is often impossible in breaking up
the hard matrix to recover more than a portion of them. The original
description by Owen was therefore based on somewhat imperfect material,
but additional specimens subsequently found have supplemented it
in such a manner as to enable us somewhat completely to restore in
imagination the form of the animal, which, though much smaller than
_Baphetes_, agrees with it in its sculptured bones, in its bony
armature, especially beneath, and in its plicated teeth.

[Illustration: Humerus and Mandibles of Dendrerpeton Acadianum. Natural
size, with one of the teeth enlarged. (From a Photograph.)

The specimen illustrates the sculptured bones of Dendrerpeton and its
plaited teeth, as well as large size and massive development of the arm
bone.]

In form, _Dendrerpeton Acadianum_ was probably lizard-like; with a
broad flat head, short stout limbs and an elongated tail; and having
its skin, and more particularly that of the belly, protected by small
bony plates closely overlapping each other, and arranged _en chevron_,
in oblique rows meeting on the mesial line, where in front was a
thoracic plate. It may have attained the length of two feet. The form
of the head is not unlike that of _Baphetes_, but longer in proportion;
and much resembles that of the labyrinthodont reptiles of the Trias.
The bones of the skull are sculptured as in Baphetes, but in a smaller
pattern.

The fore limb of the adult animal, including the toes, must have been
four or five inches in length, and is of massive proportions. The bones
were hollow, and in the case of the phalanges the bony walls were thin,
so that they are often crushed flat. The humerus, or arm bone, however,
was a strong bone, with thick walls and a cancellated structure toward
its extremities; still even these have sometimes yielded to the great
pressure to which they have been subjected. The cavity of the interior
of the limb bones is usually filled with calc-spar stained with organic
matter, but showing no structure; and the inner side of the bony wall
is smooth without any indication of cartilaginous matter lining it.

The vertebræ, in the external aspect of their bodies, remind one of
those of fishes, expanding toward the extremities, and being deeply
hollowed by conical cavities, which appear even to meet in the centre.
There is, however, a large and flattened neural spine. The vertebræ are
usually much crushed, and it is almost impossible to disengage them
from the stone. The ribs are long and curved, showing a reptilian style
of chest. The posterior limb seems to have been not larger than the
anterior, perhaps smaller. The tibia, or principal bone of the fore leg
is much flattened at the extremity, as in some Labyrinthodonts, and the
foot must have been broad, and probably suited for swimming, or walking
on soft mud, or both. That the hind limb was adapted for walking is
shown, not merely by the form of the bones, but also by that of the
pelvis.

The external scales are thin, oblique-rhomboidal or elongated-oval,
marked with slight concentric lines, but otherwise smooth, and
having a thickened ridge or margin, in which they resemble those of
Archegosaurus, and also those of _Pholidogaster pisciformis_, described
by Huxley from the Edinburgh coal field,--an animal which indeed
appears in most respects to have a close affinity with _Dendrerpeton_.
The microscopic structure of the scales is quite similar to that of the
other bones, and different from that of the scales of ganoid fishes,
the shape of the cells being batrachian. For other particulars of its
structure reference may be made to the papers named at the end of the
chapter.

With respect to the affinities of the creature, I think it is obvious
that it is most nearly related to the group of Lahyrinthodonts, and
that it has the same singular mixture of batrachian and reptilian
characters which distinguish these ancient animals, and which give
them the appearance of prototypes of the reptilian class. A second
and smaller species of Dendrerpeton was subsequently obtained at the
Joggins, and others have been found, more especially by Fritsch, in the
Carboniferous and Permian of Europe.

This ancient inhabitant of the coal swamps of Nova Scotia was, in
short, as we often find to be the case with the earliest forms of life,
the possessor of powers and structures not usually, in the modern
world, combined in a single species. It was certainly not a fish, yet
its bony scales and the form of its vertebræ, and of its teeth, might,
in the absence of other evidence, cause it to be mistaken for one. We
call it a Batrachian, yet its dentition, the sculpturing of the bones
of its skull, which were certainly no more external plates than the
similar bones of a crocodile, its ribs, and the structure of its limbs,
remind us of the higher reptiles; and we do not know that it ever
possessed gills, or passed through a larval or fish-like condition.
Still, in a great many important characters, its structures are
undoubtedly batrachian. It stands, in short, in the same position with
the _Lepidodendra_ and _Sigillariæ_ under whose shade it crept, which,
though placed by palæobotanists in alliance with certain modern groups
of plants, manifestly differed from these in many of their characters,
and occupied a different position in nature. In the coal period the
distinctions of physical and vital conditions were not well defined.
Dry land and water, terrestrial and aquatic plants and animals, and
lower and higher forms of animal and vegetable life, are consequently
not easily separated from each other. This is no doubt a state of
things characteristic of the earlier stages of the earth's history, yet
not necessarily so; for there are some reasons, derived from fossil
plants, for believing that in the preceding Devonian period there was
less of this, and consequently that there may then have been a higher
and more varied animal life than in the coal period.[134]

[134] See the author's paper on Devonian plants, _Journal of the
Geological Society_, vol. xviii. p. 328.

The dentition of _Dendrerpeton_ shows it to have been carnivorous in a
high degree. It may have captured fishes and smaller reptiles, either
on land or in water, and very probably fed on dead carcases as well.
If, as seems likely, any of the footprints referred to previously
belong to this animal, it must have frequented the shores, either in
search of garbage, or on its way to and from the waters. The occurrence
of its remains in the stumps of Sigillaria, with land snails and
millipedes, shows also that it crept in the shade of the woods in
search of food; and in noticing coprolitic matter, in a subsequent
page, I shall show that remains of excrementitious substances, probably
of this species, contain fragments attributable to smaller reptiles,
and other animals of the land.

All the bones of _Dendrerpeton_ hitherto found, as well as those of the
smaller reptilian species hereafter described, have been obtained from
the interior of erect Sigillariæ, and all of these in one of the many
beds, which, at the Joggins, contain such remains. The thick cellular
inner bark of Sigillaria was very perishable; the slender woody axis
was somewhat more durable; but near the surface of the stem, in large
trunks, there was a layer of elongated cells, or bast tissue, of
considerable durability, and the outer bark was exceedingly dense and
indestructible.[135] Hence an erect tree, partly imbedded in sediment,
and subjected to the influence of the weather, became a hollow shell
of bark; in the bottom of which lay the decaying remains of the woody
axis, and shreds of the fibrous bark. In ordinary circumstances such
hollow stems would be almost immediately filled with silt and sand,
deposited in the numerous inundations and subsidences of the coal
swamps. Where, however, they remained open for a considerable time,
they would constitute a series of pitfalls, into which animals walking
on the surface might be precipitated; and being probably often partly
covered by remains of prostrate trunks, or by vegetation growing around
their mouths, they would be places of retreat and abode for land snails
and such creatures. When the surface was again inundated or submerged,
all such animals, with the remains of those which had fallen into the
deeper pits, would be imbedded in the sediment which would then fill up
the holes. These seem to have been the precise conditions of the bed
which has afforded all these remains.

[135] See a paper by the author, on the Structures of Coal, _Journal
of the Geological Society_, vol. xv.; also "Supplement to Acadian
Geology."

[Illustration: A reptiliferous Tree _in situ_, South Joggins, N. Scotia.

This is a sketch of a tree which afforded remains of Dendrerpeton,
Pupæ, etc.]

The history of a bed containing reptiliferous erect trees would thus be
somewhat as follows:--

A forest or grove of the large-ribbed trees known as _Sigillariæ_, was
either submerged by subsidence, or, growing on low ground, was invaded
with the muddy waters of an inundation, or successive inundations,
so that the trunks were buried to the depth of several feet. The
projecting tops having been removed by subaërial decay, the buried
stumps became hollow, while their hard outer bark remained intact. They
thus became hollow cylinders in a vertical position, and open at top.
The surface having then become dry land, covered with vegetation, was
haunted by small quadrupeds and other land animals, which from time
to time fell into the open holes, in some cases nine feet deep, and
could not extricate themselves. On their death, and the decomposition
of their soft parts, their bones and other hard portions remained in
the bottom of the tree intermixed with any vegetable _débris_ or soil
washed in by rain, and which formed thin layers separating successive
animal deposits from each other. Finally, the area was again submerged
or overflowed by water, bearing sand and mud. The hollow trees were
filled to the top, and their animal contents thus sealed up. At length
the material filling the trees was by pressure and the access of
cementing matter hardened into stone, not infrequently harder than that
of the containing beds, and the whole being tilted to an angle of 20°,
and elevated into land exposed to the action of the tides and waves,
these singular coffins present themselves as stony cylinders projecting
from the cliff or reef, and can be extracted and their contents studied.

The singular combination of accidents above detailed was, of course,
of very rare occurrence, and in point of fact we know only one set of
beds at the South Joggins in which such remains so preserved occur; nor
is there, so far as I am aware, any other known instance elsewhere.
Even in the beds in question only a portion of the trees, about fifteen
in thirty, have afforded animal remains. We have, however, thus been
enabled to obtain specimens of a number of species which would probably
otherwise have been unknown, being less likely than others to be
preserved in properly aqueous deposits. Such discoveries, on the one
hand impress us with the imperfection of the geological record; on the
other, they show us the singular provisions which have been made in
the course of geological time for preserving the relics of the ancient
world, and which await the industry and skill of collectors to disclose
their hidden treasures.

I may add that I believe all the trees, about thirty in number,
which have become exposed in this bed since its discovery, have been
ransacked for such remains; and that while the majority have afforded
some reward for the labour, some have been far more rich than others
in their contents. It is also to be observed that owing to the mode
of accumulation of the mass filling the trees, the bones are usually
found scattered in every position, and those of different species
intermingled; and that being often much more friable than the matrix,
much labour is required for their development; while after all has been
done, the result is a congeries of fragments. A few specimens only
have been found, showing skeletons complete, or nearly so, and I shall
endeavour to figure one or two of these by way of illustration in the
present chapter.

The beds on a level with the top of the reptiliferous erect trees
are arenaceous sandstones, with numerous erect _Calamites_. I have
searched the surfaces of these beds in vain for bones or footprints of
the reptiles which must have traversed them, and which, but for hollow
erect trees," would apparently have left no trace of their existence.
On a surface of similar character, sixty feet higher, and separated
by three coals, with their accompaniments, and a very thick compact
sandstone, I observed a series of footprints, which may be those of
_Dendrerpeton_ or _Hylonomus_.

[Illustration: A typical Carboniferous Microsaurian, _Hylonomus Lyelli_
Restoration showing dermal armour and ornaments. Skeleton restored from
measurements of the bones of the type specimen figured at the beginning
of the chapter.]


Species of Microsauria. Hylonomus Lyelli.

In the original reptiliferous tree discovered by Sir C. Lyell and
the writer, at the Joggins, in 1851, there were, beside the bones of
_Dendrerpeton Acadianum_, some small elongated vertebræ, evidently
of a different species. These were first detected by Prof. Wyman,
in his examination of these specimens, and were figured, but not
named, in the original notice of the specimens. In a subsequent visit
to the Joggins I obtained from another erect stump many additional
remains of these smaller reptiles, and, on careful comparison of the
specimens, was induced to refer them to three species, all apparently
generically allied. I proposed for them the generic name _Hylonomus_,
"forest dweller." They were described in the Proceedings of the
Geological Society for 1859, with illustrations of the teeth and other
characteristic parts.[136] The smaller species first described I named
_H. Wymani_; the next in size, that to which this article refers, and
which was represented by a larger number of specimens, I adopted as a
type of the genus, and dedicated to Sir Charles Lyell. The third and
largest, represented only by a few fragments of a single skeleton, was
named _H. aciedentatus_. This I had subsequently to remove to a new
genus, _Smilerpeton_.

[136] _Journal of Geological Society_, vol. xvi.

_Hylonomus Lyelli_ was an animal of small size. Its skull is about an
inch in length, and its whole body, including the tail, could not have
been more than six or seven inches, long. The bones appear to have
been thin and easily separable; and even when they remain together,
are so much crushed as to render the shape of the skull not easily
discernible. They are smooth on the outer surface to the naked eye; and
under a lens show only delicate, uneven striæ and minute dots. They are
more dense and hard than those of _Dendrerpeton_, and the bone-cells
are more elongated in form. The bones of the snout would seem to have
been somewhat elongated and narrow. A specimen in my possession shows
the parietal and occipital bones, or the greater part of them, united
and retaining their form. We learn from them that the brain case was
rounded, and that there was a parietal foramen. There would seem
also to have been two occipital condyles, as in modern Batrachians.
Several well-preserved specimens of the maxillary and mandibular
bones have been obtained. They are smooth, or nearly so, like those
of the skull, and are furnished with numerous sharp, conical teeth,
anchylosed to the jaw, in a partial groove formed by the outer ridge
of the bone. In the anterior part of the lower jaw there is a group of
teeth larger than the others. The total number of teeth in each ramus
of the lower jaw was about forty, and the number in each maxillary
bone about thirty. The teeth are perfectly simple, hollow within, and
with very fine radiating tubes of ivory. The vertebræ have the bodies
cylindrical or hour-glass shaped, covered with a thin, hard, bony
plate, and having within a cavity of the form of two cones, attached
by the apices. This cavity was completely surrounded by bone, as it
is filled with stained calc-spar in the same manner as the cavities of
the limb bones. It was probably occupied by cartilage. The vertebræ
were apparently bi-concave, and are furnished with upper and lateral
processes similar to those of small lacertian animals. The ribs are
long, curved, and at the proximal end have a shoulder and neck. They
are hollow, with thin hard bony walls. The anterior limb, judging from
the fragment procured, seems to have been slender, with long toes,
four or possibly five in number. The posterior limb was longer and
stronger, and attached to a pelvis so large and broad as to give the
impression that the creature enlarged considerably in size toward the
posterior extremity of the body, and that it may have been in the
habit of sitting erect. The thigh bone is large and well-formed, with
a distinct head and trochanter, and the lower extremity flattened and
moulded into two articulating surfaces for the tibia and fibula, the
fragments of which show that they were much shorter. The toes of the
hind feet have been seen only in detached joints. They seem to have
been thicker than those of the fore foot. Detached vertebræ, which seem
to be caudal, have been found, and show that the tail was long and
probably not flattened. The limb bones are usually somewhat crushed and
flattened, especially at their articular extremities, and this seems to
have led to the error of supposing that this flattened form was their
normal condition; there can be no doubt, however, that it is merely an
effect of pressure. The limb bones present in cross section a wall of
dense bone with elongated bone-cells, surrounding a cavity now filled
with brown calc-spar, and originally occupied with cartilage or marrow.
I desire to specify the above points because I believe that most of the
creatures referred by Fritsch, Credner, and other European naturalists
to the Microsauria are of inferior grade to Hylonomus, though admitted
to present points of approximation to the true reptiles. Woodward has
recently described the remains of a Microsaurian from the English coal
formation. Nothing is more remarkable in the skeleton of this creature
than the contrast between the perfect and beautiful forms of its bones,
and their imperfectly ossified condition, a circumstance which raises
the question whether these specimens may not represent the young of
some reptile of larger size.

The dermal covering of this animal is represented in part by oval
bony scales, which are so constantly associated with its bones that
I can have no doubt that they belonged to it, being, perhaps, the
clothing of its lower or abdominal parts. But the most remarkable
and unexpected feature of this little creature was the beautiful and
ornate scaly covering of its back and sides. Modern Batrachians are
characteristically naked, and though we know that some fossil species
had coverings below of bony scales, these seemed rather to ally them
with bony fishes. One of the specimens of Hylonomus had associated
with it a quantity of crumpled shining skin, black and carbonaceous,
and which may perhaps have been tanned and so preserved by the water
filling the hollow tree impregnated with solution of tannin from the
bark. This skin was covered with minute overlapping scales, which,
under the microscope, showed the structure of horn rather than of
bone. Besides these ordinary scales there were bony prominences, like
those of the horned frog, on the back and shoulders, and a species of
epaulettes made of long horny bristles curved downward, and apparently
placed at the edges of the shoulders. Besides these there were in front
and at the side rows of pendants or lappets, all no doubt ornamented
with colouring, though now perfectly black. It may be asked what was
the use of the ornate covering, and perhaps the question raises that
perplexing problem, of the use of beauty in a world where there were
no animals with higher æsthetic faculties than those of Batrachians.
Scudder suggests a somewhat prosaic use in supposing them to be an
armour against the venomous scorpions which were the contemporaries
of these little reptiles, and some of them almost as large in size.
But the word "venomous" raises another question, for we only infer
that the scorpions were venomous from modern analogy and traces of an
inflated joint at the end of the tail in some specimens. We have no
absolute certainty that the subtle and complex organic poison of the
scorpion, and his beautiful injection syringe for placing it under the
skin, were perfected at this early time. Thus we have in the far back
Carboniferous age a creature as elaborately ornamented and protected
as any of the modern lizards, and this, let it be observed, constitutes
another and important departure from that batrachian type to which
these animals are supposed to conform. I may add here that subsequently
portions of skin were found, which from their size probably belonged to
_Dendrerpeton_, and that these also were scaly and had lappets, though
they did not appear to have the horny tubercles and fringes. It may
be asked why such advanced characters should be found in Nova Scotia
alone. The answer is that the circumstances of preservation in the
erect trees were peculiar, and that only animals of purely terrestrial
habits could find access to them, whereas the remains of reptiles found
in the Carboniferous elsewhere are in aqueous beds in which aquatic
forms were more likely to be preserved, and in which all the soft parts
were certain to perish.

It is evident from the remains thus described, that we have in
_Hylonomus Lyelli_ an animal of lacertian form, with large and stout
hind limbs, and somewhat smaller fore limbs, capable of walking and
running on land; and though its vertebræ were imperfectly ossified
externally, yet the outer walls were sufficiently strong, and their
articulation sufficiently firm, to have enabled the creature to
erect itself on its hind legs, or to leap. They were certainly
proportionately larger and much more firmly knit than those of
_Dendrerpeton_. Further, the ribs were long and much curved, and imply
a respiration of a higher character than that of modern Batrachians,
and consequently a more highly vitalized muscular system. If to these
structural points we add the somewhat rounded skull, indicating a large
brain, we have before us a creature which, however puzzling in its
affinities when anatomically considered, is clearly not to be ranked
as low in the scale of creation as modern tailed Batrachians, or even
as the frogs and toads. We must add to these also, as important points
of difference, the bony scales with which it was armed below, and the
ornate apparatus of horny appendages, with which it was clad above.
These last, as described in the last section, show that this little
animal was not a squalid, slimy dweller in mud, like _Menobranchus_
and its allies, but rather a beautiful and sprightly tenant of the
coal-formation thickets, vying in brilliancy, and perhaps in colouring,
with the insects which it pursued and devoured. Remains of as many
as eight or ten individuals have been obtained from three erect
Sigillariæ, indicating that these creatures were quite abundant, as
well as active and terrestrial in their mode of life.

With respect to the affinities of this species, I think it is
abundantly manifest that it presents no close relationship with any
reptile hitherto discovered in the Carboniferous system, except perhaps
some of the smaller forms in the Permian of Europe, with which Credner
and Fritsch have compared it. It is scarcely necessary to say that
the characters above described entirely remove this animal from the
Labyrinthodonts. Equal difficulties attend the attempt to place it in
any other group of recent or extinct Batrachians or proper reptiles.
The structures of the skull, and of some points in the vertebræ,
certainly resemble those of Batrachians; but, on the other hand,
the well-developed ribs, evidently adapted to enlarge the chest in
respiration, the pelvis, and the cutaneous covering, are unexampled in
modern Batrachians, and assimilate the creature to the true lizards.
I have already, in my original description of the animal in 1859,
expressed my belief that _Hylonomus_ may have had lacertian affinities,
but I do not desire to speak too positively in this matter;[137] and
shall content myself with stating the following alternatives as to
the probable relations of these animals, (1) They may have been true
reptiles of low type, and with batrachian tendencies. (2) They may have
been representatives of a new family of Batrachians, exhibiting in some
points lacertian affinities. (3) They may have been the young of some
larger reptile, too large and vigorous to be entrapped in the pitfalls
presented by the hollow Sigillaria stumps, and in its adult state
losing the batrachian peculiarities apparent in the young. Whichever of
these views we may adopt, the fact remains, that in the structure of
this curious little creature we have peculiarities both batrachian and
lacertian, in so far as our experience of modern animals is concerned.
It would, however, accord with observed facts in relation to other
groups of extinct animals, that the primitive Batrachians of the
coal period should embrace in their structures points in after times
restricted to the true reptiles. On the other hand, it would equally
accord with such facts that the first-born of Lacertians should lean
towards a lower type, by which they may have been preceded. My present
impression is, that they may constitute a separate family or order, to
which I would give the name of Microsauria, and which may be regarded
as allied, on the one hand, to certain of the humbler lizards, as the
Gecko or Agama, and, on the other, to the tailed Batrachians.

[137] I am glad to say that Fritsch and Credner now lean to the same
view.

It is likely that _Hylonomus Lyelli_ was less aquatic in its habits
than _Dendrerpeton_, Its food consisted, apparently, of insects and
similar creatures. The teeth would indicate this, and near its bones
there are portions of coprolite, containing remains of insects and
myriapods. It probably occasionally fell a prey to _Dendrerpeton_, as
bones, which may have belonged either to young individuals of this
species or to its smaller congener _H. Wymani_, are found in larger
coprolites, which may be referred with probability to _Dendrerpeton
Acadianum_. This coprolitic matter, which is somewhat plentiful on
some of the surfaces in the erect trees, also informs us that the
imprisoned animals may in some cases have continued to live for some
time, feeding on such animals as may have fallen into their place of
confinement, which was destined also to be their tomb. Some other
points of interest appear on the examination of this excrementitious
matter. It contains much carbonate of lime, indicating that snails or
other mollusks furnished a considerable part of the food of the smaller
reptiles. Some portions of it are filled with chitinous fragments,
parts of millipedes or insects, but usually so broken up as scarcely to
be distinguishable. One curious exception was a part of the head of an
insect containing a portion of one of its eyes. The facets of this can
be readily seen with the microscope, and are similar to those of modern
cockroaches. About 250 of these little eyes are discernible, and they
must have been much more numerous. Two points are of interest here:
First, the perfection of the compound eye for vision in air. It had
long before, in the case of the Trilobites, been used for seeing under
water. Secondly, the great age of the still ubiquitous and aggressive
family of the cockroaches. In point of fact the oldest known insect,
the Protoblattina of the Silurian, is one of these creatures, and they
are the most abundant insects in the Carboniferous, so that if they now
dispute with us the possession of our food, they may at least put in
the claim of prior occupancy of the world. In one mass a quantity of
thickish crust or shell appears, which under the microscope presents a
minutely tubular and laminated appearance. It may have belonged to some
small crustacean or large scorpion on which a _Dendrerpeton_ may have
been feeding before it fell into the pit in which it was entombed.

[Illustration: _Dolichosoma longissimum_, a serpentiform Permian
Batrachian after Fritsch. This and Hylonomus are opposite or extreme
types in regard to general form.]

In addition to the reptilian species above noticed, the erect trees of
Coal Mine Point have afforded several others. There is a second and
smaller species of Dendrerpeton (_D. Oweni_) and other forms belonging
to the group of Microsauria of which Hylonomus is the type. A second
species of that genus (_H. Wymani_) has already been mentioned. A
similar creature, but of larger size and with teeth of a wedge or
chisel shape, has been referred to a distinct genus, _Smilerpeton_. It
seems to have been rare, and the only skeleton found is very imperfect.
Its teeth are of a form that may have served even for vegetable food,
as their sharp edges must have had considerable cutting power. Another
curious form of tooth appears in the genus _Hylerpeton_. It has the
points worked into oblique grooves separated by sharp edges, which
must have greatly aided in piercing tough integument. These creatures
seem to have been of stout and robust build, with large limbs. Still
another generic type (_Fritschia_) is represented by a species near to
Hylonomus in several respects, and with long and beautifully formed
limb bones, but with the belly protected with rod-like bodies instead
of scales. In this respect Hylerpeton is somewhat intermediate, having
long and narrow scales on the belly instead of the oval or roundish
scales of Hylonomus. All these last-mentioned forms are Microsaurians,
with simple teeth and well-developed ribs and limbs, and smooth
cranial bones. Two other species are represented by portions of single
skeletons too imperfect to allow them to be certainly determined.

I would emphasize here that the vertebrate animals found in the erect
trees are necessarily a selection from the most exclusively terrestrial
forms, and from the smaller species of these. The numerous newt-like
and serpentiform species found in the shales of the coal formation
could not find access to these peculiar repositories, nor could the
larger species of the Labyrinthodonts and their allies, even if they
were in the habit of occasionally prowling in the forests in search of
prey, and this would scarcely be likely, more especially as the waters
must have afforded to them much more abundant supplies of food. Of
the numerous species figured by Fritsch, Cope and Huxley, only a few
approach very near to the forms entrapped in the old hollow Sigillariæ,
though several have characters half batrachian and half reptilian.


Invertebrate Air-breathers.

The coal formation rocks have afforded Land Snails, Millipedes,
Spiders, Scorpions and Insects, so that all the great types of
invertebrate life which up to this day can live on land already had
representatives in this ancient period. Some of them, indeed, we can
trace further back, the land snails probably to the Devonian, the
Millipedes to the same period, and the Scorpions and insects as far as
the Silurian. No land vertebrate is yet known, older than the Lower
Carboniferous, but there is nothing known to us in physical condition,
to preclude the existence of such creatures at least in the Devonian.

It would take us too far afield to attempt to notice the invertebrate
land life of the Palæozoic in general. This has been done in great
detail by Dr. Scudder. I shall here limit myself to the animals found
in our erect trees, and merely touch incidentally on such others as may
be connected with them.

I have already mentioned the occurrence of a land-snail, a true
pulmonate mollusk, in the first find by Lyell and myself at Coal Mine
Point, and this was the first animal of this kind known in any rocks
older than the Purbeck formation of England. It is one of the groups
of so-called Chrysalis-shells, scarcely distinguishable at first
sight from some modern West Indian species, and distinctly referable
to the modern genus Pupa. It was named _Pupa vetusta_, and a second
and smaller species subsequently found was named _P. Bigsbyi_, and a
third of different form, and resembling the modern snails, bears the
name _Zonites priscus_. The only other Palæozoic land mollusks known
at present are a few species found in the coal formation of Ohio, and
a fragment supposed to indicate another species from the Devonian
plant-beds of St. John's, New Brunswick. This last is the oldest known
evidence of pulmonate snails. If we ask the precise relations of these
creatures to modern snails, it may be answered that of the two leading
subdivisions of the group of air-breathing snails (_Pulmonifera_), the
Operculate, or those with a movable plate to close the mouth of the
shell, and the Inoperculate, or those that are destitute of any such
shelly lid or operculum to close the shell, the first has been traced
no farther back than the Eocene. The second or inoperculate division,
includes some genera that are aquatic and some that are terrestrial.
Of the aquatic genera no representatives are known in formations
older than the Wealden and Purbeck, and these only in Europe. The
terrestrial group, or the family of the _Helicidæ_, which, singularly
enough, is that which diverges farthest from the ordinary gill-bearing
Gasteropods, is the one which has been traced farthest back, and
includes the Palæozoic species. It is further remarkable that a very
great gap exists in the geological history of this family. No species
are known between the Carboniferous and the early Tertiary, though in
the intervening formations there are many fresh-water and estuarine
deposits in which such remains might be expected to occur. There is
perhaps no reason to doubt the continuance of the Helicidæ through
this long portion of geological time, though it is probable that
during the interval the family did not increase much in the numbers
of its species, more especially as it seems certain that it has its
culmination in the modern period, where it is represented by very many
and large species, which are dispersed over nearly all parts of our
continents.

[Illustration: Carboniferous Land Snails.

_Pupa vetusta_, Dawson, and _Conulus priscus_, Carpenter, with egg of
_Pupa vetusta_--the whole considerably magnified.]

[Illustration: I published in 1880, in the _American Journal of
Science_, a fragment of what seemed to be a land-snail, from the Middle
Erian plant-beds of St. John, New Brunswick (_Strophia grandava_,
figured here), but have mentioned it with some doubt in the text. Mr.
G. F. Matthew has, however, recently communicated to the Royal Society
of Canada a second species, found by Mr. W. I. Wilson in the same beds,
and which he names _Pupa primava_. It is accompanied with a scorpion
and a millipede. Thus the existence of Land Snails of the Pupa type in
the Devonian may be considered as established.]

The mode of occurrence of the Palæozoic Pulmonifera in the few
localities where they have been found is characteristic. The earliest
known species, _Pupa vetusta_, was found, as already stated, in the
material filling the once hollow stem of a Sigillaria at the South
Joggins in Nova Scotia, and many additional specimens have subsequently
been obtained from similar repositories in the same locality,
where they are associated with bones of Batrachians and remains of
Millipedes. Other specimens, and also the species _Zonites priscus_,
have been found in a thin, shaly layer, containing _débris_ of plants
and crusts of Cyprids, and which was probably deposited at the outlet
of a small stream flowing through the coal-formation forest. The two
species found in Illinois occur, according to Bradley, in an underclay
or fossil soil which may have been the bed of a pond or estuary, and
subsequently became a forest subsoil. The Erian .species occurs in
shales charged with remains of land plants, and which must consequently
have received abundant drainage from neighbouring land. It is only
in such deposits that remains of true land snails can be expected to
occur; though, had fresh-water or brackish water Pulmonates abounded
in the Carboniferous age, their remains should have occurred in those
bituminous and calcareo-bituminous shales which contain such vast
quantities of _débris_ of Cyprids, Lamellibranchs and fishes of the
period, mixed with fossil plants.

The specimen first obtained in 1887 having been taken by Sir Charles
Lyell to the United States, and submitted to the late Prof. Jeffries
Wyman, the shell in question was recognised by him and the late Dr.
Gould, of Boston, as a land shell. It was subsequently examined by M.
Deshayes and Mr. Gwyn Jeffries, who concurred in this determination;
and its microscopic structure was described by the late Prof. Quekett,
of London, as similar to that of modern land shells. The single
specimen obtained on this occasion was somewhat crushed, and did
not show the aperture. Hence the hesitation as to its nature, and
the delay in naming it, though it was figured and described in the
paper above cited in 1852. Better specimens showing the aperture were
afterward obtained by the writer, and it was named and described by
him in his "Air-breathers of the Coal Period," in 1863. Owen, in his
"Palæontology," subsequently proposed the generic name _Dendropupa_.
This I have hesitated to accept, as expressing a generic distinction
not warranted by the facts; but should the shell be considered to
require a generic or sub-generic distinction, Owen's name should be
adopted for it. There seems, however, nothing to prevent it from being
placed in one of the modern sub-genera of simple-lipped Pupæ. With
regard to the form of its aperture, I may explain that some currency
has been given to an incorrect representation of it, through defective
specimens. In the case of delicate shells like this, imbedded in a hard
matrix, it is of course difficult to work out the aperture perfectly;
and in my published figure in the "Air-breathers," I had to restore
somewhat the broken specimens in my possession. This restoration,
specimens subsequently found have shown to be very exact.

As already stated, this shell seems closely allied to some modern Pupæ.
Perhaps the modern species which approaches most nearly to it in form,
markings and size, is _Macrocheilus Gossei_ from the West Indies,
specimens of which were sent to me some years ago by Mr. Bland, of New
York, with the remark that they must be very near to my Carboniferous
species. Such edentulous species as _Pupa (Leucochila) fallax_ of
Eastern America very closely resemble it; and it was regarded by the
late Dr. Carpenter as probably a near ally of those species which are
placed by some European conchologists in the genus _Pupilla_.

_Pupa vetusta_ has been found at three distinct levels in the coal
formation of the South Joggins. The lowest is the shale above referred
to. The next, 1,217 feet higher, is that of the original discovery.
The third, 800 feet higher, is in an erect Sigillaria holding no
other remains. Thus, this shell has lived in the locality at least
during the accumulation of 2,000 feet of beds, including a number of
coals and erect forests, as well as beds of bituminous shales and
calcareo-bituminous shale, the growth of which must have been very slow.

In the lowest of these three horizons the shells are found, as already
stated, in a thin bed of concretionary clay of dark grey colour,
though associated with reddish beds. It contains _Zonites priscus_ as
well, though this is very rare, and there are a few valves of _Cythere_
and shells of _Naiadites_ as well as carbonaceous fragments, fronds of
ferns, _Trigonocarpa_, etc. The _Pupæ_ are mostly adult, but many very
young shells also occur, as well as fragments of broken shells. The bed
is evidently a layer of mud deposited in a pond or creek, or at the
mouth of a small stream. In modern swamps multitudes of fresh-water
shells occur in such places, and it is remarkable that in this case
the only Gasteropods are land shells, and these very plentiful, though
only in one bed about an inch in thickness. This would seem to imply
an absence of fresh-water Pulmonifera. In the erect _Sigillariæ_ of
the second horizon the shells occur either in a sandy matrix, more or
less darkened with vegetable matter, or in a carbonaceous mass composed
mainly of vegetable _débris_. Except when crushed or flattened, the
shells in these repositories are usually filled with brownish calcite.
From this I infer that most of them were alive when imbedded, or at
least that they contained the bodies of the animals; and it is not
improbable that they sheltered themselves in the hollow trees, as is
the habit of many similar animals in modern forests. Their residence
in these trees, as well as the characters of their embryology, are
illustrated by the occurrence of their mature ova. One of those, which
I have considered worth figuring, has been broken in such a way as to
show the embryo shell.

They may also have formed part of the food of the reptilian animals
whose remains occur with them. In illustration of this I have elsewhere
stated that I have found as many as eleven unbroken shells of _Physa
heterostropha_ in the stomach of a modern _Menobranchus_. I think it
certain, however, that both the shells and the reptiles occurring in
these trees must have been strictly terrestrial in their habits, as
they could not have found admission to the erect trees unless the
ground had been sufficiently dry to allow several feet of the imbedded
hollow trunks to be free from water. In the highest of the three
horizons the shells occurred in an erect tree, but without any other
fossils, and they had apparently been washed in along with a greyish
mud.[138]

[138] The discovery of the shells in this tree was made by Albert I.
Hill, C.E. The tree is in Group XXVI. of Division 4 of my Joggins
section. The original reptiliferous trees are in Group XV., and the
lowest bed in Group VIII.

If we exclude the alleged _Palæorbis_ referred to below, all the
Palæozoic Pulmonifera hitherto found are American. Since, however, in
the Carboniferous age, Batrachians, Arachnidans, Insects and Millipedes
occur on both continents, it is not unlikely that ere long European
species of land snails will be announced The species hitherto found
in Eastern America are in every way strangely isolated. In the plant
beds of St. John, about 9,000 feet in thickness, and in the coal
formation of the South Joggins, more than 7,000 feet in thickness,
no other Gasteropods occur, nor, I believe, do any occur in the beds
holding land snails in Illinois. Nor, as already stated, are any of
the aquatic Pulmonifera known in the Palæozoic. Thus, in so far as
at present known, these Palæozoic snails are separated not only from
any predecessors, if there were any, or successors, but from any
contemporary animals allied to them.

It is probable that the land snails of the Erian and Carboniferous
were neither numerous nor important members of the faunas of those
periods. Had other species existed in any considerable numbers, there
is no reason why they should not have been found in the erect trees,
or in those shales which contain land plants. More especially would
the discovery of any larger species, had they existed, been likely to
have occurred. Further, what we know of the vegetation of the Palæozoic
period would lead us to infer that it did not abound in those
succulent and nutritious leaves and fruits which are most congenial
to land snails. It is to be observed, however, that we know little as
yet of the upland life of the Erian or Carboniferous. The animal life
of the drier parts of the low country is indeed as yet very little
known; and but for the revelations in this respect of the erect trees
in one bed in the coal formation of Nova Scotia, our knowledge of the
land snails and Millipedes, and also of an eminently terrestrial group
of reptiles, the _Microsauria_, would have been much more imperfect
than it is. We may hope for still further revelations of this kind,
and in the meantime it would be premature to speculate as to the
affinities of our little group of land snails with animals either their
contemporaries or belonging to earlier or later formations, except to
note the fact of the little change of form or structure in this type
of life in that vast interval of time which separates the Erian period
from the present day.

It may be proper to mention here the alleged Pulmonifera of the
genus _Palæorbis_ described by some German naturalists. These I
believe to be worm tubes of the genus _Spirorbis_, and in fact to
be nothing else than the common _S. carbonarius_ or _S. pusillus_
of the coal formation. The history of this error may be stated
thus. The eminent palæobotanists Germar, Goeppert and Geinitz have
referred the _Spirorbis_, so common in the Coal measures to the fungi,
under the name _Gyromyces_, and in this they have been followed
by other naturalists, though as long ago as 1868 I had shown that
this little organism is not only a calcareous shell, attached by
one side to vegetable matters and shells of mollusks, but that it
has the microscopic structure characteristic of modern shells of
this type.[139] More recently Van Beneden, Cænius, and Goldenberg,
perceiving that the fossil is really a calcareous shell, but
apparently unaware of the observations made in this country by myself
and Mr. Lesquereux, have held the _Spirorbis_ to be a pulmonate mollusk
allied to _Planorbis_, and have supposed that its presence on fossil
plants is confirmatory of this view, though the shells are attached
by a flattened side to these plants, and are also found attached to
shells of bivalves of the genus _Naiadites_. Mr. R. Etheridge, jun.,
of the Geological Survey of Great Britain, has summed up the evidence
as to the true nature of these probably brackish-water shells, and
has revised and added to the species, in a series of articles in the
_Geological Magazine_ of London, vol. viii.

[139] "Acadian Geology," 2nd edition, p. 205.

The erect trees of Coal Mine Point are rich in remains of Millipedes.
The first of these (_Xylobius Sigillariæ_), which was the first known
Palæozoic Myriapod, was described by me from specimens found in a
tree extracted in 1852, and this, with a number of other remains
subsequently found, was afterwards placed in the hands of Dr.
Scudder, who has recognised in the material submitted to him eight
species belonging to three genera (_Xylobius_, _Archiulus_, and
_Amynilyspes_). These animals in all probability haunted these trees
to feed on the decaying wood and other vegetable matter, and were
undoubtedly themselves the prey of the Microsaurians. Though these
were the earliest known, their discovery was followed by that of many
other species in Europe and America, and some of them as old as the
Devonian.[140]

[140] The two first-named genera from the erect trees, according to
Scudder, belong to an extinct family of Millipedes, which he names
Archiulidæ, and places with other Carboniferous genera in the order
_Archipolypoda_. The third belongs to family Euphoberidæ. Proc. R. S.
of London, 1892.

The only other remains of Air-breathers found in the erect trees
belong to Scorpions, of which some fragments remain in such a state
as to make it probable that they have been partially devoured by the
imprisoned reptiles. No remains of any aquatic animals have been found
in these trees. The Scorpions are referred by Scudder to three species
belonging to two genera.[141]

[141] _Mazonia Acadica_, and a second species of _Mazonia_, with
fragments of a third species, generally distinct. Proceedings Royal
Society of London, 1892.

In the previous paper we have considered the mode of accumulation
of Coal, and it may be useful here to note the light thrown on this
subject by the Air-breathers of the coal formation and their mode of
occurrence.

In no part of the world are the coal measures better developed, or
more fully exposed, than in the coast sections of Nova Scotia and Cape
Breton; and in these, throughout their whole thickness, no indication
has been found of any of the marine fossils of the Lower Carboniferous
Limestone. Abundant remains of fishes occur, but these may have
frequented estuaries, streams and ponds, and the greater part of them
are small ganoids which, like the modern _Lepidosteus_ and _Amia_, may
have been specially fitted by their semi-reptilian respiration, for
the impure waters of swampy districts. Bivalve mollusks also abound;
but these are all of the kinds to which I have given the generic name
_Naiadites_, and Mr. Salter those of _Anthracomya_ and _Anthracoptera_.
These shells are all distinct from any known in the marine limestones.
Their thin edentulous valves, their structure consisting of a wrinkled
epidermis, a thin layer of prismatic shell and an inner layer of
imperfectly pearly shell, all remind us of the Anodons and Unios.
A slight notch in front concurs with their mode of occurrence in
rendering it probable that, like mussels in modern estuaries, they
attached themselves to floating or sunken timber. They are thus
removed, both in structure and habit, from truly marine species; and
may have been fresh-water or brackish-water mussels closely allied to
modern Unios.

[Illustration: Carboniferous Millipedes, _Xylobius Sigillariæ_, Dawson
(_a, c_), and _Archiulus xylobioides_, Scudder (_b_).

Carboniferous Cockroach.--_Blattina Bretonensis_, Sc.

Carboniferous Scorpion.--_Anthracomartus Carbonarius_, abdominal
segments.]

The crustaceans (_Eurypterus_, _Diplostylus_, _Cyprids_), and the
worm shell (_Spirorbis_) found with them, are not necessarily marine,
though some of them belonged probably to brackish water, and they have
not yet been found in those carboniferous beds deposited in the open
sea. There is thus in the whole thickness of the middle coal measures
of Nova Scotia a remarkable absence at least of open sea animals; and
if, as is quite probable, the sea inundated at intervals the areas of
coal accumulation, the waters must have been shallow, and to a great
extent land-locked, so that brackish-water rather than marine animals
inhabited them.

On the other hand, there are in these coal measures abundant evidences
of land surfaces; and subaërial decay of vegetable matter in large
quantity is proved by the occurrence of the mineral charcoal of the
coal itself, as I have elsewhere shown.[142] The erect trees which
occur at so many levels also imply subaërial decay. A tree imbedded in
sediment and remaining under water, could not decay so as to become
hollow and deposit the remains of its wood in the state of mineral
charcoal within the hollow bark. Yet this is the case with the greater
part of the erect Sigillariæ which occur at more than twenty levels in
the Joggins section. Nor could such hollow trunks become repositories
for millipedes, snails and reptiles, if under water. On the other hand,
if, as seems necessary to explain the character of the reptiliferous
erect trees, these remained dry, or nearly so, in the interior, this
would imply not merely a soil out of water, but comparatively well
drained; as would indeed always be the case, when a flat resting on a
sandy subsoil was raised several feet above the level of the water.
Further, though the peculiar character of the roots of _Sigillariæ_
and _Calamites_ may lend some countenance to the supposition that they
could grow under water, or in water-soaked soils, this will not apply
to coniferous trees, to ferns, and other plants, which are found under
circumstances which show that they grew with the _Sigillariæ_.

[142] _Journal of Geological Survey_, vol. xv.

In the coal measures of Nova Scotia, therefore, while marine conditions
are absent, there are ample evidences of fresh-water or brackish-water
conditions, and of land surfaces, suitable for the air-breathing
animals of the period. Nor do I believe that the coal measures of Nova
Scotia were exceptional in this respect. It is true that in Great
Britain evidences of marine life do occur in the coal measures; but
not, so far as I am aware, in circumstances which justify the inference
that the coal is of marine origin. Alternations of marine and land
remains, and even mixtures of these, are frequent in modern submarine
forests. When we find, as at Fort Lawrence in Nova Scotia, a modern
forest rooted in upland soil forty feet below high-water mark,[143]
and covered with mud containing living Tellinas and Myas, we are not
justified in inferring that this forest grew in the sea. We rather
infer that subsidence has occurred. In modern salt marshes it is not
unusual to find every little runnel or pool full of marine shell
fish, while in the higher parts of the marsh land plants are growing;
and in such places the deposit formed must contain a mixture of land
plants and marine animals with salt grasses and herbage--the whole _in
situ_.[144]

[143] _Journal of Geological Society_, vol. xi.

[144] In the marshes at the mouth of Scarborough River, in Maine,
channels not more than a foot wide, and far from the sea, are full of
Mussels and Myæ; and in little pools communicating with these channels
there are often many young _Limuli_, which seem to prefer such places,
and the cast-off shells and other remains of which may become imbedded
in mud and mixed with land plants, just as in the shales of the coal
measures.

These considerations serve, I think, to explain all the apparently
anomalous associations of coal plants with marine fossils; and I do
not know any other arguments of apparent weight that can be adduced
in favour of the marine or even aquatic origin of coal, except such
as are based on misconceptions of the structure and mode of growth of
sigillaroid trees and of the stratigraphical relations of the coal
itself.[145] It is to be observed, however, that while I must maintain
the essentially terrestrial character of the ordinary coal and of
its plants, I have elsewhere admitted that cannel coals and earthy
bitumen present evidences of subaquatic deposition; and have also
abundantly illustrated the facts that the coal plants grew on swampy
flats, liable not only to river inundations, but also to subsidence and
submergence.[146] In the oscillation of these conditions it is evident
that _Sigillariæ_ and their contemporaries must often have been placed
in conditions unfavourable or fatal to them, and when their remains
are preserved to us in these conditions, we may form very incorrect
inferences as to their mode of life. Further, it is to be observed that
the conditions of submergence and silting up which were favourable to
the preservation of specimens of _Sigillariæ_ as fossils, must have
been precisely those which were destructive to them as living plants;
and on the contrary, that the conditions in which these forests may
have flourished for centuries must have been those in which there was
little chance of their remains being preserved to us, in any other
condition at least than that of coal, which reveals only to careful
microscopic examination the circumstances, whether aërial or aquatic,
under which it was formed.

[145] It is unfortunate that few writers on this subject have combined
with the knowledge of the geological features of the coal a sufficient
acquaintance with the phenomena of modern marshes and swamps, and with
the conditions necessary for the growth of plants such as those of the
coal. It would be easy to show, were this a proper place to do so, that
the "swells," "rock faults," splitting of beds, and other appearances
of coal seams quite accord with the theory of swamp accumulation; that
the plants associated with _Sigillariæ_ could not have lived with
their roots immersed in salt water; that the chemical character of
the underclays implies drainage and other conditions impossible under
the sea; that the composition and minute structure of the coal are
incompatible with the supposition that it is a deposit from water, and
especially from salt water; and that it would be more natural to invoke
wind driftage as a mode of accumulation for some of the sandstones,
than water driftage for the formation of the coal. At the same time it
is pretty certain that such beds as the cannels and earthy bitumens
which appear to consist of finely comminuted vegetable matter, without
mineral charcoal, may have been deposits of muck in shallow lakes or
lagoons.

[146] _Journal of Geol. Socy._, vols. x. and xv., and "Acadian Geology."

It is also noticeable that, in conditions such as those of the coal
formation, it would be likely that some plants would be specially
adapted to occupy newly emerged flats and places liable to inundation
and silting up. I believe that many of the Sigillariæ, and still more
eminently the _Calamites_, were suitable to such stations. There
is direct evidence that the nuts named Trigonocarpa were drifted
extensively by water over submerged flats of mud. Many _Cardiocarpa_
were winged seeds which may have drifted in the air. The Calamites
may, like modern _Equiseta_, have produced spores with elaters capable
of floating them in the wind. One of the thinner coals at the Joggins
is filled with spores or spore cases that seem to have carried
hairs on their surfaces, and may have been suited to such a mode of
dissemination. I have elsewhere proved[147] that at least some species
of _Calamites_ were, by their mode of growth, admirably fitted for
growing amid accumulating sediment, and for promoting its accumulation.

[147] "Acadian Geology," chapter on Coal Plants.

The reptiles of the coal formation are probably the oldest known to us,
and possibly, though this we cannot affirm, the highest products of
creation in this period. Supposing, for the moment, that they are the
highest animals of their time, and, what is perhaps less likely, that
those which we know are a fair average of the rest, we have the curious
fact that they are all carnivorous, and the greater part of them fitted
to find food in the water as well as on the land. The plant feeders of
the period, on the land at least, are all invertebrates, as snails,
millipedes, and perhaps insects. The air-breathing vertebrates are not
intended to consume the exuberant vegetable growth, but to check the
increase of its animal enemies. Plant life would thus seem to have had
in every way the advantage. The millipedes probably fed only on roots
and decaying substances, the snails on the more juicy and succulent
plants growing in the shadow of the woods, and the great predominance
of the family of cockroaches among carboniferous insects points to
similar conclusions as to that class. While, moreover, the vegetation
of the coal swamps was most abundant, it was not, on the whole, of a
character to lead us to suppose that it supported many animals. Our
knowledge of the flora of the coal swamps is sufficiently complete to
exclude from them any abundance of the higher phænogamous plants. We
know little, it is true, of the flora of the uplands of the period; but
when we speak of the coal-formation land, it is to the flats only that
we refer. The foliage of the plants on these flats with the exception
of that of the ferns, was harsh and meagre, and there seem to have been
no grasses or other nutritious herbaceous plants. These are wants of
themselves likely to exclude many of the higher forms of herbivorous
life. On the other hand, there was a profusion of large nut-like seeds,
which in a modern forest would probably have afforded subsistence to
squirrels and similar animals. The pith and thick soft bark of many
of the trees must at certain seasons have contained much nutritive
matter, while there was certainly sufficient material for all those
insects whose larvæ feed on living and dead timber, as well as for
the creatures that in turn prey on them. It is remarkable that there
seem to have been no vertebrate animals fitted to avail themselves of
these vast stores of food. The question: "What may have fed on all
this vegetation?" was never absent from my mind in all my explorations
of the Nova Scotia coal sections; but no trace of any creature other
than those already mentioned has ever rewarded my search. In Nova
Scotia it would seem that a few snails, gally-worms, and insects
were the sole links of connection between the plant creation and
air-breathing vertebrates. Is this due to the paucity of the fauna, or
the imperfection of the record? The fact that a few erect stumps have
revealed nearly all the air-breathers yet found, argues strongly for
the latter cause; but there are some facts bearing on the other side.

A gally-worm, if, like its modern relatives, hiding in crevices of
wood in forests, was one of the least likely animals to be found in
aqueous deposits. The erect trees gave it its almost sole chance of
preservation. _Pupa vetusta_ is a small species, and its shell very
thin and fragile, while it probably lived among thick vegetation.
Further, the measures 2,000 feet thick, separating the lowest and
highest beds in which it occurs, include twenty-one coal seams, having
an aggregate thickness of about twenty feet, three beds of bituminous
limestone of animal origin, and perhaps twenty beds holding _Stigmaria_
_in situ_, or _erect_ _Sigillariæ_ and _Calamites_. The lapse of time
implied by this succession of beds, many of them necessarily of very
slow deposition, must be very great, though it would be mere guess work
to attempt to resolve it into years. Yet long though this interval must
have been, _Pupa vetusta_ lasted without one iota of change through
it all; and, more remarkable still, was not accompanied by more than
two other species of its family. Where so many specimens occur, and in
situations so diverse, without any additional species, the inference
is strong that no other of similar habits existed. If in any of those
subtropical islands, whose climate and productions somewhat resemble
those of the coal period, after searching in and about decaying trees,
and also on the bars upon which rivers and lakes drifted their burdens
of shells, we should find only three species, but one of these in very
great numbers, we would surely conclude that other species, if present,
were very rare.

Again, footprints referable to _Dendrerpeton_, or similar animals,
occur in the lower Carboniferous beds below the marine limestones, in
the middle coal measures, and in the upper coal formation, separated
by a thickness of beds which may be estimated at 15,000 feet, and
certainly representing a vast lapse of time. Did we know the creature
by these impressions alone, we might infer its continued existence for
all this great length of time; but when we also find its bones in the
principal repositories of reptile remains, and in company with the
other creatures found with it, we satisfy ourselves that of them all it
was the most likely to have left its trail in the mud flats. We thus
have reason to conclude that it existed alone during this period, in so
far as its especial kind of habitat was concerned; though there lived
with it other reptiles, some of which, haunting principally the woods,
and others the water, were less likely to leave impressions of their
footprints. These may be but slight indications of truth, but they
convey strong impressions of the persistence of species, and also of
the paucity of species belonging to these tribes at the time.

If we could affirm that the Air-breathers of the coal period were
really the first species of their families, they might acquire
additional interest by their bearing on this question of origin of
species. We cannot affirm this; but it may be a harmless and not
uninstructive play of fancy to suppose for a moment that they actually
are so, and to inquire on this supposition as to the mode of their
introduction. Looking at them from this point of view, we shall first
be struck with the fact that they belong to all of the three great
leading types of animals which include our modern Air-breathers the
Vertebrates, the Arthropods, and the Mollusks. We have besides to
consider in this connection that the breathing organs of an insect are
air tubes opening laterally (tracheæ), those of a land snail merely a
modification of the chamber which in marine species holds the gills,
while those of the reptiles represent the air bladder of the fishes.
Thus, in the three groups the breathing organs are quite distinct in
their nature and affinities. This at once excludes the supposition that
they can all have been derived from each other within the limits of the
coal period. No transmutationist can have the hardihood to assert the
convertibility, by any direct method, of a snail into a millipede or
an insect, or of either into a reptile. The plan of structure in these
creatures is not only different, but contrasted in its most essential
features. It would be far more natural to suppose that these animals
sprang from aquatic species of their respective types. We should then
seek for the ancestors of the snail in aquatic Gasteropods, for those
of the millipede in worms or Crustaceans, and for those of the reptiles
in the fishes of the period. It would be easy to build up an imaginary
series of stages, on the principle of natural selection, whereby these
results might be effected; but the hypothesis would be destitute of
any support from fact, and would be beset by more difficulties than it
removes. Why should the result of the transformation of water-snails
breathing by gills be a _Pupa ?_ Would it not much more likely be an
_Auricula_ or a _Limnea ?_ It will not solve this difficulty to say
that the intermediate forms became extinct, and so are lost. On the
contrary, they exist to this day, though they were not, in so far
as we know, introduced so early. But negative evidence must not be
relied on; the record is very imperfect, and such creatures may have
existed, though unknown to us. It may be answered that they could not
have existed in any considerable numbers, else some of their shells
would have appeared in the coal-formation beds, so rich in crustaceans
and bivalve mollusks. Further, the little Pupa remained unchanged
during a very long time, and shows no tendency to resolve itself into
anything higher, or to descend to anything lower, while in the lowest
bed in which it occurs it is associated with a round snail of quite
different type. Here, if anywhere, in what appears to be the first
introduction of air-breathing invertebrates, we should be able to find
the evidences of transition from the gills of the Prosobranchiate
and the Crustacean to the air sac of the Pulmonate and the tracheæ of
the millipede. It is also to be observed that many other structural
changes are involved, the aggregate of which makes a Pulmonate or a
millipede different in every particular from its nearest allies among
gill-bearing Gasteropods or Crustaceans.

It may be said, however, that the links of connection between the coal
reptiles and fishes are better established. All the known coal reptiles
have leanings to the fishes in certain characters; and in some, as
in _Archegosaurus_, these are very close. Still the interval to be
bridged over is wide, and the differences are by no means those which
we should expect. Were the problem given to convert a ganoid fish into
an _Archegosaurus_ or _Dendrerpeton_, we should be disposed to retain
unchanged such characters as would be suited to the new habits of the
creature, and to change only those directly related to the objects
in view. We should probably give little attention to differences in
the arrangement of skull bones, in the parts of the vertebræ, in the
external clothing, in the microscopic structure of the bone, and other
peculiarities for serving similar purposes by organs on a different
plan, which are so conspicuous so soon as we pass from the fish to the
Batrachian. It is not, in short, an improvement of the organs of the
fish that we witness so much as the introduction of new organs.[148]
The foot of the batrachian bears, perhaps, as close a relation to the
fin of the fish as the screw of one steamship to the paddle wheel
of another, or as the latter to a carriage wheel; and can be just
as rationally supposed to be not a new instrument, but the old one
changed. In this connection even a footprint in the sand startles us as
much as that of Friday did Robinson Crusoe. We see five fingers and
toes, and ask how this numerical arrangement started at once from fin
rays of fishes all over the world; and how it has continued unchanged
till now, when it forms the basis of our decimal arithmetic.

[148] An ingenious attempt by Prof. Cope, to deduce the batrachian foot
from the fins of certain carboniferous fishes, will be found in the
_Proceedings of the Philos. Academy of Philadelphia_ for the present
year.

Again, our reptiles of the coal do not constitute a continuous series,
and belong to a great number of distinct genera and families, nor
is it possible that they can all, except at widely different times,
have originated from the same source. It either happened, for some
unknown reason, that many kinds of fishes put on the reptilian guise
in the same period, or else the vast lapse of ages required for the
production of a reptile from a fish must be indefinitely increased for
the production of many dissimilar reptiles from each other; or, on the
other hand, we must suppose that the limit between the fish and reptile
being once overpassed, a facility for comparatively rapid changes
became the property of the latter. Either supposition would, I think,
contradict such facts bearing on the subject as are known to us.

We commenced with supposing that the reptiles of the Coal might
possibly be the first of their family, but it is evident from the
above considerations, that on the doctrine of natural selection, the
number and variety of reptiles in this period would imply that their
predecessors in this form must have existed from a time as early as
any in which even fishes are known to exist; so that if we adopt any
hypothesis of derivation, it would probably be necessary to have
recourse to that which supposes at particular periods a sudden and
as yet unaccountable transmutation of one form into another; a view
which, in its remoteness from anything included under ordinary natural
laws, does not materially differ from that currently received idea of
creative intervention, with which, in so far as our coal reptiles can
inform us, we are for the present satisfied.

There is one other point which strikes the naturalist in considering
these animals, and which has a certain bearing on such hypothesis.
It is the combination of various grades of reptilian types in these
ancient creatures. It has been well remarked by Hugh Miller, and more
fully by Agassiz, that this is characteristic of the first appearance
of new groups of animals. Now selection, as it acts in the hands of the
breeder, tends to specialization; and natural selection, if there is
such a thing, is supposed to tend in the same direction. But when some
distinctly new form is to be introduced, an opposite tendency seems to
prevail, a sort of aggregation in one species of characters afterward
to be separated and manifested in distinct groups of creatures. The
introduction of such new types also tends to degrade and deprive of
their higher properties previously existing groups of lower rank. It is
easy to perceive in all this, law and order, in that higher sense in
which these terms express the will and plan of the Supreme Mind, but
not in that lower sense in which they represent the insensate operation
of blind natural forces.

  References:--"Air-breathers of the Coal Period." Montreal, 1886.
    Papers on Reptiles, etc., in South Joggins Coal Field, _Journal
    of Geological Society of London_, vols. ix. x. xi. xvi. Remains
    of Animals in Erect Trees in the Coal Formation of Nova Scotia,
    _Trans. Royal Society_, 1881. "Acadian Geology," fourth edition,
    1891. Revision of Land Snails of the Palæozoic Era, _Am. Journal of
    Science_, vol. xx., 1880. Supplementary Report to Royal Society of
    London, Proceedings, 1892. Notice of additional Reptilian Remains,
    _Geological Magazine of London_, 1891.




                  _MARKINGS, FOOTPRINTS AND FUCOIDS._


                  DEDICATED TO THE MEMORY OF THE LATE

                       DR. J. J. BIGSBY, F.R.S.,

                              OF LONDON,

                  The painstaking and accurate Author

         of the Thesaurus Siluricus and Devonico-Carboniferous,

            a warm and kind Friend and Christian Gentleman

                            and one of the

                     Pioneers of Canadian Geology.


Reminiscences of Lyell's Work--Tidal Flats of the Bay of Fundy--Rill
Marks and Shrinkage Cracks--Worm Trails and Burrows--The Paces of
Limulus--Fucoids Versus Trails--Footprints of Vertebrates

[Illustration: Track of Limulus.--Modern, Orchard Beach. Showing its
resemblance to the _Protichnites_ of the Cambrian. (Page 320.)]




CHAPTER XI.

_MARKINGS, FOOTPRINTS AND FUCOIDS._


I believe my attention was first directed to the markings made by
animals on the surfaces of rocks, when travelling with the late Sir
Charles Lyell in Nova Scotia, in 1842. He noticed with the greatest
interest the trails of worms, insects, and various other creatures, and
the footprints of birds on the surface of the soft red tidal mud of
the Bay of Fundy, and subsequently published his notes on the various
markings in these deposits in his "Travels in North America," and in a
paper presented to the Geological Society of London. I well remember
how, in walking along the edge of the muddy shore, he stopped to watch
the efforts of a grasshopper that had leaped into the soft ooze, and
was painfully making a most complicated trail in his effort to escape.
Sir Charles remarked that if it had been so fortunate as to make these
strange and complicated tracks on some old formation now hardened into
stone and buried in the earth, it might have given occasion to much
learned discussion.

At a later period I found myself perplexed in the study of fossil
plants by the evident errors of many palæobotanists unacquainted with
modern markings on shores, in referring all kinds of mere markings
to the vegetable kingdom, and especially to the group of fucoids or
seaweeds, which had become a refuge for destitute objects not referable
to other kinds of fossils. It thus became necessary to collect and
study these objects, as they existed in rocks of different ages, and
to compare them with the examples afforded by the modern beach; and
perhaps no locality could have afforded better opportunities for this
than the immense tidal flats of the finest mud left bare by the great
tides of the Bay of Fundy in Nova Scotia. At a more recent period
still, the subject has come into great prominence in Europe, and if we
are to gauge its importance by the magnitude of the costly illustrated
works devoted to it by Delgado, Saporta, Nathorst, and others, and the
multitude of scattered papers in scientific periodicals, we should
regard it as one of the most salient points in Geology.[149]

[149] _Journal of London Geological Society_, vol. vii. p. 239.

It may be well further to introduce the subject by a few extracts from
Lyell's work above referred to.

"The sediment with which the waters are charged is extremely fine,
being derived from the destruction of cliffs of red sandstone and
shale, belonging chiefly to the coal measures. On the borders of even
the smallest estuaries communicating with a bay, in which the tides
rise sixty feet and upwards, large areas are laid dry for nearly a
fortnight between the spring and neap tides, and the mud is then baked
in summer by a hot sun, so that it becomes solidified and traversed by
cracks caused by shrinkage. Portions of the hardened mud may then be
taken up and removed without injury. On examining the edges of each
slab we observe numerous layers, formed by successive tides, usually
very thin, sometimes only one-tenth of an inch thick, of unequal
thickness, however, because, according to Dr. Webster, the night tides
rising a foot higher than the day tides throw down more sediment. When
a shower of rain falls, the highest portion of the mud-covered flat
is usually too hard to receive any impressions; while that recently
uncovered by the tide, near the water's edge, is too soft. Between
these areas a zone occurs almost as smooth and even as a looking-glass,
on which every drop forms a cavity of circular or oval form; and if the
shower be transient, these pits retain their shape permanently, being
dried by the sun, and being then too firm to be effaced by the action
of the succeeding tide, which deposits upon them a new layer of mud.
Hence we find, on splitting open a slab an inch or more thick, on the
upper surface of which the marks of recent rain occur, that an inferior
layer, deposited perhaps ten or fourteen tides previously, exhibits
on its under surface perfect casts of rain prints which stand out in
relief, the moulds of the same being seen in the layer below."

After mentioning that a continued shower of rain obliterates the more
regular impressions, and produces merely a blistered or uneven surface,
and describing minutely the characteristics of true rain marks in their
most perfect state, Sir Charles adds:--

"On some of the specimens the winding tubular tracks of worms are seen,
which have been bored just beneath the surface. Sometimes the worms
have dived beneath the surface, and then re-appeared. Occasionally the
same mud is traversed by the footprints of birds (_Tringa minuta_),
and of musk-rats, minks, dogs, sheep and cats. The leaves also of the
elm, maple and oak trees have been scattered by the winds over the soft
mud, and having been buried under the deposits of succeeding tides, are
found on dividing the layers. When the leaves themselves are removed,
very faithful impressions, not only of their outline, but of their
minutest veins, are left imprinted on the clay."

This is a minor illustration of that application of recent causes to
explain ancient effects of which the great English geologist was the
apostle and advocate, and which he so admirably practised in his own
work. It is also an illustration of the fact that things the most
perishable and evanescent may, when buried in the crust of the earth,
become its most durable monuments. Footprints in the sand of the tidal
shore are in the ordinary course of events certain to be obliterated
by the next tide; but when carefully filled up by gently deposited new
material, and hardened into stone, there is no limit to their duration.

Let us inquire how this may take place, and the tidal flats of the Bay
of Fundy and Basin of Minas may supply us with the information desired.
In the upper parts of the Bay of Fundy and its estuaries the rise and
fall of tide, as is well known, are excessive. I quote the following
description of the appearance they present from a work of earlier
date:--

"The tide wave that sweeps to the north-east, along the Atlantic
coast of the United States, entering the funnel-like mouth of the Bay
of Fundy, becomes compressed and elevated, as the sides of the bay
gradually approach each other, until in the narrower parts the water
runs at the rate of six or seven miles per hour, and the vertical rise
of the tide amounts to sixty feet or more. In Cobequid and Chiegnecto
Bays these tides, to an unaccustomed spectator, have rather the aspect
of some rare convulsion of nature than of an ordinary daily phenomenon.
At low tide wide flats of brown mud are seen to extend for miles, as if
the sea had altogether retired from its bed; and the distant channel
appears as a mere strip of muddy water. At the commencement of flood a
slight ripple is seen to break over the edge of the flats. It rushes
swiftly forward, and, covering the lower flats almost instantaneously,
gains rapidly on the higher swells of mud, which appear as if they were
being dissolved in the turbid waters. At the same time the torrent
of red water enters all the channels, creeks and estuaries; surging,
whirling, and foaming, and often having in its front a white, breaking
wave, or 'bore,' which runs steadily forward, meeting and swallowing up
the remains of the ebb still trickling down the channels. The mud flats
are soon covered; and then, as the stranger sees the water gaining with
noiseless and steady rapidity on the steep sides of banks and cliffs,
a sense of insecurity creeps over him, as if no limit could be set
to the advancing deluge. In a little time, however, he sees that the
fiat, 'Hitherto shalt thou come, and no farther,' has been issued to
the great bay tide: its retreat commences, and the waters rush back as
rapidly as they entered.

"The rising tide sweeps away the fine material from every exposed
bank and cliff, and becomes loaded with mud and extremely fine sand,
which, as it stagnates at high water, it deposits in a thin layer on
the surface of the flats. This layer, which may vary in thickness from
a quarter of an inch to a quarter of a line, is coarser and thicker
at the outer edge of the flats than nearer the shore; and hence these
flats, as well as the marshes, are usually higher near the channels
than at their inner edge. From the same cause,--the more rapid
deposition of the coarser sediment,--the lower side of each layer is
arenaceous, and sometimes dotted over with films of mica, while the
upper side is fine and slimy, and when dry has a shining and polished
surface. The falling tide has little effect on these deposits, and
hence the gradual growth of the flats, until they reach such a height
that they can be overflowed only by the high spring tides. They then
become natural or salt marsh, covered with the coarse grasses and
_carices_ which grow in such places. So far the process is carried on
by the hand of nature; and before the colonization of Nova Scotia,
there were large tracts of this grassy alluvium to excite the wonder
and delight of the first settlers on the shores of the Bay of Fundy.
Man, however, carries the land-making process farther; and by diking
and draining, excludes the sea water, and produces a soil capable of
yielding for an indefinite period, without manure, the most valuable
cultivated grains and grasses."

The mud of these great tidal flats is at the surface of a red colour,
and so fine that when the tide leaves it and its surface becomes dry,
it shines in the sun as if polished. It is thus capable of taking
the finest impressions. When the tide is in, numerous small fish of
various species occupy the ground and may leave marks of their fins
and tails as they gambol or seek their food. Shell fishes, worms, and
Crustaceans scramble over the same surface, or make burrows in it. As
the tide recedes flocks of sandpipers and crows follow it down, and
leave an infinity of footprints, and even quadrupeds like the domestic
hog go far out at low water in search of food. It is said that in some
parts of the Bay the hogs are so assiduous in this pursuit that they
even awake and go out on the flats in the night tide, and that they
have so learned to dread the dangers of the flood, that when in the
darkness they hear the dull sound of the approaching bore, they squeal
with fear and rush madly for the shore.

If we examine it minutely, we shall find that the tidal deposit is
laminated. The tidal water is red and muddy, and holds in suspension
sediment of various degrees of coarseness. This, undergoes a certain
process of levigation. In the first run of the flood the coarser
material falls to the bottom. As its force diminishes the finer
material is deposited, and at full tide, when the current has ceased,
the finest of all settles, forming a delicate coat of the purest and
most tenacious clay. Thus, if a block of the material is taken up and
allowed to dry, it tends to separate into thin laminæ, each of which
represents a tide, and is somewhat sandy below, and passes into the
finest moulding clay above. The tracks and impressions preserved are
naturally made on the last or finest deposit, and filled in with the
coarser or more sandy of the next tide. But this may take place in
different ways. Impressions made under water at flood tide, or on
the surface left bare by the ebb, may in favourable localities be
sufficiently tenacious or firm to resist the abrading action of the
flood, and may thus be covered and preserved by the next layer, and in
this way they may be seen on splitting up a block of the dried mud. But
in shallow places and near the shore, where the deposit has time to
consolidate and become dried by the sun and air before the next tide,
much better impressions are preserved; and lastly, on those parts of
the shore which are reached only by the spring tides, the mud of the
highest tide of course may have several days to harden before the next
tide reaches it, and in this case it becomes cracked by an infinity of
shrinkage cracks, which, when it is next covered with the tide, are
filled with new sediment. In this way is produced in great perfection
that combination of footprints, or even of impressions of rain, with
casts of cracks, which is so often seen in the older rocks. Where on
the sides of channels or near the shore the mud has a considerable
slope, another and very curious effect results. As the tide ebbs the
water drains off the surface, or oozing out of the wet sand and mud,
forms at the top of the bank minute grooves often no larger than fine
threads. These coalesce and form small channels, and these, again,
larger ones, till at low tide the whole sloping surface is seen to be
covered with a smooth and beautiful tracery resembling the rivers on
a map, or the impressions of the trunks and branches of trees, or the
fronds of gigantic seaweeds. These "rill marks," as they have been
called, are found in great abundance in the coal formation and triassic
sandstones and shales, and I am sorry to say, have often been named and
described as Fucoids, and illustrated by sumptuous plates. Sometimes
these impressions are so fine as to resemble the venation of leaves,
sometimes so large as to simulate trees, and I have even seen them
complicated with shrinkage cracks, the edges of which were minutely
crenulated by little rills running into them from the surface.

It is further to be noticed that all these markings and impressions
on tidal shores may, when covered by succeeding deposits, appear
either in intaglio or relief. On the upper surface they are of course
sunken, but on the lower surface of the bed deposited on them they are
in relief. It often happens also that these casts in relief are the
best preserved. This arises from the fact that the original moulds or
impressions are usually made in clay, whereas the filling material
is sandy, and the latter, infiltrated with calcareous or siliceous
matter, may become a hard sandstone, while the clay may remain a
comparatively soft shale. This tendency of casts rather than of moulds
to be preserved sometimes produces puzzling effects. A cylindrical
or branching trail thus often assumes the appearance of a stem, and
any pits or marginal impressions assume the form of projections or
leaves, and thus a trail of a worm or Gastropod or a rill mark may
easily simulate a plant. It is to be observed, however, that these
prominent casts are on the under side of the beds, that their material
is continuous with that of the beds to which they belong, and that
they are destitute of any carbonaceous matter. There are, however,
cases where markings may be in relief, even on the upper surfaces of
beds. The following are illustrations of this. Just as a man walking
in newly fallen snow compresses it under his feet, and if the snow be
afterwards drifted away or melted away by the sun, the compressed part
resists longest, and may appear as a raised footmark, so tracks made on
soft material may consolidate it so that if the soft mud be afterwards
washed away the tracks may remain projecting. Again, worms eject earthy
matter from their burrows, forming mounds, patches or raised ridges of
various forms on the surface, and some animals burrow immediately under
the surface, pushing up the mud over them into a ridge, while others
pile up over their bodies pellets of clay, forming an archway or tunnel
as they go. Zeiller has shown that the mole cricket forms curious
roofed trails of this kind, and it seems certain that Crustaceans and
marine worms of different kinds execute similar works, and that their
roofed burrows, either entire or fallen in, produce curious imitations
of branches of plants.

The great and multiform army of the sea worms is indeed the most
prolific source of markings on sea-formed rocks. Sometimes they cover
very large surfaces of these, or penetrate the beds as perforations,
with tortuous furrows, or holes perfectly simple, or marked with
little striæ made by bristles or minute feet, sometimes with a
fringe of little footmarks a each side, sometimes with transverse
furrows indicating the joints of the animal's body. Multitudes of
these markings have been described and named either as plants or as
worm-tracks. Again, these creatures execute subterranean burrows,
sometimes vertical, sometimes tortuous. These are often mere
cylindrical holes afterwards filled with sand, but sometimes they have
been lined with a membranous tube, or with the rejectamenta of the food
of the animals, or with little fragments of organic matter cemented
together. Sometimes they open on the surface as simple apertures, but
again they may be surrounded with heaps of castings, sometimes spiral
in form, or with dumps of sand produced in their excavation, and which
may assume various forms, according to circumstances. Sometimes the
aperture is double, so that they seem to be in pairs. Sometimes, for
the convenience of the animal, the aperture is widened into the form
of a funnel, and sometimes the creature, by extending its body and
drawing it in, surrounds its burrow with a series of radiating tracks
simulating the form of a starfish or sea anemone, or of the diverging
branches of a plant.

Creatures of higher grade, provided with jointed limbs, naturally make
their actions known in more complicated ways. Some years ago I had
the pleasure of spending a few weeks at the favourite sea-side resort
of Orchard Beach on the New England coast, and there made my first
acquaintance with that very ancient and curious creature the Limulus,
or Horse-shoe Crab, or King-crab, as it is sometimes called. Orchard
Beach is, I presume, near its northern range on our coast, and the
specimens seen were not very large in size, though by no means rare,
and not infrequently cast on shore in storms. But the best facilities
for studying their habits were found in a marsh at no great distance
from the hotel, where there were numerous channels, ditches and little
ponds filled with sea water at high tide. In these were multitudes of
young Limuli, varying from an inch to three or four inches in breadth,
and though many were dead or merely cast shells, it was easy to take
young specimens with a landing net. A number of these were secured, and
I made it my business for some time to study their habits and mode of
life, and especially the tracks which they made in sand or mud.

The King-crab, viewed from above, consists of three parts. The anterior
shield or carapace is semi-circular in form, with two spines or
projecting points at the angles, raised in the middle and sloping down
to a smooth or moderately sharp edge in front. The eyes are set like
windows in this shield. Two large ones at the sides, which are compound
eyes consisting of numerous ocelli or little eyes, and two microscopic
ones in front, at the base of a little spine, which are simple. The
second or abdominal part is also in one piece, somewhat quadrate in
form, with ridges and serratures at the sides armed with spines, and
which may be said to simulate the separate joints into which the
abdomen of an ordinary Crustacean is divided. The third part is a
long tail spine, triangular in cross section, sharply pointed, and so
jointed to the posterior end of the abdomen that it can be freely moved
in any direction as a bayonet-like weapon of defence. When unable to
escape from an enemy it is the habit of the creature to double itself
up by bending the abdomen against the carapace, and erecting the sharp
spine. Thus, with fixed bayonet it awaits attack, like the kneeling
soldier in front of a square.

Below this upper shield, which is thin and papery in the young,
somewhat horny in the adult, are the numerous limbs of the creature,
with which we are at present most concerned. Under the carapace
are several pairs of jointed limbs differing in size and form. The
two anterior are small and peculiarly formed claws, used apparently
in manipulating the food. The four next are larger in size, and are
walking feet, each furnished with two sharp points which form a pincer
for holding. The last pair is much larger and stronger than any of the
others, and armed not only with a pair of pincers, but with four blunt
nail-like points. Under the abdomen are flat swimming feet, as they
have been called, each composed of a broad plate notched and divided in
the middle. When at rest these lie flat on each other, but they can be
flapped back and forth at the will of the animal.

Let us now see what use the creature can make of these numerous and
varied pedal appendages, and for distinctness' sake we shall call the
anterior set thoracic and the posterior abdominal. When placed in
shallow water on fine sand it walked slowly forward, and its tracks
then consisted of a number of punctures on the sand in two lines. If,
however, the water was very shallow or the sand very soft or inclined
upward the two edges of the carapace touched the bottom, making a
slight furrow at each side; and if the tail was trailed on the bottom,
this made a third or central furrow. When climbing a slope, or when
placed at the edge of the water, it adopted another mode of locomotion,
pushing with great force with its two posterior limbs, and thus moving
forward by jerks. It then made four deep marks with the toes of each
hind limb, and more or less interrupted marks with the edges of the
carapace and the tail. In these circumstances the marks were almost
exactly like those of some forms of the Protichnites of the Potsdam
sandstone. When in sufficiently deep-water and desirous to escape,
it flapped its abdominal feet, and then swam or glided close to the
bottom. In this case, when moving near the soft bottom, it produced
a series of transverse ridges and furrows like small ripple marks,
with a slight ridge in the middle, and sometimes, when the edges of
the carapace touched the bottom, with lateral furrows. In this way
the animals were able to swim with some ease and rapidity, and on
one occasion I observed an individual, confined in a tub of water,
raise itself from the bottom and swim around the tub at the surface
in search of a way of escape. Lastly, the young Limuli were fond of
hiding themselves by burrowing in the sand. They did this by pushing
the anterior rounded end of the carapace under the sand, and then
vigorously shovelling out the material from below with their feet, so
that they gradually sank under the surface, and the sand flowed in upon
them till they were entirely covered. If carefully removed from the
hollow they had made, this was found to be ovoid or hoof shaped in form
and bilobed, not unlike the curious hollows (_Rusophycus Grenvillensis_
of Billings) which I have supposed to be burrows of Trilobites.

I thus found that the common King-crab could produce a considerable
variety of tracks and burrows comparable with those which have been
named Protichnites, Climactichnites, Bilobites, Cruziana, Rusichnites,
etc.; and that the kind of markings depended partly on the differences
of gait in the animal, and partly on the circumstances in which it was
placed; so that different kinds of tracks do not always prove diversity
in the animals producing them.

The interest of this investigation as applied to Limulus is increased
by the fact that this creature is the near ally of Trilobites,
Eurypterids and other Crustaceans which were abundant in the earlier
geological ages, and whose footprints are probably among the most
common we find on the rocks.

[Illustration: Rusichnites Grenvillensis, Billings a "Bilobite."
Probably the Cast of a Crustacean burrow.]

Lastly, on this part of the subject, it is to be observed that many
other marine animals, both crustaceans and worms, make impressions
resembling in general character those of Limulus. In addition to those
already mentioned, Nathorst and Bureau have shown that various kinds
of shrimps and lobster-like Crustaceans, when swimming rapidly by
successive strokes of the tail, make double furrows with transverse
ridges resembling those of Bilobites, and there are even some mollusks
which by the undulations of the foot or the hook-like action of its
anterior part, can make similar trails. A question arises here as to
the value of such things as fossils. This depends on the fact that
many creatures have left their marks on the rocks when still soft on
the sea bottom, of which we have no other indications, and it also
depends on our ability to understand the import of these unconscious
hieroglyphics. They will certainly be of little use to us so long as
we persist in regarding them as vegetable forms, and until we have
very carefully studied all kinds of modern markings.[150] Nor does it
seem of much use to assign to them specific names. The same trail
often changes from one so-called species, or even genus, to another in
tracing it along, and the same animal may in different circumstances
make very different kinds of tracks. There will eventually, perhaps,
arise some general kind of nomenclature for these markings under a
separate sub-science of Ichnology or the doctrine of Footprints.

[150] Geologists are greatly indebted to Dr. Nathorst of Stockholm for
his painstaking researches of this kind.

I have said nothing of true Algæ or seaweeds, of which there are many
fossil species known to us by their forms, and also by the carbonaceous
or pyritous matter, or discharge of colour from the matrix, which
furnishes evidence of the presence of organic material; nor of the
marks and trails left by seaweeds and land plants drifting in currents,
some of which are very curious and fantastic; nor of those singular
trails referred to the arms of cuttle-fishes and the fins of fishes,
or to sea jellies and starfishes. These might form materials for a
treatise. My object here is merely to indicate the mode of dealing with
such things, and the kind of information to be derived from them.

When we come to the consideration of actual footprints of vertebrate
animals having limbs, the information we can obtain is of a far more
definite character. This has already been referred to in treating of
the first Air-breathers in a previous chapter. One very curious example
we may close with. It is that of the celebrated "bird tracks" of the
sandstone quarries in the Trias of Connecticut and Massachusetts.
These tracks, of immense size, as much as eighteen inches in length,
and so arranged as to indicate the stride of a long-legged biped, were
naturally referred to gigantic birds, allied to modern waders. But
when it was found that some of them showed a central furrow indicating
a long tail trailing behind, this conclusion was shaken, and when in
tracing them along, places were found where the animal had sat down
on its haunches and the end of its tail, and had brought down to the
ground a pair of small fore feet with four or five fingers, it was
discovered that we had to deal with biped reptiles; and when the
tracks were correlated with the bones of the extinct reptiles known
as Dinosaurs, we found ourselves in the presence of a group of the
most strange and portentous reptilian forms that the earth has ever
known. Marsh has been enabled, by nearly perfect skeletons of some
allied reptilian bipeds found in the West, to reproduce them in their
exact forms and proportions, so that we can realize in imagination
their aspect, their gait, and their gigantic proportions. Examples of
this putting together of footprints and osseous remains of vertebrate
animals are not rare in the history of geology, and show us how the
monsters of the ancient world, equally with their human successors,
could leave "footprints on the sands of time."

The Dinosaurs which have left their footprints on the sandstones of
Connecticut and Massachusetts are, however, greatly more numerous
than those known to us by osseous remains. Thus footprints have the
further use of filling up the imperfections of our geological record,
or at least of pointing out gaps which but for them we might not have
suspected. The remarkable inferences of Matthew already referred to,
respecting cuttle-fishes in the Cambrian period, constitute a case in
point. Footprints of Batrachians in the Carboniferous rocks were known
before their bones. The strange hand-like tracks in the Trias were
known before we knew the Labyrinthodon that produced them. We are still
ignorant of the animals whose tracks in the old Potsdam sandstones we
name Protichnites.

  References:--On Rusichnites (a form of Bilobite), _Canadian
    Naturalist_, 1864. On Footprints of Limulus compared with
    Protichnites, etc. _Ibid._ On Footprints and Impressions of Aquatic
    Animals and Imitative Markings, _Amer. Journal of Science_, 1873.
    On Burrows and Tracks of Invertebrate Animals, _Quarterly Journal
    of Geological Society_, 1890. On Footprints of Carboniferous
    Batrachians. "Acadian Geology," "Air-breathers of the Coal Period,"
    etc.




                    _PRE-DETERMINATION IN NATURE._


                      DEDICATED TO THE MEMORY OF

                           ELKANAH BILLINGS,

                        First Palæontologist of

                   the Geological Survey of Canada,

               who laid the Foundations of our Knowledge

                of the Invertebrate Fossils of Canada.


Fixity of Laws and Properties of Energy and Matter--Permanence of
Continents and Oceans--The Permanent and the Changeable--Permanence of
Animal and Vegetable Forms and Structures--Principles of Construction
in the Parts of Trilobites--In the Skeletons of Sponges--In Early
Vertebrates--In Plants Laws of Fixity and Diversity

[Illustration: Restoration of Protospongia Tetranema. Quebec group;
Siluro-Cambrian, Little Metis (p. 335).]




CHAPTER XII.

_PRE-DETERMINATION IN NATURE._


The natural prejudice of persons not acquainted with geology is that
in the world all things continue as they were from the beginning.
But a little observation and experience dispels this delusion, and
perhaps replaces it with an opposite error. When our minds have been
familiarized with the continuous processes by which vaporous nebulæ
may be differentiated into distinct planets, and these may be slowly
cooled from an incandescent state till their surfaces become resolved
into areas of land and water; and still more, when we contemplate the
grand procession of forms of life from the earliest animals and plants
to man and his contemporaries, we become converts to the doctrine that
all things are in a perpetual flux, and that every succeeding day sees
them different from what they were the day before. In this state of
mind the scientific student is apt to overlook the fact that there are
many things which remain the same through all the ages, or which, once
settled, admit of no change. I do not here refer to those fundamental
properties of matter and forces and laws of nature which form the basis
of uniformitarianism in geology, but to determinations and arrangements
which might easily have been quite different from what they are, but
which, once settled, seem to remain for ever.

We have already considered the great fact that the nuclei and ribs of
the continental masses were laid down as foundations in the earliest
periods, and have been built upon by determinate additions, more
especially upon their edges and their hollows, so that while there
has been a constant process of removal of material from the higher
parts of the land, and deposition in the sea, and while there have
been periodical elevations and subsidences, the great areas of land
and water have remained substantially the same, and the main lines
of elevation and folding have conformed to the directions originally
fixed. Thus, in regard to the dry land itself, there has been fixity,
on the one hand, and mutation on the other, of a most paradoxical
aspect, till we understand something of the great law of constant
change united with perennial fixity in nature. From want of attention
to this, the permanence of continents is still a debated question,
and it is difficult for many to understand how the frequent dips
of the continental plateaus and margins under the sea, and their
re-elevation, often along with portions of the shallower sea bottom,
can be consistent with a general permanence of the position of the
continents and of the corresponding ocean abysses; yet, when this is
properly understood, it becomes plain that the union of fixity with
changes of level has been a main cause of the continuity and changes
of organic beings. Only the submergence of inland plateaus under
shallow and warm waters could have given scope for the introduction
of new marine faunas, and only re-elevation could have permitted
the greatest extension of plants and animals of the land. Thus, the
continuity of life with continual advance has depended on the permanent
existence of continental and oceanic areas; and the continents that
remain to us with all their diversity of elevation and outline, their
varied productions, both mineral and organic, and their life, which
is a select remainder of all that went before, have been produced and
furnished by a succession of changes, modified by the most conservative
retention of general arrangements and forms.

It is evident, however, that it is not merely permanence we have
to deal with here, but permanence of position along with change of
elevation; and this modified by the fact that there have always been
mountain ridges, internal plateaus, and marginal areas affected in
various ways by the vertical movement of the land. Further, the
elevation and subsidence of the land have not always been uniform,
but often differential, while every movement has tended to produce
modifications of ocean currents and of atmospheric conditions. The
whole subject, more especially in its relations to life, thus becomes
very complicated, and it is perhaps in consequence of partial and
imperfect views on these points that so much diversity of opinion has
arisen. For example, it is evident that we can gain nothing by adding
to the continents those submerged margins delineated by Murray in
the _Challenger_ reports, and which have in periods of continental
elevation themselves formed portions of the land. Nor do we establish a
case in favour of perished oceanic continents by the argument that they
are needed to furnish the materials of marginal mountains which are due
to the continuous sweeping of arctic material to the south by currents,
as we see in the coast of North America to-day. Nor do we invalidate
the permanence of the continents by the bridges of land, islands,
and shallow water at various times thrown across the Atlantic. The
distribution of Cambrian Trilobites, as illustrated by Matthew,[151]
seems to show a bridge of this kind in the north in very early times,
and similar evidence is furnished by the animals and plants of the
Devonian and Carboniferous, and by the sea animals and plants of the
later Tertiary and modern. Gardener has postulated a southern bridge
in the region of the West Indies for the migrations of plants, and
Gregory has adduced the evidence of those conservative and slow-moving
creatures, the sea urchins, in favour of similar connection in the West
Indian region at two distinct periods of time (the Lower Cretaceous and
the Miocene Tertiary). But bridges do not involve want of permanence
in their termini. Because an engineer has bridged the Firth of Forth,
it does not follow that the banks of this inlet did not exist before
the bridge was built; and if the bridge were to perish, the evidence
that trains had once passed that way would not justify the belief that
the bed of the Firth had been dry land, and the areas north and south
of it depressed. The more we consider this question the more we see
that the permanence, growth and sculpture of the continents are parts
of a great continuous and far-reaching plan. This view is strengthened
rather than otherwise, when we consider the probable manner in which
the enormous weight of the continents is sustained above the waters. We
may attribute this, on the one hand, to rigidity and lateral arching
and compression, or, on the other, to what may be termed flotation of
the lighter parts of the crust; and there seems to be little doubt
that both of these principles have been employed in constructing the
"pillars which support the earth." It is evident, however, that an arch
thrown over the internal abyss of the earth, or a portion of its crust
so lightened as to be pressed upward by its heavier surroundings, must,
when once established, have become a permanent feature of the earth's
foundations, not to be disturbed without calamitous consequences to its
inhabitants.

[151] Transactions Royal Society of Canada, 1892.

It is the part of the philosophical naturalist to bring together these
apparent contrarieties of mutation and permanence; both of which are
included, each in its proper place, in the great plan of nature. It is
therefore my purpose in the present chapter to direct attention to some
of the terminal points or fixed arrangements that we meet with in the
course of the geological history, and even in its earlier parts, and
more particularly in reference to the organic world. This, which is in
itself constantly changing, has been placed under necessity to adhere
to certain determinations fixed of old, and which regulate its forms
and possibilities down to our own time.

The argument, as we have seen in a previous chapter, for the animal
nature of Eozoon depends on our assuming certain parts of this fixity.
We suppose that then as now calcium carbonate had been selected as the
material for the skeletons of such creatures; that then, as now, minute
tubuli and large canals were necessary to enable the soft animal matter
to permeate and pass through the skeleton, and that the protoplasmic
animal matter of these far back geological periods had the same vital
properties of contraction and extension, digestion, etc., that it has
to-day. Could any one prove that these determinations of vital and
other forces had not been established, or that living protoplasmic
matter, with all its wonderful properties, had not been constructed in
the Laurentian period, the existence of this ancient animal would be
impossible. Yet how much is implied in all this, and though nothing
is more unstable chemically or vitally than protoplasm, if it were
introduced in the Laurentian, it has continued practically unchanged up
to the present time.

If we pass on to the undoubted and varied life of the Cambrian period,
we shall find that multitudes of things which might have been otherwise
were already settled in a way that has required no change.

In the oldest Trilobites the whole of the mechanical conditions of an
external articulated skeleton had been finally settled. The material
chitinous or partly calcareous, its microscopic structure, fitted to
combine lightness and strength with facility for rapid growth, the
subdivision of its several rings, so as to form a protective armour
and a mobile skeleton, the arrangement of its spines for defence
without interfering with locomotion, the contrivance of hinge joints
arranged in different planes in the limbs, all these were already in
full perfection, and just as they are found to-day in the skeleton of a
king-crab or any other Crustacean. They have, it is true, been modified
into a vast number of subordinate forms and uses, but the general
principles and main structures all stand. I was much struck with this
recently in studying a remarkable specimen now in the National Museum
at Washington. It is a large species of Asaphus; the same genus which
gave to the late Mr. Billings the limbs of a Trilobite, the first ever
described; but in the Washington specimen they are remarkably perfect.
Each limb presents a series of joints resembling those of the tarsus of
an insect, each joint being of conical form with the narrow proximal
end articulated to the enlarged distal end of the previous one, so
as to give great facility of movement and accommodation for delicate
muscular bands. This tells us of muscular fibre and tendon fitted for
flexing and extending these numerous joints, of motor nerves to work
that marvellous contractile power of the striated muscle, whose mode
of action is still an insoluble mystery, yet one practically solved in
the remote Cambrian age for the benefit of these humble inhabitants
of the sea. If we could imagine that the inventive power to perfect
such machinery was present in the brains of these old Crustaceans or
Arachnidans, we might wish that some of them had survived to instruct
us in matters which baffle our research.

It is long since the compound eyes of these Trilobites, as illustrated
by Burmeister, gave Buckland the opportunity to infer that the laws
of light and of vision were the same from the first as now. But what
does this imply? Not only that the light of the sun penetrating to the
depths of the Cambrian sea, was regulated by the same laws as to-day,
but that a series of cameras was perfected to receive the light as
reflected from objects, to picture the appearance of these objects on
a retinal screen as sensitive as the film of the photographer, and
thereby to produce true perceptions of vision in the sensorium of these
ancient animals. I have before me a fragment of the eye of a Trilobite
(_Phacops_), in which may be seen the little radiating tubes provided
for the several ocelli of the compound eye, just as we see in the
modern Limulus; and each of these ocelli must have been a perfect
photographic camera, and more than this, since absolutely automatic,
and probably having the power to represent colour as well as light
and shade. We know also, from the recent experiments of an Austrian
physiologist on the eyes of insects, that such compound eyes are so
constructed as to present a single picture, just as we can see the
whole landscape in looking through the many little panes of a cottage
window. In our own time the king-crab and lobster no doubt see just
as their predecessors did millions of years ago, and with precisely
similar instruments.

But the eyes of the modern Crustaceans have to compete with eyes of a
dissimilar type, constructed on the same general optical principles,
but quite different in detail. These are the simple or single eyes
of the cuttle-fishes and the true fishes. The same rivalry existed
in the oldest seas, when the competition of Crustaceans and cuttles
was just as keen as now. Though the eyes of the latter have not been
preserved, or at least have not yet been found, we have a right to
infer that the cuttles of the Cambrian and Silurian seas must have
been able to see as well as their Crustacean foes and competitors. If
so, the other type of eye must have been perfected for aquatic vision
as early as the compound type. In any case we know that a little
later, in the Carboniferous period, we have evidence that the eyes of
fishes conformed to those of their modern successors. I have myself
described[152] a carboniferous fish (_Palæoniscus_) from the bituminous
shales of Albert County, New Brunswick, in which the hard globular lens
of the eye had been sufficiently firm and durable to retain its form,
and to be replaced by calcite, showing even that like the lens of the
eye of a modern fish it had been constructed of concentric laminæ. In
the Carboniferous period also, both types of eye, the compound and
the single, experienced the further modifications necessary to fit
them for vision in air, the compound eye in insects, the simple eye in
Batrachians.[153] The original photographic cameras, strange though
this may appear to us, were intended for use under water; but at a very
early time they were adapted to work in air.

[152] _Canadian Naturalist._

[153] See _ante_, chapter on Air-breathers.

But we must bear in mind that this early solving of advanced problems
in mechanics, optics and physiology was in favour of Crustaceans
and cuttles, which were lords of creation in their time. There were
in those early days humbler creatures whose structures also present
wonderful contrivances.

I have already referred, in the chapter on imperfection of the
geological record, to the fossil sponges which have been found in so
great number and perfection in some of the oldest rocks of Canada, and
which have for the first time enabled us to appreciate the forms and
structures of the wonderful silicious sponges which preceded those
with which the dredgings of the _Challenger_ have made us familiar in
the modern seas. Humble sarcodous animals, without distinct muscular
or nervous system or external senses, the sponges have at least to
live and grow, and to that end they must already, in the dawn of life
on our planet,[154] have perfected those arrangements of ciliated
cells in chambers and canals which the microscope shows us driving
currents of water through the modern sponges, and thereby bringing to
them the materials of food and means of respiration. It is true we
know as little as the sponges themselves of the _modus operandi_ of
those perpetually waving threads which we call cilia or flagella, yet
they must have existed with all their powers even before the Cambrian
period.[155]

[154] I have found spicules of sponges in the chert nodules from the
Huronian limestones of Canada.

[155] Many species of hexaclinelled sponges have been described from
the upper Cambrian or lower Cambro-Silurian of Canada. See paper by the
author in the Transactions of the Royal Society of Canada, 1889.

[Illustration: A Giant Net-sponge.--_Palæosaccus Dawsoni_, Hinde. From
the Quebec group (Ordovician), Little Metis, Canada. Reduced to 3/7 the
diameter. (From the _Geological Magazine_, 1803.)]

The sponge, in order to support its delicate protoplasmic structures,
must have a skeleton. In modern times we find these creatures
depositing corneous or horny fibres, as in the common washing sponges,
or forming complex and beautiful structures of needles, or threads of
silica or calcite, and they seem from the first to have been able to
avail themselves of all these different materials. The oldest species
that we know had silicious or calcareous skeletons, though some of them
must also have had a certain amount, at least, of the ordinary spongy
or corneous fibres. But the most astonishing feature in what remains
of their skeletons, flattened out as they are on the surfaces of dark
slaty rock, is the manner in which they worked up so refractory a
material as silica into fibres like spun glass rods and crosses, and
built these up into beautiful basket-like forms, globular, cylindrical
or conical. It was necessary that they should fix themselves on the
soft muddy bottoms on which they grew, and to this end they produced
slender silicious fibres or anchoring rods, which, fine though they
were, had the form of hollow tubes. Sometimes a single rod sufficed,
but in this case it had a cross-like anchor affixed to its lower end, to
give it stability. Sometimes there were several simple rods, and then
they were skilfully braced by spreading them apart at the ends, and by
flattening their extremities into blades. Sometimes four rods joined in
a loop at the end gave the required support. Some larger species wound
together many threads like a wire rope, and even added to this flanges
like the thread of a screw, anticipating the principle of the modern
screw pile.

The body of the sponge must be hollow within, and must have a large
aperture or opening for the discharge of water, and smaller pores for
its admission. Various general forms were adopted for this. Some were
globular, or oval, or pear-shaped; others cylindrical, concave, or
mitre-shaped. To give form and strength to these shapes there were
sometimes vertical and transverse rods soldered together. In other
cases there were four-rayed or six-rayed needles of silica, with their
points attached so as to form a beautiful lattice-work, with its
meshes either square or lozenge-shaped. For protection sharp needles
were arranged like _chevaux de frize_ at the sides and apertures, and
these last were sometimes covered with a hood or grating of needles,
to exclude intruders from the interior cavity. Other species, however,
like some in the modern seas, seemed to despise these niceties, and
contented themselves with long straight needles placed in bundles, or
radiating from a centre, and thus supporting and protecting their soft
and sensitive protoplasm.

Curiously enough, these old sponges did not avail themselves of the
natural cystallization of silica, which, left to itself, would have
formed six-rayed stars, with the rays at angles of sixty degrees, or
six-sided plates, rods, or pyramids. They adopted another and peculiar
form of the mineral, known as colloidal silica, and being thus relieved
from any need to be guided by its crystalline form, treated it as we do
glass, and shaped it into cylindrical tubes, round needles and stars or
crosses, with the rays at right angles to each other.

The sponges whose skeletons are thus constructed, and which anticipated
so many mechanical contrivances long afterwards devised by man,
belonged to a group of silicious sponges (_Hexaclinellidæ_) which is
still extant, and represented by many rare and beautiful species of
the deep sea, which are the ornaments of our museums, and of which the
beautiful Eupleectella or Venus flower-basket, from the Philippine
Islands, and the glass-rope sponge (_Hyalonema_), from Japan, are
examples. But contemporary with these there was another group
(_Lithistidæ_), constructing skeletons of carbonate of lime, and which
preferred, instead of the regular mechanical structures of the others,
a kind of rustic work, made up of irregular fibres, very beautiful and
strong, but as a matter of pattern and taste standing quite by itself.
If there were any sponges with altogether soft and spongy skeletons in
these old times, their remains do not seem to have been preserved.

Here, it will be observed, are a great variety of vital and mechanical
contrivances devised in the very early history of the earth, settled
for all time, and handed down without improvement, and with little
change, to our later day. They are indeed vastly more wonderful than
the above general account can show; for to go into the details of
structure of any one of the species would develop a multitude of minor
complexities and niceties which no one not specially a student of these
animals could appreciate.

These are not solitary cases. The student of fossils meets with them
at every turn; and if he possesses the taste and imagination of a true
naturalist, cannot fail to be impressed with them.

To turn to a later but very ancient period, what can be more
astonishing than those first air-breathing vertebrates of the Coal
formation referred to in a previous chapter, with all their special
arrangements for an aërial habitat? I have mentioned their footprints,
and when we see the quarrymen split open a slab of sandstone and expose
a series of great plantigrade tracks, not unlike those of a human foot,
with the five toes well-developed, we are almost as much astonished as
Crusoe was when he saw the footprints on the sand. Crusoe inferred the
presence of another man in his island; we infer the earliest appearance
of an air-breathing vertebrate and the pre-human determination of the
form and number of parts of the human foot and hand, to appear in the
world long ages afterward. We see also that already that decimal system
of notation which we have founded on the counting of our ten fingers
was settled in the framework of most unmathematical Batrachians. It has
approved itself ever since as the typical and most perfect number of
parts for such organs.

If sceptically inclined, we may ask, Why five rather than four or six?
In the case of man we see that individuals who have lost one finger
have the use of the hand impaired, while the few who happen to have
six do not seem to be the better. How it was with the old Batrachians
we do not know; but it is certain that if we could have amputated the
claw-bearing little toe of _Sauropus unguifer_, or the reflexed little
toe of _Cheirotherium_, we should have much injured their locomotive
power.

The vegetable kingdom is full of similar examples of the early
settlement of great questions. Perhaps nothing is more marvellous
than the power of the green cells of the leaf as workers of those
complex and inimitable chemical changes whereby out of the water,
carbon dioxide and ammonia of the soil and the atmosphere, the living
vegetable cell, with the aid of solar energy, elaborates all the varied
organic compounds produced by the vegetable kingdom. Yet this seems all
to have been settled and perfected in the old Silurian period, long
before any kind of plant now living was on the earth. Perhaps in some
form it existed even in the Laurentian age, and was instrumental in
laying up its great beds of carbon. So all that is essential in plant
reproduction, whether in that simpler form in which a one-celled spore
is the reproductive organ, or in that more complex form in which an
embryo plant is formed in the seed, with a store of nourishment laid up
for its sustenance.

These arrangements were obviously as perfect in the great club mosses
and pines of the Devonian and Carboniferous as they have ever been
since, and we have specimens so preserved as to show their minute parts
just as well as in recent plants. The microscope also shows us that
the contrivances for thickening and strengthening the woody fibres and
trunk of the stem by bars or interrupted linings of ligneous matter, so
as to give strength and at the same time permit transudation of sap,
were all perfected, down to their minutest details, in the oldest land
plants. It is true that flowers with gay petals and some of the more
complicated kinds of fruit are later inventions, but the additions
in these consist mainly of accessories. The essentials of vegetable
reproduction were as well provided for from the first.

The same principle applies to many of the leading forms and types of
life, considered as genera or species. While some of these are of
recent introduction, others have continued almost unchanged from the
remotest ages. Such creatures as the Lingulæ, some of the Crustaceans
and of the Mollusks, the Polyzoa and some Corals have remained with
scarcely any change throughout geological time, while others have
disappeared, and have been replaced by new types.

We began this chapter with a consideration of the permanence of
continental areas, and may close with a reference to the same great
fact in connection with the continuity of life. Whether with some we
attach more importance to the support of the continents by lateral
pressure and rigidity, or with others to what may be termed flotation,
by virtue of their less density, as compared with that of the lower
parts of the earth; there can be little doubt that both principles have
been applied, and that both admit of some vertical movement. Thus the
stability of the continents is one of position rather than height, and
their internal plateaus as well as their partially submerged marginal
slopes have undergone great and unequal elevations and depressions,
causing most important geographical changes. Among these are the
formation of connecting bridges of shoals, islands, or low land,
connecting the continental masses at different periods, and permitting
migrations of shallow-water animals and even of denizens of the land.
The facts adduced in previous pages are sufficient to show connections
across the north of the Atlantic at intervals reaching from the
Cambrian to the Modern.

The conclusion of the whole matter is that there is a fixity and
unchangeableness in determinations and arrangements of force just
as much as in natural laws; and that while God has made everything
beautiful in its time He has also made everything beautiful and useful
in some sense for all time. With all this, while the great principles
and modes of operation remain unchanged, there is ample scope for
development, modification and adaptation to new ends, without deviation
from essential properties and characters. It is a wise and thoughtful
philosophy which can distinguish what is fixed and unchangeable from
that which is fluctuating and capable of development. Until this
distinction is fully understood, we may expect one-sided views and
faulty generalizations in our attempts to understand nature.

  References:--"The Chain of Life in Geological Times." London. New
    Species of Fossil Sponges from the Quebec Group at Little Metis.
    Trans. Royal Society of Canada, 1889. Fossil Fishes from the Lower
    Carboniferous of New Brunswick. _Canadian Naturalist_, "Acadian
    Geology," 1855, and later editions to 1892. London and Montreal.
    "The Story of the Earth," 1872 and later editions to 1891. London.




                         _THE GREAT ICE AGE._


                      DEDICATED TO THE MEMORY OF

                            MY LATE FRIEND

               DAVID MILNE HOME, LL.D., F.R.S.E., ETC.,

            An eminent and judicious Advocate of sound and

              moderate Views respecting the Glacial Age.


Exaggerated Ideas--The St. Lawrence Valley--Modern Ice Action in the
St. Lawrence--Coast Ice--The Icebergs of Belle-Isle--Mt. Blanc and its
Glaciers--Effects of Glaciers--Possible Extension of Glaciers--Facts
of Glaciation in Canada--Cordilleran Glacier, Laurentide Glacier,
Appalachian Glacier--Submerged Valleys and Plains--Double Submergence
and Intermediate Partial Elevation--Interglacial Periods--Questions as
to Alternate Glaciation of Northern and Southern Hemispheres

[Illustration: Modern Boulder Beach.--Little Metis, St. Lawrence
Estuary. (From a Photograph.) Showing the manner in which travelled
boulders are piled up against the beach by the floating ice of the
Modern time (p. 346).]




CHAPTER XIII.

_THE GREAT ICE AGE._


Scientific superstitions, understanding by this name the reception
of hypotheses of prominent men, and using these as fetishes to be
worshipped and to be employed in miraculous works, are scarcely less
common in our time than superstitions of another kind were in darker
ages. One of these which has been dominant for a long time in geology,
and has scarcely yet run its course, is that of the Great Ice Age,
with its accompaniments of Continental Glaciers and Polar Ice Cap.
The cause of this it is not difficult to discern. The covering of
till, gravel and travelled boulders which encumbers the surface of the
northern hemisphere from the Arctic regions more than half way to the
equator, had long been a puzzle to geologists, and this was increased
rather than diminished when the doctrine of appeal to recent causes on
the principle of uniformity became current. It was seen that it was
necessary to invoke the action of ice in some form to account for these
deposits, and it was at the same time perceived that there was much
evidence to prove that between the warm climate of the early Tertiary
and the more subdued mildness of the modern time there had intervened a
period of unusual and extreme cold. In this state of affairs attention
was attracted to the Alpine glaciers. Their movement, their erosion
of surfaces, their heaping up of moraines bearing some resemblance to
the widely extended boulder deposits, their former greater extension,
as indicated by old moraines at lower levels than those in process of
formation, were noted. Here was a modern cause capable of explaining
all the phenomena. Men's minds were taken by storm, and as always
happens in the case of new and important discoveries, the agency of
glaciers was pushed at once far beyond the possibilities of their
action under any known physical or climatal laws. This exaggerated idea
of the action of land ice in the form of glaciers is not yet exploded,
more especially in the United States, where official sanction has been
given to it by the Geological Survey, and where it has been introduced
even into school and college text-books. It affords also a telling
bit of scientific sensationalism, which can scarcely be resisted by a
certain class of popular writers. America has also afforded greater
facilities for extreme theories of this kind, owing to the wide and
uninterrupted distribution of glacial deposits, and the more simple
and less broken character of its great internal plateau, while the
influence of great leading minds, like those of the elder Agassiz and
of Dana, naturally held sway over the younger geologists. Fortunately
Canada, which possesses the larger and more northern half of the
North American continent; though numerically inferior, and therefore
overborne in the discussion, has, in the main, remained steadfast to
facts rather than to specious theories, and has been confirmed in this
position by the clearer testimony of nature in a region where many of
the features of the glacial age still persist.[156]

[156] I may refer here to the recent researches of Dr. G. M. Dawson,
Mr. R. Chalmers, Mr. McConnell and Dr. Ells.

The writer of these pages has, ever since the publication of the first
edition of his "Acadian Geology,"[157] steadily resisted the more
extreme views of glaciation, and has opposed the southward progress of
the great continental glacier. Though, figuratively speaking, overborne
and pressed back in the course of its extension, he has now, like
those primitive men who are imagined in the post-glacial age to have
followed up the retreat of the ice, the pleasure of seeing the once
formidable continental glacier broken up into great local glaciers on
the mountain ranges separated by intervening areas of submergence.

[157] 1855.

The questions relating to this subject are too numerous and varied
for treatment here. The question of the causes of the great lowering
of temperature in the glacial age I shall leave for consideration in
the next chapter, and merely state here that I believe changes of
distribution of sea and land and of ocean currents are sufficient to
account for all the refrigeration of which there is good evidence. I
content myself with a comparison of the glacial phenomena of Mont Blanc
and of the Gulf of St. Lawrence from my own observation,[158] and some
general deductions as to glacier possibilities.

[158] Published in 1867.

A scientific voyager carries with him a species of questioning peculiar
to himself. Not content with vacantly gazing at the sea, scrutinizing
his fellow passengers, noting the changes of the weather and the length
of the day's run, he recognises in the sea one of the great features
of the earth, and questions it daily as to its present and its past
The present features of the sea include much of surpassing interest,
but the questions which relate to its origin and early history are
still more attractive. Some of these questions are likely to interest
a voyager from Canada entering the Atlantic by one of its greatest
tributaries, the St. Lawrence.

In doing so, we approach the ocean not at a right angle, but along a
line only slightly inclined to its western side, and we find ourselves
in a broad estuary or trough, having on its north-western side rugged
hills of old crystalline rocks, the Laurentian, ridged up in great
folds or earth waves parallel to the river. On the south-east or
right-hand side we have a lower barrier of earth waves composed of
sedimentary rocks somewhat later in date, but still geologically very
ancient. We are thus introduced to a remarkable feature of the west
side of the North Atlantic, namely, that its border is made up of
very old rocks folded into mountain ridges thrown up at an ancient
period, and approximately parallel to the coast. The Lower St. Lawrence
occupies a furrow between two of these ridges.

Here, however, a more modern feature attracts our attention. The sides
of the bounding hills are cut in a succession of terraces, rising one
above another from the level of the sea to a height of 500 feet or
more, capped with long ranges of the white houses and barns of the
Canadian habitants, and furnishing level lines for the "concession
roads" which run along the coast. These terraces are really old sea
margins indicating the stages of the elevation of the land out of the
sea immediately before the modern period. On these terraces, and in the
clays and sands which form the plateaus extending in some places in
front of them, are sea shells of the same kinds with those now living
in the Gulf of St. Lawrence, and occasionally we find bones of whales
which have been stranded on the old beaches.

These terraces are, of course, indications of change of level in very
modern times. They show that in what we call the Pleistocene age the
land was lower than at present, and we shall find that in the Lower
St. Lawrence there is evidence of a depression extending to over 1,000
feet, carrying the sea far up the valley, so that sea shells are found
in the clays as far up as Kingston and Ottawa, and stranded skeletons
of whales as far west as Smith's Falls, in Ontario.

If we examine the shores more minutely, we shall find all along the
south coast a belt of boulders which are often as much as eight to ten
feet in diameter, and consist largely of rocks found only in the hills
of the northern coast, more than thirty miles distant, from which
they must have been drifted to their present position. This boulder
belt, which extends from the lowest tide mark about fifty feet or
more upward, is sometimes piled in ridges and sometimes flattened out
into a rude pavement. It is a product of the modern field ice, which,
attaining a great thickness in winter, has boulders frozen into its
bottom, and floating up and down with the tide, deposits these on the
shore. At Little Metis, two hundred miles below Quebec, where I have a
summer residence, I have from year to year cleared a passage through
the boulder belt for bathing and for launching boats, and nearly every
spring I find that boulders have been thrown into the cleared space
by the ice, while one can notice from year to year differences in the
position of very large boulders.

If we pass inland from the shore belt of boulders, we shall find
similar appearances on the inland terraces at various heights, up to
at least 400 feet. These are inland boulder belts belonging to old
shores now elevated. Like the modern boulder belt these inland belts
and patches consist partly of Laurentian rocks from the North Shore,
partly of sandstones and conglomerates in place near to their present
sites. In some places the stones are smaller than those of the present
beach, in other places of gigantic size. These boulders lie not only
on the bare rock striated in places with ice grooves pointing to the
north-north-east; but on the old till or boulder clay, which also
abounds with boulders, and which is more ancient than the superficial
boulder drift. Locally we find here and there masses of fossiliferous
limestone which must have been derived from the high ground to the
south of the St. Lawrence, and which have been borne northward either
by drift ice or by local glaciers.

If now we study the polished and scored surfaces of rocks in the St.
Lawrence valley and the bounding hills, we shall find that while the
former testify to a great movement of ice and boulders up the river
from the north-east, the latter show evident signs of the movement
of local glaciers down the valleys of the Laurentide hills to the
south, and on the continuation of the Appalachians south of the river
similar evidence of the movement of land ice to the north. Thus we
have evidence of the combined action of local glaciers and floating
ice. To add to all this, we can find on the flat tops of the hard
sandstone boulders on the beach the scratches made by the ice of last
winter, often in the same north-easterly direction with those of the
Pleistocene time.

In addition to the ice formed in winter in the St. Lawrence itself,
the snow-clad hills of Greenland send down to the sea great glaciers,
which in the bays and fiords of that inhospitable region form at their
extremities huge cliffs of everlasting ice, and annually "calve," as
the seamen say, or give off a great progeny of ice islands, which,
slowly drifted to the southward by the arctic current, pass along the
American coast, diffusing a cold and bleak atmosphere, until they melt
in the warm waters of the Gulf Stream. Many of these bergs enter the
Straits of Belle-Isle, for the Arctic current clings closely to the
coast, and a part of it seems to be deflected into the Gulf of St.
Lawrence through this passage, carrying with it many large bergs. The
voyager passing through this strait in clear weather may see numbers
of these ice islands glistening in snowy whiteness, or showing deep
green cliffs and pinnacles--sometimes with layers of earthy matter
and stones, or dotted with numerous sea birds, which rest upon them
when gorged with the food afforded by shoals of fish and others marine
animals which haunt these cold seas. In early summer the bergs are
massive in form, often with flat tops, but as the summer advances they
become eroded by the sun and warm winds, till they present the most
grotesque forms of rude towers and spires rising from broad foundations
little elevated above the water.

Mr. Vaughan, late superintendent of the Lighthouse at Belle-Isle, has
kept a register of icebergs for several years. He states that for ten
which enter the straits, fifty drift to the southward, and that most
of those which enter pass inward on the north side of the island,
drift toward the western end of the straits, and then pass out on the
south side of the island, so that the straits seem to be merely a sort
of eddy in the course of the bergs. The number in the straits varies
much in different seasons of the year. The greatest number are seen
in spring, especially in May and June; and toward autumn and in the
winter very few remain. Those which remain until autumn are reduced
to mere skeletons; but if they survive until winter, they again grow
in dimensions, owing to the accumulations upon them of snow and new
ice. Those that we saw early in July were large and massive in their
proportions. The few that remained when we returned in September were
smaller in size, and cut into fantastic and toppling pinnacles. Vaughan
records that on the 30th of May, 1858, he counted in the Straits of
Belle-Isle 496 bergs, the least of them sixty feet in height, some of
them half a mile long and 200 feet high. Only one-eighth of the volume
of floating ice appears above water, and many of these great bergs may
thus touch the ground in a depth of thirty fathoms or more, so that if
we imagine four hundred of them moving up and down under the influence
of the current, oscillating slowly with the motion of the sea, and
grinding on the rocks and stone-covered bottom at all depths from the
centre of the channel, we may form some conception of the effects of
these huge polishers of the sea floor.

Of the bergs which pass outside of the straits, many ground on the
banks off Belle-Isle. Vaughan has seen a hundred large bergs aground
at one time on the banks, and they ground on various parts of the
banks of Newfoundland, and all along the coast of that island. As they
are borne by the deep-seated cold current, and are scarcely at all
affected by the wind, they move somewhat uniformly in a direction from
north-east to south-west, and when they touch the bottom, the striation
or grooving which they produce must be in that direction.

In passing through the straits in July, I have seen great numbers of
bergs, some low and flat-topped, with perpendicular sides, others
convex or roof-shaped, like great tents pitched on the sea; others
rounded in outline or rising into towers and pinnacles. Most of them
were of a pure dead white, like loaf sugar, shaded with pale bluish
green in the great rents and recent fractures. One of them seemed as
if it had grounded and then overturned, presenting a flat and scored
surface covered with sand and earthy matter.

At present we wish to regard the icebergs of Belle-Isle in their
character of geological agents. Viewed in this aspect, they are in
the first place parts of the cosmical arrangements for equalizing
temperature, and for dispersing the great accumulations of ice in the
Arctic regions, which might otherwise unsettle the climatic and even
the static equilibrium of our globe, as they are believed by some
imaginative physicists and geologists to have done in the so-called
glacial period. If the ice islands in the Atlantic, like lumps of ice
in a pitcher of water, chill our climate in spring, they are at the
same time agents in preventing a still more serious secular chilling
which might result from the growth without limit of the Arctic snow
and ice. They are also constantly employed in wearing down the Arctic
land, and aided by the great northern current from Davis's Straits, in
scattering stones, boulders and sand over the banks along the American
coast. Incidentally to this work, they smooth and level the higher
parts of the sea bottom, and mark it with furrows and striæ indicative
of the direction of their own motion.

When we examine a chart of the American coast, and observe the deep
channel and hollow submarine valleys of the Arctic current, and the
sandbanks which extend parallel to this channel from the great bank
of Newfoundland to Cape Cod, we cannot avoid the conclusion that the
Arctic current and its ice have great power both of excavation and
deposition. On the one hand, deep hollows are cut out where the current
flows over the bottom, and on the other, great banks are heaped up
where the ice thaws and the force of the current is abated. I have
been much struck with the worn and abraded appearance of stones and
dead shells taken up from the banks off the American coast, and am
convinced that an erosive power comparable to that of a river carrying
sand over its bed, and materially aided by the grinding action of ice,
is constantly in action under the waters of the Arctic current.[159]
The unequal pressure resulting from this deposition and abrasion is
not improbably connected with the slight earthquakes experienced in
Eastern America, and also with the slow depression of the coast; and
if we go back to that earliest of all geological periods when the
Laurentian rocks of Sir Wm. Logan, constituting the Labrador coast and
the Laurentide Hills, were alone above water, we may even attribute in
no small degree to the Arctic current of that old time the heaping up
of those thousands of feet of deposits which now constitute the great
range of the Alleghany and Appalachian mountains, and form the breast
bone of the American continent. In those ancient times also large
stones were floated southward, and enter into the composition of very
old conglomerates.

[159] At the time when this was written I had only studied stones
brought up accidentally by fishermen and others from the banks of
Newfoundland and elsewhere. At a later date Murray of the _Challenger_
has given more ample material. He states that the bottom in the
Labrador current, 100 miles from land, was found to be blue mud with
60 per cent, of sand and stones; and mentions a block of syenite
weighing 490 lbs. taken up in 1,340 fathoms, and stones and pebbles
of quartzite, limestone, dolomite, mica schist and serpentine, one
of which was glaciated. This is the modern boulder clay produced by
Greenland glaciers and the field ice of Baffin's Bay and the Labrador
coast.

But such large speculations might soon carry us far from Belle-Isle,
and to bring us back to the American coast and to the domain of common
things, we may note that a vast variety of marine life exists in the
cold waters of the Arctic current, and that this is one of the reasons
of the great and valuable fisheries of Labrador, Newfoundland and Nova
Scotia, regions in which the sea thus becomes the harvest field of much
of the human population. On the Arctic current and its ice also floats
to the southward the game of the sealers of St. John and the whalers of
Gaspé.

We may now proceed to connect these statements as to the distribution
of icebergs, with the glaciated condition of our continents, with the
remarkable fact that the same effects now produced by the ice and
the Arctic current in the Strait of Belle-Isle and the deep-current
channel off the American coast, are visible all over the North American
and European land north of forty degrees of latitude, and that there
is evidence that the St. Lawrence valley itself was once a gigantic
Belle-Isle, in which thousands of bergs worked perhaps for thousands
of years, grinding and striating its rocks, cutting out its deeper
parts, and heaping up in it quantities of northern _débris_. Out of
this fact of the so-called glaciated condition of the surface of our
continents has, however, arisen one of the great controversies of
modern geology. While all admit the action of ice in distributing and
arranging the materials which constitute the last coating which has
been laid upon the surface of our continents, some maintain that land
glaciers have done the work, others, that sea-borne ice has been the
main agent employed. As in some other controversies, the truth seems to
lie between the extremes. Glaciers are slow, inactive, and limited in
their sphere. Floating ice is locomotive and far-travelled, extending
its action to great distances from its sources. So far, the advantages
are in favour of the flotation. But the work which the glacier does is
done thoroughly, and, time and facilities being given, it may be done
over wide areas. Again, the iceberg is the child of the glacier, and
therefore the agency of the one is indirectly that of the other. Thus,
in any view we must plough with both of these geological oxen, and the
controversy becomes like that old one of the Neptunists and Plutonists,
which has been settled by admitting both water and heat to have been
instrumental in the formation of rocks.

In the midst of these controversies a geologist resident in Great
Britain or Canada should have some certain doctrine as to the
question whether at that period, geologically recent, which we call
the Pleistocene period, the land was raised to a great height above
the sea, and covered like Greenland with a mantle of perpetual ice,
or whether it was, like the strait of Belle-Isle and the banks of
Newfoundland, under water, and annually ground over by icebergs,
or whether, as now seems more probable, it was in part composed of
elevated ridges covered with snow and sending down glaciers, and partly
depressed under the level of ice-laden straits and seas.

A great advocate of the glacier theory has said that we cannot
properly appreciate his view without exploring thoroughly the present
glaciers of Greenland and ascertaining their effects. This I have not
had opportunity to do, but I have endeavoured to do the next best thing
by passing as rapidly as possible from the icebergs of Belle-Isle to
the glaciers of Mont Blanc, and by asking the question whether Canada
was in the Pleistocene period like the present Belle-Isle or the
present Mont Blanc, or whether it partook of the character of both? and
taking advantage of these two most salient points in order to elicit a
reply.

Transporting ourselves, then, to the monarch of the Alps, let us
suppose we stand upon the Flegere, a spur of the mountains fronting
Mont Blanc, and commanding a view of the entire group. From this point
the western end of the range presents the rounded summit of Mont Blanc
proper, flanked by the lower eminences of the Dome and Aiguille de
Gouté, which rise from a broad and uneven plateau of _nevé_ or hard
snow, sending down to the plain two great glaciers or streams of ice,
the Bossons and Tacony glaciers. Eastward of Mont Blanc the _nevé_
or snow plateau is penetrated by a series of sharp points of rock or
aiguilles, which stretch along in a row of serried peaks, and then
give place to a deep notch, through which flows the greatest of all
the glaciers of this side of Mont Blanc, the celebrated Mer de Glace,
directly in front of our standpoint. To the left of this is another
mass of aiguilles, culminating in the Aiguille Verte. This second group
of needles descends into the long and narrow Glacier of Argentiere,
and beyond this we see in the distance the Glacier and Aiguille de
Tour. As seen from this point, it is evident that the whole system of
the Mont Blanc glaciers originates in a vast mantle of snow capping
the ridge of the chain, and extending about twenty miles in length,
with a breadth of about five miles. This mass of snow being above the
limits of perpetual frost, would go on increasing from year to year,
except so far as it might be diminished by the fall of avalanches from
its sides, were it not that its plasticity is sufficient to enable the
frozen mass to glide slowly down the valleys, changing in its progress
into an icy stream, which, descending to the plain, melts at its base
and discharges itself in a torrent of white muddy water. The Mont Blanc
chain sends forth about a dozen of large glaciers of this kind, besides
many smaller ones. Crossing the valley of Chamouni, and ascending
the Montanvert to a height of about 6,000 feet, let us look more
particularly at one of these glaciers, the Mer de Glace. It is a long
valley with steep sides, about half a mile wide, and filled with ice,
which presents a general level or slightly inclined surface, traversed
with innumerable transverse cracks or crevasses, penetrating apparently
to the bottom of the glacier, and with slippery sloping edges of moist
ice threatening at every step to plunge the traveller into the depths
below. Still the treacherous surface is daily crossed by parties of
travellers, apparently without any accident. The whole of the ice is
moving steadily along the slope on which it rests, at the rate of eight
to ten inches daily--the rate of motion is less in winter and greater
in summer; and farther down, where the glacier goes by the name of the
Glacier du Bois, and descends a steeper slope, its rapidity is greater;
and at the same time by the opening of immense crevasses its surface
projects in fantastic ridges and pinnacles. The movements and changes
in the ice of these glaciers are in truth very remarkable, and show a
mobility and plasticity which at first sight we should not have been
prepared to expect in a solid like ice.[160] The crevasses become open
or closed, curved upwards or downwards, perpendicular or inclined,
according to the surface upon which the glacier is moving, and the
whole mass is crushed upward or flattens out, its particles evidently
moving on each other with much the same result as would take place in
a mass of thick mud similarly moving. On the surface of the ice there
are a few boulders and many stones, and in places these accumulate in
long irregular bands indicating the lines of junction of the minor ice
streams coming in from above to join the main glacier. At the sides
are two great mounds of rubbish, much higher than the present surface
of the glacier. They are called the lateral moraines, and consist of
boulders, stones, gravel and sand, confusedly intermingled, and for the
most part retaining their sharp angles. This mass of rubbish is moved
downward by the glacier, and with the stones constituting the central
moraine, is discharged at the lower end, accumulating there in the
mass of detritus known as the terminal moraine.

[160] I need scarcely say that I adopt the explanation of glacier
motion given by Forbes. "The fuller consideration of the physical
properties of glacier ice leads essentially to the same conclusions
as those to which Forbes was led forty-one years ago by the study of
the larger phenomena of glacier motion, that is, that the motion is
that of a slightly viscous mass, partly sliding upon its bed, partly
shearing upon itself under the influence of gravity."--Trotter, _Proc.
Royal Society of London_, xxxviii. 107.

Glaciers have been termed rivers of ice; but there is one respect in
which they differ remarkably from rivers. They are broad above and
narrow below, or rather, their width above corresponds to the drainage
area of a river. This is well seen in a map of the Mer de Glace. From
its termination in the Glacier du Bois to the top of the Mer de Glace
proper, a distance of about three and a half miles, its breadth does
not exceed half a mile, but above this point it spreads out into three
great glaciers, the Geant, the Du Chaud, and the Talefre, the aggregate
width of which is six or seven miles. The snow and ice of a large
interior table-land or series of wide valleys are thus emptied into
one narrow ravine, and pour their whole accumulations through the Mer
de Glace. Leaving, however, the many interesting phenomena connected
with the motion of glaciers, and which have been so well interpreted
by Saussure, Agassiz, Forbes, Hopkins, Tyndall, and others, we may
consider their effects on the mountain valleys in which they operate.

1. They carry quantities of _débris_ from the hill tops and mountain
valleys downward into the plains. From every peak, cliff and ridge the
frost and thaw are constantly loosening stones and other matters which
are swept by avalanches to the surface of the glacier, and constitute
lateral moraines. When two or more glaciers unite into one, these
become medial moraines, and at length are spread over and through the
whole mass of the ice. Eventually all this material, including stones
of immense size, as well as fine sand and mud, is deposited in the
terminal moraine, or carried off by the streams.

2. They are mills for grinding and triturating rock. The pieces of rock
in the moraine are, in the course of their movement, crushed against
one another and the sides of the valley, and are cracked and ground
as if in a crushing mill. Further the stones on the surface of the
glacier are ever falling into crevasses, and thus reach the bottom of
the ice, where they are further ground one against another and the
floor of rock. In the movement of the glacier these stones seem in
some cases to come again to the surface, and their remains are finally
discharged in the terminal moraine, which is the waste-heap of this
great mill: The fine material which has been produced, the flour of the
mill, so to speak, becomes diffused in the water which is constantly
flowing from beneath the glacier, and for this reason all the streams
flowing from glaciers are turbid with whitish sand and mud.

The Arve, which drains the glaciers of the north side of Mont Blanc,
carries its burden of mud into the Rhone, which sweeps it, with the
similar material of many other Alpine streams, into the Mediterranean,
to aid in filling up the bottom of that sea, whose blue waters
it discolours for miles from the shore, and to increase its own
ever-enlarging delta, which encroaches on the sea at the rate of about
half a mile per century. The upper waters of the Rhone, laden with
similar material, are filling up the Lake of Geneva; and the great
deposit of "loess" in the alluvial plain of the Rhine, about which Gaul
and German have contended since the dawn of European history, is of
similar origin. The mass of material which has thus been carried off
from the Alps, would suffice to build up a great mountain chain. Thus,
by the action of ice and water--

  "The mountain falling cometh to naught,
   And the rock is removed out of its place."

Many observers who have commented on these facts have taken it for
granted that the mud thus sent off from glaciers, and which is so
much greater in amount than the matter remaining in their moraines,
must be ground from the bottom of the glacier valleys, and hence have
attributed to these glaciers great power of cutting out and deepening
their valleys. But this is evidently an error, just as it would be
an error to suppose the flour of a grist mill ground out of the mill
stones. Glaciers, it is true, groove and striate and polish the rocks
over which they move, and especially those of projecting points and
slight elevations in their beds; but the material which they grind up
is principally derived from the exposed frost-bitten rocks above them,
and the rocky floor under the glacier is merely the nether mill stone
against which those loose stones are crushed. The glaciers, in short,
can scarcely be regarded as cutting agents at all, in so far as the
sides and bottoms of their beds are concerned, and in the valleys which
the old glaciers have abandoned, it is evident that the torrents which
have succeeded them have far greater cutting power.

The glaciers have their periods of advance and of recession. A series
of wet and cool summers causes them to advance and encroach on the
plains, pushing before them their moraines, and even forests and human
habitations. In dry and warm summers they shrink and recede. Such
changes seem to have occurred in bygone times on a gigantic scale. All
the valleys below the present glaciers present traces of former glacier
action. Even the Jura mountains seem at one time to have had glaciers.
Large blocks from the Alps have been carried across the intervening
valley and lodged at great heights, on the slopes of the Jura, leading
the majority of the Swiss and Italian geologists to believe that even
this great valley and the basin of Lake Leman were once filled with
glacier ice. But, unless we can suppose that the Alps were then vastly
higher than at present, this seems scarcely to be physically possible,
and it seems more likely that the conditions were just the reverse
of those supposed, namely, that the low land was submerged, and that
the valley of Lake Leman was a strait like Belle-Isle, traversed by
powerful currents and receiving icebergs from both Jurassic and Alpine
glaciers, and probably from farther north. One or other supposition
is required to account for the appearances, which may be explained on
either view. The European hills may have been higher and colder, and
changes of level elsewhere may have combined with this to give a cold
climate with moisture; or a great submergence may have left the hills
as islands, and may have so reduced the temperature by the influx of
arctic currents and ice, as to enable the Alpine glaciers to descend to
the level of the sea. Now, we have evidence of such submergence in the
beds of sea-shells and travelled boulders scattered over Europe, while
we also have evidence of contemporaneous glaciers, in their traces on
the hills of Wales and Scotland and elsewhere, where they do not now
occur.

I have long maintained that in America all the observed facts imply
a climate no colder than that which would have resulted from the
subsidence which we know to have occurred in the temperate latitudes
in the Pleistocene period, and though I would not desire to speak so
positively about Europe, I confess to a strong impression that the
same is the case there, and that the casing of glacier ice imagined
by many geologists, as well as the various hypotheses which have been
devised to account for it, and to avoid the mechanical, meteorological,
and astronomical difficulties attending it, are alike gratuitous and
chimerical, as not being at all required to account for observed facts,
and being contradictory, when carefully considered, to known physical
laws as well as geological phenomena.[161]

[161] _Canadian Naturalist_, vols. viii. and ix. _Geological Magazine_,
December, 1865.

Carrying with me a knowledge of the phenomena of the glacial drift as
they exist in North America, and of the modern ice drift on its shores,
I was continually asking myself the question To what extent do the
phenomena of glacier drift and erosion resemble these? and standing on
the moraine of the Bosson glacier, which struck me as more like boulder
clay than anything else I saw in the Alps, with the exception of some
recent avalanches, I jotted down what appeared to me to be the most
important points of difference. They stand thus:--

1. Glaciers heap up their _débris_ in abrupt ridges. Floating ice
sometimes does this, but more usually spreads its load in a more or
less uniform sheet.[162]

[162] Under floating ice I include floe, pack, and bordage ice as well
as bergs.

2. The material of moraines is all local. Floating ice carries its
deposits often to great distances from their sources.

3. The stones carried by glaciers are mostly angular, except where they
have been acted on by torrents. Those moved by floating ice are more
often rounded, being acted on by the waves and by the abrading action
of sand drifted by currents.

4. In the marine glacial deposits mud is mixed with stones and
boulders. In the case of land glaciers, most of this mud is carried off
by streams and deposited elsewhere.

5. The deposits from floating ice may contain marine shells. Those
of glaciers cannot, except where, as in Greenland and Spitzbergen,
glaciers push their moraines out into the sea.

6. It is of the nature of glaciers to flow in the deepest ravines they
can find, and such ravines drain the ice of extensive areas of mountain
land. Floating ice, on the contrary, acts with greatest ease on flat
surfaces or slight elevations in the sea bottom.

7. Glaciers must descend slopes and must be backed by large supplies of
perennial snow. Floating ice acts independently, and being water-borne
may work up slopes and on level surfaces.

8. Glaciers striate the sides and bottoms of their ravines very
unequally, acting with great force and effect only on those places
where their weight impinges most heavily. Floating ice, on the
contrary, being carried by constant currents and over comparatively
flat surfaces, must striate and grind more regularly over large areas,
and with less reference to local inequalities of surface.

9. The direction of the striæ and grooves produced by glaciers depends
on the direction of valleys. That of floating ice, on the contrary,
depends upon the direction of marine currents, which is not determined
by the outline of the surface, but is influenced by the large and wide
depressions of the sea bottom.

10. When subsidence of the land is in progress, floating ice may carry
boulders from lower to higher levels. Glaciers cannot do this under any
circumstances, though in their progress they may leave blocks perched
on the tops of peaks and ridges.

I believe that in all these points of difference the boulder clay and
drift on the lower lands of Canada and other parts of North America,
correspond rather with the action of floating ice than of land ice;
though certainly with glaciers on such land as existed at the different
stages of the submergence, and these glaciers drifting stones and
earthy matter in different directions from higher land toward the sea.
More especially is this the case in the character of the striated
surfaces, the bedded distribution of the deposits, the transport of
material up the natural slope, the presence of marine shells, and the
mechanical and chemical characters of the boulder clay. In short, those
who regard the Canadian boulder clay as a glacier deposit, can only do
so by overlooking essential points of difference between it and modern
accumulations of this kind.

I would wish it here to be distinctly understood, that I do not doubt
that at the time of the greatest Pleistocene submergence of Eastern
America, at which time I believe the greater part of the boulder clay
was formed, and the more important striation effected, the higher
hills then standing as islands would be capped with perpetual snow,
and through a great part of the year surrounded with heavy field and
barrier ice, and that in those hills there might be glaciers of greater
or less extent. Further, it should be understood that I regard the
boulder clays of the St. Lawrence valley as of different ages, ranging
from those of the early Pleistocene to that now forming in the Gulf
of St. Lawrence; and that during these periods great changes of level
occurred. Further, that this boulder clay shows in every place where I
have been able to examine it, evidence of subaqueous accumulation, in
the presence of marine shells or in the unweathered state of the rocks
and minerals enclosed in it; conditions which, in my view, preclude
any reference of it to glacier action, except possibly in some cases
to that of glaciers stretching from the land over the margin of the
sea, and forming under water a deposit equivalent in character to the
_bone glaciare_ of the bottom of the Swiss glaciers. But such a deposit
must have been local, and would not be easily distinguishable from
the marine boulder clay. It is of some interest to compare Canadian
deposits with those of Scotland,[163] which in character and relations
so closely resemble those of Canada; but I confess several of the facts
lead me to infer that much of what has been regarded as of subaërial
origin in that country must really be marine, though whether deposited
by icebergs or by the fronts of glaciers terminating in the sea, I do
not pretend to determine.[164] It must, however, be observed that the
antecedent probability of a glaciated condition is much greater in
the case of Scotland than in that of Canada, from the high northern
latitude of the former, its hilly and maritime character, and the fact
that its present exemption from glaciers is due to what may be termed
exceptional and accidental geographical conditions; more especially
to the distribution of the waters of the Gulf Stream, which might be
changed by a comparatively small subsidence in Central America. To
assume the former existence of glaciers in a country in north latitude
56°, and with its highest hills, under the present exceptionally
favourable conditions, snow-capped during most of the year, is a very
different thing from assuming a covering of continental ice over wide
plains more than ten degrees farther south, and in which, even under
very unfavourable geographical accidents, no snow can endure the summer
sun, even in mountains several thousand feet high. Were the plains
of North America submerged and invaded by the cold arctic currents,
the Gulf Stream being at the same time turned into the Pacific, the
temperature of the remaining North American land would be greatly
diminished; but under these circumstances the climate of Scotland
would necessarily be reduced to the same condition with that of South
Greenland or Northern Labrador. As we know such a submergence of
America to have occurred in the Pleistocene period, it does not seem
necessary to have recourse to any other cause for either side of the
Atlantic. It would, however, be a very interesting point to determine,
whether in the Pleistocene period the greatest submergence of America
coincided with the greatest submergence of Europe, or otherwise. It
is quite possible that more accurate information on this point might
remove some present difficulties. I think it much to be desired that
the many able observers now engaged on the Pleistocene of Europe,
would at least keep before their minds the probable effects of the
geographical conditions above referred to, and inquire whether a due
consideration of these would not allow them to dispense altogether with
the somewhat extravagant theories of glaciation now agitated.

[163] _Journal of Geological Society._ Papers by Jamieson, Bryce,
Crosskey, and Geikie.

[164] Geikie, _Trans. Royal Society of Edin._ Geikie assigns a more
complicated structure than appears to be present in Canada; but there
are Canadian equivalents of the principal glacial periods which he
assumes.

The preceding pages give the substance of my conclusions of
twenty-four years ago. I give those of to-day from a paper of
1891,[165] relating to Eastern Canada only:--

[165] Supplement to 4th edition of "Acadian Geology," 1891.

These conclusions have, in my judgment, been confirmed, and their
bearing extended, more especially by the researches of Mr. Chalmers,
who has shown in the most convincing way that glaciers proceeding from
local centres along with sea-borne ice, may have been the agents in
glaciating surfaces and transporting boulders in Nova Scotia and New
Brunswick. Taken in connection with the observations of Dr. Dawson
and Mr. McConnell in the Cordillera region of the west, and those of
Dr. Bell, Dr. Ells, Mr. Low, and others in the Laurentian country
north of the St. Lawrence, and in the Province of Quebec, we may now
be said to know that there was not, even at the height of the glacial
refrigeration of America, a continental ice sheet, but rather several
distinct centres of ice action,--one in the Cordillera of the West,
one on the Laurentian V-shaped axis, and one on the Appalachians, with
subordinate centres on isolated masses like the Adirondacks, and at
certain periods even on minor hills like those of Nova Scotia. It would
further seem that, in the west at least, elevation of the mountain
ridges coincided with depression of the plains. In Newfoundland also,
it would appear from the observations of Captain Kerr, with which those
of Mr. Murray are in harmony,[166] though they have been differently
interpreted, that the gathering ground of ice was in the interior
of the island, and that glaciers moved thence to the coasts, but
principally to the east coast, as was natural from the conformation of
the land and the greater supply of moisture from the Atlantic.

[166] _Trans. Royal Society of Canada_, vol. i.

The labours of Murray in Newfoundland, of Matthew, Chalmers, Bailey,
and others, in Nova Scotia and New Brunswick, have considerably
enlarged our knowledge of Pleistocene fossils, showing, however, that
the marine fauna is the same with that of the beds of like age in the
St. Lawrence valley, and with the existing fauna of the Labrador coast
and colder portions of the Gulf and River St. Lawrence, as ascertained
by Prickard, Whiteaves, and the writer. It would seem that throughout
this region, the 60 feet and the 600 feet terraces were the most
important with reference to these marine remains, and that their chief
repository is in the Upper Leda Clay, a marine deposit intermediate
between the Lower and Upper boulder drift, and corresponding to the
interglacial beds of the interior of America.

The general conditions of the period may be thus summarized:--

In this district, and the eastern part of North America generally, it
is, I think, universally admitted that the later Pliocene period was
one of continental elevation, and probably of temperate climate. The
evidence of this is too well known to require re-statement here. It is
also evident, from the raised beaches holding marine shells, extending
to elevations of 600 feet, and from drift boulders reaching to a far
greater height, that extensive submergence occurred in the middle and
later Pleistocene. This was the age of the beds I have named the _Leda_
clays and _Saxicava_ sands, found at heights of 600 feet above the sea
in the St. Lawrence valley, nearly as far west as Lake Ontario.

It is reasonable to conclude that the till or boulder clay, under
the Leda clay, belongs to the earliest period of probably gradual
subsidence, accompanied with a severe climate, and with snow and
glaciers on all the higher grounds, sending glaciated stones into
the sea. This deduction agrees with the marine shells, polyzoa, and
cirripedes found in the boulder deposits on the lower St. Lawrence,
with the unoxidized character of the mass, which proves subaqueous
deposition, with the fact that it contains soft boulders, which would
have crumbled if exposed to the air, with its limitation to the lower
levels and absence on the hillsides, and with the prevalent direction
of striation and boulder drift from the north-east.[167]

[167] Notes on the Post-Pliocene _Canadian Naturalist_, _op. cit._;
also Paper by the author on Boulder Drift at Metis, _Canadian Record of
Science_, vol. ii., 1886, p. 36, _et seq._

All these indications coincide with the conditions of the modern
boulder drift on the lower St. Lawrence and in the Arctic regions,
where the great belts and ridges of boulders accumulated by the coast
ice would, if the coast were sinking, climb upward and be filled in
with mud, forming a continuous sheet of boulder deposit similar to that
which has accumulated and is accumulating on the shores of Smith's
Sound and elsewhere in the Arctic, and which, like the older boulder
clay, is known to contain both marine shells and driftwood.[168]

[168] For references see "Royal Society's Arctic Manual," London, 1875,
_op. cit._

The conditions of the deposit of "till" diminished in intensity as
the subsidence continued. The gathering ground of local glaciers was
lessened, the ice was no longer limited to narrow sounds, but had a
wider scope, as well as a freer drift to the southward, and the climate
seems to have been improved. The clays deposited had few boulders and
many marine shells, and to the west and north there were land-producing
plants akin to those of the temperate regions; and in places only
slightly elevated above the water, peaty deposits accumulated. The
shells of the Leda clay indicate depths of less than 100 fathoms.
The numerous Foraminifera, so far as have been observed, belong to
this range, and I have never seen in this clay the assemblage of
foraminiferal forms now dredged from 200 to 300 fathoms in the Gulf of
St. Lawrence.

I infer that the subsidence of the Leda clay period and of the
interglacial beds of Ontario belongs to the time of the sea beaches
from 450 to 600 feet in height, which are so marked and extensive as
to indicate a period of repose. In this period there were marine
conditions in the lower and middle St. Lawrence and in the Ottawa
valley, and swamps and lakes on the upper Ottawa and the western end
of Lake Ontario. It is quite probable, nay, certain, that during this
interglacial period re-elevation had set in, since the upper Leda
clay and the Saxicava sand indicate shallowing water, and during this
re-elevation the plant-covered surface would extend to lower levels.

This, however, must have been followed by a second subsidence, since
the water-worn gravels and loose, far-travelled boulders of the later
drift rose to heights never reached by the till or the Leda clay, and
attained to the tops of the highest hills of the St. Lawrence valley,
1,200 feet in height, and elsewhere to still greater elevations. This
second boulder drift must have been wholly marine, and probably not
of long duration. It shows no evidence of colder climate than that
now prevalent, nor of extensive glaciers on the mountains; and it was
followed by a paroxysmal elevation in successive stages till the land
attained even more than its present height, as subsidence is known to
have been proceeding in modern times.

I am quite aware that the above sequence and the causes assumed are
somewhat different from those held by many geologists with reference to
regions south of Canada; but must hold that they are the only rational
conclusions which can be propounded with reference to the facts
observed from the parallel of 45° to the Arctic Ocean.

My own observations have been chiefly in the eastern part of North
America. My son, Dr. G. M. Dawson, has much more ably and thoroughly
explored those of the west; and after describing the immense
Cordilleran ice mass which extended for a length of 1,200 miles along
the mountains of British Columbia and discharged large glaciers to the
north, as well as to the west and south, and stating his reasons for
believing in that differential elevation and depression which caused
the greatest height of the mountains to coincide with the greatest
depression of the plains, and _vice versâ_, and showing the Cordilleran
glacier must have been separated by a water area from that of the
Laurentide hills on the east, thus concludes:--

"It is now distinctly known, as the result of work done under the
auspices of the Geological Survey of Canada, and more particularly
of observations by the writer and his colleagues, Messrs. McConnell
and Tyrrell, that the extreme margins of the western and eastern
glaciated areas of the continent barely overlap, and then only to a
very limited extent, while the two great centres of dispersion were
entirely distinct. For numerous reasons which cannot be here entered
into, the writer does not consider it probable, or even possible,
that the great confluent glacier of the north-eastern part of the
continent extended at any time far into the area of the great plains;
but erratics and drift derived from this ice mass did so extend,
and are found between the 49th and 50th parallels, stranded on the
surface of moraines produced by the large local glaciers of the Rocky
Mountains. Recognising, however, the essential separateness of the
western and eastern confluent ice masses, and the fact that it is no
longer appropriate to designate one of these the "continental glacier,"
the writer ventures to propose that the eastern _mer de glace_ may
appropriately be named the great _Laurentide glacier_, while its
western fellow is known as the "_Cordilleran glacier_." It may be
added that there is good evidence to show that both the Laurentide and
Cordilleran glaciers discharged into open water to the north."

These conclusions, based on a large induction of facts applying to a
very large area of the North American Continent, coincide with my own
observations in the east, and with the inferences deducible from the
present condition of Greenland and Arctic America.

When extreme glacialists point to Greenland and ask us to believe
that in the Glacial age the whole continent of North America, as far
south as the latitude of 40°, was covered with a continuous glacier,
having a wide front, and thousands of feet thick, we may well ask,
first, what evidence there is that Greenland or even the Antarctic
continent is at present in such a condition; and, secondly, whether
there exists a possibility that the interior of a great continent could
ever receive so large an amount of precipitation as that required. So
far as present knowledge exists, it is certain that the meteorologist
and the physicist must answer both questions in the negative. In
short, perpetual snow and glaciers must be local, and cannot be
continental, because of the vast amount of evaporation and condensation
required. These can only be possible where comparatively Warm seas
supply moisture to cold and elevated land, and this supply cannot, in
the nature of things, penetrate far inland. The actual condition of
interior Asia and interior America in the higher northern latitudes
affords positive proof of this. In a state of partial submergence
of our northern continents, we can readily imagine glaciation by
the combined action of local glaciers and great ice floes; but in
whatever way the phenomena of the boulder clay and of the so-called
"terminal moraines" are to be accounted for, the theory of a continuous
continental glacier must be given up.

The great interior plain of western Canada, between the Laurentian
axis on the east and the Rocky Mountains on the west, is seven hundred
miles in breadth, and is covered with glacial drift, presenting one
of the greatest examples of this deposit in the world. Proceeding
eastward from the base of the Rocky Mountains, the surface, at first
more than 4,000 feet above the sea level, descends by successive steps
to 2,500 feet, and is based on Cretaceous and Laramie rocks, covered
with boulder clay and sand, in some places from one hundred to two
hundred feet in depth, and filling up pre-existing hollows, though
itself sometimes piled into ridges. Near the Rocky Mountains the
bottom of the drift consists of gravel not glaciated. This extends
to about one hundred miles east of the mountains, and must have been
swept by water out of their valleys. The boulder clay resting on this
deposit is largely made up of local _débris_, in so far as its paste
is concerned. It contains many glaciated boulders and stones from
the Laurentian region to the east, and also smaller pebbles from the
Rocky Mountains, so that at the time of its formation there must have
been driftage of large stones for seven hundred miles or more from
the east, and of smaller stones from a less distance on the west. The
former kind of material extends to the base of the mountains, and to a
height of more than 4,000 feet. One boulder is mentioned as being 42 ×
40 × 20 feet in dimensions. The highest Laurentian boulders seen were
at an elevation of 4,660 feet on the base of the Rocky Mountains. The
boulder clay, when thick, can be seen to be rudely stratified, and at
one place includes beds of laminated clay with compressed peat, similar
to the forest beds described by Worthen and Andrews in Illinois, and
the so-called interglacial beds described by Hinde on Lake Ontario.
The leaf beds on the Ottawa river, and the drift trunks found in the
boulder clay of Manitoba, belong to the same category, and indicate in
the midst of the Glacial period many forest oases far to the north,
having a temperate rather than an arctic flora. In the valleys of
the Rocky Mountains opening on these plains there are evidences of
large local glaciers now extinct, and similar evidences exist on the
Laurentian highlands on the east. A recent paper of Dr. G. M. Dawson on
the Palæography of the Rocky Mountains illustrates in a most convincing
manner the changes which have occurred in the Cordillera of North
America, and the differential elevation and depression which have
affected its climate in the later geological periods.[169]

[169] _Transactions Royal Society of Canada_, 1890.

Perhaps the most remarkable feature of the western drift region is
that immense series of ridges of drift piled against an escarpment of
Laramie and Cretaceous rocks, at an elevation of about 2,500 feet, and
known as the "Missouri Coteau." It is in some places 30 miles broad
and 180 feet in height above the plain at its foot, and extends north
and south for a great distance: being, in fact, the northern extension
of those great ridges of drift which have been traced south of the
great lakes, and through Pennsylvania and New Jersey, and which figure
on the geological maps as the edge of the continental glacier--an
explanation obviously inapplicable in those western regions where
they attain their greatest development. It is plain that in the north
it marks the western limit of the deep-water of a glacial sea, which
at some periods extended much farther west, perhaps with a greater
proportionate depression in going westward, and on which heavy ice from
the Laurentian districts on the east was wafted south-westward by the
arctic currents, while lighter ice from the Rocky Mountains was being
borne eastward from these mountains by the prevailing westerly winds.
We thus have in the west, on a very wide scale, the same phenomena of
varying submergence, cold currents, great ice floes and local glaciers
producing icebergs, to which I have attributed the boulder clay and
upper boulder drift of eastern Canada. In short, we arrive at the
conclusion that there never has been a continental glacier, properly so
called, but that in the extreme Glacial period there have been great
centres of snow and glacial action, in the Cordillera of the west, in
the Laurentian plateau of the north, and in the northern Appalachians,
and the Adirondacks, while the lower lands have been either submerged,
or enjoying a climate habitable by hardy animals and plants.

The till or boulder clay has been called a "ground moraine," but there
are really no Alpine moraines at all corresponding to it. On the other
hand, it is more or less stratified, often rests on soft materials
which glaciers would have swept away, sometimes contains marine
shells, or passes into marine clays in its horizontal extension, and
invariably in its embedded boulders and its paste, shows an unoxidized
condition, which could not have existed if it had been a subaërial
deposit. When the Canadian till is excavated and exposed to the air, it
assumes a brown colour, owing to oxidation of its iron, and many of its
stones and boulders break up and disintegrate under the action of air
and frost. These are unequivocal signs of a subaqueous deposit. Here
and there we find associated with it, and especially near the bottom
and at the top, indications of powerful water action, as if of land
torrents acting at particular elevations of the land, or heavy surf
and ice action on coasts, and the attempts to explain these by glacial
streams have been far from successful. A singular objection sometimes
raised against the subaqueous origin of the till is its general want
of marine remains; but this is by no means universal, and it is well
known that coarse conglomerates of all ages are generally destitute of
fossils, except in their pebbles, and it is further to be observed that
the conditions of an ice-laden sea are not those most favourable for
the extension of marine life, and that the period of time covered by
the glacial age must have been short, compared with that represented by
some of the older formations.

It follows from all this that the great "continental moraine," which
the United States Geological Survey has now "delineated for several
thousand miles extending from the Atlantic to the Pacific," cannot be
a glacier moraine, but must be, like its great continuation northward,
the Missouri coteau, a margin of sea drift, and that we must explain
the whole of the drift of the American continent by the supposition,
first, of a period of elevation of the hills and subsidence of the
valleys in which there were great accumulations of snow on the Western
Cordillera; the Laurentian axis, and the Appalachians and Adirondacks
radiating in every direction from these points, while minor areas of
radiation may have temporarily existed on smaller elevations: that
this was followed by a period of more equal level, in which parts of
the low grounds were clothed with a temperate flora, the "Interglacial
period" so called, succeeded by a second great depression, in which the
high level boulders of the second boulder drift were wafted to great
distances by floating ice.

The late Prof. Alexander Winchell, a man who did not hesitate to
express his convictions, thus bears similar testimony:--"There has been
no continental glacier. There has been no uniform southerly movement of
glacier masses. There has been no persistent declivity as a _sine qua
non_, down which glacier movements have taken place. The continuity of
the supposed continental glacier was interrupted in the regions of the
dry and treeless plains of the west; and in the interior and Pacific
belts of the continent within the United States, ancient glaciation was
restricted to the elevated slopes."[170] He might have added that the
St. Lawrence valley was submerged and received the ends of Appalachian
and Adirondack glaciers on the south-east, and those of Laurentide
glaciers on the north-west.

[170] Nov., 1890.

My friend Prof. Claypole, who, however, has some hesitation, fearing,
I presume, to be cast out of the synagogue for heresy, ventures to
say,[171] "We deduce from the facts and arguments stated above, that
all the observations of glacial action in the northern hemisphere are
explicable by assuming the existence of enormous and confluent[172]
glacier-systems in and about the high lands of Europe, Asia, and
America, which high lands became, therefore, glacial radiants, and shed
their load of ice in all directions over the lower adjacent ground,
along the lines of easiest flow; that this theory does no violence
to the analogy of the existing order of things, requiring merely
an enlargement of actual glaciers by the intensification of actual
conditions : that abundant evidence can be obtained, as, for example,
from Switzerland, that the present glacier system of the earth was
once of sufficient magnitude to produce all the observed phenomena;
that the most important glacial radiants in the northern hemisphere
were, in North America, the district round Hudson Bay, New England
and the Adirondacks, with certain areas in the western Cordilleras,
and in Europe the Norwegian Dovrefelds and the Alps, Asia apparently
possessing none of commensurate importance; that it satisfactorily
explains, also, the previously puzzling absence of glacial action
over the great plain of Siberia, the coldest portion of the northern
temperate zone; that the belief in a vast polar ice cap, thousands of
feet thick, covering the whole Arctic region, and extending almost
continuously down to low latitudes, is an assumption doing violence to
observed physical facts and to probability, that it is not required to
account for the phenomena, and is, in fact, contradictory to some of
them."

[171] _American Geologist_, Feb., 1889.

[172] The term "confluent" is not necessary here. The glaciers of all
mountain chains may be said to be more or less confluent in the nevé,
from which individual glaciers radiate.

In Europe there is equally good evidence of the existence of huge
glaciers on the Scandinavian mountains and the Alps, and of lesser
accumulations of ice on the hills, as, for instance, those of the
British Islands; but the Scandinavian boulders scattered over the
plains of Great Britain must have been water-borne.[173]

[173] The reports of the Scottish boulder committee, and Lapworth's
recent careful examination of the deposits on the East of England
(_Journ. Geol. Soc._, Aug., 1891), strongly confirm me in this opinion.

In connection with these extracts I would observe that the writer,
and those with whom he has acted in this matter, have never held that
icebergs alone, or fields of ice alone, have produced the Pleistocene
deposits. Their contention has been that the period was one in which
glaciers, icebergs, and field ice acted together, and along with
aqueous agencies, in producing the complicated formations of this
remarkable age. They have, however, objected strenuously to the sole
employment of one agent to the exclusion of others, and to attributing
to that agent powers and extension which obviously could not belong to
it, under the known laws which regulate the movement of glaciers by
the force of gravity, and the precipitation of moisture in the form
of snow on mountains and plateaus. These laws show that the movement
of glaciers over level surfaces, or against the slope of the ground,
and their moving stones otherwise than down slopes, are physical
impossibilities, and that the accumulation of snow to form glaciers
can take place only on elevated and cold land, supplied with large
quantities of vapour from neighbouring water. Such accumulation can
under no imaginable conditions take place in the interior plains and
table lands of great continents.

Applying these laws and conclusions to the whole northern hemisphere,
we learn that the conditions to produce a glacial period are the
diversion of the warm currents from the northern seas, the submergence
of land in the temperate regions, and its invasion by cold Arctic
water, and great condensation of snow on the higher lands. Whether this
condensation has a tendency finally to rectify the state of affairs, by
pressing down the mountains and elevating the plains, we do not know,
but I should imagine that it has not; for the high lands will, in the
case supposed, be lightened by denudation, while the plains will be
burdened with a great weight of deposit. Perhaps we should rather look
to this as the agency for depressing and submerging the plains and
elevating the hills, and suppose some other and more general pressure
proceeding from the great sea basins, to effect the re-elevation of the
plains.

These questions suggest that of the date of the Glacial period. This
subject has recently been discussed by Prestwich and others, with
the result that there is no purely geological ground for referring
the Glacial age to a period so remote as that advocated by Croll on
astronomical grounds. Claypole has recently discussed the matter at
some length, and in a temperate spirit.[174] He takes the rate of
erosion of the Niagara gorge as a measure, and shows that the Falls
of St. Anthony, as described by Winchell, and all the other falls
and river gorges in North America, give similar estimates, which are
confirmed by the evidences of lake ridges, of the rate of erosion,
and of the conditions of animal and plant life. The whole go to show
that the culmination of the Glacial age may have occurred less than
10,000 years ago. He further shows that the differential elevation of
Lakes Erie and Ontario, the greater ease with which the river could
cut the lower part of its ravine, the probability that the part of the
gorge between the whirlpool and the fall was not cut, but only cleaned
out in modern times, and the possible greater flow of water in the
early modern period, all tend to shorten the time required, and that,
as Prestwich has inferred from other data, and the writer also in
various papers, some of them of old date, the so-called post-glacial
period, that of the melting away of the ice, may come within 8,000 to
10,000 years of our own time. Probably the first of these figures is
the nearest to the truth,[175] so that, geologically considered, the
Glacial age is very recent.

[174] _Trans. Edinburgh Geol. Soc._, vol. v., 1888.

[175] Upham, one of the ablest and most experienced of the Glacial
geologists in the United States, in a recent paper on the causes of the
glacial period, states similar conclusions, and adduces the evidence of
Gilbert, Andrews, Wright, Emerson and others in the same sense.

Still another question of great cosmic interest relates to the possible
alternation of glacial conditions in the northern and southern
hemispheres. There is evidence of drift in the southern part of South
America, similar to that in the north; but was it deposited at the same
time? If we could be sure that it was not, many difficulties would be
removed. The southern hemisphere is at present emphatically the ocean
hemisphere; the northern, the land hemisphere. Perhaps these conditions
may be capable of being reversed, in which case the periods of
depression in the south may have corresponded with those of elevation
in the north. One thing which we know is, that there is a polar ice
ring, not an ice cap, for we do not know what is within its edges at
the South Pole, about 2,000 miles in diameter, and this in the only
circumstances in which it can exist, namely, surrounded by a vast ocean
furnishing it with abundant aqueous vapour. We also know that from this
ice ring radiate glaciers, carrying _débris_, with which the sea bottom
is strown half way to the equator. If continents were elevated out of
the Southern Ocean, we should probably have on their surfaces glacial
deposits more widespread and continuous than any remaining on the
continents of the northern hemisphere, and like some of them thinning
out to a terminal edge or border, instead of a terminal moraine like
that of a glacier.[176] Thus we may say with some truth that the
southern hemisphere is now passing through one phase of the Glacial
period.

[176] This is now admitted by Chamberlain and others to be the case
with the oldest boulder clay on the American continent.

I have often thought that in the southern hemisphere the condition
of Kerguelen Island and Heard Island, as described in the reports of
the _Challenger_,[177] must very nearly represent the state of some
mountain ranges and peaks in North America in the Glacial age. Heard
Island, in S. latitude 53° 2′, is a mountain peak 6,000 feet high,
and 25 miles in length. It sends down large glaciers to the sea. In
its larger neighbour, Kerguelen, the glaciers do not reach the sea;
but there is evidence that at one time they did. It is still more
curious that, in Kerguelen the modern ice overlies late tertiary
deposits, holding remains of large trees, indicating a more continental
condition and mild climate at no very remote period. The glaciers of
Heard Island and Kerguelen have, no doubt, been carrying down moraine
material into the sea, and this is certainly done on a still greater
scale by those of the Antarctic continent. This sends off bergs which
fill the whole ocean south of 60°, and float much farther north. Some
of them have been seen 2,000 feet long and 200 high, and though most
of the boulders they contain are necessarily concealed, yet masses of
rock, supposed to weigh many tons, have been seen on them. The whole
sea bottom off this continent, as far south as 64°, consists of blue
mud, with boulders and pebbles, some of them glaciated, and farther
north there is, as far as 47 degrees of latitude, a considerable
percentage of drift material, and this sometimes in depths of 1,950
fathoms. It is evident that, if large areas of the southern hemisphere
were elevated into land, we should have phenomena to deal with not much
unlike those of North America at present.

[177] Vol. i. p. 370, etc.

Perhaps no discussion carries with it more of warning to geologists
to exercise caution in framing theories than this of the great ice
age; and if the collapse of extreme views on this subject shall
have the effect of inducing geologists to keep within the limits of
well-ascertained facts and sound induction, to adhere to the Lyellian
doctrine of modern causes to explain ancient phenomena, and to bear
in mind that most great effects involve not one cause, but many
co-operating causes, it may lead to consequences beneficial to science;
and so, emerging from the cold shadows of the continental glacier, we
may find ourselves in the sunshine of truth.

  References:--"Acadian Geology," 1st ed., 1855; 4th ed., 1892.
    Icebergs of Belle-Isle, and Glaciers of Mont Blanc, _Canadian
    Naturalist_, 1865. "Notes on Pleistocene of Canada," Montreal,
    1871. Papers at various dates in the _Canadian Naturalist_ and
    _Canadian Record of Science_. "The Ice Age in Canada," Montreal,
    1893. Canadian Pleistocene, _London Geological Magazine_, March,
    1883. Flora of the Pleistocene, _Bulletin of Geological Society of
    America_, vol. i., 1890, p. 311, Dawson and Penhallow.




                     _CAUSES OF CLIMATAL CHANGE._


                             DEDICATED TO

                      DR. T. STERRY HUNT, F.R.S.,

                             Whose Work in

            the Chemical and Cosmical Relations of Geology

                         is beyond all Praise,

                      and is destined to command

                             in the Future

               even greater Acceptance than in the Past.


Various Theories as to Changes of Climate--The Astronomical Theory
of Croll--The Geographical Theory of Lyell--Objections of a Geological
Character to the Former--Testimony of Geology and Physical Geography in
Favour of the Latter

[Illustration: North America in Periods of Warm and Cold Submergence.
(_A_) Early Cretaceous. (_B_) Glacial or Pleistocene. Shaded portion
land. Unshaded portion.--Snow-clad mountains.--Crosses.--Ice-laden sea.
These maps illustrate the probable geographical conditions of warm and
cold periods. (p. 388.)]




CHAPTER XIV.

_CAUSES OF CLIMATAL CHANGE._


The subject of this chapter is one which has been in dispute ever since
I began to read anything on geology, nearly sixty years ago. It ought
to have been settled, but up to to-day one finds in geological works
and papers--especially those relating to the Glacial age--the most
divergent views; and in the writings of men not geologists, it is not
unusual to find exploded theories gravely stated as established facts
of science. The subject is one which I cannot hope to make interesting,
but if the reader will wade through a short chapter, he will be able
to find some of the data on which statements on this subject in other
papers of this series are based.

Mr. Searles V. Wood, in an able summary of the possible causes of
the succession of cold and warm climates in the northern hemisphere,
enumerates no fewer than seven theories which have met with more or
less acceptance, and he might have added an eighth. These are:--

(1) The gradual cooling of the earth from a condition of original
incandescence.

(2) Changes in the obliquity of the ecliptic.

(3) Changes in the position of the earth's axis of rotation.

(4) The effect of the precession of the equinoxes, along with changes
of the eccentricity of the earth's orbit.

(5) Variations in the amount of heat given off by the sun.

(6) Differences in the temperature of portions of space passed through
by the earth.

(7) Differences in the distribution of land and water in connection
with the flow of oceanic currents.

(8) Variations in the properties of the atmosphere with reference to
its capacity for allowing the radiation of heat.

Something may be said in favour of all these alleged causes; but as
efficient in any important degree in producing the cold and warm
climates of the Tertiary period, the greater number of them may be
dismissed as incapable of effecting such results, or as altogether
uncertain with reference to the fact of their own occurrence.

(1) That the earth and the sun have diminished in heat during
geological time seems probable; but physical and geological facts
alike render it certain that this influence could have produced no
appreciable effect, even in the times of the earliest animals and
plants, and certainly not in the case of Tertiary floras or faunas.

(2) The obliquity of the ecliptic is not believed by astronomers to
have changed to any great degree, and its effect would be merely a
somewhat different distribution of heat in different periods of the
year.

(3) Independently of astronomical objections, there is good geological
evidence that the poles of the earth must have been nearly in their
present places from the dawn of life until now. From the Laurentian
upward, those organic limestones which mark the areas where warm and
shallow equatorial water was spreading over submerged continents, are
so disposed as to prove the permanence of the poles. In like manner
all the great foldings of the crust of the earth have followed lines
which are parts of great circles tangent to the existing polar circles.
So, also, from the Cambrian age the great drift of sediment from the
north has followed the line of the existing Arctic currents from the
north-east to the south-west, throwing itself, for example, along the
line of the Appalachian uplifts in Eastern America, and against the
ridge of the Cordilleras in the west.

(4) The effects of change of eccentricity and precession have been
so ably urged by Croll, and recently by Ball, and have so strongly
influenced the minds of those who are not working geologists, that they
deserve a more detailed notice.

(5) The heat of the sun is known to be variable, and the eleven years'
period of sun spots has recently attracted much attention as producing
appreciable effects on the seasons. There may possibly be longer cycles
of solar energy; or the sun may be liable, like some variable stars, to
paroxysms of increased energy. Such changes are possible, but we have
no evidence of their occurrence, and they could not account for periods
of refrigeration of limited duration like the Glacial age.

(6) It has been supposed that the earth may have at different times
traversed more or less heated zones of space, giving alternations of
warm and cold temperature. No such differences in space are, however,
known, nor does there seem any good ground for imagining their
existence.

(7) The differences in the form and elevation of our continents, and
in the consequent distribution of surfaces of different absorbent and
radiating power, and of the oceanic currents, are known causes of
climatal change, and have been referred to in these papers as competent
to account for many, at least, of the phenomena.

(8) Reference has already been made, in connection with the
distribution of plants, to the possibility that the primeval atmosphere
was richer in carbon than that of more modern times, and that this
might operate to produce diminution of radiation, and consequent
uniformity of temperature; but this cause could not have been efficient
in the later geological periods.

There may thus be said to remain two theories of those enumerated
by Wood, to which more detailed consideration may be given, namely,
numbers four and seven, which may be named respectively those of Croll
and Lyell, or the astronomical and geographical theories.

The late Mr. Croll has, in his valuable work "Climate and Time," and
in various memoirs, brought forward an ingenious astronomical theory
to account for changes of climate. This theory, as stated by himself,
is that when the eccentricity of the earth's orbit is at a high value,
and the northern winter solstice is in perihelion, agencies are
brought into operation which make the south-east trade winds stronger
than the north-east, and compel them to blow over upon the northern
hemisphere as far as the Tropic of Cancer. The result is that all the
great equatorial currents of the ocean are impelled into the northern
hemisphere, which thus, in consequence of the immense accumulation of
warm water, has its temperature raised, so that ice and snow must, to a
great extent, disappear from the Arctic regions. In the prevalence of
the converse conditions the Arctic zone becomes clad in ice, and the
southern has its temperature raised.

At the same time, according to Croll's calculations, the accumulation
of ice on either pole would tend, by shifting the earth's centre of
gravity, to raise the level of the ocean and submerge the land on the
colder hemisphere. Thus a submergence of land would coincide with a
cold condition, and emergence with increasing warmth. Facts already
referred to, however, show that this has not always been the case, but
that in many cases submergence was accompanied with the influx of warm
equatorial waters and a raised temperature, this apparently depending
on the question of local distribution of land and water; and this, in
its turn, being regulated not always by mere shifting of the centre
of gravity, but by foldings occasioned by contraction, by equatorial
subsidences resulting from the retardation of the earth's rotation, and
by the excess of material abstracted by ice and frost from the Arctic
regions, and drifted southward along the lines of arctic currents. This
drifting must in all geological times have greatly exceeded, as it
certainly does at present, the denudation caused by atmospheric action
at the equator, and must have tended to increase the disposition to
equatorial collapse occasioned by retardation of rotation.[178]

[178] Croll, in "Climate and Time," and in a note read before the
British Association in 1876, takes an opposite view; but this is
clearly contrary to the facts of sedimentation, which show a steady
movement of _débris_ toward the south and south-west.

While such considerations as those above referred to tend to reduce
the practical importance of Mr. Croll's theory, on the other hand they
tend to remove one of the greatest objections against it--namely,
that founded on the necessity of supposing that glacial periods recur
with astronomical regularity in geological time. They cannot do so if
dependent on other causes inherent in the earth itself, and producing
important movements of its crust.

Sir Robert Ball has in a recent work very ingeniously improved this
theory by showing that Croll was mistaken in assigning equal amounts
of heat to the earth, as a whole, in the periods of greater and less
eccentricity. This would tend to augment the effect of astronomical
revolutions as causes of difference of temperature; but has no bearing
on the more serious geological objections to the theory in question.

A fatal objection, however, to Croll's theory, the force of which has
been greatly increased by recent discoveries, is that the astronomical
causes which he adduces would place the close of the last Glacial
period at least 80,000 years ago, whereas it is now certainly known
from geological facts that the close of the last Glacial period cannot
be older than about an eighth or a tenth of that time. This difficulty
seems to have caused the greater number of geologists, specially
acquainted with the later geological periods, to regard this theory as
quite inapplicable to the facts.

We are thus obliged to fall back upon the old Lyellian theory of
geographical changes, with such modifications as recent discoveries
have rendered necessary. Taking this as our guide, we reach at once the
important conclusion that the movements and distribution of animals
and plants, however dependent on climate, altitude and depth, have,
when regarded in connection with geological time, been primarily
determined by those great movements of the crust of the earth which
have established our islands, continents and ocean depths. These
geographical changes have also in connection with animal and vegetable
growth, deposition of sediments and volcanic ejections, fixed even the
stations, soils and exposures of plants and animals. Thus, subject to
those great astronomical laws which regulate the temperature of our
planet as a whole, our attention may be restricted to the factors of
physical geography itself. We must, however, carry with us the idea
that though the great continents and the ocean depths may have been
fixed throughout geological time, their relative elevations, and
consequently their limits, have varied to a great extent, and are
constantly changing.

We must also remember that something more than mere cold is necessary
to produce a glacial period. It has sometimes been assumed that the
tendency of an exceptionally cold winter would necessarily be to
accumulate so great a quantity of snow and ice, that these could
not be removed in the short though warm summer, and so would go on
accumulating from year to year. Actual experience and observation do
not confirm this supposition. In those parts of North America which
have a long and severe winter, the amount of snow deposited is not in
proportion to the lowness of the temperature, but, on the contrary, the
greatest precipitation of snow takes place near the southern margin
of a cold area, and the snow disappears with great rapidity when
the spring warmth sets in. Nor is there, as has been imagined, any
tendency to the production of fogs and mists which have been invoked
as agencies to shield the snow from the sun. In North America the
melting snow is ordinarily carried off as liquid water, or as invisible
vapour, and the sky is usually clear when the snow is melting in
spring. It is only when warm and moist winds are exceptionally thrown
upon the snow-covered land that clouds are produced; and when this is
the case, the warm rain that ensues promotes the melting of the snow.
Thus there is no possibility of continued accumulations of snow on
the lower parts of our continents, under any imaginable conditions of
climate. It is only on elevated lands in high latitudes and near the
ocean, like Greenland and the Antarctic continent, that such permanent
snow-clad conditions can occur, except on mountain tops. Wallace and
Wœickoff[179] very properly maintain, in connection with these facts,
that permanent ice and snow cannot under any ordinary circumstances
exist in low lands, and that high land and great precipitation are
necessary conditions of glaciers. The former, however, attaches rather
too much importance to snow and ice as cooling agents; for though it is
true that they absorb a large amount of heat in passing from the solid
to the liquid state, yet the quantity of snow or ice to be melted in
spring is so small in comparison with the vast and continuous pouring
of solar heat on the surface, that a very short time suffices for the
liquefaction of a deep covering of snow. The testimony of Siberian
travellers proves this, and the same fact is a matter of ordinary
observation in North America.

[179] Von Wœickoff has very strongly put these principles in a Review
of Croll's recent book, "Climate and Cosmology"; _American Journal of
Science_, March, 1886.

Setting aside, then, these assumptions, which proceed from incorrect or
insufficient information, we may now refer to a consideration of the
utmost importance, and which Mr. Croll himself, though he adduces it
only in aid of the astronomical theory of glacial periods, has treated
in so masterly a manner, as really to give it the first place as an
efficient cause. This is the varying distribution of ocean currents,
in connection with the differences in the elevation and distribution
of land. The great equatorial current, produced by the action of the
solar heat on the atmosphere and the water, along with the earth's
rotation, is thrown, by opposing continental shores, northward into
the Atlantic and Pacific in the Gulf Stream and Japan current, giving
us a hot-water apparatus which effectually raises the temperature of
the whole northern hemisphere, and especially of the western sides of
the continents. Mr. Croll imagined that if his astronomical causes
could, to ever so small an extent, intensify the action of these
currents, or their determination to the north, we should have a period
of warmth, while a similar advantage given to the southern hemisphere
would produce a glacial age in the north. But this requires us to
assume what ought to be proved; namely, that the position of aphelion,
and the increase or decrease of eccentricity, would actually so swing
the equatorial current to the north or south. It further requires us
to assume--and this is the most important defect of the theory--that
no change occurs in the distribution of land and water; because
any important change of this kind might obviously exert a dominant
influence on the currents. Let us take two examples in illustration of
this.

At the present time the warm water thrown into the North Atlantic,
co-operating with the prevalent westerly winds, not only increases
the temperature of its whole waters, but gives an exceptionally mild
climate to western Europe. Still the countervailing influence of the
Arctic currents and the Greenland ice, is sufficient to permit numerous
icebergs to remain unmelted on the coast of Labrador and Newfoundland
throughout the summer. Some of the bergs which creep down to the mouth
of the Strait of Belle-Isle, in the latitude of the south of England,
actually remain unmelted till the snows of a succeeding winter fall
upon them. Now let us suppose that a subsidence of land in tropical
America were to allow the equatorial current to pass through into the
Pacific. The effect would at once be to reduce the temperature of
Norway and Britain to that of Greenland and Labrador at present, while
the latter countries would themselves become colder. The northern
ice, drifting down into the Atlantic, would not, as now, be melted
rapidly by the warm water which it meets in the Gulf Stream. Much
larger quantities of it would remain undissolved in summer, and thus
an accumulation of permanent ice would take place, along the American
coast at first, but probably at length even on the European side.
This would still further chill the atmosphere, glaciers would be
established on all the mountains of temperate Europe and America, the
summer would be kept cold by melting ice and snow, and at length all
eastern America and Europe might become uninhabitable, except by Arctic
animals and plants, as far south as perhaps 40° of north latitude. This
would be simply a return of the glacial age. I have assumed only one
geographical change; but other and more complex changes of subsidence
and elevation might take place, with effects on climate still more
decisive.[180]

[180] According to Bonney, the west coast of Wales is about 12° above
the average for its latitude, and if reduced to 12° below the average,
its mountains would have large glaciers. So near is England even now to
a glacial age.

We may suppose an opposite case. The high plateau of Greenland might
subside, or be reduced in height, and the opening of Baffin's Bay might
be closed. At the same time the interior plain of America might be
depressed, so that, as we know to have been the case in the Cretaceous
period, the warm waters of the Mexican gulf might circulate as far
north as the basins of the present great American lakes. In these
circumstances there would be an immense diminution of the sources
of floating ice, and a correspondingly vast increase in the surface
of warm water. The effects would be to enable a temperate flora to
subsist in Greenland, and to bring all the present temperate regions of
Europe and America into a condition of subtropical verdure.

It is only necessary to add that we actually know that changes
not dissimilar from those above sketched have really occurred in
comparatively recent geological times, to enable us to perceive that
we can dispense with all other causes of change of climate, though
admitting that some of them may have occupied a secondary place. This
will give us, in dealing with the distribution of life, the great
advantage of not being tied up to definite astronomical cycles of
glaciation, which do not well agree with the geological facts, and
of correlating elevation and subsidence of the land with changes of
climate affecting living beings. It will, however, be necessary, as
Wallace well insists, that we shall hold to a certain fixity of the
continents in their position, notwithstanding the submergences and
emergences which they have experienced.

Sir Charles Lyell, more than forty years ago, published in his
"Principles of Geology" two imaginary maps, which illustrate the
extreme effects of various distribution of land and water. In one, all
the continental masses are grouped around the equator. In the other
they are all placed around the poles, leaving an open equatorial ocean.
In the one case the whole of the land and its inhabitants would enjoy a
perpetual summer, and scarcely any ice could exist in the sea. In the
other, the whole of the land would be subjected to an Arctic climate,
and it would give off immense quantities of ice to cool the ocean. Sir
Charles remarks on the present apparently capricious distribution of
land and water, the greater part being in the northern hemisphere, and,
in this, placed in a very unequal manner. But Lyell did not suppose
that any such distribution as that represented in his maps had actually
occurred, though this supposition has been sometimes attributed to him.
He merely put what he regarded as an extreme case to illustrate what
might occur under conditions less exaggerated. Sir Charles, like all
other thoughtful geologists, was well aware of the general fixity of
the areas of the continents, though with great modifications in the
matter of submergences and of land conditions. The union, indeed, of
these two great principles of fixity and diversity of the continents
lies at the foundation of theoretical geology.

We can now more precisely indicate this than was possible when Lyell
produced his "Principles," and can reproduce the conditions of our
continents in even the more ancient periods of their history. An
example of this may be given from the American continent, which is
more simple in its arrangements than the double continent of Eurasia.
Take, for instance, the early Devonian or Erian period, in which the
magnificent flora of that age, the earliest certainly known to us,
made its appearance. Imagine the whole interior plain of North America
submerged, so that the continent is reduced to two strips on the
east and west, connected by a belt of Laurentian land on the north.
In the great mediterranean sea thus produced, the tepid water of the
equatorial current was circulated, and it swarmed with corals, of
which we know no less than 150 species, and with other forms of life
appropriate to warm seas. On the islands and coasts of this sea was
introduced the Erian flora, appearing first in the north, and with that
vitality and colonizing power of which, as Hooker has well shown, the
Scandinavian flora is the best modern type, spreading itself to the
south. A very similar distribution of land and water in the Cretaceous
age gave a warm and equable climate in those portions of North America
not submerged, and coincided with the appearance of the multitude
of broad-leaved trees of modern types which appeared in the middle
Cretaceous, and prepared the way for the mammalian life of the Eocene.

We have in America ancient periods of cold as well as of warmth. I
have elsewhere referred to the boulder conglomerates of the Huronian,
of the early Lower Silurian, and of the Millstone grit period of the
Carboniferous; but I have not ventured to affirm that either of these
periods was comparable in its cold with the later glacial age, still
less with that imaginary age of continental glaciation, assumed by
the more extreme theorists. We know that these ancient conglomerates
were produced by floating ice, and this at periods when in areas not
very remote, temperate floras and faunas could flourish. The glacial
periods of our old continent occurred in times when the surface of the
submerged land was opened up to the northern currents drifting over it
mud and sand and stones, and rendering nugatory, in so far, at least,
as the bottom of the sea was concerned, the effects of the superficial
warm streams. Some of these beds are also peculiar to the eastern
margin of the continent, and indicate ice drift along the Atlantic
coast much as at present, while conditions of greater warmth existed in
the interior. Even in the more recent glacial age, while the mountains
were covered with snow, and the low lands submerged under a sea laden
with ice, there were interior tracts in somewhat high latitudes of
America in which hardy forest trees and herbaceous plants flourished
abundantly, and these were by no means exceptional "interglacial"
periods. Thus we can prove that from the remote Huronian period to the
Tertiary, the American land occupied the same position as at present,
and that its changes were merely changes of relative level, as compared
with the sea; but which so influenced the ocean currents as to cause
great vicissitudes of climate.

Uniformitarian geologists have recently been taunted with a willingness
to assume great and frequent elevations and submergences of
continents, as if this were contrary to their principle. But rational
uniformitarianism allows us to use any cause of whose operation in the
past there is good geological evidence, and Lyell himself was perfectly
aware of this.

While no geologists can fail to appreciate the evidence of the power
of geographical change in affecting climatal change, and the fact that
such change has occurred at various geological periods, there are some,
and especially those who take extreme views as to the latest period
of cold climate, who doubt its sufficiency to account for all the
phenomena observed. It is instructive, however, to notice that some of
the ablest of these, in default of other probable causes, are driven to
fall back either on agencies of a wholly improbable character, or to
give up the problem as insoluble. Two recent examples of this deserve
citation.

The late Dr. Newmayr, of Vienna, a veteran physical geographer, in
an able discussion of the climates of past ages, one of his last
scientific papers, has fallen back on the hypothesis of a change in
the position of the poles.[181] His failure to account for ancient
climates by other causes evidently, however, depends on an inadequate
conception of the effects of geographical changes, along with serious
misconceptions as to the distribution of plants and the characters of
vegetation at different periods. These points we shall have to discuss
in subsequent pages.

[181] _Society for Dissemination of Natural Science._ Vienna, January,
1889.

In an address before the American Association, in 1886, Dr.
Chamberlain, one of the ablest American authorities on the Glacial
period, makes the following remarks as to the causes of the Pleistocene
cold:--

"If we turn to the broader speculations respecting the origin of the
Glacial epoch, we find our wealth little increased. We have on hand
practically the same old stock of hypotheses, all badly damaged by
the deluge of recent facts. The earlier theory of northern elevation
has been rendered practically valueless; and the various astronomical
hypotheses seem to be the worse for the increased knowledge of the
distribution of the ancient ice sheet. Even the ingenious theory
of Croll becomes increasingly unsatisfactory as the phenomena are
developed into fuller appreciation. The more we consider the asymmetry
of the ice distribution in latitude and longitude, and its disparity
in elevation, the more difficult it becomes to explain the phenomena
upon any astronomical basis. If we were at liberty to disregard the
considerations forced upon us by physicists and astronomers, and
permit ourselves simply to follow freely the apparent leadings of the
phenomena, it appears at this hour as though we should be led upon an
old and forbidden trail,--the hypothesis of a wandering pole. It is
admitted that there is a _vera causa_ in elevations and depressions of
the earth's crust, but it is held inadequate. It is admitted that the
apparent changes of latitude shown by the determinations of European
and American observatories are remarkable, but their trustworthiness
is challenged. Were there no barriers against free hypotheses in
this direction, glacial phenomena could apparently find adequate
explanation; but debarred--as we doubtless should consider ourselves to
be at present--from this resource, our hypotheses remain inharmonious
with the facts, and the riddle remains unsolved."

It should be observed here that the unsolved "riddle" is that of a
continental ice sheet. This, as we have already seen, is probably
insoluble in any way, but fortunately needs no solution, being merely
imaginary. If we adopt a moderate view as to the actual conditions of
the Pleistocene, the geographical theory will be found quite sufficient
to account for the facts.

Let it be observed here also, in connection with the above thoughtful
and frank avowal of one of the ablest of American glacialists, that
the geographical theory provides for that "asymmetry "'or irregular
distribution of glacial deposits to which he refers; since, at every
stage of continental elevation and depression, there must have been
local changes of circumstances; and the same inequality of temperature
in identical latitudes which we observe at present must have existed,
probably in a greater degree, in the Glacial age.

The sufficiency of the Lyellian theory to account for the facts, in so
far as plants are concerned, may, indeed, be inferred from the course
of the isothermal lines at present. The south end of Greenland is on
the latitude of Christiania, in Norway, on the one hand, and of Fort
Liard, in the Peace River region, on the other; and while Greenland
is clad in ice and snow, wheat and other grains, and the ordinary
trees of temperate climates, grow at the latter places. It is evident,
therefore, that only exceptionally unfavourable circumstances prevent
the Greenland area from still possessing a temperate flora, and these
unfavourable circumstances possibly tell even on the localities with
which we have compared it. Further, the mouth of the McKenzie River
is in the same latitude with Disco, near which are some of the most
celebrated localities of fossil Cretaceous and Tertiary plants. Yet
the mouth of the McKenzie River enjoys a much more favourable climate,
and has a much more abundant flora than Disco. If North Greenland were
submerged, and low land reaching to the south terminated at Disco,
and if from any cause either the cold currents of Baffin's Bay were
arrested, or additional warm water thrown into the North Atlantic by
the Gulf Stream, there is nothing to prevent a mean temperature of 45°
Fahrenheit from prevailing at Disco; and the estimate ordinarily formed
of the requirements of its extinct floras is 50°, which is probably
above, rather than below, the actual temperature required.

We thus know that the present distribution of land and water greatly
influences climate, more especially by affecting that of the ocean
currents and of the winds, and by the different action of land as
compared with water in the reception and radiation of heat. The
present distribution of land gives a large predominance to the Arctic
and sub-Arctic regions, as compared with the equatorial and with
the Antarctic; and we might readily imagine other distributions that
would give very different results. But this is not an imaginary
case, for we can to some extent restore, on geological grounds, the
ancient geography of large regions, and can show that it has been
very different from that prevailing at present. We know also that,
while the forms and positions of the great continents have been fixed
from a very early date, they have experienced many great submergences
and re-elevations, and that these have occurred in somewhat regular
sequence, as evidenced by the cyclical alternations of organic
limestones and earthy sediments in the successive great geological
periods, each of which, as may be seen in any geological text-book,
presents a dip of the continental plateaus, with subsequent elevation,
as if the land was subject to a series of regular pulsations.[182]

[182] See "Acadian Geology"--Introduction to the Carboniferous System.

Finally, the Lyellian theory tends to abate the tendency to imagine
portentous and impossible climatal changes; and it inclines geologists
to give more attention to the connection of palæogeography with changes
in the life history of the earth.

  References:--"Acadian Geology," 1st ed., 1855; 4th ed., 1892.
    Icebergs of Belle-Isle, and Glaciers of Mont Blanc, _Canadian
    Naturalist_, 1865. "Notes on Pleistocene of Canada," Montreal,
    1871. Papers at various dates in the _Canadian Naturalist_ and
    _Canadian Record of Science_. "The Ice Age in Canada," Montreal,
    1892. Canadian Pleistocene, _London Geological Magazine_, March,
    1883. Flora of the Pleistocene, Dawson and Penhallow. _Bulletin of
    Geological Society of America_, vol. i., 1890, p. 311.




         _THE DISTRIBUTION OF ANIMALS AND PLANTS AS RELATED TO
                 GEOGRAPHICAL AND GEOLOGICAL CHANGES._


              DEDICATED TO THE MEMORY OF MY LATE FRIEND,

                          MR. GWYN JEFFRIES,

               who so ably investigated the Distribution

                         of Oceanic Molluska,

                more especially in the North Atlantic.


Changes of Climate and of Land and Water with Reference to
Distribution of Life--Regions of the Continents--Insular Faunas and
Floras--Their History Applications to Geology and to Man--Geological
Time--Theories of Introduction And Migration

[Illustration: Distribution of Animals in Time. (p. 420.)

_Vertebrata._ 1, Ganoid Fishes; 2, Teliort Fishes; 3, Batrachians; 4,
Reptiles; 5, Birds; 6, Mammals.

_Invertebrata._ 1, Trilobites, etc.; 2, Worms; 3, Bivalve and Univalve
Shellfishes; 4, Nautiloid Shellfishes; 5, Cuttlefishes; 6, Brachiopods.

It will be noticed that Nos. 2 and 5 in the first table, and 3 and
5 in the second, follow a different order of curve from the others,
indicating their exceptional culmination in modern times.]




CHAPTER XV.

_THE DISTRIBUTION OF ANIMALS AND PLANTS AS RELATED TO GEOGRAPHICAL AND
GEOLOGICAL CHANGES._


All are now agreed that to explain the extraordinary and often
apparently anomalous distribution of animals and plants over the
surface of the earth, and the occurrence of like forms in very distant
localities, and even on islands separated by vast stretches of ocean
from one another and from the continents, we must invoke the aid of
geology. We must have reference to those changes of climate and of
elevation which have occurred in the more recent periods of the earth's
history, and must carry with us the idea, at first not apparently very
reasonable, that living beings have existed much longer than many of
the lands which they inhabit, or at least than the present state of
those lands in reference to isolation or continental connection. To
what extent we may further require to call in the aid of varietal or
specific modification to explain the facts, may be more doubtful; and I
think we shall find that a larger acquaintance with geological truths
would enable us to dispense with the aid of hypotheses of evolution, at
least in so far as the local establishment of new generic and specific
types is concerned.

One of the most remarkable and startling results of geological
investigation, and one which must be accepted as an established fact,
independently of all theoretical explanations, is that the earth has
experienced enormous revolutions of climate within comparatively
late periods, and since the date of the introduction of many existing
species of animals and plants. To this great truth, in some of its
bearings, I have endeavoured to direct attention in the previous
articles. In the present case it will be necessary to consider these
vicissitudes in their more general aspects, and with some reference to
their effects on the distribution of living beings.

The modern or human period of geology, that in which man and his
contemporaries are certainly known to have inhabited the earth, was
immediately preceded by an age of climatal refrigeration known as
the Glacial or Ice age. This was further characterized not only by
a prevalence of cold, unexampled so far as known either before or
since, but by immense changes of the relative levels of sea and land,
amounting, in some cases, at least, to several thousands of feet. The
occurrence of these changes is clearly proved by the undoubted traces
of the action of ice, whether land ice or floating ice, on all parts
of our continents, half way to the equator, and by the occurrence of
sea terraces and modern marine shells at high levels on mountains and
table-lands. Perhaps we scarcely realize as we should the stupendous
character of the changes involved in the driftage of heavy ice over
our continents as far south as the latitude of 40°, in the deposit
of boulders on hills several thousands of feet in height, and in the
occurrence of shells of species still living in the sea, in beds raised
to more than twelve hundred feet above its present level. Yet such
changes must have occurred in the latest geological period immediately
preceding that in which we live. Proceeding farther back in geological
time, we find the still more extraordinary fact that in the middle and
earlier Tertiary the northern hemisphere enjoyed a climate so much more
mild than that which now prevails, that plants at present confined to
temperate latitudes could flourish in Greenland and Spitzbergen.[183]
The age in which we live is thus one of mediocrity, attaining neither
to the Arctic rigour of the later Pleistocene, nor to the universal
mildness of the preceding Miocene.

[183] As I have elsewhere shown, a warm climate in an Arctic region
seems to have afforded the necessary conditions for the great
colonizing floras of all geological periods.

The causes of these changes of climate we have discussed elsewhere.
It remains for us now to consider the actual condition of our present
continents, and the bearing of past conditions on the distribution of
their living inhabitants.

In speaking of continents and islands, it may be as well to remark at
the outset that all the land existing, or which probably has at any
time existed, consists of islands great or small. It is all surrounded
by the ocean. Two of the greater masses of land are, however,
sufficiently extensive to be regarded as continents, and from their
very extent and consequent permanence may be considered as the more
special homes of the living beings of the land. Two other portions of
land, Australia and the Antarctic polar continent, may be regarded
either as smaller continents or large islands, but partake of insular
rather than continental characters in their animals and plants. All the
other portions of land are properly islands; but while these islands,
and more especially those in mid-ocean, cannot be regarded as the
original homes of many forms of life, we shall find that they have a
special interest as the shelters and refuges of numerous very ancient
and now decaying species.

The two great continents of America and Eurasia have been the most
permanent portions of the land throughout geological time, some parts
of them having always been above water, probably from the Laurentian
age downward, though at various times they have been reduced to little
more than groups of islands. On them, and more especially in their
more northern parts, in which the long continuance of daylight in
summer seems in warm periods to have been peculiarly favourable to the
introduction of new vegetable and animal forms, and to the giving to
them that vigour necessary for active colonization, have originated the
greater number of the inhabitants of the land.

Regarded as portions of the earth's crust, the continents are areas
in which the lateral thrust, caused by the secular contraction of the
interior of the earth and unequal settlement of the crust, has ridged
up and folded the rocks, producing mountain chains. This process began
in the earliest geological periods, and has been repeated at long
intervals, the original lines of folding guiding those formed in each
new thrust proceeding from the broad oceanic areas. Along the ridges
thus produced, and in the narrower spaces between them, the greater
part of the sediment carried by water was laid down, thus producing
plateaus in connection with the mountain-chains, while the weight of
new sediments and the removal of matter from other areas by denudation,
have been constantly producing local depression and elevation. The
tendency of the ocean to be thrown toward the poles by the retardation
of the earth's rotation, alternating with great collapses of the
crust at the equator proceeding from the same cause, along with the
secular cooling, have produced alternate submergence and emergence
of these plateaus. This has been further complicated by the constant
tendency of the Arctic and Antarctic currents, aided by ice, to drift
solid materials, set free by the vast denuding action of frost, from
the polar to the temperate regions, and by the further tendency of
animal life to heap up calcareous accumulations under the warm waters
of the tropical regions. All these changes, as already stated, have
conspired to modify the directions of the great oceanic currents, and
to produce vicissitudes of climate under which animals and plants have
been subjected in geological time to those migrations, extinctions,
and renovations of which their fossil remains and present distribution
afford evidence.

Still, it is true that throughout the whole of these great mutations,
since the beginning of geological history, there seems never to have
been any time when the ocean so regained its dominion as to produce a
total extinction of land life; still less was there any time when the
necessary conditions of all the various forms of marine life failed to
be found; nor was there any climatal change so extreme as to banish any
of the leading forms of life from the earth. To geologists it is not
necessary to say that the conclusions sketched above are those that
have been reached as the results of long and laborious investigation,
and which have been illustrated and established by Lyell, Dana,
Wallace,[184] and many other writers.[185] Let us now place beside them
some facts as to the present distribution of life, and of the agencies
which influence it.

[184] Wallace, "Geographical Distribution of Animals" and "Island
Life." Second edition.

[185] The writer has endeavoured to popularize these great results of
geology in his work, the "Story of the Earth." Ninth Edition. London,
1887. They are often overlooked by specialists, and by compilers of
geological manuals.

Just as political geography sometimes presents boundaries not
in accordance with the physical structure of countries, so the
distribution of animals and plants shows many peculiar and unexpected
features. Hence naturalists have divided the continents into what
Sclater has called zoological regions, which are, so to speak, the
great empires of animal life, divisible often by less prominent
boundaries into provinces. In vegetable life similar boundaries may
be drawn, more or less coincident with the zoological divisions.
Zoologically, North America and Greenland may be regarded as one
great region, the Nearctic, or new Arctic, the prefix not indicating
that the animals are newer than those of the old world, which is by
no means the case. South America constitutes another region the
Neotropical. If now we turn to the greater Eurasian continent, with
its two prolongations to the south in Africa and Australia, we shall
find the whole northern portion, from the Atlantic to the Pacific,
constituting one vast region of animal life, the Palearctic, which also
includes Iceland and a strip across North Africa. Africa itself, with
Madagascar, whose allegiance is, however, only partial, constitutes
the Ethiopian region. India, Burmah, the south of China, and certain
Asiatic islands form the Oriental region. Australia, New Guinea, and
the Polynesian islands constitute the Australian region. All of these
regions may in a geological point of view be considered as portions of
old and permanent continental masses, which, though with movements of
elevation and depression, have continued to exist for vast periods.
Some of them, however, seem to have enjoyed greater immunity from
causes of change than others, and present, accordingly, animals and
plants having, geologically speaking, an antique aspect in comparison.
In this sense the Australian province may be regarded as the oldest of
all in the facies of its animal forms, since creatures exist there of
genera and families which have very long ago become extinct everywhere
else. Next in age to this should rank the Neotropical or South American
region, which, like Australia, presents many low and archaic forms
of animal life. The Ethiopian region stands next to it in this, the
Oriental and Nearctic next, and last and most modern in its aspect is
the great Palearctic region, to which man himself belongs, and the
animals and plants of which vindicate their claims to youth by that
aggressive and colonizing character already referred to, and which has
enabled them to spread themselves widely over the other regions, even
independently of the influence of man. On the other hand, the animals
and plants of the Australian and South American regions show no such
colonizing tendency, and can scarcely maintain themselves against those
of other regions when introduced among them. Thus we have at once
in these continental regions a great and suggestive example of the
connection of geographical and geological distribution, the details of
which are of the deepest interest, and have not yet been fully worked
out. One great principle is, however, sufficiently established; namely,
that the northern regions have been the birthplace of new forms of
land life, whence they have extended themselves to the south, while
the comparative isolation and equable climate of the South American
and Australian regions have enabled them to shelter and retain the old
moribund tribes.

Those smaller portions of land separated from the continental masses,
the islands properly so called, present, as might be expected, many
peculiar features. Wallace divides them into two classes, though he
admits that these pass into each other. Continental islands are those
in the vicinity of continents. They consist of ancient as well as
modern rock formations, and contain animals which indicate a former
continental connection. Some of these are separated from the nearest
mainland only by shallow seas or straits, and may be assumed to have
become islands only in recent geological times. Others are divided from
the nearest continent by very deep-water, so that they have probably
been longer severed from the mainland. These contain more peculiar
assemblages of animals and plants than the islands of the former class.
Oceanic islands are more remote from the continents. They consist
mostly of rocks belonging to the modern geological periods, and contain
no animals of those classes which can migrate only by land. Such
islands may be assumed never to have been connected with any continent.
The study of the indigenous population of these various classes of
islands affords many curious and interesting results, which Wallace
has collected with vast industry and care, and which, on the whole,
he explains in a judicious manner and in accordance with the facts of
geology. When, however, he maintains that evolution of the Darwinian
type is "the key to distribution," he departs widely from any basis of
scientific fact. This becomes apparent when we consider the following
results, which appear everywhere in the discussion of the various
insular faunas and floras:--(1) None of these islands, however remote,
can be affirmed to have been peopled by the spontaneous evolution of
the higher animals or plants from lower forms. Their population is in
every case not autochthonous, but derived. (2) Even in those which are
most distant from the continents, and may be supposed to have been
colonized in very ancient times, there is no evidence of any very
important modification of their inhabitants. (3) While the facts point
to the origin of most forms of terrestrial life in the Palearctic and
Nearctic regions, they afford no information as to the manner or cause
of their origination. In short, so far is evolution from being a key
to distribution, that the whole question would become much more simple
if this element were omitted altogether. A few examples may be useful
to illustrate this, as well as the actual explanation of the phenomena
afforded by legitimate science.

The Azores are situated in a warm temperate latitude about 900 miles
west of Portugal, and separated from it by a sea 2,500 fathoms in
depth. The islands themselves are almost wholly volcanic, and the
oldest rocks known in them are of late Miocene age. There is no
probability that these islands have ever been connected with Europe
or Africa, nor is there at present any certainty that they have been
joined to one another, or have formed part of any larger insular
tract. In these islands there is only one indigenous mammal, a bat,
which is identical with a European species, and no doubt reached the
islands by flight. There is no indigenous reptile, amphibian, or
fresh-water fish. Of birds there are, exclusive of waterfowl, which
may be regarded as visitors, twenty-two land birds; but of these, four
are regarded as merely accidental stragglers, so that only eighteen
are permanent residents. Of these birds fifteen are common European or
African species, which must have flown to the islands, or have been
drifted thither in storms. Of the remaining three, two are found also
in Madeira and the Canaries, and therefore may reasonably be supposed
to have been derived from Africa. One only is regarded as peculiar
to the Azores, and this is a bullfinch, so nearly related to the
European bullfinch that it may be regarded as merely a local variety.
Wallace accounts for these facts by supposing that the Azores were
depopulated by the cold of the Glacial age, and that all these birds
have arrived since that time. There is, however, little probability in
such a supposition. He further supposes that fresh supplies of stray
birds from the mainland, arriving from time to time, have kept up
the identity of the species. Instead of evolution assisting him, he
has thus somewhat to strain the facts to agree with that hypothesis.
Similar explanations are given for the still more remarkable fact that
the land plants of the Azores are almost wholly identical with European
and African forms. The insects and the land snails are, however, held
to indicate the evolution of a certain number of new specific forms on
the islands. The beetles number no less than 212 species, though nearly
half of them are supposed to have been introduced by man. Of the whole
number 175 are European, 19 are found in Madeira and the Canaries, 3
are American. Fourteen remain to be accounted for, though most of these
are closely allied to European and other species; but a few are quite
distinct from any elsewhere known. Wallace, however, very truly remarks
that our knowledge of the continental beetles is not complete; that the
species in question are small and obscure; that they may be survivors
of the Glacial period, and may thus represent species now extinct on
the mainland; and that for these reasons it may not be irrational to
suppose that these peculiar insects either still inhabit, or did once
inhabit, some part of the continents, and may be portions of "ancient
and widespread groups," once widely diffused, but now restricted to
a few insular spots. Among the land snails, if anywhere, we should
find evidence either of autochthonous evolution or of specific change.
These animals have existed on the earth since the Carboniferous period,
and, notwithstanding their proverbial slowness and sedentary habits,
they have contrived to colonize every habitable spot of land on the
globe--that is, unless in some of these places they have originated _de
novo_. In the Azores there are sixty-nine species of land snails, of
which no less than thirty-two, or nearly one-half, are peculiar, though
nearly all are closely allied to European types. What, then, is the
origin of these thirty-two species, admitting for the sake of argument
that they are really distinct, and not merely varietal forms, though it
is well known that in this group species are often unduly multiplied.
Three suppositions are possible, (1) These snails may have originated
in the islands themselves, either by creation or evolution from lower
forms; say, from sea snails. (2) They may have been modified from
modern continental species. (3) They may be unmodified descendants of
species of Miocene or Pliocene age now existing on the continents only
as fossils. As the islands appear to have existed since Miocene times,
it is no more improbable that species of that or the Pliocene age
should have found their way to them than that modern species should;
and as we know only a fraction of the Tertiary species of Europe or
Africa, it is not likely that we shall be able to identify all of these
early visitors. Unfortunately no Miocene or Pliocene deposits holding
remains of land snails are known in the Azores themselves, so that
this kind of evidence fails us. In Madeira and Porto Santo, however,
where there are numerous modern snails, there are Pliocene beds holding
remains of these animals. In Madeira there are, according to Lyell, 36
Pliocene species, and in Porto Santo 35, and of these only eight are
extinct. Thus we can prove that many of the peculiar species of these
islands have remained unchanged since Pliocene times. While differing
from modern European shells, several of these species are very near to
European Miocene species. Thus we seem to have evidence in the Madeira
group, not of modification, but of unchanged survival of Tertiary
species long since extinct in Europe. May we not infer that the same
was the case in the Azores? These results are certainly very striking
when we consider how long the Azores must have existed as islands, how
very rarely animals, and especially pairs of animals, must have reached
them, and how complete has been the isolation of these animals, and
how peculiar the conditions to which they have been subjected in their
island retreat.

Other oceanic islands present great varieties of conditions, but
leading to similar conclusions. Some, as the Bermudas, seem to have
been settled in very modern times with animals and plants nearly all
identical with those of neighbouring countries, though even here
it would appear that there are some indigenous species which would
indicate a greater age or more extended lands, now submerged.[186]
Others, like St. Helena, are occupied apparently with old settlers,
which may have come to them in early Tertiary, or even in Secondary
periods, which have long since become extinct on the continents, and
whose nearest analogues are now widely scattered over the world.
Islands are therefore places of survival of old species--special
preserves for forms of life lost to the continents. One of the most
curious of these is Celebes, which seems to be a surviving fragment
of Miocene Asia, which, though so near to that continent, has been
sufficiently isolated to preserve its old population during all
the vast lapse of time between the middle Tertiary and the present
period. This is a fact which gives to the oceanic islands the greatest
geological interest, and induces us to look into their actual fauna and
flora for the representatives of species known on the mainland only as
fossils. It is thus that we look to the marsupials of Australia as the
nearest analogues of those of the Jurassic of Europe, and that we find
in the strange Barramunda (_ceratodus_) of its rivers the only survivor
of a group of fishes once widely distributed, but which has long since
perished elsewhere.

[186] Heilprin mentions eleven marine mollusks supposed to be peculiar
to the islands, and eight species of land shells, as well as a few
Crustaceans hitherto found only in the Pacific. The comparisons are,
however, admitted to be incomplete.

Perhaps one of the most interesting examples of this is furnished by
the Galapagos Islands, an example the more remarkable that no one who
has read in Darwin's fascinating "Journal" the description of these
islands, can have failed to perceive that the peculiarities of this
strange Archipelago must have been prominent among the facts which
first planted in his mind the germ of that theory of the origin of
species which has since grown to such gigantic dimensions. It is
curious also to reflect that had the bearing of geological history on
the facts of distribution been as well known forty years ago as it is
now, the reasoning of the great naturalist on this and similar cases
might have taken an entirely different direction.

The Galapagos are placed exactly on the equator, and therefore out
of reach of even the suspicion of having been visited by the glacial
cold, though from their isolation in the ocean, and the effects of
the currents flowing along the American coast, their climate is not
extremely hot. They are 600 miles west of South America, and the
separating ocean is in some parts 3,000 fathoms deep. The largest of
the islands is 75 miles in length, and some of the hills attain an
elevation of about 4,000 feet, so that there are considerable varieties
of station and climate. So far as is known they are wholly volcanic,
and they may be regarded as the summits of submerged mountains not
unlike in structure to the Andes of the mainland. Their exact
geological age is unknown, but there is no improbability in supposing
that they may have existed with more or less of extension since the
Secondary or Mesozoic period. In any case their fauna is in some
respects a survival of that age. Lyell has truly remarked, "In the
fauna of the Galapagos Islands we have a state of things very analogous
to that of the Secondary period."

Like other oceanic islands, the Galapagos have no indigenous mammals,
with the doubtful exception of a South American mouse; but, unlike
most others, they are rich in reptiles. At the head of these stand
several species of gigantic tortoises. This group of animals, so far
as known, commenced its existence in the Eocene Tertiary; and in this
and the Miocene period still more gigantic species existed on the
continents. It has been supposed that at some such early date they
reached the Galapagos from South America. Another group of Galapagan
reptiles, perhaps still more remarkable, is that of iguana-like lizards
of the genus _Amblyrhyncus_, which are vegetable feeders,--one of them
browsing on marine weeds. They recall the great iguana-like reptiles
of the European Wealden, and stand remote from all modern types. There
are also snakes of two species, but these are South American forms,
and may have drifted to the islands in comparatively recent times on
floating trees. The birds are a curious assemblage. A few are common
American species, like the rice bird. Others are quaint and peculiar
creatures, allied to South American birds, but probably representing
forms long since extinct on the continent. The bird fauna, as Wallace
remarks, indicates that some of these animals are old residents, others
more recent arrivals; and it is probable that they have arrived at
various times since the early Tertiary. He assumes that the earlier
arrivals have been modified in the islands "into a variety of distinct
types"; but the only evidence of this is that some of the species are
closely related to each other. It is more likely that they represent
to our modern eyes the unmodified descendants of continental birds of
the early Tertiary. Darwin remarks that they are remarkably sombre
in colouring for equatorial birds; but perhaps their ancestors came
from a cooler climate, and have not been able to don a tropical garb;
or perhaps they belong to a far-back age, when the vegetable kingdom
also was less rich in colouring than it is at present, and the birds
were in harmony with it. This, indeed, seems still to be the character
of the Galapagos plants, which Darwin says have "a wretched, weedy
appearance," without gay flowers, though later visitors have expressed
a more favourable opinion.

These plants are in themselves very remarkable, for they are largely
peculiar species, and are in many cases confined to particular islands,
having apparently been unable to cross from one island to another,
though in some way able to reach the group. The explanation is that
they resemble North American plants, and came to the Galapagos at a
time when a wide strait separated North and South America, allowing
the equatorial current to pass through, and drift plants to the
Galapagos, where they have been imprisoned ever since. This was
probably in Miocene times, and when we know more of the Miocene flora
of the southern part of North America we may hope to recover some of
the ancestors of the Galapagos plants. In the meantime their probable
origin and antiquity, as stated by Wallace, render unnecessary any
hypothesis of modification.

Before leaving this subject, it is proper to observe that on the
continents themselves there are many remarkable cases of isolation of
species, which help us better to understand the conditions of insular
areas. The "variable hare" of the Scottish highlands, and of the
extreme north of Europe, appears again in the Alps, the Pyrenees, and
the Caucasus, being in these mountains separated by a thousand miles
of apparently impassable country from its northern haunts. It no doubt
extended itself over the intervening plains at a time when Europe was
colder than at present. Another curious case is that of the marsh-tit
of Europe. This little bird is found throughout south-western Europe.
It reappears in China, but is not known anywhere between. In Siberia
and northern Europe there is, however, a species or distinct race which
connects these isolated patches. In this case, if the Siberian species
is truly distinct, we have a remarkable case of isolation and of the
permanence of identical characters for a long time; for in that case
this bird must be a survivor of the Pliocene or Miocene time. On the
other hand, if, as is perhaps more likely, the marsh-tit is only a
local variety of the Siberian species, we have an illustration of the
local recurrence of this form when the conditions are favourable, even
though separated by a great space and long time.

The study of fossils gives us the true meaning of such facts, and
causes us to cease to wonder at any case of local repetition of
species, however widely separated. The "big trees" of California
constitute a remarkable example. There are at present two very distinct
species of these trees, both found only in limited areas of the western
part of North America. Fossil trees of the same genus (_Sequoia_)
occur as far back as the Cretaceous age; but in this age ten or more
species are known. Nor are they confined to America, but occur in
various parts of the Eurasian continent as well. Two of the Lower
Cretaceous species are so near to the two modern ones that even an
unbeliever in evolution may suppose them to be possible ancestors; the
remaining eight are distinct, but some of them intermediate in their
characters. In the Tertiary period, intervening between the Cretaceous
and the modern, fourteen species of _Sequoia_ are believed to have been
recognised, and they appear to have existed abundantly all over the
northern hemisphere. Thus we know that these remarkable Californian
giants are the last remnant of a once widely distributed genus,
originating, as far as known, in the Cretaceous age. Now had a grove
of _Sequoias_, however small, survived anywhere in Europe or Asia, and
had we no knowledge of the fossil forms, we might have been quite at
a loss to account for their peculiar distribution. The fossil remains
of the Tertiary rocks, both animal and vegetable, present us with many
instances of this kind.

The discussion of the distribution of animals and plants, when carried
on in the light of geology, raises many interesting questions as to
time, which we have already glanced at, but which deserve a little more
attention. As to the vast duration of geological time all geologists
are agreed. It is, however, now well understood that science sets
certain limits to the time at our disposal. Edward Forbes humorously
defined a geologist to be "an amiable enthusiast who is content if
allowed to appropriate as much as he pleases of that which other men
value least, namely, past time "; but now even the geologist is obliged
to be content with a limited quantity of this commodity.

The well-known estimate of Lord Kelvin gave one hundred millions of
years as the probable time necessary for the change of the earth from
the condition of a molten mass to that which we now see. On this
estimate we might fairly have assumed fifty millions of years as
covering the time from the Laurentian age to the modern period. The
great physicist has, however, after allowing us thus much credit in the
bank of time, "suddenly put up the shutters and declared a dividend of
less than four shillings in the pound."[187] In other words, he has
reduced the time at our disposal to twenty millions of years. Other
physicists, reasoning on the constitution of the sun, agree with this
latter estimate, and affirm that "twenty millions of years ago the
earth was enveloped in the fiery atmosphere of the sun."[188] Geology
itself has attempted an independent calculation based on the wearing
down of our continents, which appears to proceed at the rate of about
a foot in four or five thousand years, and on the time required to
deposit the sediments of the several geological formations, estimated
at about 70,000 feet in thickness. These calculations would give us,
say, eighty-six millions of years since the earth began to have a solid
crust, which would, like Lord Kelvin's earlier estimate, give us nearly
fifty millions of years for the geological time since the introduction
of life. The details of the several estimates made it would be tedious
and unprofitable to enter into, but I may state as my own conclusion,
that the modern rates of denudation and deposit must be taken as far
below the average, and that perhaps the estimate stated by Wallace on
data supplied by Houghton, namely, twenty-eight millions, may be not
far from the truth, though perhaps admitting of considerable abatement.

[187] Bonney, Address before British Association, 1888.

[188] Newcomb, Helmholtz, Tait, etc.

This reduced estimate of geological time would still give scope enough
for the distribution of animals and plants, but it will scarcely
give that required by certain prevalent theories of evolution. When
Darwin says, "If the theory (of natural selection) be true, it is
indisputable that before the lowest Cambrian stratum was deposited
long periods elapsed, as long as, or probably far longer than, the
whole interval from the Cambrian to the present day," he makes a demand
which geology cannot supply; for independently of our ignorance of
any formations or fossils, except those included in the Archæan, to
represent this vast succession of life, the time required would push
us back into a molten state of the planet. This difficulty is akin to
that which meets us with reference to the introduction of many and
highly specialized mammals in the Eocene, or of the forests of modern
type in the Cretaceous. To account for the origin of these by slow and
gradual evolution requires us to push these forms of life so far back
into formations which afford no trace of them, but, on the contrary,
contain other creatures that appear to be exclusive of them, that our
faith in the theory fails. The only theory of evolution which seems to
meet this difficulty is that advanced by Mivart, Leconte, and Saporta,
of "critical periods," or periods of rapid introduction of new species
alternating with others of comparative inaction. This would much better
accord with the apparently rapid introduction of many new forms of life
over wide regions at the same period. It would also approach somewhat
near, in its manner of stating the problem to be solved, to the theory
of "creation by law" as held by the Duke of Argyll, or to what may be
regarded as "mediate creation," proceeding in a regular and definite
manner, but under laws and forces as yet very imperfectly known,
throughout geological time.

It seems singular, in view of the facts of palæontology, that
evolutionists of the Darwinian school are so wedded to the idea of one
introduction only of each form of life, and its subsequent division by
variation into different species, as it progressively spreads itself
over the globe, or is subjected to different external conditions. It
is evident that a little further and very natural extension of their
hypothesis would enable them to get rid of many difficulties of time
and space. For example, certain Millipedes and Batrachians are first
known in the coal formation, and this not in one locality only, but
in different and widely separated regions. If they took beginning in
one place, and spread themselves gradually over the world, this must
have required a vast lapse of time--more than we can suppose probable.
But if, in the coal-formation age, a worm could anywhere change into
a Millipede, or a fish into a Batrachian, why might this not have
occurred in many places at once? Again, if the oldest known land snails
occur in the coal formation, and we find no more specimens till a much
later period, why is it necessary to suppose that these creatures
existed in the intervening time, and that the later species are the
descendants of the earlier? Might not the process have been repeated
again and again, so as to give animals of this kind to widely separated
areas and successive periods without the slow and precarious methods
of continuous evolution and migration? This apparent inconsistency
strikes one constantly in the study of discussions of the theory of
derivation in connection with geographical and geological distribution.
We constantly find the believers in derivation laboriously devising
expedients for the migration of animals and plants to the most unlikely
places, when it would seem that they might just as well have originated
in those places by direct evolution from lower forms. Those who believe
in a separate centre of creation for each species must of course invoke
all geological and geographical possibilities for the dispersion of
animals and plants; but surely the evolutionist, if he has faith in his
theory, might take a more easy and obvious method, especially when in
any case he is under the necessity of demanding a great lapse of time.
That he does not adopt this method perhaps implies a latent suspicion
that he must not repeat his miracle too often. He also perceives that
if repeated and unlimited evolution of similar forms had actually
occurred, there could have remained little specific distinctness,
and the present rarity of connecting links would not have occurred.
Further, a new difficulty would have sprung up in the geographical
and geological relations of species and genera, which would then have
assumed too much of the aspect of a preconceived plan. It is only fair
to a well-known and somewhat extreme European evolutionist, Karl Vogt,
to state that he launches boldly into the ocean of multiple evolution,
not fearing to hold that identical species of mollusks have been
separately evolved in separate Swiss lakes, and that the horse has been
separately evolved in America and in Europe, in the former along a line
beginning with Eohippus, and in the latter along an entirely separate
line, commencing with _Palæotherium_. The serious complications
resulting from such admissions are evident, but Vogt deserves credit
for faith and consistency beyond those of his teachers.

With reference to the actual distribution of species, the question
of time becomes most important when applied to the Glacial period,
since it is obvious that much of the present distribution must have
been caused, or greatly modified, by that event. The astronomical
theory would place the close of the Glacial age as far back as 70,000
or 80,000 years ago. But we have already seen in the chapter on that
period that geological facts bring its close to only from 10,000 to
7,000 years before our time. If we adopt the shorter estimates afforded
by these facts, it will follow that the submergences and emergences
of land in the Glacial ages were more rapid than has hitherto been
supposed, and that this would react on our estimate of time by giving
facilities for more rapid denudation and deposition. Such results would
greatly shorten the duration assignable to the human period. They
would render it less remarkable that no new species of animals seem to
have been introduced since the Glacial age, that many insular faunas
belong to far earlier times, and that no changes even leading to the
production of well-marked varieties have occurred in the post-glacial
or modern age.

In conclusion, does all this array of fact and reasoning bring us any
nearer to the comprehension of that "mystery of mysteries," the origin
and succession of life? It certainly does not enable us to point to any
species, and to say precisely here, at this time and thus it originated.
If we adopt the theory of evolution, the facts seem to restrict us to
that form of it which admits paroxysmal or intermittent introduction of
species, depending on the concurrence of conditions favourable to the
action of the power, whatever it may be, which produces new organisms.
Nor is there anything in the facts of distribution to invalidate the
belief in creation, according to definite laws, if that really differs
in its nature from certain forms of the hypothesis of evolution. We
have also learned that, time being given, animals and plants manifest
wonderful powers of migration, that they can vary within considerable
limits without ceasing to be practically the same species, and that
under certain conditions they can endure far longer in some places than
in others. We also see evidence that it is not on limited islands,
but on the continents, that land animals and plants have originated,
and that swarms of new and vigorous species have issued from the more
northern regions in successive periods of favourable Arctic climate.
The last of these new swarms or "centres of creation," that with which
man himself is more closely connected, belongs to the Palearctic
region. We have already seen that in every geological period, when the
submerged continental plateaus were pervaded by the warm equatorial
waters, multitudes of new marine species appear. In times when, on
the contrary, the colder Arctic currents poured over these submerged
surfaces, carrying mud and stones, great extinction took place, but
certain northern forms of life swarmed abundantly, and when elevation
took place, marine species became extinct or were forced to migrate.
Everywhere and at all times multiplication of species was promoted
by facilities for expansion. The great limestones of our continents,
full of corals and shells of new species, belong to times when the
ocean spread itself over the continental plateaus, affording wide,
untenanted areas of warm and shallow water. The introduction of new
faunas and floras on the land belongs to times when vast supplies of
food for plants and animals and favourable conditions of existence were
afforded by the emergence of new lands possessing fertile soils and
abundantly supplied with light, heat, and moisture. Thus geological and
geographical facts concur with ordinary observation and experience in
reference to varietal forms, in testifying that it is not mere struggle
for existence, but facilities for easy existence and rapid extension,
that afford the conditions necessary for new and advanced forms of
life. These considerations do not, of course, reach to the first cause
of the introduction of species, nor even to the precise mode in which
this may have acted in any particular case: but perhaps we cannot
fully attain to this by any process of inductive inquiry. The study of
geographical distribution,' therefore, does not enable us to solve the
question of the origin of specific types, but, on the contrary, points
to marvellous capacities for migration and a wonderful tenacity of life
in species. In these respects, however, it is a study full of interest,
and in nothing more so than in the evidence which it affords of the
practically infinite provisions made for the peopling of every spot of
land or sea with creatures fitted to flourish and enjoy life therein,
and to carry on the great and progressive plan of the Creator.

  References:--Continental and Island Life, _Princeton Review_, July,
    1881. Address to American Association, 1883. Papers and Addresses
    to Natural History Society, _Canadian Naturalist_, Montreal. "The
    Story of the Earth and Man," 1st ed., 1873, 9th ed., London, 1887.




   _ALPINE AND ARCTIC PLANTS IN CONNECTION WITH GEOLOGICAL HISTORY_


                      DEDICATED TO THE MEMORY OF

                             DR. ASA GRAY,

             THE GREATEST AND MOST PHILOSOPHICAL EXPONENT

                          OF AMERICAN BOTANY.


A Botanico-Geological Excursion in the White Mountains--Distribution
and Migrations of Alpine Plants--Relations to the Later Geological
Changes--Bearing on the Vegetation of Earlier Times

[Illustration: Mount Washington, from Tuckerman's Ravine. (p. 426.)

(After Filmer, in King's "White Hills.")]




CHAPTER XVI.

_ALPINE AND ARCTIC PLANTS IN CONNECTION WITH GEOLOGICAL HISTORY._


The group of the White Mountains is the culminating point of the
northern division of the great Appalachian range, extending from
Tennessee to Gaspé in a south-west and north-east direction, and
constituting the breast bone of the North American continent. This
great ridge or succession of ridges has its highest peaks near its
southern extremity, in the Black Mountains; but these are little
higher than their northern rivals, which at least hold the undisputed
distinction of being the highest hills in north-eastern America. As
Guyot[189] has well remarked, the White Mountains do not occur in
the general line of the chain, but rather on its eastern side. The
central point of the range, represented by the Green Mountains and
their continuation, describes a great curve from Gaspé to the valley
of the Hudson, and opposite the middle of the concave side of this
curved line towers the almost isolated group of the White Hills. On the
other side is the narrow valley of Lake Champlain, and beyond this the
great isolated mass of the Adirondack Mountains, nearly approaching in
the altitude of their highest peaks, and greatly exceeding in their
geological age, the opposite White Mountain group. The Appalachian
range is thus, in this part of its course, supported on either side by
outliers higher than itself. The dense grouping of mountains in this
region is due to the resistance offered by the old Adirondack mass
to the westward thrust of the Atlantic and the subsequent piling up
against this mass of the ridges of palæozoic sediments. Southward of
this the Atlantic thrust has driven these ridges back in a great bend
to the westward.

[189] _Silliman's Journal._

My present purpose is not to give a general geographical or geological
sketch of the White Mountains, but to direct attention to the
vegetation which clothes their summits, and its relation to the history
of the mountains themselves. For this purpose I may first shortly
describe the appearances presented in ascending the highest of them,
Mount Washington, and then turn to the special points to which these
notes relate.

In approaching Mount Washington by the Grand Trunk Railway, the
traveller has ascended from the valley of the St. Lawrence to a height
of 802 feet at the Alpine House at Gorham. Thence, in a distance of
about eight miles along the bank of the Peabody River, to the Glen
House, he ascends to the elevation of 1,632 feet above the sea; and it
is here, or immediately opposite the Glen House, that the actual ascent
begins. The distance from the Peabody River, opposite the hotel, to
the summit is nine miles, and in this distance we ascend 4,656 feet,
the total height being 6,288 feet above the sea.[190] Formerly only a
bridle path led up this ascent; but now access can be had to the summit
by carriage roads and by rail.

[190] According to Guyot, but some recent surveys make it a little
higher.

These royal roads to the summit are, however, too democratic for the
taste of some visitors, who mourn the olden days of ponies, guides and
adventures; and though they give an excellent view of the geological
structure of the mountain, they do not afford a good opportunity for
the study of the alpine flora, which is one of the chief attractions
of Mount Washington. For this reason, though I availed myself of the
new road for gaining a general idea of the features of the group,
I determined to ascend by Tuckerman's Ravine, a great chasm in the
mountain side, named in honour of the indefatigable botanist of the
North American lichens.[191] I was aided in this by the kindness of a
gentleman of Boston, well acquainted with these hills, and passionately
fond of their scenery.[192] Our party, in addition to this gentleman
and myself, consisted of two ladies, two children, and two experienced
guides, whose services were of the utmost importance, not only in
indicating the path, but in removing windfalls and other obstructions,
and in assisting members of the party over difficult and dangerous
places.

[191] Peck, Bigelow and Booth were the early botanical explorers of the
White Mountains; though Pursh was the first to determine some of the
more interesting plants, and Oakes and Tuckerman deserve honourable
mention, as the most thorough modern explorers.

[192] Mr. Raymond.

We followed the carriage road for two miles, and then struck off to the
left by a bridle path that seemed not to have been used for several
years the gentlemen and guides on foot, the ladies and children mounted
on the sure-footed ponies used in these ascents. Our path wound around
a spur of the mountain, over rocky and uneven ground, much of the rock
being mica slate, with beautiful cruciform crystals of andalusite,
which seemed larger and finer here than in any other part of the
mountain which I visited. At first the vegetation was not materially
different from that of the lower grounds, but as we gradually ascended
we entered the "evergreen zone," and passed through dense thickets of
small spruces and firs, the ground beneath which was carpeted with
moss, and studded with an immense profusion of the delicate little
mountain wood sorrel (_Oxalis acetosella_), a characteristic plant of
wooded hills on both sides of the Atlantic, and which I had not before
seen in such profusion since I had roamed on the hills of Lochaber
Lake in Nova Scotia. Other herbaceous plants were rare, except ferns
and club mosses; but we picked up an aster (_A. acuminatus_), a golden
rod (_Solidago thyrsoidea_), and the very pretty tway blade (_Listera
cordata_), a species[193] very widely distributed throughout British
America.

[193] _L. macrophylla_ Pursh (Macoun).

In ascending the mountain directly, the spruces of this zone gradually
degenerate, until they present the appearance of little gnarled
bushes, flat on top and closely matted together, so that except where
paths have been cut, it is almost impossible to penetrate among them.
Finally, they lie flat on the ground, and become so small that, as
Lyell remarks, the reindeer moss may be seen to overtop the spruces.
This dwarfing of the spruces and firs is the effect of adverse
circumstances, and of their struggle to extend their range toward the
summit. Year by year they stretch forth their roots and branches,
bending themselves to the ground, clinging to the bare rocks, and
availing themselves of every chasm and fissure that may cover their
advance; but the conditions of the case are against them. If their
front advances in summer, it is driven back in winter, and if in a
succession of mild seasons they are able to gain a little ground, less
favourable seasons recur, and wither or destroy the holders of their
advanced positions. For thousands of years the spruces and firs have
striven in this hopeless escalade, but about 4,000 feet above the sea
seems to be the limit of their advance, and unless the climate shall
change, or these trees acquire a new plasticity of constitution, the
genus _Abies_ can never displace the hardier alpine inhabitants above,
and plant its standard on the summit of Mount Washington.

I was struck by the similarity of this dwarfing of the upper edges of
the spruce woods, to that which I have often observed on the exposed
northern coasts of Cape Breton and Prince Edward Island, where the
woods often gradually diminish in height toward the beach or the edge
of a cliff, till the external row of plants clings closely to the soil,
or rises above it only a few inches. The causes are the same, but the
appearance is more marked on the mountain than on the coast. It is in
miniature a picture of the gradual dwarfing of vegetation in the great
barren grounds of Arctic America.

On the path which we followed, before we reached the upper limit
of trees, we arrived at the base of a stupendous cliff, forming the
termination of a promontory or spur of the mountain, separating
Tuckerman's Ravine from another deep depression known as the Great
Gulf. From the top of this precipice poured a little cascade, that lost
itself in spray long before it touched the tops of the trees below. The
view at this place was the most impressive that it was my fortune to
see in these hills.

Opposite the mouth of the Great Gulf, and I suppose at a height of
about 3,000 feet, is a little pond known as Hermit Lake. It is nearly
circular, and appears to be retained by a ridge of stones and gravel,
perhaps an old moraine or sea beach. On its margin piped a solitary
sandpiper, a few dragon flies flitted over its surface, and tadpoles in
the bottom indicated that some species of frog dwells in its waters.
High overhead, and skirting the edges of the precipices, soared an
eagle, intent, no doubt, on the hares that frequent the thickets of the
ravines.

Before we reached Hermit Lake we had been obliged to leave our horses,
and now we turned aside to the left and entered Tuckerman's ravine,
where there is no path, but merely the bed of a brook, whose cold clear
water tumbles in a succession of cascades over huge polished masses
of white gneiss, while on both sides of it the bottom of the ravine
is occupied by dense and almost impenetrable thickets of the mountain
alder (_Alnus viridis_).

Tuckerman's Ravine has been formed originally either by a subsidence
of a portion of the mountain side, or by the action of the sea. It
is, like most of the ravines and "gulfs" of these hills, a deep cut
or depression bounded by precipitous sides and terminating at the top
in a similarly precipitous manner. It must at one period have been in
part filled with boulder clay, steep banks of which still remain in
places on its sides; and extensive landslips have occurred, by which
portions of the limiting cliffs have been thrown toward the centre of
the valley, in large piles of angular blocks of gneiss and mica slate,
in the spaces between which grow gnarled birches and spruces that must
be used as ladders and bridges whereby to scramble from block to block,
by every one who would cross or ascend one of these rivers of stones.
These "gulfs" of the White Mountains are similar to the "cirques" of
the Alps, and various explanations have been given of their origin. To
me they have always appeared to be of the same nature with the "chines"
or bays with precipitous ends seen on rocky coasts, and which are
produced by the action of the surf on the softer beds or veins of rock.
They testify to the raging of the waves for long ages against the sides
of what are now lofty mountains. This, we know, must have occurred in
the great Pleistocene submergence; but in mountains so old as those now
in question, it may have in part been effected in previous periods.

At the head of the ravine we paused to rest, to admire the wild
prospect presented by the ravine and its precipitous sides, and to
collect the numerous plants that flower on the surrounding slopes and
precipices. Here, on the 19th of August, were several large patches of
snow, one of them about a hundred yards in length. From the precipice
at the head of the ravine poured hundreds of little rills, and several
of them collecting into a brook, had excavated in the largest mass of
snow a long tunnel or cavern with an arched and groined roof. Under the
front of this we took our mid-day meal, with the hot August sun pouring
its rays in front of us, and icy water gurgling among the stones at our
feet. Around the margin of the snow the vegetation presented precisely
the same appearances which are seen in the low country in March and
April, when the snow banks have just disappeared--the old grass
bleached and whitened, and many perennial plants sending up blanched
shoots which had not yet experienced the influence of the sunlight.

The vegetation at the head of this ravine and on the precipices that
overhang it, presents a remarkable mixture of lowland and mountain
species. The head of the ravine is not so high as the limit of trees
already stated, but its steep sides rise abruptly to a plateau of 5,000
feet in height, intervening between Mount Washington and Mount Munro,
and on which are the dark ponds or tarns known as the Lakes of the
Clouds, forming the sources of the Amonoosook river, which flows in
the opposite direction. From this plateau many alpine plants stretch
downward into the ravine, while lowland plants, availing themselves
of the shelter and moisture of this _cul-de-sac_, climb boldly upward
almost to the higher plateau. Other species again occur here, which
are found neither on the exposed alpine summits and ridges, nor in
the low country. Conspicuous among the hardy climbers are two coarse
and poisonous weeds of the river valleys, that look like intruders
into the company of the more dwarfish alpine plants;--the cow parsnip
(_Heracleum lanatum_) and the white hellebore (_Veratrum viride_).
Both of these plants were seen struggling up through the ground at the
margin of the snow, and climbing up moist hollows almost to the tops
of the precipices. Some specimens of the latter were crowded with the
infant caterpillars of a mountain butterfly or moth. Less conspicuous,
and better suited to the surrounding vegetation, were the bluets
(_Oldenlandia cœrulea_), now in blossom here, as they had been months
before in the low country, the dwarf cornel (_Cornus Canadensis_) and
the twin-flower (_Linnæa borealis_), the latter reaching quite to
the plateau of the lake of the Clouds, and entering into undisputed
companionship with the truly alpine plants, though it is also found at
Gorham, 4,000 feet lower.

Of the plants which seemed to be confined, or nearly so, to the upper
part of the ravine, one of the most interesting was the northern
painted cup (_Castelleia septentrionalis_), a plant which abounds on
the coast of Labrador, and extends thence through all Arctic North
America to the Rocky Mountains, and is perhaps identical with the _C.
Sibirica_ of Northern Asia and the _C. pallida_ of Northern Europe.
Large beds of it were covered with their pale yellow blossoms on the
precipitous banks overhanging the head of the ravine. With the painted
cup, and here alone, was another beautiful species of a very different
order, the northern green orchis (_Platanthera hyperborea_), a plant
which occurs, though rarely, in Canada, but is more abundant to the
northward. Here also occurred Peck's geum (_G. radiatum_, var.),
_Arnica mollis_, and several other interesting plants.

Of the alpine plants which descend into the ravine, the most
interesting was the Greenland sand-wort (_Arenaria_ (_Alsine_)
_Grænlandica_) which was blooming abundantly, with its clusters of
delicate white flowers, on the very summit of the mountain, and could
be found here and there by the side of the brook in the bottom of the
ravine.

Clambering by a steep and dangerous path up the right side of the
ravine, we reach almost at once the limit, beyond which the ordinary
flora of New England can extend no longer, and are in the presence of
a new group of plants comparable with those of Labrador and Greenland.
Here, on the plateau of the Lake of the Clouds, the traveller who has
ascended the giddy precipices overhanging Tuckerman's Ravine is glad
to pause, that he may contemplate the features of the new region which
he has reached. We have left the snow behind us, except a small patch
which lingers on the shady side of Mount Munro; for it is only in the
ravines into which it has drifted a hundred feet deep or more, that
it can withstand the summer heat until August. We stand on a dreary
waste of hard angular blocks of mica slate and gneiss that lie in rude
ridges, as if they had been roughly raked up by Titans, who might have
been trying to pile Monro upon Washington, but which seem to be merely
the remains of the original outcropping edges of the rocks broken up
by the frost, but not disturbed or rounded by water.[194] Behind us
is the deep trench-like ravine out of which we have climbed; on the
left hand a long row of secondary summits stretching out from Mount
Washington to the south-westward, and designated by the names of a
series of American statesmen. In front this range descends abruptly
in great wooded spurs or buttresses to the valley of the Amonoosook,
which shines in silvery spots through the trees far below. On our
right hand towers the peak of Mount Washington, still more than a
thousand feet above us, and covered with angular blocks, as if it
were a pile of fragments rather than a solid rock. These stones all
around and up to the summit of the mountain, are tinted pale green
by the map lichen (_Lecidea geographica_), which tinges in the same
way the alpine summits of European mountains. Between the blocks
and on their sheltered sides nestle the alpine flowering plants, of
which twenty species or more may be collected on this shoulder of the
mountain, and some of which extend themselves to the very summit,
where _Alsine Grœnlandica_ and the little tufts of deep green leaves
of _Diapensia Lapponica_ with a few Carices seem to luxuriate. Animal
life accompanies these plants to the summit, near which I saw a family
of the snow bird, evidently summer residents here, instead of seeking
the far north for a breeding place, as is the habit of the species, and
a number of insects, conspicuous among which was a brown butterfly of
the genus _Hipparchia_. Shortly before sundown, when the thermometer at
the summit house was fast settling toward the freezing point, a number
of swallows were hawking for flies at a great height above the highest
peak. To what species they belonged I could not ascertain. Possibly
the cliff swallows find breeding places in the sides of the ravines,
and rise over the hill top to bask in the sunbeams, after the mountain
has thrown its shadows over their homes.

[194] Hitchcock has since found travelled blocks on the summit, bearing
evidence to its submergence under the waves of the glacial sea, and
to the grinding of ice floes upon it. Such a fact helps to account
for the broken character of the summit, and also implies that unequal
subsidence of the land elsewhere referred to, since we know of no
agency which could carry boulders so high as the present mountain top.

To return to the Alpine flora which is peculiar to the peaks of these
mountains--are the species comprising it autochthones originating on
these hill tops, and confined to them, or are they plants occurring
elsewhere, and if so, where? and how and when did they migrate to their
present abodes? These are questions which must occur to every one
interested in geology, botany, or physical geography.

Not one of the Alpine plants of Mount Washington is peculiar to
the place. Nearly all of them are distinct from the plants of the
neighbouring lowlands, but they occur on other hills of New England
and New York, and on the distant coasts of Labrador and Greenland, and
some of them are distributed over the Arctic regions of Europe, Asia
and America. In short, they are stragglers from that Arctic flora which
encompasses the north polar region, and extends in promontories and
islands along the high cold mountain summits far to the southward.

Some of the humble flowerless plants of these hills are of nearly
world-wide distribution. I have already noticed the pale green map
lichen which tints the rocks of the Pyrenees, the Alps, and the
Scottish Highlands; and the curious ring lichen (_Parmelia centrifuga_)
paints its conspicuous rings and arcs of circles alike on Mount
Washington and the Scottish hills. A little club moss (_Lycopodium
selago_) is not only widely distributed over the northern hemisphere,
but Hooker has recognised it in the Antarctic regions. Not long ago we
unrolled in Montreal an Egyptian mummy, preserved in the oldest style
of embalming, and found that, to preserve the odour of the spices,
quantities of a lichen (_Evernia furfuracea_) had been wrapped around
the body, and have no doubt been imported into Egypt from Lebanon, or
the hills of Macedonia, for such uses. Yet the specimens from this old
mummy were at once recognised by Professor Tuckerman as identical with
this species as it occurs on the White Hills and on Katahdin, in Maine.
These facts are, however, easily explicable in comparison with those
that relate to the flowering plants.

The spores of lichens and mosses float lighter than the lightest down
in the air, and may be wafted over land and sea, and dropped everywhere
to grow where conditions may be favourable. We can form an idea of this
from the fact that the volcanic dust, consisting of shreds of pumice,
etc., thrown up by the eruption of Krakatoa, in 1883, was wafted, in a
day or two, round the globe, and remained suspended for months in the
atmosphere. The spores of many cryptogamous plants are even lighter
than volcanic dust. Had the Egyptian embalmer used some of the first
created specimens of _Evernia furfuracea_, it might easily, within the
three thousand years or so since his work was done, have floated round
the world and established itself on the White Hills. But, as we shall
see, neither the time nor means would suffice for the flowering plants.
The only available present agency for the transmission of these would
be in the crops or the plumage of the migratory birds; and when we
consider how few of these, on their migrations from the north, could
ever alight on these hills, and the rarity of their carrying seeds in
a state fit to vegetate, and further, that few of these plants produce
fruits edible by birds, or seeds likely to attach themselves to their
feathers, the chances become infinitely small of their transmission in
this way. The most profitable course of investigation in this and most
other cases of apparently unaccountable geographical distribution, is
to inquire as to the past geological conditions of the region, and how
these may have affected the migrations of plants.

The earlier geological history of these mountains far antedates our
existing vegetation. It belongs, in the first instance, to the Archæan
and early Palæozoic period, in which the materials of these mountains
were accumulating, as beds of clay and gravel, in the sea bottom. These
were buried under great depths of newer deposits, and were folded
and crumpled by lateral pressure, baked and metamorphosed into their
present crystalline condition.[195] Again heaved above the sea level,
they were hewn by the action of the waves to some degree into their
present forms, and constituted part of the nucleus of the American
continent in the later Tertiary period, when they were probably higher
than now. They were again, with all the surrounding land, depressed
under the sea in the Pleistocene period, and in the Post-glacial or
modern, slowly upheaved again to their present height. These last
changes are those that concern their present flora, and their relations
to it are well stated by Sir C. Lyell in the following passages from
his interesting account of his ascent of Mount Washington in 1840.

[195] While the mass of the White Mountains is probably older than the
Silurian, there are beds of mica schist which contain corals of the
genus Halysites, and stems of large crinoids.

"If we attempt to speculate on the manner in which the peculiar
species of plants now established on the highest summits of the White
Mountains were enabled to reach those isolated spots, while none of
them are met with in the lower lands around, or for a great distance
to the north, we shall find ourselves trying to solve a philosophical
problem which requires the aid, not of botany alone, but of geology,
or a knowledge of the geographical changes which immediately preceded
the present state of the earth's surface. We have to explain how
an Arctic flora, consisting of plants specifically identical with
those which inhabit lands bordering the sea in the extreme north of
America, Europe and Asia, could get to the top of Mount Washington.
Now geology teaches us that the species living at present on the earth
are older than many parts of our existing continents; that is to say,
they were created before a large portion of the existing mountains,
valleys, plains, lakes, rivers, and seas were formed. That such must
be the case in regard to Sicily I announced my conviction in 1833,
after first returning from that country; and a similar conclusion
is no less obvious to any naturalist who has studied the structure
of North America, and observed the wide area occupied by the modern
or glacial deposits, in which marine shells of living but northern
species are entombed. It is clear that a great portion of Canada, and
the country surrounding the great lakes, was submerged beneath the
ocean when recent species of molluska flourished, of which the fossil
remains occur about 500 feet above the level of the sea at Montreal.
Lake Champlain was a gulf or strait of the sea at that period, large
areas in Maine were under water, and the White Mountains must then
have constituted an island or group of islands. Yet, as this period
is so modern in the earth's history as to belong to the epoch of the
existing marine fauna, it is fair to infer that the Arctic flora, now
contemporary with this, was then also established on the globe.

"A careful study of the present distribution of animals and plants
over the globe has led nearly all the best naturalists to the opinion
that each species had its origin in a single birthplace, and spread
gradually from its original centre to all accessible spots fit for its
habitation, by means of the powers of migration given to it from the
first. If we adopt this view, or the doctrine of specific centres,
there is no difficulty in comprehending how the _Cryptogamous_ plants
of Siberia, Lapland, Greenland and Labrador scaled the heights of Mount
Washington, because the sporules of the fungi, lichens and mosses may
be wafted through the air for indefinite distances, like smoke; and,
in fact, heavier particles are actually known to have been carried
for thousands of miles by the wind. But the cause of the occurrence
of Arctic plants of the _Phænogamous_ class on the top of the New
Hampshire Mountains, specifically identical with those of remote polar
regions, is by no means so obvious. They could not in the present
condition of the earth effect a passage over the intervening lowlands,
because the extreme heat of summer and cold of winter would be fatal to
them. We must suppose, therefore, that originally they extended their
range in the same way as the plants now inhabiting Arctic and Antarctic
lands disseminate themselves. The innumerable islands in the polar seas
are tenanted by the same species of plants, some of which are conveyed
as seeds by animals over the ice, when the sea is frozen in winter,
or by birds; while a still larger number are transported by floating
icebergs and field ice, on which soil containing the seeds of plants
may be carried in a single year for hundreds of miles. A great body of
geological evidence has now been brought together to show that this
machinery for scattering plants, as well as for carrying erratic blocks
southward, and polishing and grooving the floor of the ancient ocean,
extended in the western hemisphere to lower latitudes than that of the
White Mountains. When these last still constituted islands, in a sea
chilled by the melting of floating ice, we may assume that they were
covered entirely by a flora like that now confined to the uppermost or
treeless region of the mountains, except in such portions of the period
as were sufficiently cold to clothe their summits permanently in snow.
As the continent grew by the slow upheaval of the land, and the islands
gained in height, and the climate around these hills grew milder, the
Arctic plants would retreat to higher zones, and finally occupy an
elevated area, which probably had been, at first, or in the Glacial
period, always covered with perpetual snow. Meanwhile the newly formed
plains around the base of the mountain, to which northern species of
plants could not spread, would be occupied by others migrating from
the south, and perhaps by many trees, shrubs, and plants, then first
created, and remaining to this day peculiar to North America."

The time to which the above views of Sir. C. Lyell would refer the
migration of the White Mountain flora, is historically, very remote.
The changes of level which have submerged the American continent and
re-elevated its land have occupied long periods. Whether, with Lyell,
we measure these periods by the recession of the Falls of Niagara,
or by the growth of the alluvial plain of the Mississippi; or, with
Agassiz, by the extension of the peninsula of Florida, or endeavour to
estimate the time required for the abrasion and deposition of the great
mass of clay that fills the valley of the St. Lawrence, and allowing
for the reductions of the antiquity of the Glacial period arising from
recent observations and calculations, we cannot suppose that less than
8,000 or 10,000 years have elapsed since the Alpine plants of the White
Mountains were cut off from all connection with their Arctic relatives.
Their reign upon the mountain tops not only antedates all human
dynasties, but probably reaches beyond the creation of man himself, and
many of his contemporaries.

Positive evidence of the existence of some of these plants during a
large portion of this lapse of time has actually been preserved in
the Pleistocene deposits of Canada. At Green's Creek, on the Ottawa,
in nodules in the clay containing marine shells, and coeval with the
Leda clay of Montreal, there are numerous remains of plants that have
been embedded in this clay at a time when the Ottawa valley was a bay
or estuary, and when the Adirondack Mountains of New York and the
mountains of New England were two rocky islands, separated from each
other and from the mainland on the north by wide arms of the sea. The
plants found in these nodules all appear to be of modern species.
Several of these plants are found on the White Mountains, and they are
all northern or boreal, but scarcely Arctic, belonging as they do to
the southern margin of the Arctic land species. I have no doubt that
further examination of these deposits will lead to the discovery of
additional examples. This fact, proving as it does the existence of
these species at the period in which the theory of Lyell and Forbes
requires them to have migrated, is in itself strong corroborative
evidence. We can say that some of these species were waiting on the
shores of the north, ready to be drifted to the insular spots to the
south-west, and that their seeds were actually being washed out to sea
by the streams which emptied themselves into the then estuary of the
Ottawa.

Another aspect of the inquiry is that which relates to the reduction of
temperature, which might be consequent on the great depression of the
land which we know to have existed at the close of the Tertiary period,
a fact on which I have insisted in former papers on the Pleistocene
deposits of Canada.[196] A very clever writer on the subject of
geographical distribution[197] has pictured the case of a subsiding
continent, with the fauna and flora of its lowlands becoming gradually
concentrated on the spots which had previously been Alpine summits, but
now reduced to low and temperate islands. But he has left out of view
the fact, that if land still existed in mass in the Arctic regions, and
if the subsidence was that of land in temperate regions, and if the
remaining islands were encompassed with cold and ice-laden currents,
then, on the principles long ago so well stated by Sir C. Lyell, these
islands might have a mean temperature far below that of the former
plains, and might, in consequence, be suitable only to such an Alpine
flora as that which they had previously borne.

[196] _Canadian Naturalist_, vol. iv.

[197] Wollaston.

Now this is precisely what seems to have occurred in the Pleistocene
period. The Arctic land remained in great mass, detaching into the sea
annual crops of icebergs and fields of coast ice, which have strewed
all the northern hemisphere with boulders: the temperate regions were
submerged, except a few insular spots. These are the very conditions
required for a low mean temperature, both in the sea and on the land,
and these geographical conditions correspond precisely with the facts
as indicated by the fossil animals and plants of the period. We must
bear in mind, however, that under certain contingencies the high
mountain summits might have been clad in snow and ice, like Greenland,
and the Alpine plants might have been able to live only on their
margins.

Further, it would be easy to show that the Alpine plants of Mount
Washington would thrive under such conditions as those supposed, at
the sea level; a low and equable temperature, with a moist atmosphere,
being that which they most desire, and their greatest enemy being the
dry parching heat of the plains of the temperate regions. Those of
them, such as _Potentilla tridentata_ and _Alsine Grœnlandica_, which
occur in low ground within the limits of the United States, are found
under shaded woods, in damp ravines, or on the moist sea-coast; and
as we follow the coasts northward, we find these plants, on these and
on neighbouring islands, in lower latitudes than those in which they
occur inland. This is well seen in Northern New Brunswick and in the
south shore of the St. Lawrence, where several northern species occur
in shady and moist localities. I have, for example, collected _Cornus
Suecica_ and the Alpine birch in such places. When the summer mists
roll around the summit of Mount Washington, it is in every respect the
precise counterpart of an islet anywhere on the coast of America, from
Cape Breton to the Arctic seas, and when winter wraps everything in
a mantle of snow, all these lands are in like manner under the same
conditions. So, in the Pleistocene period, though the islets of the
White Mountains may have experienced a less degree of winter cold, they
must have had very nearly the same summer temperature as now; and as
this is the season of growth for our Alpine and Arctic plants, it is
its character that determines the suitableness of the locality to them.

Those stupendous vicissitudes of land and water which have changed the
aspect of continents, and swept into destruction races of gigantic
quadrupeds, have dealt gently with these Alpine plants, which long
ages ago looked out upon a waste of ice-laden waters that had engulfed
the Pliocene land with all its inhabitants, as securely as they now
look down upon the pleasant valleys of New England. It is curious, too,
that the humbler tenants of the sea have shared a similar exemption. In
the clay banks of the Saco, on the shores of Lake Champlain, and mixed
with the remains of these very plants in the valley of the Ottawa, are
shells that now live in the Gulf of St. Lawrence and on the coast of
Maine, intermixed with other species that are now found only in a few
bays of the Arctic seas. Just as in the Post-pliocene clays of the
Ottawa, the remains of northern plants are found in the same nodule
with those of _Leda glacialis_, so now similar associations maybe
taking place on the coasts at the mouth of the Great Fish River. Truly,
in nature as in grace, God hath chosen the weak things of the world to
confound those that are mighty, and has left in the earth's geological
history, monuments of His respect and regard for the humblest of His
works.

It is interesting to notice here that Greenland, at the present time,
presents conditions as to vegetation which may, in some respects,
correspond to those of the White Mountains in Pleistocene times. Its
flora, though altogether Arctic, contains 386 species, none of which
are peculiar to it, but many of them range quite round the Polar
circle. Of those that are not so generally distributed, some, more
especially on the west coast, are common to Greenland and Arctic
America. Others, and a larger number, more especially on the east
coast, are common to Greenland, Iceland and Norway, between which and
Greenland there may have been a closer land connection than now, in
Pliocene and Post-glacial times.

We look in vain among the Alpine plants, so long isolated in these
mountains, for any evidence of decided change in specific characters.
The Alpine plants, for ages separated from their Arctic brethren,
are true to their kinds, and show little tendency to vary, and none
to adapt themselves to new forms in the sunny plains below. This is
especially noteworthy on Mount Washington and the neighbouring peaks,
because the soil of these is the same with that of the valleys.
Several of the plants peculiar to these hills, as the black crowberry
(_Empetrum nigrum_), for instance, even when other conditions are
favourable, shun rich calcareous soils, and affect those of granitic
origin. In many cases the difference in soil is a sufficient reason for
the non-occurrence of such plants, except on certain hills. At Murray
Bay, and on the shores of Lake Superior, the plant above named occurs
only on the Laurentian gneiss. In Nova Scotia, its relative, _Corema
Conradi_, is confined to the granite barrens of the south coast. Many
such plants skirt the whole Laurentian range from Labrador to Lake
Superior, but refuse to extend themselves over the calcareous plains
of Canada. But in the White Hills the soil of the river alluvium is
the same micaceous sand that fills the crevices of the rocks in the
mountains, and hence there is no obstruction, in so far as soil is
concerned, to the diffusion of plants upward and downward in the hills.
In like manner there is every possible condition as to moisture and
dryness, sunshine and shade, in both localities. These circumstances
are of all others the most favourable to such variation as these plants
are capable of undergoing. The case is the same with that which Hugh
Miller so strongly puts in relation to the species of algæ that occur
at different distances below high water mark on the coast of Scotland,
each species there attaining a certain limit, and then, instead of
changing to suit the new conditions, giving place to another. So it is
on Mount Washington; and this, whether we regard the lowland plants
that climb to a certain height, and there stop, the plants that are
common to the base and summit, or the plants that are confined to the
latter.

I have already referred to the evident struggle of the spruces and
firs, and the plants associated with them, to ascend the mountain,
and the same remark applies to all the plants that one after another
cease to appear at various heights from the lower valleys. One by one
they become stunted and depauperated, and then cease, without any
semblance of an attempt to vary into new and hardier forms. And this
must have been proceeding, be it observed, from all those thousands
of years that have elapsed since the elevation of the mountains out
of the glacial seas. It is to be observed, also, that the new plants
that occur in ascending, often belong to different genera and families
from those left behind, not to closely allied species; and in the few
cases in which this last kind of change occurs, there is no graduation
into intermediate forms. For instance, _Solidago thyrsoidea_ and _S.
virga-aurea_[198] occur around the base of the mountain, and for some
distance up its sides. At the height of four to five thousand feet the
latter only remains, and this in a dwarfish condition. This corresponds
to its distribution elsewhere, for, according to Richardson, it occurs
in lat. 55° to 65° in Arctic America, and according to Hooker, it is
found in the Rocky Mountains, while it also occurs in the hills of
Scotland, and very abundantly in some parts of Norway. In the White
Mountains _S. thrysoidea_ prevails toward the base, _S. virga-aurea_
toward the summit; and at the top of Tuckerman's ravine I found the
former of these golden rods in blossom, within a few hundred feet of
the latter, each preserving its distinctive peculiarities. Much has
lately been said of the appearance of specific diversity that results
from the breaking up of the continuity of the geographical areas of
plants by geological changes; but here we probably have the converse
of this. The mountain species is no doubt a part of the older Arctic
flora, the other perhaps belong to a more modern flora, and they have
met on the sides of the White Hills.

[198] Macoun thinks that most of the specimens referred to this species
belong to the allied form, _S. Mulllinallata_, Ast, which is very
extensively distributed on the mountains of British America and in the
Arctic regions.

Some hardy species climb from the plains to heights of 5,000 feet
or more, with scarcely even the usual change of being depauperated,
and then suddenly disappear. This is very noteworthy in the case
of two woodland plants, the dwarf cornel or pigeon-berry (_Cornus
Canadensis_), and the twin-flower (_Linnæa borealis_). The former of
these is a plant most widely distributed over northern America, and
probably belongs to that newer flora which overspread the continent
after its re-elevation. In August this plant in the woods around
the base of Mount Washington is loaded with its red berries. At an
elevation of four to five thousand feet it may be found in bloom; above
this a few plants appear, destitute of flowers, dwarfish in aspect,
and nipped by cold, and then the species disappears. No doubt the
birds that feed on its little drupes have carried it up the mountain,
and have sown it a little farther up than the limit of its probable
reproductiveness. The beautiful little _Linnæa_ is a still more widely
distributed plant; for it occurs on the hills of northern Europe,
and is found across the whole breadth of the American continent from
Nova Scotia to the Columbia River. It is almost beyond question a
member of the old Arctic flora which colonized the islands of the
Pleistocene sea, and 'has descended from them on all sides as the land
became elevated. This plant also climbs Mount Washington to a height
of 5,000 feet, and presents precisely the same characters on the top
as at the bottom, only losing a little in the length of its stem.
Specimens bearing blossoms, and quite in the same stage of growth,
may be collected at the same time on the highest shoulders of Mount
Washington, and on the flats at Gorham. The _Linnæa_ in this is true to
its designation. For, as if it belonged to it to support the reputation
of the great systematist after whom it is named, it preserves its
specific characters with scarcely a tittle of change throughout all its
great range. One cannot see this hardy little survivor of the Glacial
period, so unchanging yet so gentle, so modest yet so adventurous,
so wide in its migrations yet so choice in the selection of the mossy
nooks which it adorns with its pendant bells, and renders fragrant with
its delicious perfume, without praying that we might, in these days
of petty distinctions and narrow views, be favoured with more such
minds as that of the great Swede, to combine the little details of the
knowledge of natural history into grand views of the unity of nature.

Another plant which, being less dependent on shade and shelter than the
_Linnæa_, mounts still higher, is the cowberry or foxberry (_Vaccinium
vitis-Idæa_). This, also, is both European and American, and is
probably a survivor of the Pleistocene period. It still occurs in at
least one locality in the low country of Massachusetts, and on the
coast of Maine. It is found along the granitic coast of Nova Scotia,
and extends thence northward to the Arctic circle, being found at Great
Bear Lake and at Unalaska. This, too, is a most unchanging species,
and the same statement may be made respecting the cloudberry (_Rubus
Chamæmorus_), the black crowberry (_Empetrum nigrum_), the Labrador
tea (_Ledum latifolium_), the three-toothed cinquefoil (_Potentilla
tridentata_), which grows on the coast of Nova Scotia, and is found in
the nodules of the Ottawa clay, the same in every detail as on Mount
Washington, the bog bilberry (_Vaccinium uliginosum_), and the dwarf
bilberry (_V. cæspitosum_). Several of these, too, it will be observed,
are berry-bearing plants, whose seeds must be deposited in all kinds of
localities by birds. Yet they never occur in the warm plains, nor do
they show much tendency to vary in the distant and somewhat dissimilar
places in which they occur. In the case of most of these species, the
most careful comparison of specimens from Mount Washington with those
from Labrador, shows no tittle of difference. When we consider the
vast length of time during which such species have existed, and the
multiplied vicissitudes through which they have passed, one is tempted
to believe that it is the tendency of the "struggle for existence" to
confirm and render permanent the characters of species rather than to
modify them.

Of the more specially Arctic plants which have held their ground
unchanged on Mount Washington, the following are some of the principal.
_Diapensia Lapponica_, in beautiful deep green tufts, ascends quite
to the summit. It occurs also in the Adirondack Mountains, on Mount
Katahdin, in Maine, and on the summit of Mount Albert, Gaspé (Macoun).
It is found in Labrador, and, according to Hooker, extends north to
Whale Island, in the Arctic seas; but it is not found west of the
Great Fish River. It occurs also on the mountains of Lapland, and
is described as the hardiest plant of that bleak region. _Arenaria_
(_Alsine_) _Grænlandica_, the Greenland sand-wort, adorns with its
clusters of white flowers every sandy crevice in the rocks of the very
summit of Mount Washington, and is trodden under foot like grass by
the hundreds of careless sightseers that haunt that peak in summer;
though I should add, that not a few of them carry off little tufts as
a memento of the mountains, along with the fragments of mica which
appear to form the ordinary keepsakes of unscientific visitors. It
is a most frail and delicate plant, seemingly altogether unsuited to
the dangerous pre-eminence which it seeks, yet it loves the bare,
unsheltered mountain peaks, and when it occurs in the more sheltered
ravines, has only its stems a little longer and more slender. It occurs
on the Adirondack Mountains and on Katahdin, where, if I may judge from
specimens kindly sent to me by Prof. Goodale, it attains to smaller
dimensions than on Mount Washington, on the Catskills, and at one place
on the sea coast of Maine. I have not seen it in Nova Scotia, but it
ranges north to Greenland.

Another of the truly Arctic plants is the alpine azalea (_Loiseleuria
procumbens_), a densely tufted mountain shrub, with hard glossy
leaves, that look as if constructed to brave extremest hardships. It
is found on the mountains of Norway, at the height of 3,550 feet on
the Scottish hills, according to Watson, and according to Fuchs, at
the height of 7,000 feet in the milder climate of the Venetian Alps.
In America it is found in Newfoundland, in Labrador, at 4,000 feet on
Mount Albert, Gaspé,[199] and in the barren grounds from lat. 65 to the
extreme Arctic islands. Gray does not mention its occurrence elsewhere
in the United States than the summits of the White Mountains. A member
of the same family of the heaths, the yew-leaved phyllodoce (_P.
taxifolia_), presents a still more singular distribution. It is found
on all the higher mountains of New England and New York, and occurs
also on the mountains of Scotland and Scandinavia, but its only known
station in northern America is, according to Hooker, in Labrador. As
many as nine or ten of the Alpine plants of the White Mountains belong
to the order of the Heaths (Ericaceæ). Another example from this
order is _Rhododendron Lapponicum_, a northern European species, as
its name indicates, and scattered over all the high mountains of New
England and New York, occurring also in Labrador, on the Arctic sea
coasts, and the northern part of the Rocky Mountains, and at 4,000 feet
on Mount Albert, Gaspé (Macoun).

[199] Macoun.

It would be tedious to refer in detail to more of these plants, but I
must notice two herbaceous species belonging to different families,
but resembling each other in size and habit the Alpine epilobium (_E.
alpinum_ or _alsinefolium_), and the Alpine speedwell (_Veronica
alpina_). Both are in the United States confined to the highest
mountain tops. Both occur as alpine northern plants in Europe, being
found on the Alps, on the Scottish Highlands, and in Scandinavia. Both
are found in Labrador and on the Rocky Mountains, and the Veronica
extends as far as Greenland. The Alpine epilobium is one of the few
White Mountain plants that have attained the bad eminence of being
regarded as doubtful species. Gray notes as the typical form, that with
obtuse and nearly entire leaves, and as a variety, that with acute and
slightly toothed leaves, which some other botanists seem to regard
as distinct specifically. Thus we find that this little plant has
been induced to assume a suspicious degree of variability; yet it is
strange that both species or varieties are found growing together, as
if the little peculiarities in the form of the leaves were matters of
indifference, and not induced by any dire necessities in the struggle
for life. Facts of this kind are curious, and not easily explained
under the supposition either of specific unity or diversity. For why
should this plant vary without necessity? and why should two species so
much alike be created for the same locality? Perhaps these two species
or varieties, wandering from far distant points of origin, have met
here fortuitously, while the lines of migration have been cut off by
geological changes; and yet the points of difference are too constant
to be removed, even after the reason for them has disappeared. If this
could be proved, it would afford a strong reason for believing the
existence of a real specific diversity in these plants.

I have said nothing of the grasses and sedges of these mountains; but
one of them deserves a special notice. It is the Alpine herd's grass
(_Phleum alpinum_), a humble relation of our common herd's grass. This
plant not only occurs on the White Mountains, in Arctic America, in
the Canadian Mountains, from the summit of Mount Albert, in Gaspé, to
the mountains of British Columbia, and on the hills of Scotland and
Scandinavia, but has been found on the Mexican Cordillera and at the
Straits of Magellan. The seeds of this grass may perhaps be specially
suited for transportation by water, as well as by land. It is observed
in Nova Scotia that when the wide flats of mud deposited by the tides
of the Bay of Fundy, are dyked in from the sea, they soon become
covered with grasses and carices, the seeds of which are supposed to be
washed down by streams and mingled with the marine silt; and fragments
of grasses abound in the Post-tertiary clays of the Ottawa.

It seems almost ridiculous thus to connect the persistence of the
form of a little plant with the subsidence and elevation of whole
continents, and the lapse of enormous periods of time. Yet the Power
which preserves unchanged from generation to generation the humblest
animal or plant, is the same with that which causes the permanence
of the great laws of physical nature, and the continued revolutions
of the earth and all its companion spheres. A little leaf, entombed
ages on ages ago in the Pleistocene clays of Canada, preserves in all
its minutest features the precise type of that of the same species as
it now lives, after all the prodigious geological changes that have
intervened. An Arctic and Alpine plant that has survived all these
changes maintains, in its now isolated and far removed stations, all
its specific characters unchanged. The flora of a mountain top is
precisely what it must have been when it was an island in the glacial
seas. These facts relate not to hard crystalline rocks that remain
unaltered from age to age, but to little delicate organisms that
have many thousands of times died and been renewed in the lapse of
time. They show us that what we call a species represents a decision
of the unchanging creative will, and that the group of qualities
which constitutes our idea of the species goes on from generation
to generation animating new organisms constructed out of different
particles of matter. The individual dies, but the species lives, and
will live until the Power that has decreed its creation shall have
decreed its extinction; or until, in the slow process of physical
change depending on another section of His laws, it shall have been
excluded from the possibility of existence anywhere on the surface of
the earth, unless we suppose with modern evolutionists that there is
a possibility of these plants so changing their characters that in the
lapse of ages they might appear to us to be distinct specific types.
The fact, however, that the Arctic species have migrated around the
whole Arctic circle, and have advanced southward and retreated to the
north, again and again, without changing their constitutions or forms,
augurs for them at least a remarkable fixity as well as continuity.

While the huge ribs of mother earth that project into mountain summits,
and the grand and majestic movement of the creative processes by which
they have been formed, speak to us of the majesty of Him to whom the
sea belongs, and whose hand formed the dry land, the continuance of
these little plants preaches the same lessons of humble faith in the
Divine promises and laws, which our Lord drew from the lilies of the
field.

It is suggestive, in connection with the antiquity and migrations of
these plants, to consider the differences in this respect of some
closely allied species of the same genera. Of the blueberries that
grow on the White Mountains, one species, _Vaccinium uliginosum_,
is found in Behring's Straits and very widely in Arctic and boreal
America,[200] also in northern Europe. _V. cæspitosum_ has a wide
northern range in America, but is not European. _V. Pennsylvanicum_ and
_V. Canadense_, from their geographical distribution, do not seem to
belong to the Arctic flora at all, but to be of more southern origin.
The two bearberries (_Arctostaphylos uva-ursi_ and _alpina_) occur
together on the White Hills, and on the Scottish and Scandinavian
mountains; but the former is a plant of much wider and more southern
distribution in America than the latter. Two of the dwarf willows of
the White Mountains (_Salix repens_ and _S. herbacea_) are European as
well as American, but _S. uva-ursi_ seems to be confined to America.
_Rubus triflorus_, the dwarf raspberry, and _R. chamæmorus_, the cloud
berry, climb about equally high on Mount Washington; but the former
is exclusively American, and ranges pretty far southward, while the
latter extends no farther south than the northern coast of Maine,
and is distributed all around the Arctic regions of the Old and New
Worlds. It is to be observed, however, that the former can thrive on
rich and calcareous soils, while the latter loves those that are barren
and granitic; but it is nevertheless probable that _R. triflorus_
belongs to a later and more local flora. Similar reasons would induce
the belief that the American dwarf cornel or pigeon-berry (_Cornus
Canadensis_), whose distribution is solely American, and not properly
Arctic, is of later origin than the _C. Suecica_,[201] which occurs in
northern America locally, and is extensively distributed in northern
Europe.

[200] Macoun, Catalogue of Canadian plants.

[201] I have found _C. Suecica_ growing along with _C. Canadensis_ in
shaded and northern exposures on the south side of the St. Lawrence,
near Caconna and Metis. Its seeds may have been brought over from
Labrador by migratory birds.

I can but glance at such points as these; but they raise great
questions which are to be worked out, not merely by the patient
collection of facts, but by a style of scientific thought very much
above those which, on the one hand, escape such problems by the
supposition of multiplied centres of creation, or on the other,
render their solution worthless by confounding races due to external
disturbing causes with species originally distinct. Difficulties of
various kinds are easily evaded by either of these extreme views; but
with the fact before him of specific diversity and its manifestly long
continuance, on the one hand, and the remarkable migrations of some
species on the other, the true naturalist must be content to work out
the problems presented to him with the data afforded by the actual
observation of nature, following carefully the threads of guidance
thus indicated, not rudely breaking them by too hasty generalizations.

But it is time to leave the scientific teachings of our little Alpine
friends, and to inquire if they can teach anything to the heart as well
as to the head.

The mountains themselves, heaving their huge sides to the heavens,
speak of forces in comparison with which all human power is nothing;
and we can scarcely look upon them in their majesty without a psalm
of praise rising up within us to Him who made the sea, and from whose
hands the dry land took its form. As we ascend them, and as our vision
ranges more and more widely over the tops of wooded hills, along the
courses of streams, over cultivated valleys, and to the shores of the
blue sea itself, our mental vision widens too. We think that the great
roots of these hills run beneath a whole continent, that their tops
look down on the wide St. Lawrence plain, on the beautiful valleys of
New England, and on the rice fields of the sunny south. We are reminded
of the brotherhood of man, which overleaps all artificial boundaries,
and should cause us to pray that throughout their whole extent these
hills may rise amidst a happy, a free, and a God-fearing people.

Our Alpine plants have still higher lessons to teach. They are fitting
emblems of that little flock, scattered everywhere, yet one in heart,
and in all lands having their true citizenship in heaven. They tell us
that it is the humble who are nearest God, and they ask why we should
doubt the guardian care of the Father who cares for them. They witness,
too, of the lowly and hidden ones who may inhabit the barren and lowly
spots of earth, yet are special subjects of God's love, as they should
be of ours. We may thus read in the Alpine plants truths that beget
deeper faith in God, and closer brotherhood with His people.

The history of these plants has also a strange significance. It might
have been written of them, "Though the dry land be removed out of its
place, and the mountains cast into the midst of the sea, yet the Lord
will not forsake the work of His hands"; for this has been literally
their history. In this they hold forth an omen of hope to the people of
God in that once happy land through which these hills extend, and who
now mourn the evil times on which they have fallen. The mountain plants
may teach them that though the floods of strife should rise even to the
tops of the hills, and leave but scattered islets to mark the place of
a united land, their rock is sure, and their prayers will prevail.[202]
The power that has waked the storm is after all their Father's hand.
For years a cry has risen high above these hills: the cry of the
bondman who has reaped the fields and received no hire. That cry is
sure to be heard in heaven, whatever other prayers may go unanswered.
An apostle tells us that it enters directly into the ears of the God
of Sabaoth, and is potent to call down the day of slaughter on the
proud ones of earth. The prayer of the slave has been answered; and the
tempest is abroad, sweeping away his oppressors and their abettors. Yet
God rules in all this, and those whom He has chosen will be spared,
even like the hardy plants of the hill tops, to look again on a renewed
and smiling land, from which many monsters and shapes of dread have for
ever passed away.

[202] This paper was originally written at the time when the American
Civil War was raging.

But last of all, the Alpine flowers have a lesson that should come
near to all of us individually. They tell us how well natural law is
observed, as compared with moral. Obeying with unchanging fidelity the
law of their creation, they have meekly borne the cold and storms of
thousands of winters, yet have thankfully expanded their bosoms to the
returning sun of every summer, and have not once forgot to open their
tiny buds, and bring forth flowers and fruit, doing thus their little
part to the glory of their Maker and ours. How would the moral wastes
of earth rejoice and be glad, did the sunshine of God's daily favours
evoke a similar response from every human heart!

  References:--Paper on Destruction and Renewal of Forests in North
    America, _Edinburgh Philosophical Journal_, 1847-8. Alpine and
    Arctic Plants, _Canadian Naturalist_, 1862. "The Geological History
    of Plants," International Scientific Series, 2nd edition, 1891.
    "The Pleistocene Flora of Canada," Dawson and Penhallow, _Bulletin
    American Geological Society_, 1890. Papers on Pleistocene Climate
    of Canada, _Canadian Naturalist_, 1857 to 1890.




                             _EARLY MAN._


                  DEDICATED TO THE MEMORY OF THE LATE

                  SIR DANIEL WILSON, LL.D., F.R.S.E.,

                       a dear and valued Friend,

         and one of the most eminent and judicious Students of

             Pre-historic Man both in Europe and America.


Summary of the Story of Early Man--Classification of Tertiary
Time--Probabilities as to the Introduction of Man--The Anthropic Age As
Distinguished from the Pleistocene--Its Division into Palanthropic and
Neanthropic--Sketches of Palanthropic Man and His Immediate Successors

[Illustration: Four Pre-historic Skulls. (p. 472.)

Outer outline, _Cromagnon_; second, _Engis_; third, _Cannstadt_;
fourth, _Canadian Hochelagan_ on smaller scale.]




CHAPTER XVII.

_EARLY MAN._


The science of the earth has its culmination and terminus in man; and
at this, the most advanced of our salient points, as we look back on
the long process of the development of the earth, we may well ask,
Was the end worthy of the means? We may well have doubts as to an
affirmative answer if we do not consider that the means were perfect,
each in its own time, and that man, the final link in the chain of
life, is that which alone takes hold of the unseen and eternal. He
alone can comprehend the great plan, and appreciate its reason and
design. Without his agency in this respect nature would have been a
riddle without any solution--a column without a capital, a tree without
fruit. Besides this, even science may be able to perceive that man may
be not merely the legatee of all the ages that lie behind, but the
heir of the eternity that lies before, the only earthly being that has
implanted in him the germ and instinct of immortality.

Whatever view we may take of these questions, it is of interest to us
to know, if possible, how and when this chief corner stone was placed
upon the edifice of nature, and what are the precise relations of
man to the later geological ages, as well as to the present order of
nature, of which he is at once a part, and its ruler and head. Let us
put this first in the form of a narrative based on geological facts
only, and then consider some of its details and relations to history.

The Glacial age had passed away. The lower land, in great part a bare
expanse of mud, sand, and gravel, had risen from the icy ocean in
which it had been submerged, and most of the mountain tops had lost
their covering of perennial snow and ice. The climate was ameliorated,
and the sun again shone warmly on the desolate earth. Gradually the
new land became overspread with a rich vegetation, and was occupied
by many large animals. There were species of elephant, rhinoceros,
hippopotamus, horse, bison, ox and deer, multiplying till the plains
and river valleys were filled with their herds, in spite of the fact
that they were followed by formidable carnivorous beasts fitted to prey
on them. At this time, somewhere in the warm temperate zone, in an
oasis or island of fertility, appeared a new thing on the earth, a man
and woman walking erect in the forest glades, bathing in the waters,
gathering and tasting every edible fruit, watching with curious and
inquiring eyes the various animals around them, and giving them names
which might eventually serve not merely to designate their kinds, but
to express actions and emotions as well. When, where, and how did this
new departure, fraught with so many possibilities, occur--introducing
as it did the dexterous fingers and inventive mind of Man upon the
scene? The last of these questions science is still unable to answer,
and though we may frame many hypotheses, they all remain destitute of
certain proof in so far as natural science is concerned. We can here
only fall back on the old traditional and historical monuments of
our race, and believe that man, the child of God, and with God-like
intellect, will, and consciousness, was placed by his Maker in an
Edenic region, and commissioned to multiply and replenish the earth.
The when and where of his introduction, and his early history when
introduced, are more open to scientific investigation.

That man was originally frugivorous, his whole structure testifies.
That he originated in some favourable climate and fertile land is
equally certain, and that his surroundings must have been of such a
nature as to give him immunity from the attacks of formidable beasts
of prey, also goes without saying. These are all necessary conditions
of the successful introduction of such a creature as man, and theories
which suppose him to have originated in a cold climate, to struggle at
once with the difficulties and dangers of such a position, are, from a
scientific point of view, incredible.

But man was introduced into a wide and varied world, more wide and
varied than that possessed by his modern descendants. The earliest
men that we certainly know inhabited out continents in the second
Continental age of the Kainozoic Period, when, as we know from ample
geological evidence, the land of the northern hemisphere was much more
extensive than at present, with a mild climate, and a rich flora and
fauna. If he was ambitious to leave the oasis of his origin the way
was open to him, but at the expense of becoming a toiler, an inventor,
and a feeder on animal food, more especially when he should penetrate
into the colder climates. The details of all this, as they actually
occurred, are not within the range of scientific investigation, for
these early men must have left few, if any, monuments; but we can
imagine some of them. Man's hands were capable of other uses than the
mere gathering of fruit. His mind was not an instinctive machine, like
that of lower animals, but an imaginative and inventive intellect,
capable of adapting objects to new uses peculiar to himself. A fallen
branch would enable him to obtain the fruits that hung higher than his
hands could reach, a pebble would enable him to break a nut too hard
for his teeth. He could easily weave a few twigs into a rough basket to
carry the fruit he had gathered to the cave or shelter, or spreading
tree, or rough hut that served him for a home; and when he had found
courage to snatch a brand from some tree, ignited by lightning, or by
the friction of dry branches, and to kindle a fire for himself, he
had fairly entered on that path of invention and discovery which has
enabled him to achieve so many conquests over nature.

Our imagination may carry us yet a little farther with reference to his
fortunes. If he needed any weapon to repel aggressive enemies, a stick
or club would serve his purpose, or perhaps a stone thrown from his
hand. Soon, however, he might learn from the pain caused by the sharp
flints that lay in his path the cutting power of an edge, and, armed
with a flint chip held in the hand, or fitted into a piece of wood, he
would become an artificer of many things useful and pleasing. As he
wandered into more severe climates, where vegetable food could not be
obtained throughout the year, and as he observed the habits of beasts
and birds of prey, he would learn to be a hunter and a fisherman,
and to cook animal food; and with this would come new habits, wants
and materials, as well as a more active and energetic mode of life.
He would also have to make new weapons and implements, axes, darts,
harpoons, and scrapers for skins, and bodkins or needles to make skin
garments. He would use chipped flint where this could be procured, and
failing this, splintered and rubbed slate, and for some uses, bone and
antler. Much ingenuity would be used in shaping these materials, and
in the working of bone, antler and wood, ornament would begin to be
studied. In the meantime the hunter, though his weapons improved, would
become a ruder and more migratory man, and in anger, or in the desire
to gain some coveted object, might begin to use his weapons against his
brother man. In some more favoured localities, however, he might attain
to a more settled life; and he, or more likely the woman his helpmate,
might contrive to tame some species of animals, and to begin some
culture of the soil.

It was probably in this early time that metals first attracted the
attention of men. The ages of stone, bronze, and iron believed in by
some archæologists, are more or less mythical to the geologist, who
knows that these things depend more on locality and on natural products
than on stages of culture. The analogy of America teaches us that the
use of different metals may be contemporaneous, provided that they can
be obtained in a native state. At the time of the discovery of America
the Esquimaux were using native iron, which, though rare in most parts
of the world, is not uncommon in some rocks of Greenland. The people of
the region of the great lakes, and of the valleys of the Mississippi
and Ohio, were using native copper from Lake Superior for similar
purposes. Gold was apparently the only metal among the natives of
Central America. The people of Peru had invented bronze, or had brought
the knowledge of it with them from beyond the sea. Thus the Peruvians
were in the bronze age, the Mexicans and Mound builders in the copper
age, and the Esquimaux in the iron age, while at the same time the
greater part of the aboriginal tribes were at one and the same time
in the ages of chipped and polished stone and in these ages what have
been called palæolithic and neolothic weapons were contemporaneous,
the former being most usually unfinished examples of the latter, or
extemporized tools roughly made in emergencies.[203] How long this
had lasted, or how long it would have continued, had not Europeans
introduced from abroad an iron age, we do not know. It was probably
the same in other parts of the world, in pre-historic times. In any
case, the discovery of native metals must have occurred very early.
Men searching in the beds of streams for suitable pebbles to form
hammers and other implements, would find nuggets of gold and copper,
and the properties of these, so different from those of other pebbles,
would at once attract attention, and lead to useful applications.
Native iron is of rarer occurrence, but in certain localities would
also be found.[204] It must have been experiments on these ores,
which resemble the native metals in colour, lustre and weight, that
led to the first attempts at smelting metals, and these must have
occurred at a very early period. Yet for ages the metals must have
been extremely scarce, and we know that in comparatively modern times
civilized nations like the Egyptians were using flint flakes after they
had domesticated many animals, had become skilful agriculturists and
artisans, and had executed great architectural works.

[203] "Fossil Men," by the Author. W. H. Holmes, "American
Anthropologist," 1890.

[204] The rarity of native iron, whether meteoric or telluric, and
its rapid decay by rusting, sufficiently account for its absence in
deposits where implements of stone and bone have been preserved.

Probably all these ends had been to some extent, and in some
localities, attained in the earliest human period, when man was
contemporary with many large animals now extinct. But a serious change
was to occur in human prospects. There is the best geological evidence
that in the northern hemisphere the mild climate of the earlier
Post-glacial period relapsed into comparative coldness, though not so
extreme as that of the preceding Glacial age. Hill tops, long denuded
of the snow and ice of the Glacial period, were again covered, and cold
winters sealed up the lakes and rivers, and covered the ground with
wintry snows of long continuance, and with this came a change in animal
life and in human habits. The old southern elephant (_E. antiquus_),
the southern rhinoceros (_E. leptorhinus_), and the river hippopotamus
(_H. major_), which had been contemporaries, in Europe at least,
of primitive man, retired from the advancing cold, and ultimately
perished, while their places were taken by the hairy mammoth (_E.
primigenius_), the woolly rhinoceros (_R. tichorhinus_), the reindeer,
and even the musk ox. Now began a fierce struggle for existence in
the more northern districts inhabited by man a struggle in which only
the hardier and ruder races could survive, except, perhaps, in some
of the more genial portions of the warm temperate zone. Men had to
become almost wholly carnivorous, and had to contend with powerful and
fierce animals. Tribe contended with tribe for the possession of the
most productive and sheltered habitats. Thus the struggle with nature
became aggravated by that between man and man. Violence disturbed the
progress of civilization, and favoured the increase and power of the
rudest tribes, while the more delicately organized and finer types of
humanity, if they continued to exist in some favoured spots, were in
constant danger of being exterminated by their fiercer and stronger
contemporaries.

In mercy to humanity, this state of things was terminated by a great
physical revolution, the last great subsidence of the continents--that
Post-glacial flood, which must have swept away the greater part of men,
and many species of great beasts, and left only a few survivors to
re-people the world, just as the mammoth and other gigantic animals had
to give place to smaller and feebler creatures. In these vicissitudes
it seemed determined, with reference to man, that the more gigantic and
formidable races should perish, and that one of the finer types should
survive to re-people the world.

The age of which we have been writing the history, is that which has
been fitly named the Anthropic, in that earlier part of it preceding
the great diluvial catastrophe, which has fixed itself in all the
earlier traditions of men, and which separates what may be called the
Palanthropic or Antediluvian age from the Neanthropic or Postdiluvian.
Independently altogether of human history, these are two geological
ages distinguished by different physical conditions and different
species of animals; and the time has undoubtedly come when all the
speculations of archæologists respecting early man must be regulated
by these great geological facts, which are stamped upon those later
deposits of the crust of the earth, which have been laid down since man
was its inhabitant. If they have only recently assumed their proper
place in the geological chronology, this is due to the great difficulty
in the case of the more recent deposits in establishing their actual
succession and relations to each other. These difficulties have,
however, been overcome, and new facts are constantly being obtained
to render our knowledge more definite. Lest, however, the preceding
sketch of the Palanthropic age--that in which gigantic men were
contemporaries of a gigantic fauna now extinct--should be regarded as
altogether fanciful, we may proceed to consider the geological facts
and classification as actually ascertained.

The Tertiary or Kainozoic period, the last of the four great "times"
into which the earth's geological history is usually divided, and
that to which man and the mammalia belong, was ingeniously subdivided
by Lyell, on the ground of percentages of marine shells and other
invertebrates of the sea. According to this method, which with some
modification in details is still accepted, the _Eocene_, or dawn of the
recent, includes those formations in which the percentage of modern
species of marine animals does not exceed 3-1/2, all the other species
found being extinct. The _Miocene_ (less recent) includes formations
in which the percentage of living species does not exceed 35, and the
_Pliocene_ (more recent) contains formations having more than 35 per
cent, of recent species. To these three may be added the _Pleistocene_,
in which the great majority of the species are recent, and the _Modern_
or Anthropic, in which we are still living. Dawkins and Gaudry give
us a division substantially the same with Lyell's, except that they
prefer to take the evidence of the higher animals instead of the marine
shells. The Eocene thus includes those formations in which there are
remains of mammals or ordinary land quadrupeds, but none of these
belong to recent species or genera, though they may be included in
the same families and orders with the recent mammals. This is a most
important fact, as we shall see, and the only exception to it is that
Gaudry and others hold that a few living genera, as those of the dog,
civet, and marten, are actually found in the later Eocene. The Miocene,
on the same mammalian evidence, will include formations in which there
are living genera of mammals, but no species which survive to the
present time. The Pliocene and Pleistocene show living species, though
in the former these are very few and exceptional, while in the latter
they become the majority.

With regard to the geological antiquity of man, no geologist expects
to find any human remains in beds older than the Tertiary, because
in the older periods the conditions of the world do not seem to have
been suitable to man, and because in these periods no animals nearly
akin to man are known. On entering into the Eocene Tertiary we fail
in like manner to find any human remains; and we do not expect to
find any, because no living species and scarcely any living genera
of mammals are known in the Eocene; nor do we find in it remains of
any of the animals, as the anthropoid apes, for instance, most nearly
allied to man. In the Miocene the case is somewhat different. Here we
have living genera at least, and we have large species of apes; but
no remains of man have been discovered, if we except some splinters
of flint found in beds of this age at Thenay, in France, and some
notched bones. Supposing these objects to have been chipped or notched
by animals, which is by no means certain in the case of the flints,
the question remains, Was this done by man? Gaudry and Dawkins prefer
to suppose that the artificer was one of the anthropoid apes of the
period. It is true that no apes are known to do such work now; but then
other animals, as beavers and birds, are artificers, and some extinct
animals were of higher powers than their modern representatives. But
if there were Miocene apes which chipped flints and cut bones, this
would, either on the hypothesis of evolution or that of creation by
law, render the occurrence of man still less likely than if there were
no such apes. The scratched and notched bones, on the other hand,
indicate merely the gnawing of sharks or other carnivorous animals. For
these reasons neither Dawkins nor Gaudry, nor indeed any geologists of
authority in the Tertiary fauna, believe in Miocene man.

In the Pliocene, though the facies of the mammalian fauna of Europe
becomes more modern, and a few modern species occur, the climate
becomes colder, and in consequence the apes disappear, so that the
chances of finding fossil men are lessened rather than increased in
so far as the temperate regions are concerned. In Italy, however,
Capellini has described a skull, an implement, and a notched bone
supposed to have come from Pliocene beds. To this it may be objected
that the skull--which I examined in 1883 in the museum at Florence--and
the implement are of recent type, and probably mixed with the Pliocene
stuff by some slip of the ground. As the writer has elsewhere
pointed out,[205] similar and apparently fatal objections apply to
the skull and implements alleged to have been found in Pliocene
gravels in California. Dawkins further informs us that in the Italian
Pliocene beds supposed to hold remains of man, of twenty-one mammalia
whose bones occur, all are extinct species, except possibly one, a
hippopotamus. This, of course, renders very unlikely in a geological
point of view the occurrence of human remains in these beds.

[205] "Fossil Men," 1880.

In the Pleistocene deposits of Europe--and this applies also to
America--we for the first time find a predominance of recent species
of land animals. Here, therefore, we may look with some hope for
remains of man and his works, and here, in the later Pleistocene, or
the early Modern, they are actually found. When we speak, however, of
Pleistocene man, there arise some questions as to the classification of
the deposits, which it seems to the writer Dawkins and other British
geologists have not answered in accordance with geological facts, and
a misunderstanding as to which may lead to serious error. They have
extended the term Pleistocene over that Post-glacial period in which
we find remains of man, and thus have split the "Anthropic" period
into two; and they proceed to divide the latter part of it into the
Pre-historic and Historic periods, whereas the name Pleistocene should
not be extended to the Post-glacial age. The close of the Glacial
period, introducing great physical and climatal changes, some new
species of mammalia and man himself, should be regarded as the end of
the Pleistocene, and the introduction of what some French geologists
have called the _Anthropic_ period, which I have elsewhere divided
into Palanthropic, corresponding to the so-called Palæolithic age, and
Neanthropic, corresponding to the later stone and metal ages.[206]
These may be termed respectively the earlier and later stages of the
Modern period as distinguished from the Pleistocene Tertiary.

[206] "Modern Science in Bible Lands."

In point of logical arrangement, and especially of geological
classification, the division into historic and pre-historic periods
is decidedly objectionable. Even in Europe the historic age of the
south is altogether a different thing from that of the north, and to
speak of the pre-historic period in Greece and in Britain or Norway
as indicating the same portion of time is altogether illusory. Hence
a large portion of the discussion of this subject has to be properly
called "the overlap of history." Further, the mere accident of the
presence or absence of historical documents cannot constitute a
geological period comparable with such periods as the Pleistocene
and Pliocene, and the assumption of such a criterion of time merely
confuses our ideas. On the one hand, while the whole Tertiary or
Kainozoic, up to the present day, is one great geological period,
characterized by a continuous though gradually changing fauna and
series of physical conditions, and there is consequently no good basis
for setting apart, as some geologists do, a Quaternary as distinct from
the Tertiary period; on the other hand, there is a distinct physical
break between the Pliocene and the Modern in the great Glacial age.
This, in its Arctic climate and enormous submergence of the land,
though it did not exterminate the fauna of the northern hemisphere,
greatly reduced it, and at the close of this age some new forms came
in. For this reason the division between the Pleistocene and Anthropic
ages should be made at the beginning of the Post-glacial age. The
natural division would thus be:--

I. Pleistocene, including--

(_a_) _Early Pleistocene_, or first continental period. Land very
extensive, moderate climate. This passes into the preceding Pliocene.

(_b_) _Later Pleistocene_, or glacial, including Dawkins' "Mid
Pleistocene." In this there was a great prevalence of cold and glacial
conditions, and a great submergence of the northern land.

II. Anthropic, or period of man and modern mammals, including--

(_a_) _Palanthropic_, _Post-glacial_, or second continental period,
in which the land was again very extensive, and Palæocosmic man was
contemporary with some great mammals, as the mammoth, now extinct,
and the area of land in the northern hemisphere was greater than at
present. This includes a later cold period, not equal in intensity
to that of the Glacial period proper, and was terminated by a great
and very general subsidence, accompanied by the disappearance of
Palæocosmic man and some large mammalia, and which may be identical
with the historical deluge.

(_b_) _Neanthropic_ or _Recent_, when the continents attained their
present levels, existing races of men colonized Europe, and living
species of mammals. This includes both the Pre-historic and Historic
periods.

On geological grounds the above should clearly be our arrangement,
though of course there need be no objection to such other subdivisions
as historians and antiquarians may find desirable for their purposes.
On this classification _the earliest certain indications of the
presence of man in Europe, Asia, or America, so far as yet known,
belong to the Modern or Anthropic period alone_. That man may have
existed previously no one need deny, but no one can at present
positively affirm on any ground of actual fact. It may be necessary
here to explain the contentions often made that in Britain and Western
Europe man belongs to an interglacial period. When with Dr. James
Geikie, the great Scottish glacialist, we hold that there were several
interglacial periods, the Glacial age may be extended by including the
warm period of the Palanthropic, and the cold at its termination, as
one of the interglacial and Glacial periods. In this way, as a matter
of classification, man appears in the latest Interglacial periods.
This, however, as above stated, I regard as an error in arrangement;
but it makes no practical difference as to the facts.

Inasmuch, however, as the human remains of the Post-glacial epoch are
those of fully developed men of high type, it may be said, and has
often been said, that man in some lower stage of development _must_
have existed at a far earlier period. That is, he must, if certain
theories as to his evolution from lower animals are to be sustained.
This, however, is not a mode of reasoning in accordance with the
methods of science. When facts fail to sustain certain theories we are
usually in the habit of saying "so much the worse for the theories,"
not "so much the worse for the facts," or at least we claim the right
to hold our judgment in suspense till some confirmatory facts are
forth-coming.

We have now to inquire as to the actual nature of the indications
of man in Europe and Western Asia at the close of the Glacial or
Pleistocene period. These are principally such of his tools or weapons
as could escape decay when embedded in river gravels, or in the earth
and stalagmite of caverns or rock shelters, or buried with his bones
in caves of sepulture. Very valuable accessory fossils are the broken
bones of the animals he has used as food. Most valuable, and rarest
of all, are well-preserved human skulls and skeletons. Some doubt may
attach to mere flint flakes, in the absence of other remains; but
the other indications above referred to are indisputable, and when
proper precautions are taken to notice the succession of beds, and to
eliminate the effects of any later disturbance of the deposits, human
fossils become as instructive and indisputable as any others.

When the whole of the facts thus available are put together, we
find that the earliest men of whom we have osseous remains, and
who, undoubtedly, inhabited Europe and Western Asia in the second
continental period, before the establishment of the present geography,
and before the disappearance of the mammoth and its companions, were
of two races or subraces, agreeing in certain respects, differing in
others. Both have long or dolichocephalic heads, and seem to have
been men of great strength and muscular energy, with somewhat coarse
countenances of Mongolian type, and they seem to have been of roving
habits, living as hunters and fishermen in a semi-barbarous condition,
but showing some artistic skill and taste in their carvings on bone and
other ornaments.

The earliest of the two races locally, though, on the whole, they
were contemporaneous, is that known as the Cannstadt or Neanderthal
people, who are characterized by a low forehead, with beetling brows,
massive limb bones and moderate stature. So far as known they were
the ruder and less artistic of the two races. The other, the Engis or
Cromagnon race, was of higher type, with well-formed and capacious
skull, and a countenance which, if somewhat broad, with high cheek
bones, eyes lengthened laterally, and heavy lower jaw, must have been
of somewhat grand and impressive features. These men are of great
stature, some examples being seven feet in height, and with massive
bones, having strong muscular impressions. The Engis skull found in
a cave in Belgium, with bones of the mammoth, the skeletons of the
Cromagnon cave in the valley of the Vezere, in France, and those of the
caves of Mentone, in Italy, represent this race. Doubts, it is true,
have been entertained as to whether the last-mentioned race is really
palanthropic; but the latest facts as to their mode of occurrence and
associations seem to render this certain. These men were certainly
contemporaneous with the mammoth, and they disappeared in the cataclysm
which closed the earlier anthropic period. Attempts have, however,
been made to separate them into groups according to age, within this
period;[207] and there can be no doubt that both in France and England
the lower and older strata of gravels and caves yield ruder and less
perfect implements than the higher. Independently, however, of the fact
that the very earliest men may have been peaceful gatherers of fruit,
and not hunters or warriors, having need of lethal weapons, such facts
may rather testify to local improvement in the condition of certain
tribes than to any change of race. Such local improvement would be very
likely to occur wherever a new locality was taken possession of by a
small and wandering tribe, which, in process of time, might increase in
numbers and in wealth, as well as in means of intercourse with other
tribes. A similar succession would occur when caves, used at first as
temporary places of rendezvous by savage tribes, became afterwards
places of residence, or were acquired by conquest on the part of
tribes a little more advanced, in the manner in which such changes are
constantly taking place in rude communities.

[207] Mortillet, "Pre-historic Men."

Yet on facts of this nature have been built extensive generalizations
as to a race of river-drift men, in a low and savage condition,
replaced, after the lapse of ages, by a people somewhat more advanced
in the arts, and specially addicted to a cavern life; and this
conclusion is extended to Europe and Asia, so that in every case where
rude flint implements exist in river gravels, evidence is supposed to
be found of the earlier of these races. But no physical break separates
the two periods; the fauna remained the same; the skulls, so far
as known, present little difference; and even in works of art the
distinction is invalidated by grave exceptions, which are intensified
by the fact, which the writer has elsewhere illustrated, that in the
case of the same people their residences in caves, etc., and their
places of burial are likely to contain very different objects from
those which they leave in river gravels.

It is admitted that the whole of these Palæocosmic men are racially
distinct from modern men, though most nearly allied in physical
characters to some of the Mongoloid races of the northern regions.
Some of their characters also appear in the native races of America,
and occasional cases occur, when even the characters of the Cannstadt
skull reappear in modern times. The skull of the great Scottish king
Robert Bruce was of this type; and his indomitable energy and governing
power may have been connected with this fact. Attempts have even been
made[208] to show an intimate connection between the cave men and the
Esquimaux of Greenland and Arctic America, but, as Wilson has well
shown,[209] this is not borne out by their cranial characters, and the
resemblances, such as they are, in arts and implements, are common
to the Esquimaux and many other American tribes. In many respects,
however, the arts and mode of life, as well as some of the physical
characters of the Palæocosmic men of Europe were near akin to those of
the ruder native races of America.

[208] Dawkins, "Early Man in Britain."

[209] Address to Anthropological section of the American Association,
1882.

Perhaps one of the most curious examples of this is the cave at
Sorde, in the western Pyrenees. On the floor of this cave lay a human
skeleton, covered with fallen blocks of stone. With it were found
forty canine teeth of the bear, and three of the lion, perforated for
suspension, and several of these teeth are skilfully engraved with
figures of animals, one bearing the engraved figure of an embroidered
glove. This necklace, no doubt just such a trophy of the chase as
would now be worn by a red Indian hunter, though more elaborate, must
have belonged to the owner of the skull, who would appear to have
perished by a fall of rock, or to have had his body covered after death
with stones. In the deposit near and under these remains were flint
flakes. Above the skull were several feet of refuse, stones, and bones
of the horse, reindeer, etc., and "Palæolithic" flint implements, and
above all were placed the remains of thirty skulls and skeletons with
beautifully chipped flint implements, some of them as fine as any
of later age. After the burial of these the cave seems to have been
finally closed with large stones. The French explorers of this cave
refer the lower and upper skulls to the same race, that of Cromagnon;
but others consider the upper remains as "Neolithic," though there is
no reason why a man who possessed a necklace of beautifully carved
teeth should not have belonged to a tribe which used well-made stone
implements, or why the weapons buried with the dead should have been
no better than the chips and flakes left by the same people in their
rubbish heaps. In any case the interment and this applies also to the
Mentone caves recalls the habits of American aborigines. In some of
these cases we have even deposits of red oxide of iron, representing
the war paint of the ancient hunter.

Widely different opinions have been held by archæologists as to the
connection of the Palanthropic and Neanthropic ages. It suits the
present evolutionist and exaggerated uniformitarianism of our day
to take for granted that the two are continuous, and pass into each
other. But there are stubborn facts against this conclusion. Let us
take, for example, the area represented by the British Islands and the
neighbouring continent. In the earlier period Britain was a part of the
mainland, and was occupied by the mammoth, the woolly rhinoceros, and
other animals, now locally or wholly extinct. The human inhabitants
were of a large-bodied and coarse race not now found anywhere. In the
later period all this is changed. Britain has become an island. Its
gigantic Post-glacial fauna has disappeared. Its human inhabitants are
now small in stature and delicate in feature, and represented to this
day by parts of the population of the south of Wales and Ireland. They
buried their dead in the peculiar cemeteries known as long barrows, and
their implements and weapons are of a new type, previously unknown.
All this shows a great interval of physical and organic mutation.
In connection with this we have the high-level gravel and rubble,
which Prestwich has shown to belong to this stage, and which proves
a subsidence even greater than that to be inferred from the present
diminution of the land area. Knowing as we do that the close of the
Glacial period was not more than 8,000 years ago, and deducting from
this the probable duration of the Palanthropic age on the one hand, and
that of modern history on the other, we must admit that the interval
left for the great physical and faunal changes above referred to is
too small to permit them to have occurred as the result of slow and
gradual operations. Considerations of this kind have indeed some of
the best authorities on the subject, as Cartailhac, Forel, and de
Mortillet, to hold that there is "an immense space, a great gap,
during which the fauna was renewed, and after which a new race of men
suddenly made its appearance, and polished stone instead of chipping
it, and surrounded themselves with domestic animals."[210] There is
thus, in the geological history of man an interval of physical and
organic change, corresponding to that traditional and historical deluge
which has left its memory with all the more ancient nations. Thus our
men of the Palanthropic, Post-glacial or Mammoth age are the same
we have been accustomed to call Antediluvians, and their immediate
successors are identical with the Basques and ancient Iberians, a
non-Aryan or Turanian people who once possessed nearly the whole of
Europe, and included the rude Ugrians and Laps of the north, the
civilized Etruscans of the south, and the Iberians of the west, with
allied tribes occupying the British Islands. This race, scattered
and overthrown before the dawn of authentic history in Europe by the
Celts and other intrusive peoples, was unquestionably that which
succeeded the now extinct Palæocosmic race, and constituted the men
of the so-called "Neolithic period," which thus connects itself with
the modern history of Europe, from which it is not separated by any
physical catastrophe like that which divides the older men of the
mammoth age and the widely spread continents of the Post-glacial period
from our modern days. This identification of the Neolithic men with
the Iberians, which the writer has also insisted on, Dawkins deserves
credit for fully elucidating, and he might have carried it farther,
to the identification of these same Iberians with the Berbers, the
Guanches of the Canary Islands, and the Caribbean and other tribes of
eastern and central America. On these hitherto dark subjects light
is now rapidly breaking, and we may hope that much of the present
obscurity will soon be cleared away.

[210] Quatrefages, "The Human Species." The interval should not,
however, be placed after the reindeer period, as this animal occurs in
both ages.

Supposing, then, that we may apply the term Anthropic to that portion
of the Kainozoic period which intervenes between the close of the
Glacial age and the present time, and that we admit the division of
this into two portions, the earlier, called the Palanthropic, and the
later, which still continues, the Neanthropic, it will follow that one
great physical and organic break separates the Palanthropic age from
the preceding Glacial, and a second similar break separates the two
divisions of the Anthropic from each other. This being settled, if
we allow say 2,500 years from the Glacial age for the first peopling
of the world and the Palanthropic age, and if we consider the modern
history of the European region and the adjoining parts of Asia and
Africa to go back for 5,000 years, there will remain a space of from
500 to 1,000 years for the destruction of the Palæocosmic men and the
re-peopling of the old continent by such survivors as founded the
Neocosmic peoples. These later peoples, though distinct racially from
their predecessors, may represent a race contemporary with them in some
regions in which it was possible to survive the great cataclysm, so
that we do not need to ask for time to develop such new race.[211]

[211] For details of the physical characters of the older races of men
I may refer to the works mentioned below, or to the writings of Dawkins
and Quatrefages.

We cannot but feel some regret that the grand old Palæocosmic race was
destined to be swept away by the flood, but it was no doubt better
for the world that it should be replaced by a more refined if feebler
race. When we see how this has, in some of its forms, reverted to the
old type, and emulated, if not surpassed it in filling the earth with
violence, we may, perhaps, congratulate ourselves on the extinction of
the giant races of the olden time.

  References:--"Fossil Men," London, 1880. The Antiquity of Man,
    _Princeton Review_. "Pre-historic Man in Egypt and the Lebanon,"
    _Trans. Vict. Institute_, 1884. Pre-historic Times in Egypt and
    Palestine, _North American Review_, June and July, 1892.




                           _MAN IN NATURE._


                      DEDICATED TO THE MEMORY OF

                  MY DEAR FRIEND DR. P. P. CARPENTER,

                   at once an eminent Naturalist and

                              Educator--

                      equally a Lover of Nature,

                     of his Fellow Men and of God.


What is Nature--Man a Part of Nature--Distinction between Man and
other Animals--Man as an Imitator of Nature--Man As at War With
Nature--Man in Harmony With Nature

[Illustration: Carving of the Palanthropic Age.--Cave of Mas d'Azil,
France; after Cartailhac.

Heads of the wild horse, carved on antler of the reindeer, and showing
accurate imitation of nature, with ideal and adaptive art on the part
of the antediluvian sculptor. (See p. 490.)]




CHAPTER XVIII.

_MAN IN NATURE._


Few words are used among us more loosely than "nature." Sometimes
it stands for the material universe as a whole. Sometimes it is
personified as a sort of goddess, working her own sweet will with
material things. Sometimes it expresses the forces which act on matter,
and again it stands for material things themselves. It is spoken of as
subject to law, but just as often natural law is referred to in terms
which imply that nature itself is the lawgiver. It is supposed to be
opposed to the equally vague term "supernatural"; but this term is used
not merely to denote things above and beyond nature, if there are such,
but certain opinions held respecting natural things. On the other hand,
the natural is contrasted with the artificial, though this is always
the outcome of natural powers, and is certainly not supernatural.
Again, it is applied to the inherent properties of beings for which we
are unable to account, and which we are content to say constitute their
nature. We cannot look into the works of any of the more speculative
writers of the day without meeting with all these uses of the word, and
have to be constantly on our guard lest by a change of its meaning we
shall be led to assent to some proposition altogether unfounded.

For illustrations of this convenient though dangerous ambiguity, I
may turn at random to almost any page in Darwin's celebrated work on
the "Origin of Species." In the beginning of Chapter III. he speaks
of animals "in a state of nature" that is, not in a domesticated or
artificial condition, so that here nature is opposed to the devices
of man. Then he speaks of species as "arising in nature," that is,
spontaneously produced in the midst of certain external conditions
or environment outside of the organic world. A little farther on he
speaks of useful varieties as given to man by "the hand of Nature,"
which here becomes an imaginary person; and it is worthy of notice
that in this place the printer or proof-reader has given the word an
initial capital, as if a proper name. In the next section he speaks
of the "works of Nature" as superior to those of art. Here the word
is not only opposed to the artificial, but seems to imply some power
above material things and comparable with or excelling the contriving
intelligence of man. I do not mean by these examples to imply that
Darwin is in this respect more inaccurate than other writers. On the
contrary, he is greatly surpassed by many of his contemporaries in
the varied and fantastic uses of this versatile word. An illustration
which occurs to me here, as at once amusing and instructive, is an
expression used by Romanes, one of the cleverest of the followers of
the great evolutionist, and which appears to him to give a satisfactory
explanation of the mystery of elevation in nature. He says, "Nature
selects the best individuals out of each generation to live." Here
nature must be an intelligent agent, or the statement is simply
nonsensical. The same alternative applies to much of the use of the
favourite term "natural selection." In short, those who use such modes
of expression would be more consistent if they were at once to come
back to the definition of Seneca, that nature is "a certain divine
purpose manifested in the world."

The derivation of the word gives us the idea of something produced
or becoming, and it is curious that the Greek _physis_, though
etymologically distinct, conveys the same meaning--a coincidence which
may perhaps lead us to a safe and serviceable definition. Nature,
rightly understood, is, in short, an orderly system of things in time
and space, and this not invariable, but in a state of constant movement
and progress, whereby it is always becoming something different
from what it was. Now man is placed in the midst of this orderly,
law-regulated yet ever progressive system, and is himself a part of
it; and if we can understand his real relations to its other parts, we
shall have made some approximation to a true philosophy. The subject
has been often discussed, but is perhaps not yet quite exhausted.[212]

[212] "Man's Place in Nature," _Princeton Review_, November, 1878. "The
Unity of Nature," by the Duke of Argyll, 1884, may be considered as
suggestive of the thoughts of this chapter.

Regarding man as a part of nature, we must hold to his entering into
the grand unity of the natural system, and must not set up imaginary
antagonisms between man and nature as if he were outside of it. An
instance of this appears in Tyndall's celebrated Belfast address,
where he says, in explanation of the errors of certain of the older
philosophers, that "the experiences which formed the weft and woof of
their theories were chosen not from the study of nature, but from that
which lay much nearer to them--the observation of Man": a statement
this which would make man a supernatural, or at least a preternatural
being. Again, it does not follow, because man is a part of nature,
that he must be precisely on a level with its other parts. There are
in nature many planes of existence, and man is no doubt on one of its
higher planes, and possesses distinguishing powers and properties of
his own. Nature, like a perfect organism, is not all eye or all hand,
but includes various organs, and so far as we see it in our planet, man
is its head, though we can easily conceive that there may be higher
beings in other parts of the universe beyond our ken.

The view which we may take of man's position relatively to the beings
which are nearest to him, namely, the lower animals, will depend on our
point of sight--whether that of mere anatomy and physiology, or that
of psychology and pneumatology as well. This distinction is the more
important, since, under the somewhat delusive term "biology," it has
been customary to mix up all these considerations, while, on the other
hand, those anatomists who regard all the functions of organic beings
as merely mechanical and physical, do not scruple to employ this term
biology for their science, though on their hypothesis there can be no
such thing as life, and consequently the use of the word by them must
be either superstitious or hypocritical.

Anatomically considered, man is an animal of the class _Mammalia_.
In that class, notwithstanding the heroic efforts of some modern
detractors from his dignity to place him with the monkeys in the
order _Primates_, he undoubtedly belongs to a distinct order. I have
elsewhere argued that, if he were an extinct animal, the study of
the bones of his hand, or of his head, would suffice to convince
any competent palæontologist that he represents a distinct order,
as far apart from the highest apes as they are from the carnivora.
That he belongs to a distinct family no anatomist denies, and the
same unanimity of course obtains as to his generic and specific
distinctness. On the other hand, no zoological systematist now doubts
that all the races of men are specifically identical. Thus we have the
anatomical position of man firmly fixed in the system of nature, and
he must be content to acknowledge his kinship not only with the higher
animals nearest to him, but with the humblest animalcule. With all he
shares a common material and many common features of structure.

When we ascend to the somewhat higher plane of physiology we find in
a general way the same relationship to animals. Of the four grand
leading functions of the animal, nutrition, reproduction, voluntary
motion, and sensation, all are performed by man as by other animals.
Here, however, there are some marked divergences connected with special
anatomical structures, on the one hand, and with his higher endowments
on the other. With regard to food, for example, man might be supposed
to be limited by his masticatory and digestive apparatus to succulent
vegetable substances. But by virtue of his inventive faculties he is
practically unlimited, being able by artificial processes to adapt the
whole range of vegetable and animal food substances to his use. He is
very poorly furnished with natural tools to aid in procuring food,
as claws, tusks, etc., but by invented implements he can practically
surpass all other creatures. The long time of helplessness in infancy,
while it is necessary for the development of his powers, is a practical
disadvantage which leads to many social arrangements and contrivances
specially characteristic of man. Man's sensory powers, while inferior
in range to those of many other animals, are remarkable for balance
and completeness, leading to perceptions of differences in colours,
sounds, etc., which lie at the foundation of art. The specialization
of the hand again connects itself with contrivances which render an
animal naturally defenceless the most formidable of all, and an animal
naturally gifted with indifferent locomotive powers able to outstrip
all others in speed and range of locomotion. Thus the physiological
endowments of man, while common to him with other animals, and in
some respects inferior to theirs, present in combination with his
higher powers points of difference which lead to the most special and
unexpected results.

In his psychical relations, using this term in its narrower sense, we
may see still greater divergencies from the line of the lower animals.
These may no doubt be connected with his greater volume of brain; but
recent researches seem to show that brain has more to do with motory
and sensory powers than with those that are intellectual, and thus,
that a larger brain is only indirectly connected with higher mental
manifestations. Even in the lower animals it is clear that the ferocity
of the tiger, the constructive instinct of the beaver, and the sagacity
of the elephant depend on psychical powers which are beyond the reach
of the anatomist's knife, and this is still more markedly the case in
man. Following in part the ingenious analysis of Mivart, we may regard
the psychical powers of man as reflex, instinctive, emotional, and
intellectual; and in each of these aspects we shall find points of
resemblance to other animals, and of divergence from them. In regard
to reflex actions, or those which are merely automatic, inasmuch
as they are intended to provide for certain important functions
without thought or volition, their development is naturally in the
inverse ratio of psychical elevation, and man is consequently, in
this respect, in no way superior to lower animals. The same may be
said with reference to instinctive powers, which provide often for
complex actions in a spontaneous and unreasoning manner. In these
also man is rather deficient than otherwise; and since, from their
nature, they limit their possessors to narrow ranges of activity, and
fix them within a definite scope of experience and efficiency, they
would be incompatible with those higher and more versatile inventive
powers which man possesses. The comb-building instinct of the bee, the
nest-weaving instinct of the bird, are fixed and invariable things,
obviously incompatible with the varied contrivance of man; and while
instinct is perfect within its narrow range, it cannot rise beyond this
into the sphere of unlimited thought and contrivance. Higher than mere
instinct are the powers of imagination, memory, and association, and
here man at once steps beyond his animal associates, and develops these
in such a variety of ways, that even the rudest tribes of men, who
often appear to trust more to these endowments than to higher powers,
rise into a plane immeasurably above that of the highest and most
intelligent brutes, and toward which they are unable, except to a very
limited degree, to raise those of the more domesticable animals which
they endeavour to train into companionship with themselves. It is,
however, in these domesticated animals that we find the highest degree
of approximation to ourselves in emotional development, and this is
perhaps one of the points that fits them for such human association. In
approaching the higher psychical endowments, the affinity of man and
the brute appears to diminish and at length to cease, and it is left to
him alone to rise into the domain of the rational and ethical.

Those supreme endowments of man we may, following the nomenclature of
ancient philosophy and of our Sacred Scriptures, call "pneumatical" or
spiritual. They consist of consciousness, reason, and moral volition.
That man possesses these powers every one knows; that they exist or can
be developed in lower animals no one has succeeded in proving. Here,
at length, we have a severance between man and material nature. Yet it
does not divorce him from the unity of nature, except on the principles
of atheism. For if it separates him from animals, it allies him with
the Power who made and planned the animals. To the naturalist the fact
that such capacities exist in a being who in his anatomical structure
so closely resembles the lower animals, constitutes an evidence of the
independent existence of those powers and of their spiritual character
and relation to a higher power which, I think, no metaphysical
reasoning or materialistic scepticism will suffice to invalidate. It
would be presumption, however, from the standpoint of the naturalist
to discuss at length the powers of man's spiritual being. I may refer
merely to a few points which illustrate at once his connection with
other creatures, and his superiority to them as a higher member of
nature.

And, first, we may notice those axiomatic beliefs which lie at the
foundation of human reasoning, and which, while apparently in harmony
with nature, do not admit of verification except by an experience
impossible to finite beings. Whether these are ultimate truths, or
merely results of the constitution bestowed on us, or effects of the
direct action of the creative mind on ours, they are to us like the
instincts of animals infallible and unchanging. Yet, just as the
instincts of animals unfailingly connect them with their surroundings,
our intuitive beliefs fit us for understanding nature and for existing
in it as our environment. These beliefs also serve to connect man with
his fellow man, and in this aspect we may associate with them those
universal ideas of right and wrong, of immortality, and of powers above
ourselves, which pervade humanity.

Another phase of this spiritual constitution is illustrated by the
ways in which man, starting from powers and contrivances common to
him and animals, develops them into new and higher uses and results.
This is markedly seen in the gift of speech. Man, like other animals,
has certain natural utterances expressive of emotions or feelings. He
can also, like some of them, imitate the sounds produced by animate
or inanimate objects; while the constitution of his brain and vocal
organs gives him special advantages for articulate utterance. But when
he develops these gifts into a system of speech expressing not mere
sounds occurring in nature, but by association and analogy with these,
properties and relations of objects and general and abstract ideas,
he rises into the higher sphere of the spiritual. He thus elevates a
power of utterance common to him with animals to a higher plane, and
connecting it with his capacity for understanding nature and arriving
at general truths, asserts his kinship to the great creative mind, and
furnishes a link of connection between the material universe and the
spiritual Creator.

The manner of existence of man in nature is as well illustrated by
his arts and inventions as by anything else; and these serve also
to enlighten us as to the distinction between the natural and the
artificial. Naturalists often represent man as dependent on nature
for the first hints of his useful arts. There are in animal nature
tailors, weavers, masons, potters, carpenters, miners, and sailors,
independently of man, and many of the tools, implements, and machines
which he is said to have invented were perfected in the structures
of lower animals long before he came into existence. In all these
things man has been an assiduous learner from nature, though in some of
them, as for example in the art of aërial navigation, he has striven
in vain to imitate the powers possessed by other animals. But it may
well be doubted whether man is in this respect so much an imitator as
has been supposed, and whether the resemblance of his plans to those
previously realized in nature does not depend on that general fitness
of things which suggests to rational minds similar means to secure
similar ends. But in saying this we in effect say that man is not only
a part of nature, but that his mind is in harmony with the plans of
nature, or, in other words, with the methods of the creative mind. Man
is also curiously in harmony with external nature in the combination
in his works of the ideas of plan and adaptation, of ornament and
use. In architecture, for example, devising certain styles or orders,
and these for the most part based on imitations of natural things; he
adapts these to his ends, just as in nature types of structure are
adapted to a great variety of uses, and he strives to combine, as in
nature, perfect adaptation to use with conformity to type or style. So,
in his attempts at ornament he copies natural forms, and uses these
forms to decorate or conceal parts intended to serve essential purposes
in the structure. This is at least the case in the purer styles of
construction. It is in the more debased styles that arches, columns,
triglyphs, or buttresses are placed where they can serve no useful
purpose, and become mere excrescences. But in this case the abnormality
resulting breeds in the beholder an unpleasing mental confusion, and
causes him, even when he is unable to trace his feelings to their
source, to be dissatisfied with the result. Thus man is in harmony with
that arrangement of nature which causes every ornamental part to serve
some use, and which unites adaptation with plan.

The following of nature must also form the basis of those fine arts
which are not necessarily connected with any utility, and in man's
pursuit of art of this kind we see one of the most recondite and at
first sight inexplicable of his correspondences with the other parts
of nature; for there is no other creature that pursues art for its
own sake. Modern archæological discovery has shown that the art of
sculpture began with the oldest known races of man, and that they
succeeded in producing very accurate imitations of natural objects.
But from this primitive starting-point two ways diverge. One leads to
the conventional and the grotesque, and this course has been followed
by many semi-civilized nations. Another leads to accurate imitation of
nature, along with new combinations arising from the play of intellect
and imagination. Let us look for a moment at the actual result of the
development of these diverse styles of art, and at their effect on the
culture of humanity as existing in nature. We may imagine a people who
have wholly discarded nature in their art, and have devoted themselves
to the monstrous and the grotesque. Such a people, so far as art is
concerned, separates itself widely from nature and from the mind of the
Creator, and its taste and possibly its morals sink to the level of the
monsters it produces. Again, we may imagine a people in all respects
following nature in a literal and servile manner. Such a people would
probably attain to but a very moderate amount of culture, but having a
good foundation, it might ultimately build up higher things. Lastly,
we may fancy a people who, like the old Greeks, strove to add to the
copying of nature a higher and ideal beauty by combining in one the
best features of many natural objects, or devising new combinations
not found in nature itself. In the first of these conditions of art
we have a falling away from or caricaturing of the beauty of nature.
In the second we have merely a pupilage to nature. In the third we
find man aiming to be himself a creator, but basing his creations on
what nature has given him. Thus all art worthy of the name is really a
development of nature. It is true the eccentricities of art and fashion
are so erratic that they may often seem to have no law. Yet they are
all under the rule of nature; and hence even uninstructed common
sense, unless dulled by long familiarity, detects in some degree their
incongruity, and though it may be amused for a time, at length becomes
wearied with the mental irritation and nervous disquiet which they
produce.

I may be permitted to add that all this applies with still greater
force to systems of science and philosophy. Ultimately these must be
all tested by the verities of nature to which man necessarily submits
his intellect, and he who builds for aye must build on the solid ground
of nature. The natural environment presents itself in this connection
as an educator of man. From the moment when infancy begins to exercise
its senses on the objects around, this education begins training the
powers of observation and comparison, cultivating the conception of
the grand and beautiful, leading to analysis and abstract and general
ideas. Left to itself, it is true this natural education extends but
a little way, and ordinarily it becomes obscured or crushed by the
demands of a hard utility, or by an artificial literary culture, or by
the habitude of monstrosity and unfitness in art. Yet, when rightly
directed, it is capable of becoming an instrument of the highest
culture, intellectual, æsthetic, and even moral. A rational system of
education would follow nature in the education of the young, and drop
much that is arbitrary and artificial. Here I would merely remark,
that when we find that the accurate and systematic study of nature
trains most effectually some of the more practical powers of mind, and
leads to the highest development of taste for beauty in art, we see in
this relation the unity of man and nature, and the unity of both with
something higher than either.

It may, however, occur to us here, that when we consider man as an
improver and innovator in the world, there is much that suggests a
contrariety between him and nature, and that, instead of being the
pupil of his environment, he becomes its tyrant. In this aspect man,
and especially civilized man, appears as the enemy of wild nature, so
that in those districts which he has most fully subdued, many animals
and plants have been exterminated, and nearly the whole surface has
come under his processes of culture, and has lost the characteristics
which belonged to it in its primitive state. Nay more, we find that by
certain kinds of so called culture man tends to exhaust and impoverish
the soil, so that it ceases to minister to his comfortable support, and
becomes a desert. Vast regions of the earth are in this impoverished
condition, and the westward march of exhaustion warns us that the time
may come when even in comparatively new countries, like America, the
land will cease to be able to sustain its inhabitants. Behind this
stands a still farther and portentous possibility. The resources of
chemistry are now being taxed to the utmost to discover methods by
which the materials of human food may be produced synthetically, and we
may possibly, at some future time, find that albumen and starch may be
manufactured cheaply from their elements by artificial processes. Such
a discovery might render man independent of the animal and vegetable
kingdoms. Agriculture might become an unnecessary and unprofitable
art. A time might come when it would no longer be possible to find on
earth a green field, or a wild animal; and when the whole earth would
be one great factory, in which toiling millions were producing all the
materials of food, clothing, and shelter. Such a world may never exist,
but its possible existence may be imagined, and its contemplation
brings vividly before us the vast powers inherent in man as a subverter
of the ordinary course of nature. Yet even this ultimate annulling of
wild nature would be brought about not by anything preternatural in
man, but simply by his placing himself in alliance with certain natural
powers and agencies, and by their means attaining dominion over the
rest.

Here there rises before us a spectre which science and philosophy
appear afraid to face, and which asks the dread question,--What is the
cause of the apparent abnormality in the relations of man and nature?
In attempting to solve this question, we must admit that the position
of man, even here, is not without natural analogies. The stronger
preys upon the weaker, the lower form gives place to the higher,
and in the progress of geological time old species have died out in
favour of newer, and old forms of life have been exterminated by later
successors. Man, as the newest and highest of all, has thus the natural
right to subdue and rule the world. Yet there can be little doubt that
he uses this right unwisely and cruelly, and these terms themselves
explain why he does so, because they imply freedom of will. Given a
system of nature destitute of any being higher than the instinctive
animal, and introduce into it a free rational agent, and you have at
once an element of instability. So long as his free thought and purpose
continue in harmony with the arrangements of his environment, so long
all will be harmonious; but the very hypothesis of freedom implies that
he can act otherwise, and so perfect is the equilibrium of existing
things, that one wrong or unwise action may unsettle the nice balance,
and set in operation trains of causes and effects producing continued
and ever-increasing disturbance. Thus the most primitive state of man,
though destitute of all mechanical inventions, may have been better in
relation to the other parts of nature than any that he has subsequently
attained to. His "many inventions" have injured him in his natural
relations. This "fall of man" we know as a matter of observation and
experience has actually occurred, and it can be retrieved only by
casting man back again into the circle of merely instinctive action,
or by carrying him forward until, by growth in wisdom and knowledge, he
becomes fitted to be the lord of creation. The first method has been
proved unsuccessful by the rebound of humanity against all the attempts
to curb and suppress its liberty. The second has been the effort of
all reformers and philanthropists since the world began, and its
imperfect success affords a strong ground for clinging to the theistic
view of nature, for soliciting the intervention of a Power higher than
man, and for hoping for a final restitution of all things through the
intervention of that Power. Mere materialistic evolution must ever and
necessarily fail to account for the higher nature of man, and also for
his moral aberrations. These only come rationally into the system of
nature under the supposition of a Higher Intelligence, from whom man
emanates, and whose nature he shares.

But on this theistic view we are introduced to a kind of unity and of
evolution for a future age, which is the great topic of revelation, and
is not unknown to science and philosophy, in connection with the law
of progress and development deducible from the geological history, in
which an ascending series of lower animals culminates in man himself.
Why should there not be a new and higher plane of existence to be
attained to by humanity--a new geological period, so to speak, in
which present anomalies shall be corrected, and the grand unity of the
universe and its harmony with its Maker fully restored. This is what
Paul anticipates when he tells us of a "pneumatical" or spiritual body,
to succeed to the present natural or "psychical" one, or what Jesus
Himself tells us when He says that in the future state we shall be like
to the angels. Angels are not known to us as objects of scientific
observation, but such an order of beings is quite conceivable, and
this not as supernatural, but as part of the order of nature. They are
created beings like ourselves, subject to the laws of the universe,
yet free and intelligent and liable to error, in bodily constitution
freed from many of the limitations imposed on us, mentally having
higher range and grasp, and consequently masters of natural powers not
under our control. In short, we have here pictured to us an order of
beings forming a part of nature, yet in their powers as miraculous to
us as we might be supposed to be to lower animals, could they think of
such things. This idea of angels bridges over the great natural gulf
between humanity and deity, and illustrates a higher plane than that of
man in his present state, but attainable in the future. Dim perceptions
of this would seem to constitute the substratum of the ideas of the
so-called polytheistic religions. Christianity itself is in this aspect
not so much a revelation of the supernatural as the highest bond of
the great unity of nature. It reveals to us the perfect Man, who is
also one with God, and the mission of this Divine Man to restore the
harmonies of God and humanity, and consequently also of man with his
natural environment in this world, and with his spiritual environment
in the higher world of the future. If it is true that nature now groans
because of man's depravity, and that man himself shares in the evils
of this disharmony with nature around him, it is clear that if man
could be restored to his true place in nature he would be restored
to happiness and to harmony with God, and if, on the other hand, he
can be restored to harmony with God, he will then be restored also to
harmony with his natural environment, and so to life and happiness and
immortality. It is here that the old story of Eden, and the teaching
of Christ, and the prophecy of the New Jerusalem strike the same note
which all material nature gives forth when we interrogate it respecting
its relations to man. The profound manner in which these truths appear
in the teaching of Christ has perhaps not been appreciated as it
should, because we have not sought in that teaching the philosophy of
nature which it contains. When He points to the common weeds of the
fields, and asks us to consider the garments more gorgeous than those
of kings in which God has clothed them, and when He says of these same
wild flowers, so daintily made by the Supreme Artificer, that to-day
they are, and to-morrow are cast into the oven, He gives us not merely
a lesson of faith, but a deep insight into that want of unison which,
centring in humanity, reaches all the way from the wild flower to the
God who made it, and requires for its rectification nothing less than
the breathing of that Divine Spirit which first evoked order and life
out of primeval chaos.

  References:--Articles in _Princeton Review_ on Man in Nature and on
    Evolution. "The Story of the Earth and Man." London, 1890. "Modern
    Ideas of Evolution." London, 1891. Nature as an Educator. _Canadian
    Record of Science_, 1890.




INDEX OF PRINCIPAL TOPICS.


  Air-breathers, their Origin and History, 257, 303.

  Alpine and Arctic Plants, their Geological History, 425.

  American Stone Age, 464.

  Animals, their Apparition and Succession, 169.

  ---- their Geological History, 176, 187, 194.

  ---- Permanent Forms of, 87, 180.

  Anthropic Age, 461.

  Antiquity of Man, 469.

  Arctic Climates in the Past, 213.

  Atlantic, its Origin and History, 57.

  ---- Cosmical Functions of, 72.

  ---- its Influence on Climate, 81.

  ---- Deposits in, 83.

  ---- Migrations across, 84.

  ---- Future of, 90.

  Azores, their Animals, 408.


  Baphetes planiceps, 263.

  Bay of Fundy, its Deposits, 312.

  ---- Footprints on Shores of, 311.

  Bermudas, their Flora, etc., 85.

  Boulders, Belts of, on Lower St. Lawrence, 345.

  Boulder-Clay, Nature, etc., of, 360.


  Cave Men, 476.

  Cannstadt Race, 474

  Chaos, Vision of, 90.

  Chronology of Pleistocene, 470.

  Climate, its Causes, 81.

  ---- as related to Plants, 215.

  Climatal Changes, 382.

  Coal, its Nature and Structure, 235.

  ---- its Origin and Growth, 233.

  ---- Summary of Facts relating to, 241.

  ---- of Mesozoic and Tertiary, 249.

  ---- its Connection with Erect Forests, 296.

  Continents and Islands, 402.

  ---- Permanence of, 31, 403.

  Contrast of land and sea-borne Ice, 360.

  Cordilleran Glaciers, 369.

  Cromagnon Race, 474.

  Crust and Sub-crust, 62.


  Dawn of Life, 95.

  Deluge, The, 467.

  Dendrerpeton Acadianum, 270.

  Determination in Nature, 329.

  Development of Life, 23.

  ---- Laws of, 194.

  Distribution of Animals and Plants, 401.

  Drift of Western Canada, 369


  Early Man, 459.

  Engis Race, 472.

  Eozoon, Discovery of, 111.

  ---- Nature of, 112.

  ---- Contemporaries of, 129.

  ---- Teachings of, 135.

  Eozoon, Preservation of and Structure, 143.

  Eyes, earliest Types of, 331.

  Evolution, its partial Character, 188.


  Flora of White Mountains, 421.

  Floras originate in the Arctic, 297.

  Floating Ice, 360.

  Footprints of Reptiles, 260.

  ---- of Limulus, 319.

  Fossils, Preservation of, 136.

  Fucoids, 311.


  Galapagos, how Peopled, 412.

  Geographical Changes and Climate, 390.

  Geological Record, Imperfection of, 40.

  Glaciers, Work of, 353.

  Glacial Period, Conditions of, 375.

  Gulf Stream, 388.


  Hydrous Silicates, 144.

  Huronian as a Geological System, 104.

  Hylonomus Lyelli, 279.


  Icebergs, their Nature and Work, 348.

  Ice Age, the, 343.

  Imperfection of the Geological Record, 40.


  Land and Water, 58.

  Land Snails, Earliest, 247.

  Labyrinthodonts, their Origin and History, 265.

  Laurentian System, 97.

  ---- Life in the, 107.

  Laurentide Glaciers, 364, 368.

  Leda Clay of Lower St. Lawrence, 365.

  Life, First Appearance of, 19, 96, 157.

  Limbs, the Earliest, 337.

  Limulus, Footprints of, 319.


  Magmas under Crust of the Earth, 63.

  Mammoth Age, 466.

  Man in Nature, 484.

  ---- Early, 461.

  ---- an Imitator of Natural Objects, 490.

  ---- at War with other Natural Agencies, 495.

  ---- in harmony with Nature, 496.

  Markings, Footprints, etc., 301.

  ---- Rill and Rain, etc., 317.

  Microsauria, 279.

  Migrations of Plants, 434.

  Millipedes of Carboniferous Age, 295.

  Mineral Charcoal, 237.

  Missouri Coteau, 271.

  Mountains, Origin of, 33.

  ---- Classes of, 66.

  Mount Washington, 426.


  Nature, Various Senses of the Term, 483.

  Neanthropic Age, 472.


  Ocean, the Atlantic, 58, 67.

  Oceanic Islands, 407.


  Palanthropic Age, 462.

  Permanence of Continents, 31, 403.

  ---- of Animal Forms, 87, 180.

  Plants, Geological History of, 202.

  ---- as Indicators of Time and Climate, 229.

  ---- of the Erian, Carboniferous, etc., 202.

  ---- of the Pleistocene, 439.

  Pleistocene, Tabular View of, 472.

  Polygenesis of Species, 418.

  Pre-determination in Nature, 329.

  Primitive Rocks, 16.

  Protozoa, their Place in Nature, 152.

  Pseudo-Fucoids, 318.

  Pupa vetusta, 288.


  Races of Early Men, 474.

  Rill Marks, 317.


  Scorpions, Carboniferous, 295.

  Sigillariæ, Erect, 276.

  Sorde, Cave of, 476.

  Species, Permanence of, 87, 180.

  ---- Origin of, 418.

  Sponges in Cambro-Silurian, 46.

  Spore-cases in Coal, 234.

  Stigmaria, 246.

  Stone Age in America, 464.


  Terraces of Lower St Lawrence, 346.

  Tides of the Bay of Fundy, 312.

  Time, Geological, 416.

  Tracks of Animals, 51.

  Trees, Erect, with Animal Remains, 276.

  Tuckerman's Ravine, 427.


  Underclays, their Origin and Nature, 236.


  Vegetable Life, the Earliest, 338.

  Vegetable Kingdom, its History, 202.

  Vertebrates, History of, 183.

  Vision of Creation, 90.


  Worlds, the Making of, 9, 14.

  Worm Tracks, 318.

  White Mountains, 426.

  Zoological Regions, 405.


=SCIENCE IN BIBLE LANDS.=

Modern Science in Bible Lands. By Sir J. W. Dawson, C.M.G., LL.D.,
F.R.S. With Maps and Illustrations. 12mo, Cloth, $2 00.

  The special object of the work, the author tells us, is "to notice
    the light which the scientific explorations of the countries of
    the Bible may throw on the character and statements of the book."
    It contains much interesting and valuable matter, and Sir J. W.
    Dawson's opinions and explanations will doubtless meet with the
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  Will add to Professor Dawson's deservedly high reputation as a
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  One of the most valuable of recent books for Bible students.... This
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  At once intensely interesting and instructive.--_Albany Press._

  The author writes delightfully, even in his technical passages. His
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  A very interesting and instructive work.... Not its least charm
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  A valuable book with a valuable aim.... The whole book is vigorous,
    clear, strong, and adds another word of deep and honest thought to
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  A work of great scientific and Biblical value.--_Lutheran Observer_,
    Philadelphia.

  The book is plain, straightforward, and interesting, and its
    scientific facts and deductions are of value.--_Western Christian
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  Professor Dawson in this volume adds to his well-earned fame, and we
    predict for it an extensive sale.--_Evangelist_, New York.

  Of priceless value for those who would read with understanding the
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Published by HARPER & BROTHERS, New York.

_The above work in for sale by all booksellers, or will be sent by the
publishers, postage prepaid, to any part of the United States, Canada,
or Mexico, on receipt of price._


=THE EARTH AND MAN.=

The Story of the Earth and Man. By J. W. Dawson, LL.D., F.R.S., F.G.S.,
Principal and Vice-Chancellor of McGill University, Montreal. New
Edition with Corrections and Additions. With a Colored Diagram and
Illustrations. 12mo, Cloth, $1 50.

  This little book is, on the whole, the best popular geology that has
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    book is remarkable for its simplicity, clearness, interest, and
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  The work is full of absorbing interest.--_Toledo Blade._

  The book is a recognized authority on the subject of which it treats,
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  We advise any of our readers who have been carried away with the
    evolution craze as something that indicates advanced thinking to
    read this most valuable work.--_Christian Standard_, Cincinnati, O.

  An excellent summary of geological history.--_Boston Literary World._

  The author is an able opponent of the theories of the evolutionists,
    and his discussion of the theme is interesting. His account of the
    lowest and earliest form of animal life as exemplified in what he
    calls the "dawn animal," found by him in fossil state in Canada, is
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  The last two chapters of the work on "Primitive Man" contain an
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  We cannot but give the greatest respect to the writer of this book,
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Published by HARPER & BROTHERS, N. Y.

  [hand] Harper & Brothers _will send the above work, postage prepaid, to
    any part of the United States or Canada, on receipt of the price._


=THE ORIGIN OF THE WORLD.=

The Origin of the World, according to Revelation and Science. By J. W.
Dawson, LL.D., F.R.S., F.G.S. 12mo, Cloth, $2 00.

  The revised work is a cyclopædia that will be welcome to all who
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  To all reverent students of the Bible this work will prove a valuable
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    references to creation, and how these may be harmonized with
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    Evangelist._

  Briefly described, the book is a singularly suggestive study of the
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  The book will commend itself to both scholars and the common people;
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    it.--_The Churchman_, N. Y.

  Although most scientists and many theologians will doubtless differ
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  Mr. Dawson has devoted much study to the treatment of the subject
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  The work treats of the mystery of "origins," the beginning of
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  Whether the reader accepts Dr. Dawson's conclusions or not,
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  As a summary of creation, the book is lively and fresh. It will be
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  At least no student of theology can afford not to possess this most
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Published by HARPER & BROTHERS, N. Y.

  [hand] Harper & Brothers _will send the above work, postage prepaid, to
    any part of the United States or Canada, on receipt of the price._


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  A Naturalist's Wanderings in the Eastern Archipelago. A Narrative
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       *       *       *       *       *


Transcriber Note


All images were obtained from The Internet Archive. A clearer version
of the illustration of Hylonomus Lyelli (facing p. 257) was obtained
from Plate 9, The Coal Measures Amphibia of North America, by Roy Lee
Moodie. Illustrations were repositioned so as to not split paragraphs.
Hyphenation was standardized to the most prevalent form and several
presumed typos were corrected.