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THE STORY OF THE HILLS.




  [Illustration]




  [Illustration: NORHAM CASTLE. AFTER TURNER.]




    THE

    STORY OF THE HILLS.

    A BOOK ABOUT MOUNTAINS
    FOR GENERAL READERS.

    BY

    REV. H. N. HUTCHINSON, B.A., F.G.S.

    AUTHOR OF "THE AUTOBIOGRAPHY OF THE EARTH."

    With Sixteen Full-page Illustrations.

They are as a great and noble architecture, first giving shelter,
comfort, and rest; and covered also with mighty sculpture and painted
legend.--RUSKIN.

    New York:
    MACMILLAN AND CO.
    AND LONDON.

    1892.




    _Copyright, 1891_,
    BY MACMILLAN AND CO.


    University Press:
    JOHN WILSON AND SON, CAMBRIDGE, U.S.A.




TO

ALL WHO LOVE MOUNTAINS AND HILLS

This little Book is Dedicated,

   IN THE HOPE THAT EVEN A SLIGHT KNOWLEDGE OF THEIR PLACE IN
   NATURE, AND PREVIOUS HISTORY, MAY ADD TO THE WONDER AND DELIGHT
   WITH WHICH WE LOOK UPON THESE NOBLE FEATURES OF THE SURFACE OF
   THE EARTH.



PREFACE.


Now that travelling is no longer a luxury for the rich, and thousands
of people go every summer to spend their holidays among the
mountains of Europe, and ladies climb Mont Blanc or ramble among the
Carpathians, there must be many who would like to know something of
the secret of the hills, their origin, their architecture, and the
forces that made them what they are.

For such this book is chiefly written. Those will best understand it
who take it with them on their travels, and endeavour by its use to
interpret what they see among the mountains; and they will find that
a little observation goes a long way to help them to read mountain
history.

It is hoped, however, that all, both young and old, who take an
intelligent interest in the world around, though they may never have
seen a mountain, may find these pages worth reading.

If readers do not find here answers to all their questions, they
may be reminded that it is not possible within the present limits
to give more than a brief sketch of the subject, leaving the gaps
to be filled in by a study of the larger and more important works
on geology. The author, assuming that the reader knows nothing of
this fascinating science, has endeavoured to interpret into ordinary
language the story of the hills as it is written in the rocks of
which they are made.

It can scarcely be denied that a little knowledge of natural objects
greatly adds to our appreciation of them, besides affording a deep
source of pleasure, in revealing the harmony, law, and order by which
all things in this wonderful world are governed. Mountains, when
once we begin to observe them, seem to become more than ever our
companions,--to take us into their counsels, and to teach us many a
lesson about the great part they play in the order of things. And
surely our admiration of their beauty is not lessened, but rather
increased, when we learn how much we and all living things owe to
the life-giving streams that flow continually from them. The writer
has, somewhat reluctantly, omitted certain parts of the subject
which, though very interesting to the geologist, can hardly be made
attractive to general readers.

Thus, the cause of earth movements, by which mountains are pushed up
far above the plains that lie at their feet, is at present a matter
of speculation; and it is difficult to express in ordinary language
the ideas that have been put forward on this subject. Again, the
curious internal changes, which we find to have taken place in the
rocks of which mountains are composed, are very interesting to those
who know something of the minerals of which rocks are made up, and
their chemical composition; but it was found impossible to render
these matters sufficiently simple.

So again with regard to the geological structure of mountain-chains.
This had to be very briefly treated, in order to avoid introducing
details which would be too complicated for a book of this kind.

The author desires to acknowledge his obligations to the writings
of Sir A. Geikie; Professor Bonney, Professor Green, and Professor
Shaler, of Harvard University; the volumes of the "Alpine Journal;"
"The Earth," by Reclus; the "Encyclopædia Britannica." Canon Isaac
Taylor's "Words and Places," have also been made use of; and if in
every case the reference is not given, the writer hopes the omission
will be pardoned. A few passages from Mr. Ruskin's "Modern Painters"
have been quoted, in the hope that others may be led to read that
wonderful book, and to learn more about mountains and clouds, and
many other things, at the feet of one of the greatest teachers of the
century.

Some of our engravings are taken from the justly celebrated
photographs of the High Alps,[1] by the late Mr. W. Donkin, whose
premature death among the Caucasus Mountains was deeply deplored
by all. Those reproduced were kindly lent by his brother, Mr. A. E.
Donkin, of Rugby. To Messrs. Valentine & Son of Dundee, Mr. Wilson
of Aberdeen, and to Messrs. Frith we are indebted for permission to
reproduce some of their admirable photographs; also to Messrs. James
How & Sons of Farringdon Street, for three excellent photographs of
rock-sections taken with the microscope.

  [1] Published by Messrs. Spooner, of the Strand.




CONTENTS.

    Part I.

    THE MOUNTAINS AS THEY ARE.

    CHAPTER                                          PAGE

    I. MOUNTAINS AND MEN                                3

    II. THE USES OF MOUNTAINS                          33

    III. SUNSHINE AND STORM ON THE MOUNTAINS           70

    IV. MOUNTAIN PLANTS AND ANIMALS                   103


    Part II.

    CHAPTER                                          PAGE

    HOW THE MOUNTAINS WERE MADE.

    V. HOW THE MATERIALS WERE BROUGHT TOGETHER        139

    VI. HOW THE MOUNTAINS WERE UPHEAVED               174

    VII. HOW THE MOUNTAINS WERE CARVED OUT            205

    VIII. VOLCANIC MOUNTAINS                          242

    IX. MOUNTAIN ARCHITECTURE                         282

    X. THE AGES OF MOUNTAINS AND OTHER QUESTIONS      318




ILLUSTRATIONS.


    NORHAM CASTLE. After Turner                   _Frontispiece_

    BEN LOMOND. From a Photograph by J. Valentine             16

    CLOUDS ON BEN NEVIS                                       38

    SNOW ON THE HIGH ALPS. From a Photograph by
        Mr. Donkin                                            64

    A STORM ON THE LAKE OF THUN. After Turner                 86

    THE MATTERHORN. From a Photograph by Mr. Donkin           98

    ON A GLACIER.                                            116

    RED DEER. After Ansdell                                  133

    CHALK ROCKS, FLAMBOROUGH HEAD. From a Photograph by
        G. W. Wilson                                         152

    MICROPHOTOGRAPHS ILLUSTRATING ROCK FORMATION             172

    THE SKAEGGEDALSFORS, NORWAY. From a Photograph by
        J. Valentine                                         192

    THE MER DE GLACE AND MONT BUET. From a Photograph
        by Mr. Donkin                                        229

    THE ERUPTION OF VESUVIUS IN 1872. From an
        Instantaneous Photograph                             250

    COLUMNAR BASALT AT CLAMSHELL CAVE, STAFFA. From
        a Photograph by J. Valentine                         280

    MONT BLANC, SNOWFIELDS, GLACIERS, AND STREAMS.           312

    MOUNTAIN IN THE YOSEMITE VALLEY.                         336




    ILLUSTRATIONS II.

    Fig. 1. SECTION ACROSS THE WEALD OF KENT AND SURREY.     237

    Fig. 2. THE HIGHLANDS OF SCOTLAND ON A TRUE
    SCALE (after Geikie.)                                    237

    Fig. 1. THE RANGES OF THE GREAT BASIN, WESTERN
    STATES OF NORTH AMERICA, SHOWING A SERIES OF
    GREAT FRACTURES AND TILTED MASSES OF ROCK.               272

    Fig. 2. SECTION THROUGH SNOWDON.                         272

    SECTIONS OF MOUNTAIN-RANGES, SHOWING THEIR
    STRUCTURE AND THE AMOUNT OF ROCK WORN AWAY               306




PART I.

THE MOUNTAINS AS THEY ARE.




THE STORY OF THE HILLS.

Part I.

THE MOUNTAINS AS THEY ARE.




CHAPTER I.

MOUNTAINS AND MEN.

    "Happy, I said, whose home is here;
    Fair fortunes to the Mountaineer."


In old times people looked with awe upon the mountains, and
regarded them with feelings akin to horror or dread. A very slight
acquaintance with the classical writers of antiquity will suffice
to convince any one that Greeks and Romans did so regard them. They
were not so familiar with mountains as we are; for there were no
roads through them, as now through the Alps, or the Highlands of
Scotland,--to say nothing of the all-pervading railway. It would,
however, be a great mistake to suppose that the ancients did not
observe and enjoy the beauties of Nature. The fair and fertile
plain, the vine-clad slopes of the lower hill-ranges, and the
"many-twinkling smile of ocean" were seen and loved by all who had
a mind to appreciate the beautiful. The poems of Homer and Virgil
would alone be sufficient to prove this. But the higher ranges,
untrodden by the foot of man, were gazed at, not with admiration,
but with religious awe; for men looked upon mountains as the abode
of the gods. They dwelt in the rich plain, which they cultivated,
and beside the sweet waters of some river; for food and drink are
the first necessities of life. But they left the high hills alone,
and in fancy peopled them with the "Immortals" who ruled their
destiny,--controlling also the winds and the lightning, the rain and
the clouds, which seem to have their home among the mountains. A
childlike fear of the unknown, coupled with religious awe, made them
avoid the lofty and barren hills, from which little was to be got
but wild honey and a scanty supply of game. There were also dangers
to be encountered from the fury of the storm and the avalanche; but
the safer ground of the plains below would reward their toil with an
ample supply of corn and other necessaries of life.

In classical times, and also in the Middle Ages, the mountains,
as well as glens and rivers, were supposed to be peopled with
fairies, nymphs, elves, and all sorts of strange beings; and even
now travellers among the mountains of Switzerland, Norway, Wales,
or Scotland find that it is not long since the simple folk of these
regions believed in the existence of such beings, and attributed to
their agency many things which they could not otherwise explain.

Of all the nations of antiquity the Jews seem to have shown the
greatest appreciation of mountain scenery; and in no ancient writings
do we find so many or so eloquent allusions to the hills as in the
Old Testament. But here again one cannot fail to trace the same
feelings of religious awe. The Law was given to their forefathers
in the desert amidst the thunders of Sinai. To them the earth was
literally Jehovah's footstool, and the clouds were His tabernacle.
"If He do but touch the hills, they shall smoke."

But this awe was not unmixed with other and more comforting thoughts.
They felt that those cloud-capped towers were symbols of strength and
the abode of Him who would help them in their need. For so we find
the psalmists regarding them; and with our very different conceptions
of the earth's natural features, we can but dimly perceive and
realise the full force and meaning of the words, "I will lift up mine
eyes unto the hills, from whence cometh my help."

To take another example from antiquity, we find that the Himalayas
and the source of the Ganges have from very early times been
considered as holy by the people of India. Thousands of pilgrims from
all parts of that vast country still continue to seek salvation in
the holy waters of the Ganges, and at its sacred sources in the snowy
Himalayas. And to those who know India the wondrous snowclad peaks of
the Himalayas still seem to be surrounded with somewhat of the same
halo of glory as of old.

Mountains are intimately associated with the history of nations, and
have contributed much to the moulding of the human mind and the
character of those who dwell among them; they have alike inspired the
mind of the artist, the poet, the reformer, and the visionary seeking
repose for his soul, that, dwelling far from the strife and turmoil
of the world, he may contemplate alone the glory of the Eternal
Being. They have been the refuge of the afflicted and the persecuted;
they have braced the minds and bodies of heroes who have dwelt for a
time among them before descending once more to the plain that they
might play some noble part in the progress of the world.

Moses, while leading the flock of his father-in-law to the back of
the wilderness, came to Mount Horeb and received the divine summons
to return to Egypt and lead Israel out of bondage. David, with his
six hundred followers, fleeing from the face of Saul, found a refuge
in the hill country; and the life of peril and adventure which he
led during these years of persecution was a part of his training for
the great future task of ruling Israel, which he performed so well.
Elijah summoned the false prophets of Baal and Asherah to Mount
Carmel and slew them at the brook Kishon; and a little later we find
him at Mount Horeb listening, not to the wind or to the earthquake
or to the fire, but to the "still small voice" telling him to return
and anoint Jehu to be king.

Or, to take another example from a later age, we find that Mahomet's
favourite resort was a cave at the foot of Mount Hira, north of
Mecca; here in dark and wild surroundings his mind was wrought up to
rhapsodic enthusiasm.

And many, like these leaders of men, have received in mountain
retreats a firmness and tenacity of purpose giving them the right
to be leaders, and the power to redress human wrongs; or, it may
be, a temper of mind and spirit enabling them to soar into regions
of thought and contemplation untrodden by the careless and more
luxurious multitudes who dwell on the plains below. Perhaps Mr. Lewis
Morris was unconsciously offering his testimony to the influence of
mountains when he wrote those words which he puts into the mouth of
poor Marsyas,--

                        "More it is than ease,
    Palace and pomp, honours and luxuries,
    To have seen white presences upon the hills,
    To have heard the voices of the eternal gods."[2]

  [2] Epic of Hades.
The thunder and lightning, storm and cloud, as well as the soft
beauty of colour, and the harmony of mountain outline, have been a
part, and a very important part, of their training. The exhilarating
air, the struggle with the elements in their fierceness, the rugged
strength of granite, seem to have possessed the very souls of such
men, and made them like "the strong ones,"--the immortal beings to
whom in all previous ages the races of mankind have assigned their
abode in the hills, as the Greek gods were supposed to dwell on Mount
Olympus. On these heights such men seem to have gained something of
the strength of Him who dwells in the heavens far above their highest
peaks,--"the strength of the hills," which, as the Hebrew poet says,
"is His also."

We have spoken of the attitude of the human mind towards mountains in
the past; let us now consider the light in which they are regarded
at the present time by all thoughtful and cultivated people. And it
does not require a moment's consideration to perceive that a very
great change has taken place. Instead of regarding them with horror
or aversion, we look upon them with wonder and delight; we watch
them hour by hour whenever for a brief season of holiday we take
up our abode near or among them. We come back to them year by year
to breathe once more the pure air which so frequently restores the
invalid to health and brings back the colour to faded cheeks. We love
to watch the ever-varying lights and shades upon them, as the day
goes by. But it is towards evening that the most enchanting scenes
are to be witnessed, when the sinking sun sheds its golden rays upon
their slopes, or tinges their summits with floods of crimson light;
and then presently, after the sun has gone down, pale mists begin
to rise, and the hills seem more majestic than ever. Later on, as
the full moon appears from behind a bank of cloud, those wonderful
moonlight effects may be seen which must be familiar to all who know
the mountains as they are in summer or autumn,--scenes such as the
writer has frequently witnessed in the Highlands of Scotland, but
which only the poet can adequately describe.

There are few sights in Nature which more powerfully impress the mind
than a sunset among the mountains. General Sir Richard Strachey
concludes his description of the Himalayas with the following
striking passage:

   "Here may the eye, as it sweeps along the horizon, embrace a
   line of snowclad mountains such as exist in no other part of
   the world, stretching over one third of the entire circle,
   at a distance of forty or fifty miles, their peaks towering
   over a sea of intervening ranges piled one behind another,
   whose extent on either hand is lost in the remote distance,
   and of which the nearest rises from a gulf far down beneath
   the spectator's feet, where may be seen the silver line that
   marks a river's course, or crimson fields of amaranth and the
   dwellings of man. Sole representative of animal life, some
   great eagle floats high overhead in the pure dark-blue sky,
   or, unused to man, fearlessly sweeps down within a few yards
   to gaze at the stranger who intrudes among these solitudes of
   Nature. As the sun sinks, the cold grey shadow of the summit
   where we stand is thrown forward, slowly stealing over the
   distant hills, and veiling their glowing purples as it goes,
   carries the night up to the feet of the great snowy peaks,
   which still rise radiant in the rosy light above the now
   darkening world. From east to west in succession the splendour
   fades away from one point after another, and the vast shadow of
   the earth is rapidly drawn across the whole vault of heaven.
   One more departing day is added to the countless series which
   has silently witnessed the deathlike change that passes over
   the eternal snows, as they are left raising their cold pale
   fronts against the now leaden sky; till slowly with the
   deepening night the world of mountains rises again, as it were,
   to a new life, under the changed light of the thousand stars
   which stud the firmament and shine with a brilliancy unknown
   except in the clear rarefied air of these sublime heights."

Year by year a larger number of busy workers from our great towns,
availing themselves of the increased facilities for travel, come to
the mountains to spend their summer holidays,--some to the Swiss
Alps, others to Wales, Cumberland, Norway, or the Highlands of
Scotland. There are few untrodden valleys in these regions, few of
the more important mountains which have not been climbed.

Our knowledge of mountains, thanks to the labours of a zealous army
of workers, is now considerable. The professors of physical science
have been busy making important observations on the condition of
the atmosphere in the higher regions; geographers have noted their
heights and mapped their leading contours. Geologists have done a
vast amount of work in ascertaining the composition and arrangement
of the rocks of which mountain chains are composed, in observing
their peculiar structures, in recording the changes which are
continually effecting their waste and decay, and thus interpreting
the story of the hills as it is written in the very rocks of which
they are built up.

Naturalists have collected and noted the peculiar plants and animals
which have their home among the hills, and so the forms of life, both
animal and vegetable, which inhabit the mountains of Europe, and some
other countries, are now fairly well known.

The historian, the antiquary, and the student of languages have
made interesting discoveries with regard to the mountain races of
mankind. And only to mention this country, such writers as Scott,
Wordsworth, and Ruskin have given us in verse and prose descriptions
of mountain scenery which will take a permanent place in literature;
while Turner, our great landscape-painter, has expressed the glories
of mountain scenery in pictures which speak more eloquently than
many words. Thus we see that whatever line of inquiry be chosen, our
subject is full of varied interest.

With regard to the characteristics of mountain races, it is not easy
to say to what extent people in different parts of the world who
live among mountains share the same virtues or the same failings;
but the most obvious traits in the character of the mountaineer
seem to be the result of his natural surroundings. Thus we find
mountaineers generally endowed with hardihood, strength, and bravery.
To spend one's days on the hillsides for a large part of the year, as
shepherds and others do in Scotland or Wales, and to walk some miles
every day in pure bracing air, must be healthy and tend to develop
the muscles of the body; and so we find the highlanders of all
countries are usually muscular, strong, and capable of endurance. And
there can be little doubt that mountain races are kept up to a high
standard of strength and endurance by a rigorous and constant weeding
out of the weakly ones, especially among children. And if only the
stronger live to grow up and become parents, the chances are that
their children will be strong too. Thus Nature exercises a kind of
"selection;" and we have consequently "the survival of the fittest."
This "selection," together with the healthy lives they lead, is
probably sufficient to account for their strength and hardiness.

As might be expected, mountaineers are celebrated for their fighting
qualities. The fierce Afghans who have often faced a British army,
and sometimes victoriously; the brave Swiss peasantry, who have
more than once fought nobly for freedom; the Highlanders, who have
contributed so largely to the success of British arms in nearly
all parts of the world, and whose forefathers defied even the
all-conquering Roman in their mountain strongholds,--these and many
others all show the same valour and power of endurance. Etymologists,
whose learned researches into the meaning of words have thrown so
much light on the ages before history was written, tell us that the
Picts were so called from their fighting qualities, and that the
word "Pict" is derived from the Gaelic "peicta," a fighting man. And
Julius Cæsar says the chief god of the Britons was the god of war.

In some countries--as, for instance, Greece, Italy, and Spain--the
mountains are infested with banditti and robbers, who often become a
terror to the neighbourhood. In more peaceful and orderly countries,
however, we find among mountaineers many noble qualities,--such
as patience, honesty, simplicity of life, thrift, a dignified
self-reliance, together with true courtesy and hospitality. This is
high praise; but who that knows mountain peasants would say it is
undeserved? How many a tired traveller among the hills of Scotland
or Wales has had reason to be grateful for welcome, food, and rest
in some little cottage in a far-away glen! How many friendships have
thus been formed! How many a pleasant talk has beguiled the time
during a storm or shower! The old feuds are forgotten now that the
Saxon stranger and invader is at peace with the Celtic people whom
his forefathers drove into the hills. The castles, once centres of
oppression or scenes of violence, lie in peaceful and picturesque
ruins, and add not a little to the interest of one's travels in the
North. What true courtesy and consideration one meets with at the
hands of these honest folk, among whom the old kindly usages have
not died out! Often too poor to be afflicted with the greed and
thirst for wealth, which frequently marks the man of the plain as
compared with the man of the hills,--the Lowlander as compared with
the Highlander,--they exhibit many of those simple virtues which
one hardly expects to meet with among busy townspeople, all bent on
making money, or as the phrase is, "getting on in life."

  [Illustration: BEN LOMOND. FROM A PHOTOGRAPH BY J. VALENTINE.]

    "The mountain cheer, the frosty skies,
    Breed purer wits, inventive eyes;
    And then the moral of the place
    Hints summits of heroic grace.
    Men in these crags a fastness find
    To fight corruption of the mind;
    The insanity of towns to stem
    With simpleness for stratagem."

Mr. Skene, the Scotch historian, records a touching case of the
devotion of Highlanders to their chief. He says,--

   "There is perhaps no instance in which the attachment of the
   clan to their chief was so strongly manifested as in the
   case of the Macphersons of Cluny after the disaster of 'the
   Forty-five.' The chief having been deeply engaged in that
   insurrection, his life became of course forfeited to the laws;
   but neither the hope of reward nor the fear of danger could
   induce any one of his people to betray him. For nine years
   he lived concealed in a cave a short distance from his own
   house; it was situated in the front of a woody precipice of
   which the trees and shelving rocks concealed the entrance. The
   cave had been dug by his own people, who worked at night and
   conveyed the stones and rubbish into a neighbouring lake, in
   order that no vestige of their labour might appear and lead to
   the discovery of the retreat. In this asylum he continued to
   live secure, receiving by night the occasional visits of his
   friends, and sometimes by day, when the soldiers had begun to
   slacken the vigour of their pursuit. Upwards of one thousand
   persons were privy to his concealment, and a reward of £1,000
   was offered to any one who should give information against
   him.... But although the soldiers were animated by the hope
   of reward, and their officers by promise of promotion for
   the apprehension of this proscribed individual, yet so true
   were his people, so inflexibly strict in their promise of
   secrecy, and so dextrous in conveying to him the necessaries he
   required in his long confinement, not a trace of him could be
   discovered, nor an individual base enough to give a hint to his
   detriment."

The mountaineer is a true gentleman. However poor, however ignorant
or superstitious, one perceives in him a refinement of manner which
cannot fail to command admiration. His readiness to share his
best with the stranger and to render any service in his power are
pleasing traits in his character. But there is one sad feature about
mountaineers of the present day which one frequently notices in
districts where many tourists come,--especially English or American.
They are, we regret to say, losing their independence, their simple,
old-fashioned ways, and becoming servile and greedy,--at least in the
towns and villages. Such changes seem, alas! inevitable when rich
townspeople, bent on pleasure or sport, invade the recesses of the
hills where poverty usually reigns. On the one hand, we have people,
often with long purses, eager for enjoyment, waiting to be fed,
housed, or otherwise entertained; on the other hand, poor people,
anxious to "make hay while the sun shines" and to extract as much
money as possible from "the visitors," who often allow themselves
to be unmercifully fleeced. Then there are in the Highlands the
sportsmen, who require a large following of "gillies" to attend them
in their wanderings, pay them highly for their services, and dismiss
them at the end of the season; and so the men are in many cases left
without employment all the winter and spring. Is it, then, surprising
that they give way to a natural tendency to idleness, and fall into
other bad habits? Any visitor who spends a winter, or part of one,
in the Highlands will be better able to realise the extent of this
evil, which is by no means small; and one cannot help regretting that
the sportsmen's pleasure and the tourist's holiday should involve
results of such grave consequence. We are inclined to think that in
these days sport is overdone, and wish it could be followed without
taking the hillman away from the work he would otherwise find, and
which would render him a more useful member of society. With the
agitation going on in some parts against deer-forests we do not
feel much sympathy, because they are based on the erroneous idea
that "crofters" could make a living out of the land thus enclosed;
whereas those who know the land and its value for agricultural
purposes tell us that with the exception of a few small patches here
and there, hardly worth mentioning, it could not possibly be made to
produce enough to maintain crofters and their families. Nevertheless,
another way of looking at the matter is this: that the man who merely
ministers to the pleasure of others richer than himself loses some of
the self-respect and independence which he would acquire by working
in his own way for a living.

The same changes for the worse are still more manifest in
Switzerland; and even in some parts of Norway the people are being
similarly spoiled. Mr. Ruskin, speaking of the former country, says:

   "I believe that every franc now spent by travellers among
   the Alps tends more or less to the undermining of whatever
   special greatness there is in the Swiss character; and the
   persons I met in Switzerland whose position and modes of life
   render them best able to give me true information respecting
   the present state of their country, among many causes of
   national deterioration, spoke with chief fear of the influx
   of English wealth, gradually connecting all industry with the
   wants of strangers, and inviting all idleness to depend upon
   their casual help, thus resolving the ancient consistency and
   pastoral simplicity of the mountain life into the two irregular
   trades of the innkeeper and mendicant."[3]

  [3] Modern Painters, vol. iv.

Mountain people have still their superstitions; since the
introduction of railways many of the old legends and popular myths
have died out, but even what is left is interesting to the student of
folk-lore,--indeed, we might say, to every one.

Sir A. Geikie, speaking of Scotch mountain scenery says,--

    "To the influence of scenery of this kind on the mind of a
   people at once observant and imaginative, such legends as that
   of the Titans should in all likelihood be ascribed. It would be
   interesting to trace back these legends to their cradle, and to
   mark how much they owe to the character of the scenery amongst
   which they took their rise. Perhaps it would be found that the
   rugged outlines of the Boeotian hills had no small share in
   the framing of Hesiod's graphic story of that primeval warfare
   wherein the combatants fought with huge rocks, which, darkening
   the air as they flew, at last buried the discomfited Titans
   deep beneath the surface of the land. Nor would it be difficult
   to trace a close connection between the present scenery of our
   own country and some of the time-honoured traditionary stories
   of giants and hero kings, warlocks and witches, or between the
   doings of the Scandinavian Hrimthursar, or Frost Giants, and
   the more characteristic features of the landscapes and climate
   of the North."[4]

  [4] Scenery of Scotland.

The following passage from Ruskin brings out more strongly the
effects of mountains on men,--a subject to which he has given much
attention:--

   "We shall find, on the one hand, the mountains of Greece and
   Italy, forming all the loveliest dreams, first of Pagan, then
   of Christian mythology, on the other, those of Scandinavia, to
   be the first sources of whatever mental (as well as military)
   power was brought by the Normans into Southern Europe. Normandy
   itself is, to all intents and purposes, a hill country.... We
   have thus one branch of the Northern religious imagination
   rising among the Scandinavian fiords, tempered in France
   by various encounters with elements of Arabian, Italian,
   Provençal, or other Southern poetry, and then reacting upon
   Southern England; while other forms of the same rude religious
   imagination, resting like clouds upon the mountains of Scotland
   and Wales, met and mingled with the Norman Christianity,
   retaining even to the latest times some dark colour of
   superstition, but giving all its poetical and military pathos
   to Scottish poetry, and a peculiar sternness and wildness of
   tone to the Reformed faith, in its manifestations among the
   Scottish hills."[5]

  [5] Modern Painters, vol. iv.

The Alps, like most other mountainous countries, have their fair
share of legends, some of which are very grotesque. We have selected
the following, as related by Professor Bonney.[6] The wild huntsman's
yell is still heard in many places by the shuddering peasants as his
phantom train sweeps by the châlet. There is also the wild goat-herd,
a wicked lad, who crucified an old he-goat and drove his flock to
worship it; lightning consumed him; and now he wanders forever over
the Alps, miserably wailing.

  [6] "The Alpine Regions of Switzerland" (Deighton, Bell, & Co.),
  a most interesting book, especially for travellers.

When the glacier of Gétroz burst, the Archfiend himself was seen
swimming down the Rhone, with a drawn sword in one hand and a golden
ball in the other; when opposite to Martigny he halted, and at his
bidding the waters rose and swept away part of the town. A vast
multitude of imps was seen about the same time on a mountain in the
Val de Bagnes by two mendicant friars from Sion, who, hearing of this
unlawful assembly, had gone out as detectives to learn what mischief
was hatching.

Many places also have their spectral animals, the Valois, according
to Tschudi, being the headquarters of these legends. There are also
pygmies to be seen in the lonely mountains, like the Norwegian
trolls, and brownies who make or mar the house, according as the
goodwife is neat or a slattern.

Many Alpine stories have reference to the sudden destruction of
pastures by the fall of rocks or ice. Here is one from the Clariden
Alps:--

   Once upon a time these were fertile pastures, on which dwelt a
   "senn." He grew rich, so that none could match him in wealth;
   but at the same time he grew proud and haughty, and spurned
   both the laws of Nature and the commandments of God. He was
   so foolishly fond of his mistress that he paved the way from
   the châlet to the byre with cheeses, lest she should soil her
   feet, and cared so little for his mother that when she lay at
   his door fainting with hunger, he offered her only milk to
   drink in which he had thrown the foulest refuse. Righteously
   indignant, she turned away, calling upon Heaven to punish such
   an insult. Before she reached her home, the rocks and ice had
   descended, crushing beneath them her wicked son, his mistress,
   and possessions.

   In the neighbourhood of Monte Rosa there is a tradition that
   a valley exists in the heart of that mountain the entrance to
   which has been sealed up by impassable glaciers, though the
   floor of the "cirque" within is still a rich pasturage. In a
   certain valley they point out a spring which bursts from the
   ground, as the outlet of the torrent by which it is watered.
   Once, said they, a _chasseur_ found the bed of this stream dry,
   and creeping up its subterranean channel, arrived on the floor
   of the valley. It was a huntsman's paradise; chamois were there
   in plenty, bears also, and even bouquetins, wandering over the
   richest pastures. He retraced his steps to announce the good
   news; but when he returned again, the waters had resumed their
   course, and the place has ever since remained inaccessible.

Mountains play a very important part in human history. In the first
place, they are natural barriers separating the nations of the
world from one another, and tending to keep them confined within
certain definite bounds; we say, tending to keep them thus confined,
because, as every one knows, these barriers have again and again been
surmounted by conquering armies. The rugged Alps could not ward off
Hannibal, who made his way through them to march upon the capital of
the Roman empire. In like manner Napoleon defied this great natural
rampart, made a road through it, and came to Italy. No mountains
would seem to be quite impassable; but although liable in the course
of ages to be occasionally overrun, they afford good protection and
produce a feeling of security.

The Himalayas separate our great Indian empire from that of China;
and we do not at present apprehend an invasion from that quarter.
The Suliman Mountains divide us from the Afghans, and the great
Russian and Persian empires farther west. Still, we know that in the
eleventh century a great Mahometan invasion of India took place;
our own armies have more than once penetrated to Kabul. Perhaps the
common garden wall separating adjacent suburban residences furnishes
a suitable illustration of the great natural walls which divide, not
households or families, but much larger families than these,--the
nations of the world.

Just as unruly boys sometimes climb over the neighbour's wall and
play games in a garden which is not their own; or as burglars may
surmount these obstacles to their progress, and finding a way
into the house by a back door or kitchen window, commence their
ravages,--so a neighbouring (but not neighbourly) nation, bent on
conquest, may invade some natural garden of the world, such as
India, by forcing their way through physical barriers which for
ordinary purposes serve to protect those within.

The Thian Shan Mountains divide Russia from China's sphere of
influence. The Caucasus Mountains separate Russia from Asia Minor.
Austro-Hungary is bounded by the Carpathians, Spain by the Pyrenees.
The Alps of Switzerland separate four nations not very friendly
to each other; and lastly, in our own country the Cheviot Hills,
together with the Tweed, form the boundary between Scotland and
England.

Where there are no mountains or hills, rivers sometimes serve as
boundaries, but of course they do not answer the purpose so well.
Sometimes a nation actually builds a wall for a boundary. Of this the
great wall of China and the Roman wall between the Cheviots and the
Solway Firth are familiar examples.

In the second place, mountains have always been a refuge and shelter
for conquered races; and the primitive tribes who once lived in the
plains have been forced by adverse circumstances to take to the
hills. This has taken place over and over again.

We know that the Celtic people now living in Brittany, Devonshire,
Cornwall, Wales, Scotland, and Ireland, though now considerably
mixed, are the descendants of the old Celtic inhabitants of France
and Britain. But there is a great deal of unwritten history for which
we may look in vain to the ordinary sources of information, such as
books, and which is only to be read in quite different records,--in
antiquities buried up in peat-beds, in bogs, in ruins and ancient
forts, or camps; and last but not least, in the names of places,
rivers, or mountains. The hills, the valleys, the rivers, are the
only writing-tablets on which unlettered nations have been able to
inscribe their annals. For this kind of history we must go to the
antiquary, and, above all, to the philologist, who tells us the
meaning of the names of places, and who the people were who gave the
names that we see on our maps. The great advances which have of late
years been made in our knowledge of the primeval races of men, or
at least of nations but little known in the annals of history, are
largely due to the interpretation of the obscure records preserved in
local names. The Celtic, the Iberian, the Teutonic, the Scandinavian,
and Sclavonic races have thus for the most part made known to us
their migrations, conquests, and defeats. And so by studying the
names of places, rivers, and hills, as well as by careful collection
of works of art, implements, coins, such as may be seen in many a
museum, it has been possible to read a great deal of early history
which would otherwise have been lost.

Those who have studied these matters say they can trace wave after
wave of population which has thus left its mark,--Gaelic, Cymric (or
Welsh), Saxon, Anglian, Norwegian, Danish, Norman, and Flemish. Thus
it can be proved from the names on the map that almost the whole of
England was once Celtic, whereas now the Celts are almost entirely
confined to the hills. The Peak of Derbyshire and the mountains of
Cumberland retain a greater number of Celtic names than the districts
surrounding them; and the hills of Devonshire long served as a
barrier to protect the Celts of Cornwall from Anglo-Saxon conquerors.

But even mountain races are often a good deal mixed, and in the
Pyrenees we find the descendants of the Iberians, who, a very long
time ago, were driven from the lowlands of France and Spain. These
Iberians are a very interesting race, of short stature, with long
heads, and dark hair and eyes. This old type is to be met with in
Wales and the Highlands even in the present day. And so we learn--if
these conclusions are sound--that even the Celts in their early days
were invaders, and drove before them an older population. This race,
it seems, lived in Europe a very long time ago, before the discovery
of metals, when people made axes, hammers, and spear-heads out of
flints or other stones; and so they are said to belong to "the Stone
Age." Their remains are found in many of the caves which of late
years have been explored. Possibly the ancient people of Switzerland
who lived in wooden houses, erected on piles near the shores of lakes
(probably for safety), were also of the same stock.

It is curious to find how people living in separate valleys among the
mountains of Switzerland have, in the course of time, become so much
unlike their neighbours that they can hardly understand each other's
speech, so effectually have the mountains kept them apart. In some
districts almost every valley has its separate dialect. Switzerland
is only twice the size of Wales, yet the local names are derived
from half a dozen different languages, three or four of which are
still spoken by the people. In the Alps, too, the same mixture of
Celtic with an older Iberian stock has been detected.

A curious reversal of the usual order of things is noticed by the
late Dean Stanley in his "Sinai and Palestine." He points out that
the Jews took possession of many of the hills of Palestine soon after
the invasion under Joshua, but could not drive out the peoples of the
plains, because they were better armed, and had chariots of iron in
great number. The conquerors in this case kept to the hills; while
the Canaanites, Philistines, and other inhabitants of the country
retained for a long time their hold of the lower ground.




CHAPTER II.

THE USES OF MOUNTAINS.

   The valleys only feed; the mountains feed and guard and
   strengthen us.--RUSKIN.


It is not an exaggeration to say that there are no physical
features of the surface of the earth which render such a variety of
services as mountains. The operations which they perform involve
such far-reaching consequences that it is difficult to say where
their effects cease. Indeed, it might almost be maintained that
they are the mainspring of the world,--as far as its surface is
concerned,--for it would fare ill with mankind if they were removed
or in some way destroyed. Things would then very soon come to a
standstill. The soil would become exhausted; streams would cease to
flow; and the world would become a kind of stagnant pool.

The three main services of the hills are these:--

   I. Mountains help to condense water-vapour from the atmosphere,
   thus bringing back to the earth moisture which it loses
   continually by evaporation.

   II. Mountains are elevated reservoirs of water in one form or
   another, and thus not only feed the streams and rivers, but
   give them force and direction as well.

   III. Mountains suffer themselves to be slowly worn away in
   order that the face of the earth may be renewed; in other
   words, they die that we, and all created things, may live.


I. _Mountains help to condense water-vapour from the atmosphere, thus
bringing back to the earth the moisture which it loses continually by
evaporation._ Every one knows that there is abundance of water-vapour
in the atmosphere, but the question arises, How does it get there?
The answer to this lies in the simple fact that every surface of
water exposed to the air undergoes loss by evaporation. If you wish
to satisfy yourself on this point, place a saucer of water in your
room, and in a few days it will all be gone. We hang clothes out to
dry, and so avail ourselves of this curious power that air has of
taking up water in the form of vapour. Steam, or water-vapour, is
really invisible, though we frequently talk of seeing the steam
issuing from a locomotive; but what we really see is a cloud of
condensed steam, and such clouds,[7] like those that we see floating
in the air, are really masses of little tiny particles of water which
can reflect or throw back the light which falls upon them, and thus
they become visible. Again, a kettle of water, if left too long on
the fire will entirely boil away. It is all turned into steam, and
the steam is somehow hidden away in the air, though a little of it
will be condensed into slight clouds by the colder air outside the
kettle.

  [7] It has lately been proved that clouds can only form in air
  which contains dust, and that each little suspended particle of
  water contains a speck of dust or a tiny germ of some sort for
  its nucleus.

But how can water stow itself away in the air without being seen or
felt?

An illustration may help to explain this. Suppose you scatter a
spoonful of small shot over a carpet or a dark-coloured table-cloth;
you would probably not be able to see them at a little distance.
Now, gather them together in a heap, and you see them at once. The
heap of shot in some ways resembles a drop of water, for in a drop
of water the tiny particles (or molecules) of which it is composed
are close together; but by heating water you cause them to fly
asunder and scatter themselves in various directions. They are lost
to sight, and moreover have no power of attracting each other or of
acting in concert; each one then takes its own course, whereas in
the drop of water they were in some wonderful way bound together by
mutual attraction. They dance in groups; but the rude force of heat
will scatter these little dancing groups, and break them up into that
state which we call a state of vapour.

The forces of heat and cohesion are directly at variance; and it
is just a question of degree whether the one or the other gets the
mastery in this "tug of war." The more you heat the water, the faster
the little groups of molecules break up and disappear in the air.
They must in some way go moving between the particles of air, and
collisions keep taking place with inconceivable rapidity.

And now another question arises; namely, how much water-vapour can
the air take? That depends chiefly on its temperature. Air when
heated will take up a great deal of steam; and the more you heat air,
the more it can take up. When air at a given temperature can take up
no more, it is said to be saturated for that temperature; but if the
temperature be raised, it will immediately begin to take up more. For
each degree of temperature there is a certain amount of water-vapour
which can be absorbed, and no more. But suppose we take some air
which is already saturated and lower its temperature by giving it
a sudden chill, what will happen? It will immediately give up part
of its steam, or water-vapour; namely, the exact amount which it is
unable to contain at the lower temperature.[8]

  [8] Pressure also has an important influence, but was omitted
  above for the sake of simplicity.

There are various ways in which you can test this matter for
yourself. For instance, take a hand-glass, and breathe on it. You
know what will happen: a film of moisture forms upon it; and you know
the reason why. It is simply that the cold glass gives a chill to
one's breath (which being warm is highly charged with water-vapour
from the lungs), and so some of the vapour is at once condensed. Now,
this serves very well to explain how mountains catch water-vapour,
and condense it. They are, as it were, a cold looking-glass; and
the hot breath of the plains, as it strikes their sides, receiving
a sudden chill, throws down part of the vapour it contains. On the
higher parts of mountain-ranges the cold is so great that the water
assumes the form of snow.

Mountains, as every one knows, are colder than the plains below.
No one cares to stay very long on a mountain-top, for fear of
catching cold. It may be worth while to consider why they are cold.
Perhaps you answer, "Because they are so high." That is true, but
not a complete answer to our question. We must look at the matter a
little more closely. The earth is a warm body surrounded by space in
which the cold is inconceivably intense; but just as we protect our
bodies against cold with garments, so the earth is wrapped up in an
atmosphere which serves more or less to keep in the heat. All warm
bodies give out heat as luminous bodies give out light; but the rays
of heat, unlike those of light, are quite invisible to our eyes, so
that we are unaware of them. These "dark heat-rays," as they are
called, do not make any impression on the retina, because our eyes
are not capable of responding to them as they do to the ordinary rays
of light. But there is a delicate little instrument known as the
thermopile, which responds to, and so detects these invisible rays;
and if our eyes were sensitive to such vibrations as these, we should
see heat-rays (which like light and sound are due to vibrations)
streaming from every object, just as light does from a candle-flame.

Those parts of the earth which are least covered or protected by the
atmosphere lose heat most rapidly,--in the same way that on a frosty
day one's fingers become cold unless covered up. Now, there is less
air over mountains; and in those higher regions above the peaks
what air there is, is more rarefied, and therefore less capable of
stopping the heat-rays coming from the earth. Professor Tyndall has
shown that water-vapour in the air has a great power of stopping dark
heat-rays; and the lower regions, which contain more vapour, stop or
absorb a good deal of heat which would otherwise escape into space.

Look at a map of any continent, and you will see the rivers streaming
away from the mountains. All those vast quantities of water come
from the atmosphere; and mountains do a large share of the work of
condensing it from the state of vapour to that of water. Take the
map of India, and look at the great range of the Himalayas. At
their feet is the hot valley of the Ganges, which meets that of the
Brahmapootra River. An immense amount of evaporation takes place
from these mighty rivers, so that the air above them becomes laden
with water-vapour. Farther south is the tropical Indian Ocean, from
which the direct rays of the sun draw up still vaster quantities of
water. And so when south winds blow over India, they are full of
water-vapour; and presently they strike the flanks of the Himalayas,
and at once they are chilled, and consequently part with a large
amount of the vapour which they contained. This is best illustrated
by the case of the southwest monsoon wind of the summer season, which
sets in during the month of April, and continues to blow steadily
towards the northeast till October. After leaving the Bay of Bengal,
this warm wind, laden with vapour, meets ere long with the range
known as the Khasi Hills, and consequently throws down a large part
of its vapour in the form of rain. The rainfall here in the summer
season reaches the prodigious total of five hundred inches, or about
twenty times as much as falls in London during a whole year. After
passing over these hills, the monsoon wind presently reaches the
Himalayas; and another downpour then takes place, until by the time
it reaches the wide plains of Thibet, so much water has been given up
that it becomes a very dry wind instead of a moist one.

It must not be supposed, however, that the condensation effected by
mountains is entirely due to this coldness. They have another simple
and effective way of compelling the winds to give up rain: their
sloping sides force the winds which strike them to ascend into higher
regions,--wedging them up as waves run up a sloping stony bank on the
seashore,--and when the winds reach higher regions of the atmosphere
they must (as explained above) suffer loss of heat, or in other
words, have their temperature lowered. They also expand considerably
as they rise into regions where the atmospheric pressure is less;
and as every gas or vapour loses heat in the act of expansion, they
undergo a further cooling from this cause also.

We have now learned that the cooling process is brought about in
three different ways: (1) By contact with the cold body of the
mountains; (2) By giving out heat into space; (3) By expansion of
the air as it reaches into the higher regions of the atmosphere.
The "cloud-caps" on certain mountains and promontories are to be
explained by all these causes combined.

The west coast of Great Britain illustrates the same thing on a
smaller scale. There the warm waters of the Gulf Stream, travelling
in a northeasterly direction straight away from the Gulf of Mexico,
strike the west coast of Ireland, England, and Scotland; and as most
people are aware, the mild climate of Great Britain is chiefly due
to this fact. If you contrast for a moment the east and west coasts
of Britain, you will see that the latter is much more rocky and
mountainous than the east coast. Mountains run down nearly all our
western coasts. Now, it is this elevated and rocky side of Britain
which catches most of the rain. Very instructive it is to compare the
annual rainfall in different parts of Britain. On Dartmoor about 86
inches of rain fall every year, while in London only about 24 inches
fall annually; but then London has no range of mountains near, and is
far away from the west coast. Again, while people in Ambleside have
to put up with 78 inches of rain, in Norfolk they are content with
the modest allowance of 24 inches or so. At a place called Quoich on
the west coast of Scotland, about 117 inches fall every year. These
differences are chiefly due to the different contour of the land down
the west side of Britain, which is mountainous, while the east side
is flat, and also to the fact that while easterly winds, which have
come over the continent, are dry, our prevailing winds are from the
west and southwest, and are consequently heavily laden with vapour
from the Atlantic Ocean. These winds follow the direction of the Gulf
Stream, driving it along before them; and in so doing they take up
large quantities of vapour from its surface. When these warm winds
touch our western coasts, they receive a chill, and consequently are
no longer able to contain all the vapour which they bring with them,
and so down comes the rain.


II. _Mountains are elevated reservoirs of water in one form or
another, and thus not only feed the streams and rivers, but give them
force and direction as well._ It is very important that the mountains
should not allow the waters they collect to run away too fast. Try
to think for a moment what would happen if instead of being, as it
were, locked up in the form of snowfields and glaciers, the water
were all in the liquid form. It would soon run away, and for months
together the great river-valleys would be dry and desolate. When the
rain came, there would be tremendous floods; dire destruction would
be wrought in the valleys; and very soon the great rivers would
dwindle down to nothing. Vegetation too would suffer seriously for
want of water during the summer months; and the valleys generally
would cease to be the fertile sources of life which they are at
present. The earth would become for the most part like a stagnant
marsh.

But in the higher mountain regions there is a beneficent process
going on which averts such an evil. The precious supplies of water
are stored up in the solid forms of snow and ice. Now, we all know
that snow and ice take a long time to melt; and thus Nature regulates
and like a prudent housewife economises her precious stores. The
rivers which she feeds continually, from silent snowfields and
glaciers among her mountain-peaks, are the very arteries and veins
of the earth; and as the blood in our bodies is forced to circulate
by pressure from the heart, so the rivers are compelled to flow by
pressure from the great heart of the hills,--slow, steady, continuous
pressure, not the quick pulses which the human heart sends through
the body.

And again, as the blood, after circulating through the body in an
infinite number of life-giving streams, returns to the heart once
more on its journey, so the thousand streams which wander over the
plains find their way back to the heart of the mountains, for the
water is brought there in the form of vapour and clouds by the winds.

When we build water-towers, and make reservoirs on high ground to
give pressure to the water in our pipes, and make it circulate
everywhere,--even to the tops of our houses,--we are only taking a
hint from Nature. The mountains are her water-towers, and from these
strong reservoirs, which never burst, she commands her streams,
forcing them along their courses in order that they may find their
way to the utmost bounds of continents.

But there is another way in which mountains regulate the supply
of water, and prevent it from running away too fast,--one not so
effective as the freezing process, but still very useful, because it
applies to the lower hills below the line of perpetual snow. This may
be well illustrated by the state of some of the Scotch hills in the
middle of summer or autumn, when there is little if any snow resting
upon them.

Any one familiar with these hills will have noticed how full of
water their sides are. Tiny threads of streams trickle slowly along
everywhere; peat-beds are saturated with dark-brown water; even the
grass and soil are generally more or less wet, especially under pine
forests. One can generally get a cup of water somewhere, except
after a long dry summer, which is exceptional. Then there is the dew
forming every night. Forests with their undergrowth of soil--moss
and fern--also help very considerably to check the flow of water. We
have often asked ourselves when watching some swift-flowing river,
"Where does all this water come from? Why does it not dry up in
hot weather?" The answer came fully after we had climbed several
mountains, and seen with our eyes the peat-beds among the hills, and
heard the trickling of the tiny rivulets hurrying along to feed
some neighbouring burn, or perhaps to run into some mountain tarn or
loch, and noticed the damp, spongy state of the soil everywhere,--not
to mention the little springs which here and there well up to the
surface, and so contribute their share.

The rivers and streams of Scotland assume various tints of amber
and dark-brown, according to the amount of rain which has recently
fallen. These colours are due to organic matter from the peat.
Compare Scott's description of the Greta:--

    "In yellow light her currents shone,
    Matching in hue the favourite gem
    Of Albion's mountain diadem."

The waters of some Scotch rivers after heavy rain look as black as
pitch.

Nor must we omit the lakes which abound in most mountain regions,
and serve as natural reservoirs for the rivers, besides giving a
wonderful charm to mountain scenery.

The largest lakes in mountainous regions are found on the courses
of the rivers; and there is good reason to believe that they were
formed, not by any process of subsidence, but by the same operations
that carved out the valleys. In many cases they are due to the
damming up of a stream. But in some countries the streams dry up
during summer,--in Palestine or Sinai, where there is but little soil
on the hills, and consequently hardly any vegetation. Such barren
hills cannot hold the continual supplies which pour gently forth from
the mountains of higher latitudes.

The Alps feed four of the principal rivers of Europe. We cannot do
better than quote Professor Bonney, whose writings on the Alps are
familiar to all geologists. In his "Alpine Regions of Switzerland"
the following passage occurs:--

   "This mass of mountains, the great highlands of Europe, is
   therefore of the utmost physical and geographical importance.
   Rising in places to a height of more than fifteen thousand
   feet above the sea, and covered for an extent of many thousand
   square miles with perpetual snow, it is the chief feeder of
   four of the principal rivers in Europe,--the Po, the Rhone,
   the Rhine, and the Danube. But for those barren fields of ice,
   high up among the silent crags, the seeming home of winter and
   death, these great arteries of life would every summer dwindle
   down to paltry streams, feebly wandering over stone-strewn
   beds. Stand, for example, on some mountain-spur, and look down
   on the Lombardy plain, all one rich carpet of wheat and maize,
   of rice and vine; the life of those myriad threads of green
   and gold is fed from these icy peaks, which stand out against
   the northern sky in such strange and solemn contrast. As it is
   with the Po, so it is with the Rhine and the Rhone, both of
   which issue from the Alps as broad, swelling streams; so, too,
   with the Danube, which, although it does not rise in them, yet
   receives from the Inn and the Drave almost all the drainage of
   the eastern districts."

A very little reflection will serve to convince any one how vastly
important and beneficial is the slope of the mountains, and how it
gives force and direction to streams and rivers. Without this force,
due to universal gravitation, by which the waters seek continually
lower levels, the supplies in the hills would be useless. Mere lakes
on flat surfaces would not answer the purpose; and so the sources of
water are elevated in order that it may pour over the world below.

No writer has given such fascinating descriptions of mountains as
Mr. Ruskin; and no one has more eloquently described the functions
they perform. In the fourth volume of his "Modern Painters," which
every one who cares for mountains should read, we find the following
beautiful passage:--

   "Every fountain and river, from the inch-deep streamlet that
   crosses the village lane in trembling clearness, to the massy
   and silent march of the everlasting multitude of waters in
   Amazon or Ganges, owe their play and purity and power to the
   ordained elevations of the earth. Gentle or steep, extended
   or abrupt, some determined slope of the earth's surface is of
   course necessary before any wave can so much as overtake one
   sedge in its pilgrimage; and how seldom do we enough consider,
   as we walk beside the margins of our pleasant brooks, how
   beautiful and wonderful is that ordinance, of which every
   blade of grass that waves in their clear waters is a perpetual
   sign,--that the dew and rain fallen on the face of the earth
   shall find no resting-place; shall find, on the contrary,
   fixed channels traced for them from the ravines of the central
   crests down which they roar in sudden ranks of foam to the dark
   hollows beneath the banks of lowland pasture, round which they
   must circle slowly among the stems and beneath the leaves of
   the lilies; paths prepared for them by which, at some appointed
   rate of journey, they must evermore descend, sometimes slow,
   and sometimes swift, but never pausing; the daily portion of
   the earth they have to glide over marked for them at each
   successive sunrise; the place which has known them knowing
   them no more; and the gateways of guarding mountains opened for
   them in cleft and chasm, none letting them in their pilgrimage,
   and from afar off the great heart of the sea calling them to
   itself: 'Deep calleth unto deep.'"

Geologists, however, do not in these days teach that the present
paths of rivers were made for them, but rather that the rivers have
carved out their own valleys for themselves. The old teaching before
the days of Lyell and Hutton, the founders of modern geology, was
that valleys were rents in the rocks of the earth's crust formed
by some wonderful convulsion of Nature, whereby they were cracked,
torn asunder, and upheaved. But a careful study of rivers and their
valleys for many years has shown that there is no evidence of such
sudden convulsions. The world is very old indeed, and rivers have
been flowing much as we see them for ages and ages. A few thousand
years is to the geologist but a short space of time; and there can be
no doubt that a stream can in the course of time carve out for itself
a valley. The operations of Nature seem slow to us because our lives
are so short, and we can see so little change even in a generation;
but the effects of these changes mount up enormously when continued
through a long space of time. Nature works slowly; but then she has
unlimited time, and never seems in a hurry. It is like the old story
of the hare and the tortoise; and the river, working on steadily and
quietly for hundreds or thousands of years, accomplishes far more in
the end than sudden floods or violent catastrophes of any sort.


III. _Mountains suffer themselves to be slowly worn away in order
that the face of the earth may be renewed; in other words, they die
that we, and all created things, may live._ The reader will find a
full account of the methods by which these results are accomplished
in chapters v. and vii., and therefore we must not anticipate this
part of the subject. Let it suffice for the present to say that
this destruction of the hills is brought about by the action of
heat and cold, of rain and frost, of snow and ice, and the thousand
streams that flow down the mountain-sides. It is with soils that we
are chiefly concerned at present. Try to think for a moment of the
literally _vital_ consequences which follow from the presence of
good rich soils over different parts of the earth, and ask whether
it would be possible for civilised races of men to flourish and
multiply as they do if it were not for the great fertile valleys and
plains of the world. Mountain races are neither rich nor powerful.
Man exists mainly by cultivation of the soil; and among mountains
we only find here and there patches that are worthy of the labour
and expenditure of capital involved in cultivation. But in the great
plains, in the principal river-valleys of the world, and among the
lesser hill-ranges it is different. The _lowlands_ are the fertile
regions. All great and powerful nations of the world are children
of the plains. It was so in the past; it will be so in the future,
unless men learn to feed on something else than corn, milk, and
flesh, which is not very likely.

The Egyptians, the earliest civilised race of which we have
satisfactory records, dwelt in the fertile valley and delta of
the Nile. They clearly perceived the value of this great river to
themselves, and worshipped it accordingly. They knew nothing of its
source in the far-away lakes of Central Africa; but they knew truly,
as Herodotus tells us, that Egypt was "the gift of the Nile," for the
alluvial soil of its delta has been formed by the yearly floods of
that great river, as its waters, laden with a fine rich mud, spread
over its banks, and for a time filled the valley with one sheet of
water. The Assyrians and Babylonians had their home in the valley of
the Euphrates and Tigris. The Chinese, too, have their great rivers.
Russia is well watered by powerful rivers. The most populous parts of
the United States of America are watered by the great Mississippi,
and the other rivers which flow into it. England, Germany, and France
are furnished with well-watered plains.

Soils are the chief form of national wealth. Minerals, such as coal
and iron, are of course extremely valuable, and help to make an
industrious race rich; but the land is the main thing, after all, and
by land we mean soil. The two words are almost synonymous. But since
the soil is formed chiefly of débris brought from the mountains, it
would be more true to say that these are the real sources of wealth.
Soils contain besides a large amount of valuable organic matter (that
is, decayed matter which has once had animal or vegetable life)
different kinds of minerals, which are necessary to the support of
plant life: potash, soda, carbonate of lime, silica, magnesia, iron,
phosphorus, and manganese in their various compounds are all present
in the rocks of which mountains are composed. We must again fall back
upon "Modern Painters" for an effective description of the forming of
soil by destruction of the hills:--

   "The higher mountains suffer their summits to be broken into
   fragments and to be cast down in sheets of massy rock, full, as
   we shall presently see, of every substance necessary for the
   nourishment of plants; these fallen fragments are again broken
   by frost, and ground by torrents into various conditions of
   sand and clay,--materials which are distributed perpetually by
   the streams farther and farther from the mountain's base. Every
   shower that swells the rivulets enables their waters to carry
   certain portions of earth into new positions, and exposes new
   banks of ground to be moved in their turn.... The process is
   continued more gently, but not less effectively, over all the
   surface of the lower undulating country; and each filtering
   thread of summer rain which trickles through the short turf of
   the uplands is bearing its own appointed burden of earth down
   on some new natural garden in the dingles beneath."

It may be laid down as a simple economic truth, that no nation can be
powerful, rich, or prosperous, unless it possess in the first place
a good soil. Other conditions, such as large navigable rivers, a
good seaboard for harbouring ships, are also important; but unless
the land will yield plenty of food, the population cannot be very
great, for people must be fed. Foreign supplies of corn at a low
price, meat and provisions of various kinds, supplement what is
grown in England; but without a good soil we could not have become a
powerful nation.

A high state of civilisation is in a large measure to be traced to
climate and soil. The sequence is somewhat as follows:--

Mountains collect rain.

Rain fills the rivers.

Rivers make rich alluvial plains.

Agriculture follows; and food is produced.

Abundant food maintains a large population.

The population works to supply its various wants; such as roads,
railways, ships, houses, machinery, etc. Then follows exchange with
other countries. They send us what they can best produce, and we send
them what we can best and most easily produce, and so both parties
gain.

Thus towns spring up. Education, refinement, learning, and the higher
arts follow from the active life of towns, where more brain-work is
required, and the standard of life is higher.

And thus we may, in imagination, follow step by step the various
stages by which the highest phases of civilisation are brought to
pass, beginning at the mountains and ending with human beings of
the highest type,--the philosopher, artist, poet, or statesman, not
omitting the gentler sex, who are often said to rule the world.

The following lines of Milton possess, in the light of these facts, a
deeper meaning than the poet probably intended to convey:--

    "Straight mine eye hath caught new pleasures
    Whilst the landscape round it measures:
    Russet lawns and fallows grey,
    Where the nibbling flocks do stray;
    Mountains on whose barren breast
    The labouring clouds do often rest;
    Meadows trim with daisies pied,
    Shallow brooks and rivers wide;
    Flowers and battlements it sees
    Bosomed high in tufted trees,--
    Where perhaps some beauty lies,
    The cynosure of neighbouring eyes."

With a little rearrangement of the lines, the sequence we have
indicated above would be well illustrated. The mountains must come
first; then the clouds, ready to bring forth their rain; then the
brooks and rivers, then "russet lawns and fallows grey,"--with their
"nibbling flocks." Then come the human elements in the scene,--the
"towers and battlements," containing armed warriors, well fed, no
doubt, and ready to do their master's bidding; lastly, the lady
who adorns the home of her lord, and, let us hope, makes it worth
fighting for.

For commercial purposes, large navigable rivers are of great use. And
in spite of the modern railway, rivers still exert an influence in
determining the routes followed by trade. London, Liverpool, Glasgow,
and other busy centres of life owe their importance to the rivers
which flow through them, especially since they are tidal rivers.
Heavily laden barges may be seen from London Bridge going up and down
with the tide every day.

Since the direction as well as the existence of large rivers is
regulated by mountains, it is clear that mountains have a very direct
influence on the trade of the world.


_Mountains supply many of our wants._ Besides water and soil, how
many useful things come from the hills! Their slopes, watered by
the clouds, frequently support an abundant growth of pine forest;
and thus we get wood for the shipwright and joiner. Again, mountains
are composed of harder rocks than we find in the plains, and that
is one reason why they stand out high above the rest of the world.
Their substance has been hardened to withstand for a longer time the
destruction to which all rocks are subjected. They have been greatly
compressed and generally more or less hardened by subterranean heat.
We bake clay and make it into hard bricks; so Nature has baked and
otherwise hardened the once soft strata of which mountains are
chiefly composed, converting them into slates, schist, gneiss, and
other kinds of rock called "metamorphic" by geologists, because they
have been altered or metamorphosed from their original condition (see
chapter viii., page 277). Again, granite, basalt, and other rocks
known as "igneous," which once existed in a molten condition, have
forced their way up from subterranean regions into the rocks forming
mountain-chains; and a good deal of the hardening just alluded to is
due to the presence of these fiery intruders, which have baked and
hardened the rocks around them to a considerable extent, altering
at the same time their mineral composition. The same causes which
led to the injection of granite, basalt, and other igneous rocks in
mountain-ranges brought other consequences in their train. Whatever
the causes, they were closely connected with volcanic eruptions, so
that highly heated water and steam found their way through cracks and
other fissures in the rocks; and in the course of time the chemical
actions thus set up led to the deposition of valuable metallic ores
within these fissures. In this way mineral veins were formed; and
volcanic action seems to be largely responsible for the production of
minerals. Thus we find around Vesuvius, and in fact in all volcanic
regions, large and varied supplies of minerals. Now, the geologist
discovers that many mountain-chains--such, for example, as the
Grampians, Alps, and Carpathians--have in past geological periods
been the seats of volcanic action on a grand scale; and so we need
not be surprised to learn that mountainous countries yield large
supplies of valuable gems and metallic ores (see chapter viii.,
page 277). Even in the days of Solomon, the active and business-like
Phoenicians were carrying on trade with Great Britain; and the tin
came from Cornwall. Besides tin, gold, silver, lead, copper, zinc,
and other metals come from our hills. Now, however, we get our copper
mostly from the Andes, and our gold from Australia or South Africa,
because it can be got more cheaply from these countries, to which
many of our Cornish miners have emigrated.

Precious stones also come chiefly from the hills, for the same
reason; for they were formed at the same time and by the same causes.
Cairngorms, agates, chalcedony, jasper, onyx, topaz, diamonds, and
many other gems are silent but certain witnesses to the action of
subterranean heat, acting long ago on the rocks which we now see
standing up high above the general surface of the ground, though
once they were buried deep down below the surface. Diamonds as well
as gold are often got from the beds of streams, but this is easily
accounted for; the streams have washed them out and brought them down
from the hills.

The following words from the Book of Job (xxviii. 5) might well be
applied to the hills.

    "As for the earth, out of it cometh bread:
    And underneath it is turned up as it were by fire.
    The stones thereof are the place of sapphires,
    And it hath dust of gold."

We have thus explained the three principal services rendered by
mountains, but some others remain to be mentioned.


_Mountains have an important influence on climate._ The climate of
highlands everywhere has certain peculiarities which distinguish
it from that of adjacent lowlands. The air resting on mountains is
less dense than that of the lowlands, and hence has fewer molecules
to obstruct the entering sunbeams by day, or to stop the outward
radiation at night. Therefore mountain air must be cooler; and so we
find that on mountains the mean, or average, annual temperature is
lower. This rarity of the air causes the ground to become hotter by
day and colder by night than the ground of the plains; and so the
extremes of temperature are greater. These extremes are injurious to
vegetation in the higher regions, and the want of moisture still
more so. But mountain-slopes _up to a certain height_ usually have
a moist climate; that is, they have more clouds and rain than the
surrounding lowlands. Below the region of snow there is generally
a heavy growth of forest; and forests in their turn exercise an
important influence, helping to collect moisture, and in various ways
to prevent extremes either of heat or cold.

The earth is divided into three well-marked zones or belts of
climate: (1) The torrid zone within the tropics, where the sun is
vertical twice a year, and days and nights are nearly equal; (2)
The temperate zones, where the sun's rays come more obliquely,
and so are less powerful, and where the length of day and night
varies considerably; and (3) The frigid zones, round each of the
poles, regions of intense cold, where for six months of the year
the sun is never seen. Now, these broad divisions, so familiar to
school children, are considerably interfered with by the height of
various districts above the sea-level, or, as geographers say, by
altitude. High ranges of mountains bring somewhat arctic conditions
with them, even in low latitudes, where one would expect great
heat. Thus the climate of the plains is very different from that
of their neighbouring mountain-ranges, although their latitudes are
practically the same. Travellers in Switzerland know how hot it can
be in the Rhone Valley or in the plain of Lombardy, and how much
cooler it is when you get up among the glaciers and the snowfields.
Or to take an illustration from Great Britain: a hot summer would be
somewhat trying in Edinburgh, Glasgow, or even Inverness, because
they lie low, while among the Grampians, on Speyside, or Braemar, it
would be very pleasant.

Vegetation follows climate. The sultry plains of the Ganges show
a luxuriant tropical vegetation, while on the middle slopes of
the Himalayas the climate is temperate, like that of Europe, and
consequently the vegetation resembles that of a temperate region; and
the highest parts of this great range are like polar latitudes in
their climate, and partly also in their vegetation.

The arctic character of the climate of high mountain regions shows
itself in the flora; for on the High Alps and the Highlands of
Scotland and Norway, we find no small number of truly arctic plants
whose home is much farther north. A very long time ago, when the
climate of the whole of Northern Europe was extremely severe, and
when great glaciers descended from the mountains into the plains,
so that the aspect of the country was somewhat similar to that of
Greenland at the present day, arctic plants and animals came down
from their northern home, and flourished abundantly. This was during
the _Great Ice Age_, which has left behind unmistakable evidences
which the geologist can interpret as if they were written records.
Then for some reason the climate became milder, the glaciers melted
away, in Great Britain at least; but these arctic plants were left
behind, and flourished still on the cool mountains, though they died
out on the warm plains (see chap. iv., pp. 123-124).

  [Illustration: SNOW ON THE HIGH ALPS. FROM A PHOTOGRAPH BY MR.
  DONKIN.]

_Mountains help to cause movement and change in the atmosphere._
Let us see how this takes place. Mountains expose on one side their
masses of rock to the full heat of the sun. Rocks are capable of
becoming highly heated under a blazing sun: we have known stone
walls, even in England, to be almost too hot to touch; and perhaps
the reader may have often noticed the quivering of the hot air as
it rises from the ground on a summer day, especially over a road or
any piece of bare rocky ground. This quivering tells us that the air
is highly heated by the ground beneath, and is consequently rising.
You know how the pebbles look beneath a clear running stream; and
the things which we see through air in this state all seem to be
similarly moving or quivering. It is easy then to imagine how masses
of heated air would rise up from the side of a mountain-range which
faces the sun,--that is, the southern side,--while on the other, or
northern side they cast a soft shadow for leagues over the plains
at their feet. In this way mountains divide a district into two
different climates, with a light warm air on their southern slopes,
and colder air on the northern, and the rising of the warm air will
cause a certain amount of circulation and movement. Hence mountains
help to make currents in the atmosphere, and these currents produce
important consequences.

When mountain-ranges trend more or less directly across the direction
of prevailing winds, they always have a moist side and a dry one. In
the torrid zone, where easterly winds prevail, the eastern slope is
usually the moist side; but in higher latitudes, as, for example, in
Europe, the western side of mountain-ranges receives the greatest
amount of rainfall, because westerly winds prevail there.


_Mountains are barriers dividing not only one nation from another,
but separating also various tribes of plants and animals._ It will
be readily understood that with the exception of birds, whose powers
of flight render them independent of physical barriers, most animals
find mountains more impassable than men do. We can make roads and
railways, but they cannot thus aid their powers of locomotion; hence
mountains put limits to their migrations. Still, climate and food
supplies have a greater influence in determining the boundaries of
zoölogical provinces (see chapter iv.).


_Mountains are the backbones of continents._ A glance at a map of
the world will show that there is evidently a close connection
between continents and great mountain-chains. This connection shows
itself both in the shapes and general direction of continents.
Thus, the long continuous line of mountain-chain which extends from
the southern spur of the Andes to the northern end of the Rocky
Mountains,--a distance of about nine thousand miles,--corresponds
with the general trend of the North American continent, and forms
the axis or backbone of that vast tract of land. It seems as if the
sea on its western side were kept at bay by this great rocky wall,
while on its eastern side the rivers have formed new land. A line of
mountains is often the coast line, for the sea cannot overcome it
unless subsidence takes place. The backbone of Asia and Europe runs
east and west, and the continental area of the Old World follows the
same general direction.

These are the chief uses of mountains, and the facts which we have
brought forward will serve to show how indispensable they are. The
following eloquent passage from "Modern Painters" may form a fitting
close to the present chapter:--

   "And thus those desolate and threatening ranges which in nearly
   all ages of the world men have looked upon with aversion or
   with horror, and shrunk back from as if they were haunted by
   perpetual images of death, are in reality sources of life
   and happiness, far fuller and more beneficent than all the
   bright fruitfulness of the plain. The valleys only feed; the
   mountains feed and guard and strengthen us. We take our ideas
   of fearfulness and sublimity alternately from the mountains and
   the sea; but we associate them unjustly. The sea-wave, with
   all its beneficence, is yet devouring and terrible; but the
   silent wave of the blue mountain is lifted towards heaven in a
   stillness of perpetual mercy; and the one surge, unfathomable
   in its darkness, the other unshaken in its faithfulness, for
   ever bear the seal of their appointed symbolism:--

    "'Thy _righteousness_ is like the great mountains,
    Thy _judgements_ are a great deep.'"




CHAPTER III.

SUNSHINE AND STORM ON THE MOUNTAINS.

    I would entreat your company
    To see the wonders of the world.

    _Two Gentlemen of Verona._


"The spirit of the hills is action, that of the lowlands repose."[9]
The plains, with their peaceful meadows and meandering streams, might
almost be said to be asleep; but the mountains are wide awake. They
are emphatically scenes of violent or rapid action. The wind blows
more fiercely among the mountain-peaks than over the plains below;
heat and cold are more extreme; and every process of change or decay
seems quickened.

  [9] Ruskin, "Modern Painters."

Avalanches, falls of rock, earthquakes, storms, and floods exhibit
the more terrible aspects of the hills. Yet they have their gentler
moods: witness the brightness of the starry sky overhead, and its
intense blue by day, the wonderful sunrises and sunsets, the lovely
effects of light and shade, of cloud and mist, the stillness and
silence of the eternal snows in summer, and the beauty of the Alpine
flower.

Let us see what those who know mountains best have to say about the
wonderful things they have seen there. To begin with sunset and
sunrise. Professor Bonney remarks,--

   "Not the least interesting peculiarity of an Alpine sunset
   is the frequency with which its most beautiful effects are
   revealed quite unexpectedly. Often at the close of a rainy
   afternoon, the clouds, just before the sun goes down, break,
   roll up, sometimes disperse as if by magic, in the glory of
   those crimson rays that come darting upon them and piercing
   every rift. Many a time have I watched the vapours around a
   mountain-peak curling lightly upwards, and melting away into
   the sky, till at last the unclouded summit glowed with flushes
   of orange and rose, ere it grew pale and dead in its shroud of
   fresh-fallen snow."[10]

  [10] The Alpine Regions of Switzerland.

Here is a description by Professor Tyndall of a sunset witnessed in
the neighbourhood of the Weisshorn:--

   "As the day approached its end, the scene assumed the most
   sublime aspect. All the lower portions of the mountains were
   deeply shaded, while the loftiest peaks, ranged upon a
   semicircle, were fully exposed to the sinking sun. They seemed
   pyramids of solid fire; while here and there long stretches
   of crimson light drawn over the higher snowfields linked the
   glorified summits together. An intensely illuminated geranium
   flower seems to swim in its own colour, which apparently
   surrounds the petals like a layer, and defeats by its lustre
   any attempt of the eye to seize upon the sharp outline of the
   leaves. A similar effect has been observed upon the mountains;
   the glory did not seem to come from them alone, but seemed also
   effluent from the air around them. This gave them a certain
   buoyancy which suggested entire detachment from the earth.
   They swam in splendour which intoxicated the soul; and I will
   not now repeat in my moments of soberness the extravagant
   analogies which ran through my brain. As the evening advanced,
   the eastern heavens low down assumed a deep purple hue, above
   which, and blended with it by infinitesimal gradations, was a
   belt of red, and over this again zones of orange and violet. I
   walked round the corner of the mountain at sunset, and found
   the western sky glowing with a more transparent crimson than
   that which overspread the east. The crown of the Weisshorn was
   embedded in this magnificent light. After sunset the purple
   of the east changed to a deep neutral tint; and against the
   faded red which spread above it, the sun-forsaken mountains
   laid their cold and ghostly heads. The ruddy colour vanished
   more and more; the stars strengthened in lustre, until finally
   the moon and they held undisputed possession of the blue-grey
   sky."[11]

  [11] Mountaineering in 1861 (Longman).


Marvellous sunsets are to be witnessed from the mountains of the New
World. The following is a short and graphic description of sunset
glories on the Sierra Nevada Mountains by Mr. Clarence King, whose
name is well known to geologists:--

   "While I looked, the sun descended, shadows climbed the
   Sierras, casting a gloom over foothill and pine, until at last
   only the snow summits, reflecting the evening light, glowed
   like red lamps along the mountain-wall for hundreds of miles.
   The rest of the Sierra became invisible. The snow burned for a
   moment in the violet sky, and at last went out."

These marvellous effects appeal powerfully to our sense of beauty
and produce in most minds feelings of intense delight; but they also
appeal to the reasoning faculty in man, and an intelligent observer
naturally inquires, "Why are these things so? How are those glorious
colours of crimson, orange, and yellow produced?" A full explanation
cannot be attempted here; but this much may perhaps be said without
tiring the patience of the reader. White light, such as sunlight or
the light from an electric arc, is composed of all the colours of the
rainbow,--violet, indigo, blue, green, yellow, orange, and red. A ray
of sunlight on passing through a prism is split up into all these
colours in the above order, and we get them arranged in a band which
is known as the spectrum. Thus it is proved that white light is made
up of all colours (black is not a colour, but the absence of colour).
Now, when the sun is low down in the sky, as at sunset, only some of
these colour-rays are able to pass through the atmosphere and so to
reach our eyes, while others are stopped in passing through very many
miles of atmosphere (as they must obviously do when the sun is low).
Those which are stopped are the blue rays and others allied to blue,
such as purple and green; but the red and yellow rays are able to
pass on till they come to us. Hence red, yellow, and orange are the
prevailing sunset tints.

What, then, becomes of the missing blue rays? They are caught by the
myriads of little floating particles in the air, and reflected away
from us. That is why we do not see them; their course is turned
back, just as waves breaking against a stone sea-wall are turned
back or reflected. A person situated _behind_ such a wall will not
see the waves which break against it; but suppose a _very_ big wave
came: it would come right over, and then we should soon become aware
of its presence. So it is with the little waves of light: some are
stopped and turned back as they break against the myriads of little
dust particles and the still more numerous particles of mist always
floating in the air; while others, which are larger, break over
them and travel on undisturbed until they reach our eyes. Now, the
larger waves of light are the red waves, while the smaller ones are
the blue waves; hence there is no difficulty in understanding why
the red waves (or vibrations) are seen at sunset and sunrise, to
the exclusion of the blue waves. But it must be borne in mind that
light-waves are of infinitesimal smallness, thousands and thousands
of them going to make up an inch. Sound also travels in waves, and
the phenomena of sound serve to illustrate those of light; but
sound-waves are very much larger.

The reason why the sky overhead appears blue is that we see the blue
rays reflected down to the earth from myriads of tiny dust and water
particles, while the red rays pass on over our heads, which is just
the reverse of what happens at sunset.

On the southern slopes of the Alps the blues of the sky are generally
very different from those on the northern side; and this is probably
due to the greater quantity of water-vapour in the air, for the moist
winds come from the south. Sunrises in the Alps are quite as glorious
to behold as sunsets; but comparatively few people rise early enough
to see them. Speaking generally, it may be said that in Alpine
sunrises the prevailing colours are orange and gold, in sunsets
crimson or violet-pink. After a cool night the atmospheric conditions
will obviously be different from those which exist after a warm day,
and more water-vapour will have been condensed into mist or cloud.
Hence we should expect a somewhat different effect.

The snowfields on high ranges of mountains are of a dazzling
whiteness; and their bright glare is so great as to distress the
eyes of those who walk over them without blue glasses, and even
to cause inflammation. At these heights the traveller is not only
exposed to the direct rays of the sun, untempered save for a thin
veil of rarefied air, but also to an intense glare produced by the
little snow-crystals which scatter around the beams of light falling
upon them. Scientific men, who have studied these matters, say that
the scorching of the skin and "sun-burning" experienced by Alpine
travellers is not caused, as might be supposed, by the heat of the
sun, but by the rays of light darting and flashing on all sides from
myriads of tiny snow-crystals.

Occasionally a soft lambent glow has been observed on snowfields
at night. This is a very curious phenomenon, to which the name of
"phosphorescence" has, rightly or wrongly, been given. A pale light
may often be seen on the sea during a summer night, when the water
is disturbed in any way; and if one is rowing in a boat, the oars
seem glowing with a faint and beautiful light. It is well known that
this is caused by myriads of little light-producing animalcules
in the sea-water. But we can hardly suppose that the glow above
referred to is produced by a similar cause. One observer says the
glow is "something like that produced by the flame of naphtha;"
and he goes on to say that at every step "an illuminated circle
or nimbus about two inches in breadth surrounded our feet, and we
seemed to be ploughing our way through fields of light, and raising
clods of it, if I may be allowed the expression, in our progress."
Another observer, also an Alpine traveller, says that at almost every
footstep the snowy particles, which his companion in front lifted
with his feet from the freshly fallen snow, fell in little luminous
showers. The exact cause which produces this strange effect at night
has not been ascertained.

There is another curious phenomenon often seen just before sunset on
a mountain in Hungary. It is known as "The Spectre of the Brocken."
The Brocken is the highest summit of the Hartz Mountains. As you step
out upon the plateau upon the top of the hill, your shadow, grim and
gigantic, is apparently flung right out against the eastern sky,
where it flits from place to place, following your every movement.
The explanation is simply this: to the east of the Hartz Mountains
there is always a very dense and hazy atmosphere, so dense that it
presents a surface capable of receiving the impression of a shadow,
and of retaining it, as a wall does. The shadows are really close
at hand, not a long way off, as might at first sight be supposed. If
very far away, they would be too faint to be visible.


In all mountainous regions the permanent habitations of men cease
at a limit far below the most elevated points reached by the
mountain-climber. St. Veran and Gargl, the highest villages of France
and Germany, are situated at the respective heights of 6,591 and
6,197 feet; but the Hospice of St. Bernard, in Switzerland, built
centuries ago to shelter travellers when benumbed with the cold, is
much more elevated, its height being 8,110 feet above sea-level. The
most elevated cluster of houses in the world is the convent of Hanle,
inhabited by twenty Thibetan priests; its height is 14,976 feet. None
of the villages of the Andes, except perhaps that of Santa Anna, in
Bolivia, have been built at so great a height.

Travellers who venture to ascend lofty mountains not only have to
suffer all the rigours of cold and run the risk of being frozen
on their route, but they may also experience painful sensations
owing to the rarefaction of the air. It would naturally be supposed
that at an elevation at which the pressure of the atmosphere is
reduced to one half, or even to one fourth that of the plains below,
a certain uneasiness should be caused by the change, the more so
since other conditions, such as warmth and moisture, are different.
Undaunted climbers, like Professor Tyndall, who have never felt the
effect of this "mountain-sickness" (_mal de montagne_), deny that
the sensations proceed from anything else than mere fatigue. In the
Himalayas, the traveller does not begin to suffer from the attacks of
this ailment until he has reached a height of 16,500 feet; while on
the Andes a large number of persons are affected by it at an altitude
of 10,700 feet. In the South American mountains, the symptoms are
much more serious: to the fatigue, head-ache, and want of breath are
added giddiness, sometimes fainting-fits, and bleeding from lips,
gums, and eyelids. The aeronaut, however, who is spared all the
fatigue of climbing, rarely suffers any inconvenience except from
cold, at such elevations. But on rising to greater heights, 30,000 or
40,000 feet, the malady shows itself; and if the balloon continued to
rise, the aerial voyager would infallibly perish.

Professor Bonney says:--

   "I have occasionally seen persons singularly affected on high
   mountains; and as the barometer stands at about sixteen inches
   on Mont Blanc, and at thirty at sea-level, one would expect
   this great difference to be felt. Still, I do not think it easy
   to separate the inconveniences due to atmosphere from those
   caused by unwonted fatigue, and am inclined to attribute most
   of them to the latter."

But the fact that the aeronaut suffers seems conclusive.


The violent storms which break upon mountain districts often cause
floods of considerable magnitude, such as may be compared with the
memorable bursting of the Holmfirth reservoir. Hardly a year passes
without considerable damage being done: bridges are swept away; roads
are buried under torrents of mud, and fields overwhelmed with débris.
In August of the year 1860 a severe storm was witnessed by visitors
staying at Zermatt. It began with a thunder-storm; and rain fell for
about thirty-six hours, after which, as may be supposed, the torrents
were swollen far beyond their usual size. Lower down in the valleys
much harm was done, but there one bridge only was swept away. It
was, however, an awful sight to see the Visp roaring under one of the
bridges that remained, and to hear the heavy thuds of the boulders
that were being hurried on and dashed against one another by the
torrent.

In September, 1556, the town of Locarno, in the Canton Ticino, was
visited by a destructive storm and flood. The day began by several
shocks of earthquake, followed, about five o'clock, by a terrific
gale from the south. Part of the old castle was blown down; the doors
of St. Victor's Church were burst open by a blast while the priest
was at the altar; and everything within was overturned. At midday the
clouds were so thick that it was almost as dark as night. A violent
thunder-storm and torrents of rain followed, lasting from two to six
o'clock in the evening. The rivulets all became torrents; the stream
flowing through the town was so choked by uprooted trees and rocks
that its water flooded the streets and almost buried them under mud
and gravel. Such a sight as this gives one a powerful impression of
the geological work of streams when greatly swollen; for all this
débris must have been brought down from the surrounding mountains.
Many lives were lost by this calamity, and a great deal of property
was destroyed. Late in the year, during unsettled weather, the
traveller often encounters on Alpine passes a sudden storm of snow,
accompanied by violent gusts of wind, which fill the air with drifted
flakes; so that becoming bewildered, he loses his way, and at last
sinks down benumbed with cold and dies. Many a frequented pass in
Switzerland has been the scene of death from this cause. Exhausted
with fatigue, and overcome with cold, the traveller sinks down by the
wayside, and the guides, after having in vain endeavoured to urge him
on, are compelled, in order to save their own lives, to leave him to
his fate and press forward. The name "Tourmente" is given to these
storms.

On the tops of the highest mountains, even in very fine weather,
the wind often blows with great force; and the north wind, supposed
to be the mountaineer's best friend, is sometimes his enemy. It
not unfrequently happens that a gale renders the passage of some
exposed slope or ridge too dangerous, or the intense cold produces
frost-bites, so that an expedition has to be abandoned when success
is within reach, which naturally is very annoying. Professor Bonney,
speaking of such a gale which he experienced in 1864, says,--

   "The cold was something horrible; the wind seemed to blow not
   round, but through me, freezing my very marrow, and making my
   teeth chatter like castanets; and if I stopped for a moment, I
   shook as if in an ague-fit. It whisked up the small spiculæ of
   frozen snow, and dashed them against my face with such violence
   that it was hardly possible to look to windward. Thin sheets of
   ice as large as my hand were whirled along the surface of the
   glacier like paper.... When these gales are raging, the drifted
   snow is blown far to leeward of the peaks in long streamers
   like delicate cirrus-clouds; and on such occasions the mountain
   is said by the guides _fumer sa pipe_ (to smoke his pipe). This
   Mont Blanc was doing to some purpose the day that we were upon
   him."

It is a curious fact that these gales are often confined to the
crests of the mountains, so that the wind may be raging among the
peaks while a few hundred feet lower down there is comparative calm.

The chief of the prevailing winds in the Alps is the Föhn. This is
a hot blast from the south which probably comes from the African
deserts. On its approach the air becomes close and stifling, the sky,
at first of unusual clearness, gradually thickens to a muddy and
murky hue, animals become restless and disquieted by the unnatural
dryness of the hot blast which now comes sweeping over the hills. In
some villages, it is said, all the fires are extinguished when this
wind begins to blow, for fear lest some chance spark should fall on
the dry wooden roofs and set the whole place in a blaze. Still the
Föhn is not altogether an "ill wind that blows nobody any good,"
for under its warm touch the winter snows melt away with marvellous
rapidity. In the valley of Grindelwald it causes a snow-bed two
feet thick to disappear in about a couple of hours, and produces in
twenty-four hours a greater effect than the sun does in fifteen days.
There is a Swiss proverb which rather profanely says: "If the Föhn
does not blow, the golden sun and the good God can do nothing with
the snow."

In summer-time, however, the south wind is never welcome, for the
vapour which it brings from the Italian plains is condensed by the
snows of the Alps, and streams down in torrents of rain.


A thunder-storm is always a grand spectacle. Among mountains such
storms are more frequent than on the plains, and also, as might be
expected, far more magnificent, especially at night. Flashes, or
rather sheets, of unutterable brilliancy light up the sky; distant
chains of mountains are revealed for a moment, only to be instantly
eclipsed by the pall of night. Says Professor Bonney,--

   "No words can adequately express the awful grandeur of these
   tempests when they burst among the mountains. I have often
   been out in them,--in fact, far more frequently than was
   pleasant; but perhaps the grandest of all was one that welcomed
   me for the first time to Chamouni. As we entered the valley,
   and caught sight of the white pinnacles of the _glacier des
   Bossons_, a dark cloud came rolling up rapidly from the west.
   Beneath it, just where two tall peaks towered up, the sky
   glowed like a sheet of red-hot copper, and a lurid mist spread
   over the neighbouring hills, wrapping them, as it seemed, in a
   robe of flame. Onward rolled the cloud; the lightning began to
   play; down the valley rushed a squall of wind, driving the dust
   high in air before it, and followed by a torrent of rain.
   Flash succeeded flash almost incessantly,--now darting from
   cloud to cloud; now dividing itself into a number of separate
   streaks of fire, and dancing all over the sky; now streaming
   down upon the crags, and at times even leaping up from some
   lofty peak into the air. The colours were often most beautiful,
   and bright beyond description."

  [Illustration: A STORM ON THE LAKE OF THUN. AFTER TURNER.]

The mountain traveller, when caught in a thunder-storm, undergoes a
strange experience, not unattended with danger. One observer[12] thus
describes his sensations:--

  [12] Mr. R. S. Watson, in "The Alpine Journal," vol. i., p. 143.

   "A loud peal of thunder was heard; and shortly after I observed
   that a strange singing sound, like that of a kettle, was
   issuing from my alpenstock. We halted, and finding that all the
   axes and stocks emitted the same sound, stuck them into the
   snow. The guide from the hotel now pulled off his cap, shouting
   that his head burned; and his hair was seen to have a similar
   appearance to that which it would have presented had he been
   on an insulated stool under a powerful electrical machine. We
   all of us experienced the sensation of pricking and burning in
   some part of the body, more especially in the head and face,
   my hair also standing on end in an uncomfortable but very
   amusing manner. The snow gave out a hissing sound, as though a
   heavy shower of hail were falling; the veil on the wide-awake
   of one of the party stood upright in the air; and on waving
   our hands, the singing sound issued loudly from the fingers.
   Whenever a peal of thunder was heard, the phenomenon ceased, to
   be resumed before its echoes died away. At these times we felt
   shocks, more or less violent, in those portions of the body
   which were most affected. By one of these shocks my right arm
   was paralysed so completely that I could neither use nor raise
   it for several minutes, nor indeed until it had been severely
   rubbed; and I suffered much pain in it at the shoulder-joint
   for some hours."

The successive layers of snow which fall on the mountains do not
remain there for ever. Unless got rid of in some way their thickness
would mount up to an enormous extent. It is reckoned that on the
Alps the average yearly fall of snow is thirty-three feet. In the
course of a century, therefore, the height of these mountains would
be increased by 3,300 feet, which we know is not the case. Various
causes prevent its accumulating, among which we may mention the
powerful influence of the sun's rays, the evaporation promoted by
the atmosphere, the thawing influence of rain and mist, avalanches,
and lastly, which is perhaps the most important, the fact that the
snow composing the snowfields, as they are called, of the high
regions slowly creeps down towards the valleys, where they move
along as glaciers, the ends of which are gradually melted away by
the warm air surrounding them, and thus the muddy glacier-streams
are originated. Few perils are more dreaded by the inhabitant of
the Alps than those of the avalanches. The particular way in which
each avalanche descends is varied according to the shape of the
mountain, the condition of the snow, and the time of the year. Hence
there are three different kinds of avalanche. First, there is the
ice-avalanche. The smaller glaciers, which, in the Alps, cling to the
upper slopes of the higher mountains, frequently terminate abruptly
on the edge of some precipice. Thus the ice, urged on by the pressure
of the masses above it, moves forward until it plunges over and
falls into the abyss below. Large portions break off; and these, as
they bound down the cliffs, are dashed into countless pieces, which
leap from crag to crag high into the air: now the falling mass, like
some swollen torrent, dashes with sullen roar through a gully, now,
emerging, crashes over a precipice, or spreads itself out like a fan,
as it hisses down a snow-slope. These avalanches expend their force
in the higher regions, and are harmless, unless any one happens to
be crossing their track at the time; but accidents from this source
can generally be avoided. In the distance the avalanches look like
waterfalls of the purest foam, but when approached are found to be
composed of fragments of ice of every size, from one, two, or more
cubic yards down to tiny little balls. In spring and summer, when the
white layers, softened by the heat, are falling away every hour from
the lofty summits of the Alps, the pedestrian, taking up a position
on some adjacent headland, may watch these sudden cataracts dashing
down into the gorges from the heights of the shining peaks. Year
after year travellers seated at their ease on the grassy banks of
the Wengern Alp have watched with pleasure the avalanches rolling to
the base of the silvery pyramid of the Jungfrau. First, the mass of
ice is seen to plunge forth like a cataract, and lose itself in the
lower parts of the mountain; whirlwinds of powdered snow, like clouds
of bright smoke, rise far and wide into the air; and then, when the
cloud has passed away, and the region has again assumed its solemn
calm, the thunder of the avalanche is suddenly heard reverberating
in deep echoes in the mountain gorges, as if it were the voice of the
mountain itself.

The other two kinds of avalanche are composed of snow. The
dust-avalanche usually falls in winter-time, when the mountains are
covered deep with fresh-fallen snow. Such masses of snow, not yet
compacted into ice, rest insecurely upon the icy slopes, and hang
in festoons and curtains over the peaks, or lie on smooth banks of
pasture, until some accident, such as a gust of wind, breaks the
spell, and the whole mass slides down into the valley below. These
avalanches are accompanied by fearful blasts of wind which work dire
destruction. Almost the whole village of Leukerbad was destroyed by
one of these on the 14th of January, 1719, and fifty-five persons
perished. In 1749, more than one hundred persons were killed in the
village of Ruaras (Grisons), which during the night was overwhelmed
by an avalanche. So silently were some of the houses buried that the
inhabitants, on waking in the morning, could not conceive why the
day did not dawn. It is said, though it seems almost incredible,
that in the time of the Suabian War, in the year 1498, one of these
avalanches swept four hundred soldiers over a cliff, and they all
escaped without serious injury.

The army of General Macdonald, in his celebrated passage of
the Splügen in December, 1800, suffered severely from these
dust-avalanches. A troupe of horse was completely cut through while
on the march; and thirty dragoons were precipitated into a gulf below
the road, where they all perished. And again, some days afterwards,
in descending a gorge, the columns were repeatedly severed by
avalanches; and more than one hundred soldiers, with a number of
horses and mules, were lost. On one of these occasions the drummer
of a regiment was carried away; and it is said that they heard him
beating his drum in the gorge below, in the hope that his comrades
would come to his rescue. Help, however, was out of the question. The
sounds gradually became fainter, and the poor lad must have perished
in the cold.

The ground-avalanches are different from those just described,
consisting of dense and almost solid masses of snow which have lain
for a long time exposed to atmospheric influences. They are much
heavier than the dust-avalanches, and therefore more destructive;
so that the inhabitants take great pains to protect themselves from
this source of danger. Thickly planted trees are the best protection
against avalanches of every kind. Snow which has fallen in a wood
cannot very well shift its place; and when masses of snow descend
from the slopes above, they are unable to break through so strong
a barrier. Small shrubs, such as rhododendrons, or even heaths and
meadow-grass, are often sufficient to prevent the slipping of the
snow; and therefore it is very imprudent not to allow them to grow
freely on mountain-slopes. But it is still more dangerous to cut down
protecting forests, or even to do so partly. This was illustrated by
the case of a mountain in the Pyrenees, in the lofty valley of Neste;
after it had been partially cleared of trees, a tremendous avalanche
fell down in 1846, and in its fall swept away more than fifteen
thousand fir-trees.

The Swiss records tell us what a terrible scourge the avalanche can
be in villages which in summer-time appear such calm and happy
scenes of pastoral life. M. Joanne, in the introduction to his
valuable "Itinéraire de la Suisse"[13] gives a list of twelve of
the most destructive avalanches that have fallen in Switzerland. In
old days they seem to have been as great a source of danger as in
modern times. Thus we find that in the year 1500, a caravan of six
hundred persons was swept away in crossing the Great St. Bernard;
three hundred were buried under an avalanche which fell from Monte
Cassedra (Ticino). Another one in the year 1720, at Obergestelen,
in the Rhone Valley, destroyed one hundred and twenty cottages,
four hundred head of cattle, and eighty-eight persons. The bodies
were buried in a large pit in the village cemetery, on the wall
of which was engraved the following pathetic inscription: "O God,
what sorrow!--eighty-eight in a single grave!" ("Gott, welche
Trauer!--acht und achtzig in einem Grab!")

  [13] Conservateur Suisse, xlvi. p. 478, vol. xii.

It is a curious fact that animals have a wonderful power of
anticipating coming catastrophes. When human beings are unaware of
danger, they are often warned by the behaviour of animals. Country
people sometimes say that they can tell from the birds when the
weather is about to change; and there is little doubt but that
sea-gulls come inland before rough, stormy weather. But in the case
of earthquakes the behaviour of birds, beasts, and even fishes is
very striking. It is said that before an earthquake rats, mice,
moles, lizards, and serpents frequently come out of their holes, and
hasten hither and thither as if smitten with terror. At Naples, it
is said that the ants quitted their underground passages some hours
before the earthquake of July 26, 1805; that grasshoppers crossed
the town in order to reach the coast; and that the fish approached
the shore in shoals. Avalanches, it is well known, produce tremors
similar to those due to slight earthquake shocks; and there are many
stories in Switzerland of the behaviour of animals just before the
catastrophe takes place. Berlepsch relates that a pack-horse on the
Scaletta Pass, which was always most steady, became restive when
an avalanche was coming; so that he was valuable to his owners in
bad weather. One day, when near the summit of the pass, he suddenly
stopped. They foolishly took no notice of his warning this time; but
he presently darted off at full speed. In a few seconds the avalanche
came and buried the whole party.

If these stories can be relied upon, it would seem that animals are
either more sensitive to very slight tremors of the earth, or else
that they are more on the lookout than human beings. Perhaps North
American Indians have learned from animals in this respect, for they
can tell of a coming enemy on the march by putting their ears to the
ground and listening.

But there are worse dangers in the mountains than falls of snow and
ice, for sometimes masses of rock come hurtling down, or worse still,
the whole side of a mountain gives way and spreads ruin far and wide.
Perpendicular or overhanging rocks, which seem securely fastened,
suddenly become detached and rush headlong down the mountain-side.
In their rapid fall, they raise a cloud of dust like the ashes
vomited forth by a volcano; a horrible darkness is spread over a once
pleasant valley; and the unfortunate inhabitants, unable to see what
is taking place, are only aware of the trembling of the ground, and
the crashing din of the rocks as they strike together and shatter one
another in pieces. When the cloud of dust is cleared away, nothing
but heaps of stones and rubbish are to be seen where pastures once
grew, or the peasant ploughed his acres in peace. The stream flowing
down the valley is obstructed in its course, and changed into a
muddy lake; the rampart of rocks from which some débris still comes
crumbling down has lost its old form; the sharpened edges point out
the denuded cliff from which a large part of the mountain has broken
away. In the Pyrenees, Alps, and other important ranges there are but
few valleys where one cannot see the confused heaps of fallen rocks.

Many of these catastrophes, known as the "Bergfall," have been
recorded; and the records tell of the fearful havoc and destruction
to life and property due to this cause. In Italy the ancient Roman
town of Velleja was buried, about the fourth century, by the downfall
of the mountain of Rovinazzo; and the large quantity of bones and
coins that have been found proves that the fall was so sudden that
the inhabitants had no time to escape.

Taurentum, another Roman town, situated, it is said, on the banks
of Lake Geneva, at the base of one of the spurs of the Dent d'Oche,
was completely crushed in A. D. 563 by a downfall of rocks. The
sloping heap of débris thus formed may still be seen advancing like a
headland into the waters of the lake. A terrible flood-wave, produced
by the deluge of stones, reached the opposite shores of the lake and
swept away all the inhabitants. Every town and village on the banks,
from Morges to Vevay, was demolished, and they did not begin the work
of rebuilding till the following century. Some say, however, that the
disaster was caused by a landslip which fell from the Grammont or
Derochiaz across the valley of the Rhone, just above the spot where
it flows into the Lake of Geneva. Hundreds of such falls have taken
place within the Alps and neighbouring mountains within historic
times.

Two out of the five peaks of the Diablerets fell down, one in 1714
and the other in 1749, covering the pastures with a thick layer
of stones and earth more than three hundred feet thick, and by
obstructing the course of the stream of Lizerne, formed the three
lakes of Derborence. In like manner the Bernina, the Dent du Midi,
the Dent de Mayen, and the Righi have overspread with ruin vast
tracts of cultivated land. In Switzerland the most noted Bergfalls
are those from the Diablerets and the Rossberg. The former mountain
is a long flattish ridge with several small peaks, overhanging very
steep walls of rock on either side. These walls are composed of
alternating beds of limestone and shale. Hence it is easily perceived
that we have here conditions favourable for landslips, because if
anything weakens one of these beds of shale the overlying mass
might be inclined to break away. The fall in the year 1714, already
referred to, was a very destructive one.

  [Illustration: THE MATTERHORN. FROM A PHOTOGRAPH BY MR. DONKIN.]

   "For two whole days previously loud groaning had been heard to
   issue from the mountain, as though some imprisoned spirit were
   struggling to release himself, like Typhoeus from under Etna;
   then a vast fragment of the upper part of the mountain broke
   suddenly away and thundered down the precipices into the valley
   beneath. In a few minutes fifty-five châlets, with sixteen
   men and many head of cattle, were buried for ever under the
   ruins. One remarkable escape has indeed been recorded, perhaps
   the most marvellous ever known. A solitary herdsman from the
   village of Avent occupied one of the châlets which were buried
   under the fallen mass. Not a trace of it remained; his friends
   in the valley below returned from their unsuccessful search,
   and mourned him as dead. He was, however, still among the
   living; a huge rock had fallen in such a manner as to protect
   the roof of his châlet, which, as is often the case, rested
   against a cliff. Above this, stones and earth had accumulated,
   and the man was buried alive. Death would soon have released
   him from his imprisonment, had not a little rill of water
   forced its way through the débris and trickled into the châlet.
   Supported by this and by his store of cheese, he lived three
   months, labouring all the while incessantly to escape. Shortly
   before Christmas he succeeded, after almost incredible toil, in
   once more looking on the light of day, which his dazzled eyes,
   so long accustomed to the murky darkness below, for a while
   could scarcely support. He hastened down to his home in Avent,
   and knocked at his own door; pale and haggard, he scarcely
   seemed a being of this world. His relations would not believe
   that one so long lost could yet be alive, and the door was shut
   in his face. He turned to a friend's house; no better welcome
   awaited him. Terror seized upon the village; the priest was
   summoned to exorcise the supposed demon; and it was not till he
   came that the unfortunate man could persuade them that he was
   no spectre, but flesh and blood."[14]

  [14] Bonney.

The valley is still a wild scene of desolation, owing to the
enormous masses of stones of every shape and size with which its bed
is filled.

In September of the year 1806, the second fall of the mountain
Rossberg took place, after a wet summer. It is underlaid by beds of
clay which, when water penetrates, are apt to give way. The part
which fell was about three miles long and 350 yards wide and 33 yards
thick. In five minutes one of the most fertile valleys in Switzerland
was changed to a stony desert. Three whole villages, six churches,
120 houses, 200 stables or châlets, 225 head of cattle, and much land
were buried under the ruins of the Rossberg; 484 persons lost their
lives. Some remarkable escapes are recorded.

In the year 1618 the downfall of Monte Conto buried 2,400 inhabitants
of the village of Pleurs, near Chiavenna. Excavation among the
ruins was subsequently attempted, but a few mangled corpses and a
church-bell were all that could be reached.

Geologically these phenomena, appalling as they are from the human
point of view, possess a certain interest, and their effects deserve
to be studied.

There is yet another danger to which dwellers in mountains are
occasionally exposed; namely, the earthquake. It seems to be an
established fact that earthquake shocks are more frequent in
mountainous than in flat countries. The origin of these dangerous
disturbances of the earth's crust has not yet been fully explained.
They are probably caused in various ways; and it is very likely
that the upheaval of mountain-chains is one of the causes at work.
Earthquakes have for many years been carefully studied by scientific
men, and some valuable discoveries have been made. Thus we find that
they are more frequent in winter than summer, and also happen more
often by night than by day. Day and night are like summer and winter
on a small scale, and so we need not be surprised at this discovery.
Some have maintained that there is a connection between earthquakes
and the position of the moon; while others consider that the state
of the atmosphere also exerts an influence, and that earthquakes
are connected with rainy seasons, storms, etc. Earthquakes are very
often due to volcanic eruptions, but this is not always the case (see
chapter vi., page 199).




CHAPTER IV.

MOUNTAIN PLANTS AND ANIMALS.

   The high hills are a refuge for the wild goats, and so are the
   stony rocks for the conies.--_Psalm civ. 18._


There must be few people who have neither seen nor heard of the
beauty and exquisite colours of Alpine[15] flowers. They are first
seen on the fringes of the stately woods above the cultivated
land; then in multitudes on the sloping pastures with which many
mountain-chains are robed, brightening the verdure with innumerable
colours; and higher up, where neither grass nor loose herbage can
exist, among the slopes of shattered fragments which roll down from
the mountain-tops,--nay, even amidst the glaciers,--they gladden the
eye of the traveller and seem to plead sweetly with the spirits of
destruction. Alpine plants fringe the vast hills of snow and ice of
the high hills, and sometimes have scarcely time to flower and ripen
a few seeds before being again covered by their snowy bed. When
the season is unfavourable, numbers of them remain under the snow
for more than a year; and here they safely rest, unharmed by the
alternations of frost and biting winds, with moist and springlike
days. They possess the great charm of endless variety of form and
colour, and represent widely separated divisions of the vegetable
kingdom; but they are all small and low-growing compared to their
relatives grown in the plains, where the soil is richer and the
climate milder. Among them are tiny orchids quite as interesting
in their way as those from the tropics; liliputian trees, and a
tree-like moss (_Lycopodium dendroideum_) branching into an erect
little pyramid as if in imitation of a mountain pine; ferns that peep
cautiously from narrow rocky crevices as if clinging to the rock
for shelter from the cold blasts; bulbous plants, from lilies to
bluebells; evergreen shrubs, perfect in leaf and blossom and fruit,
yet so small that one's hat will cover them; exquisite creeping
plants spreading freely along the ground, and when they creep over
the brows of rocks or stones, draping them with curtains of colour
as lovely as those we see in the forests; numberless minute plants
scarcely larger than mosses, mantling the earth with fresh green
carpets in the midst of winter; succulent plants in endless variety;
and lastly the ferns, mosses, and lichens which are such an endless
source of pleasure and delight to the traveller. In short, Alpine
vegetation presents us with nearly every type of plant life of
northern and temperate climes, chastened in tone and diminished in
size.

  [15] The word "Alpine" is used in a general sense to denote the
  vegetation that grows naturally on the most elevated regions of
  the earth; that is, on all high mountains, whether they rise up
  in hot tropical plains or in cooler northern pastures.

It is not difficult to account for the small size of these plants;
for in the first place we cannot expect a large or luxuriant growth
where the air is cold, the soil scanty, and the light of the sun
often obscured by clouds, and where the changes of temperature are
rapid,--which is very unfavourable to most plants. Again, in the
close struggle for existence which takes place on the plains and low
tree-clad hills, the smaller forms of plant life are often overrun by
trees, trailing plants, bushes, and vigorous herbs; but where these
cannot find a home, owing to the severity of the winter and other
causes, the little Alpine plants, covered up by snow in the winter,
can thrive abundantly. And lastly, like the older and conquered races
of men who have been driven to the hills (see chap. i., p. 28) and
find shelter there, so there are both plants and animals living in
the mountains which man will not suffer to live in the plain where
he grows his crops, pastures his cattle, or builds his cities. We
would also venture to suggest that possibly some plants have been
ousted from plains by newer and more aggressive types, which came and
took their place. If so, vegetable life would afford an illustration
of a process which has so often taken place in human history. This
is only a speculation, but still it might be worth following up. If
Alpine plants, or any considerable number of them, could be shown
to belong to more ancient types, such as flourished in the later
geological periods, that would afford some evidence in favour of
the idea. Whether this is so or not, plant life on the mountains is
almost entirely protected from the destroying hands of men with their
ploughs and scythes, as well as from many grazing animals. As Mr.
Ruskin quaintly says:

   "The flowers which on the arable plain fell before the plough
   now find out for themselves unapproachable places, where year
   by year they gather into happier fellowship and fear no evil."

It is clear that the climate of a mountainous region determines the
character of the vegetation. Now, the climate will be different in
different parts of a mountain-range, and will depend upon the height
above the sea and other causes.[16] Some writers upon this subject
have attached too much importance to absolute height above the sea,
as though this were the only cause at work. It is a very important
cause, no doubt, but there are others which also have a great
influence, such as the position of each locality with respect to the
great mountain masses, the local conditions of exposure to the sun
and protection from cold winds, or the reverse. However, in spite of
local irregularities there are in the Alps certain broad zones or
belts of vegetation which may be briefly described as follows:--

  [16] The following remarks are largely taken from the
  Introduction to Ball's well-known "Alpine Guide."

1. _The Olive region._--This region curiously illustrates what has
just been said about other causes besides height influencing the
climate and vegetation. For along the southern base of the Alps, the
lower slopes and the mouths of the valleys have a decidedly warmer
climate than the plains of Piedmont and Lombardy. Thus, while the
winter climate of Milan is colder than that of Edinburgh, the olive
can ripen its fruit along the skirts of the mountain region, and
penetrates to a certain distance towards the interior of the chain
along the lakes and the wider valleys of the Southern Alps. Even up
the shores of the Lake of Garda, where the evergreen oak grows, the
olive has become wild. The milder climate of the Borromean Islands,
and some points on the shores of the Lago Maggiore, will permit many
plants of the warmer temperate zone to grow; while at a distance of a
few miles, and close to the shores of the same lake, but in positions
exposed to the cold winds from the Alps, plants of the Alpine region
grow freely, and no delicate perennials can survive the winter. The
olive has been known to resist a temperature of about 16° F. (or
16° below the freezing point of water), but is generally destroyed
by a less degree of cold. It can only be successfully cultivated
where the winter frosts are neither long nor severe, where the mean
temperature of winter does not fall below 42° F., and a heat of 75°
F. during the day is continued through four or five months of the
summer and autumn.

2. _The Vine region._--The vine, being more tolerant of cold than the
olive, can grow at a higher level; and so the next zone of vegetation
in the Alps may be called "the Vine region." But to give tolerable
wine it requires at the season of ripening of the grape almost as
much warmth as the olive needs. Vines can grow in the deeper valleys
throughout a great part of the Alpine chain, and in favourable
situations up to a considerable height on their northern slopes.
On the south side, although the limit of perpetual snow is lower,
the vine often reaches near to the foot of the greater peaks. But
the fitness of a particular spot for the production of wine depends
far more on the direction of the valley and of the prevailing winds
than on the height. And so it happens that in the Canton Valais, the
Valley of the Arc in Savoy, and some others on the north side of the
dividing range, tolerable wine is made at a higher level than in the
valleys of Lombardy, whose direction allows the free passage of the
keen northern blasts. It is a curious fact that in the Alps the vine
often resists a winter temperature which would kill it down to the
roots in the low country; and we must explain it by the protection
of the deep winter snow. Along with the vine many species of wild
plants, especially annuals, characteristic of the flora of the south
of Europe, show themselves in the valleys of the Alps.

3. _The Mountain region, or region of deciduous trees._--Many writers
take the growth of corn as the characteristic of the colder temperate
zone, corresponding to what has been called the mountain region of
the Alps. But so many varieties, all with different requirements,
are in cultivation, that it is impossible to take the growth of
cereals in general as marking clearly any natural division of the
surface. A more natural limit is marked by the presence of deciduous
trees (trees which shed their leaves). Although the oak, beech, and
ash do not exactly reach the same height, and are not often seen
growing side by side in the Alps, yet their upper limit marks pretty
accurately the transition from a temperate to a colder climate that
is shown by a general change in the wild, herbaceous vegetation. The
lower limit of this zone is too irregular to be exactly defined, but
its upper boundary is about 4,000 feet on the cold north side of the
Alps, and often rises to 5,500 feet on the southern slopes, which of
course get more sunshine and warmth. The climate of this region is
favourable to the growth of such trees as the oak, beech, and ash,
but it does not follow that we should see them there in any great
numbers at the present time; for it is probable that at a very early
date they were extensively destroyed for building purposes, and to
clear space for meadow and pasture land, so that with the exception
of the beech forests of the Austrian Alps, there is scarcely a
considerable wood of deciduous trees to be seen anywhere in the
chain. In many districts where the population is not too dense, the
pine and Scotch fir have taken the place of the oak and beech, mainly
because the young plants are not so eagerly attacked by goats, the
great destroyers of trees.

4. _The region of Coniferous trees._--Botanically this region is
best distinguished by the prevalence of coniferous trees, forming
vast forests, which if not kept down by man (and by goats) would
cover the slopes of the Alps. The prevailing species are the common
fir and the silver fir. In districts where granite abounds, the
larch flourishes and reaches a greater size than any other tree.
Less common are the Scotch fir and the arolla, or Siberian fir.
In the Eastern Alps the dwarf pine becomes conspicuous, forming
a distinct zone on the higher mountains above the level of other
firs. The pine forests play a most important part in the natural
economy of the Alps; and their preservation is a matter of very great
importance to the future inhabitants. But in some places they have
been considerably diminished by cutting. This has especially happened
in the neighbourhood of mines; and in consequence the people of the
unfrequented communes have become so alive to this that some jealousy
is felt of strangers wandering among the mountains, lest they should
discover metals and cause the destruction of the woods. Their fears
are not unreasonable; for the forests, besides exerting a good deal
of influence on rainfall and climate, form natural defences against
the rush of the spring avalanches (see chapter iii., page 93). It is
recorded that after the war of 1799, in which many of those near the
St. Gothard Pass were destroyed, the neighbouring villages suffered
terribly from this scourge. Hence the laws do not allow of timber
being cut in certain forests called "Bannwalde;" and in most places
the right of felling trees is strictly regulated, and the woods are
under the inspection of officials.

In spots high up among the mountains, to which access is difficult,
the timber is converted into charcoal, which is then brought down
in sacks by horses and mules. There are two ways in which timber is
conveyed down from the forest: either it is cut up into logs some
five feet long, and thrown into a neighbouring torrent, which brings
it down over cliff and gorge to the valley below; or else trough-like
slides are constructed along the mountain-sides, down which the
trunks themselves are launched.

It is this region of coniferous trees which mainly determines the
manner of life of the population of the Alps. In the month of May the
horned cattle, having been fed in houses during the winter (as they
are in the Scotch Highlands, where the cowsheds are called "byres"),
are led up to the lower pastures. The lower châlets, occupied in May
and part of June, generally stand at about the upper limit of the
mountain region. Towards the middle or end of June the cattle are
moved up to the chief pastures, towards the upper part of the region
of coniferous trees, where they usually remain for the next two or
three months. But there are some available pastures still higher up,
and hither some of the cattle are sent for a month or more.

5. _The Alpine region._--This is the zone of vegetation extending
from the upper limit of trees to where permanent masses of snow first
make their appearance; so that where the trees cease, the peculiar
Alpine plants begin; but we still find shrubs, such as the common
rhododendron, Alpine willow, and the common juniper, which extend
up to, and the latter even beyond, the level of perpetual snow. The
limits of this interesting and delightful botanical region may be
fixed between 6,000 and 8,000 feet above the sea, and at least 1,000
feet higher on the south slopes of the Alps, which get more sunshine.
It is used to some extent for pasture; and in Piedmont it is not
uncommon to find châlets at the height of 8,500 feet, and vegetation
often extends freely up to 9,500 feet. Here and there, at levels
below this zone, many Alpine species may be found, either transported
by accident from their natural home, or finding a permanent
refuge in some cool spot sheltered from the sun, and moistened by
streamlets descending from the snow region. But it is chiefly here
that those delightful flowers grow which make the Alps like a great
flower-garden,--great anemones, white and sulphur-coloured; gentians
of the deepest blue, like the sky overhead; campanulas, geums, Alpine
solanellas, and forget-me-nots; asters, ox-eyed daisies, pale pink
primulas, purple heartsease, edelweiss, saxifrages, yellow poppies,
Alpine toad-flax, monkshood, potentilla, and others too numerous to
mention. Says Professor Bonney,--

   "Who cannot recall many a happy hour spent in rambling from
   cluster to cluster on the side of some great Alp?--the scent of
   sweet herbage or of sweeter daphne perfuming the invigorating
   air, the melody of the cattle-bells borne up from some far-off
   pasture, while the great blue vault of heaven above seems
   reflected in the gentian clusters at his feet. The love of
   flowers seems natural to almost every human being, however
   forlorn his life may have been, however far it may have missed
   its appointed mark. It may well be so; they at least are fresh
   and untainted from their Maker's hand; the cry of 'Nature red
   in tooth and claw' scarce breaks their calm repose. Side by
   side they flourish without strife; none 'letteth or hindereth
   another,' yet so tender and delicate, doomed to fade all too
   soon, a touch of sadness is ever present to give a deeper
   pathos to our love."

6. _The Glacial region._--This comprehends all that portion of the
Alps that rises above the limit of perpetual snow. But a word of
explanation is necessary. The highest parts of the Alps are not
covered by one continuous sheet of snow; otherwise we should never
see any peaks or crags there. Some are too steep for the snow to
rest upon them, and therefore remain bare at heights much greater
than the so-called "limit of perpetual snow," and that limit varies
considerably. Still this term has a definite meaning when rightly
understood. Leaving out of account masses of snow that accumulate in
hollows shaded from the sun, the "snow-line" is fairly even, so that
on viewing an Alpine range from a distance, the larger patches and
fields of snow on adjoining mountains, with the same aspect, are seen
to maintain a pretty constant level.

  [Illustration: ON A GLACIER.]

Vegetation becomes scarce in this region, not, as commonly supposed,
because Alpine plants do not here find the necessary conditions for
growth, but simply for want of soil. The intense heat of the direct
rays of the sun (see chapter iii., pages 76-77) compensates for the
cold of the night; and it is probable that the greater allowance of
light also stimulates vegetable life. But all the more level parts
are covered with ice or snow; and the higher we ascend, the less the
surface remains bare, with the exception of the projecting rocks
which usually undergo rapid destruction and breaking up from the
freezing of whatever water finds its way into their fissures.

Nevertheless, many species of flowering plants have been found even
at the height of eleven thousand feet.

It is in this region that plants are found whose true home is in the
arctic regions (see chapter ii., pages 64-65).

For the sake of those who love ferns, lycopods, and other cryptogamic
or flowerless plants, a few words may be said here. Of the
polypodies, the beech fern and oak fern are generally common, so is
the limestone polypody in places where limestone occurs. Another
species (_P. alpestre_) very like the lady fern grows plentifully
in many places. The parsley fern, familiar to the botanist in Wales
and other parts of Great Britain, is common, especially on the
crystalline rocks, and ascends to above seven thousand feet. The
holly fern is perhaps the most characteristic one of the higher Alps.
It is abundant in almost every district from the Viso to the Tyrol,
ranging from about five thousand feet to nearly eight thousand feet.
The finest specimens are to be found in the limestone districts.
Nestling down in little channels worn out of the rock, it shoots out
great fronds, often more than eighteen inches long, which are giants
compared to the stunted specimens seen on rockwork in English gardens.

_Asplenium septentrionale_ is very common in most of the districts
where crystalline rocks abound. The hart's tongue is hardly to be
called a mountain fern. The common brake is confined to the lower
slopes.

_Cistopteris fragillis_ and _C. dentata_ are common, and the more
delicate _C. Alpina_ is not rare. The noble _Osmunda regalis_ keeps
to the warmer valleys. The moonwort abounds in the upper pastures.

The club-mosses (_Lycopodium_), which are found in Great Britain,
are common in most parts of the Alps, especially the _L. selago_,
which grows almost up to the verge of the snows. Lower down is the
delicate _L. velveticum_, which creeps among the damp mosses under
the shade of the forest. Many of the smaller species stain with
spots of crimson, orange, and purple the rocks among the snowfields
and glaciers, and gain the summits of peaks more than eighteen
thousand feet above the sea, reaching even to the highest rocks in
the Alpine chain. For the sake of readers who are not familiar with
that wonderful book, "Modern Painters," we will quote some exquisite
passages on lichens and mosses, full of beautiful thoughts:--

  "We have found beauty in the tree yielding fruit and in the herb
  yielding seed. How of the herb yielding no seed,--the fruitless,
  flowerless[17] lichen of the rock?

    [17] Flowerless in the ordinary, not the botanical sense.

  "Lichens and mosses (though these last in their luxuriance are deep
  and rich as herbage, yet both for the most part humblest of the
  green things that live),--how of these? Meek creatures!--the first
  mercy of the earth, veiling with trusted softness its dintless rocks,
  creatures full of pity, covering with strange and tender honour
  the scarred disgrace of ruin, laying quiet finger on the trembling
  stones to teach them rest. No words that I know of will say what
  these mosses are; none are delicate enough, none perfect enough, none
  rich enough. How is one to tell of the rounded bosses of furred and
  beaming green; the starred divisions of rubied bloom, fine-filmed, as
  if the Rock Spirits could spin porphyry as we do grass; the traceries
  of intricate silver, and fringes of amber, lustrous, arborescent,
  burnished through every fibre into fitful brightness and glossy
  traverses of silken change, yet all subdued and pensive, and framed
  for simplest, sweetest offices of grace? They will not be gathered,
  like the flowers, for chaplet or love token; but of these the wild
  bird will make its nest and the wearied child his pillow.

  "And as the earth's first mercy, so they are its last gift to us.
  When all other service is vain, from plant and tree the soft mosses
  and grey lichen take up their watch by the headstone. The woods, the
  blossoms, the gift-bearing grasses, have done their parts for a time,
  but these do service for ever. Tree for the builder's yard--flowers
  for the bride's chamber--corn for the granary--moss for the grave.

  "Yet as in one sense the humblest, in another they are the most
  honoured of the earth-children; unfading as motionless, the worm
  frets them not and the autumn wastes not. Strong in lowliness, they
  neither blanch in heat nor pine in frost. To them, slow-fingered,
  constant-hearted, is entrusted the weaving of the dark, eternal
  tapestries of the hills; to them, slow-pencilled, iris-dyed, the
  tender framing of their endless imagery. Sharing the stillness of
  the unimpassioned rock, they share also its endurance; and while the
  winds of departing spring scatter the white hawthorn blossom like
  drifted snow, and summer dims on the parched meadow the drooping
  of its cowslip,--gold far above, among the mountains, the silver
  lichen-spots rest, star-like, on the stone; and the gathering
  orange-stain upon the edge of yonder western peak reflects the
  sunsets of a thousand years."

Alpine and arctic plants are met with in Great Britain, but Scotland
has a much more extensive arctic-Alpine flora than England, Wales,
or Ireland, the reason being the greater altitude of its mountains.
The combined flora of the United Kingdom contains only ninety-one
species of arctic-Alpine plants, and of these eighty-eight--that is,
all but three--are natives of Scotland. Of these three the first is
a gentian (_Gentiana verna_), which is to be found on the hills of
West Yorkshire, Durham, Westmoreland, and other parts. It comes from
the Alps. The second is _Lloydia serotina_,--a small bulbous plant
with white flowers, which is found on the hills of Carnarvonshire,
in Wales. The third, well known in English gardens, is London pride
(_Saxifraga umbrosa_), which is only to be found on the southwest
Irish hills.

Of the ninety-one arctic-Alpine species, just about half are also
natives of England and Wales, but only twenty-five belong to Ireland.
If we examine the lists of the flora of Arctic Europe we find that
all these, except about six, are found in arctic regions; and if we
travel farther north till we come actually to polar regions, we find
nearly fifty of these species growing there near the sea-level. The
Grampian Mountains are the chief centre of the Scottish arctic-Alpine
flora. The two principal localities for such flowers in that range
are the Breadalbane Mountains in Perthshire, and the Cænlochan and
Clova Mountains of Forfarshire. There are also a goodly number on the
mountains of the Braemar district.

The history of the arctic-Alpine flora of Europe is a very
interesting one. These plants, whose true home is in the arctic
regions, living high up on the mountains of Europe, give unmistakable
evidence of a time, very far back, when Northern Europe was overrun
by glaciers and snowfields so as to resemble in appearance and in
climate the Greenland of the present day. This period is known to
geologists as the "Great Ice Age." The moraines of glaciers, ice-worn
rock surfaces, and other unmistakable signs may be well seen in
many parts of Great Britain. How long ago this took place we cannot
say; but judging from the considerable changes in geography which
have undoubtedly taken place since then, we must conclude that many
thousands of years, perhaps two hundred thousand, have intervened
between this period and the present time.

When arctic conditions prevailed over this wide area, the plants
and animals which now live in arctic latitudes flourished in Great
Britain; but as the climate gradually became more genial, and the
snow and ice melted, the plants and animals mostly retreated to
their northern home. A certain number doubtless became extinct; but
others took to the highest parts of the mountains, where snow and
ice abound; and there they remain to the present day, separated from
their fellows, but still enjoying the kind of climate to which they
have always been accustomed, and testifying to the wonderful changes
which have taken place since the mammoth, whose bones are found
embedded in our river-gravels, wandered over the plains of Northern
Europe.


_Animal Life._

The rocky fastnesses of the Alps still afford a home to some of the
larger wild animals which in other parts of Europe have gradually
disappeared with the advance of civilisation. During the latter part
of the "Stone Age," long before history was written, when men used
axes, hammers, arrow-heads, and other implements of stone, instead of
bronze or iron, Switzerland was inhabited by animals which are not to
be seen now. The gigantic urus (_Bos primigenius_), which flourished
in the forests of the interior during this prehistoric human period,
and gave its name to the canton of Uri, has become extinct. The marsh
hog was living during the period of the Swiss lake-dwellers. These
people made their houses on piles driven in near the shore, and were
acquainted with the use of bronze, and therefore later than the men
of the "Stone Age." The remains of these strange dwelling-places
have been discovered in several places, as well as many articles of
daily use. The marsh hog has disappeared; and its place is taken by
the wild boar and domestic hog, which afford sport and food to the
present population. But taking Switzerland as it now is, we will say
a few words about the more interesting forms of animal life dwelling
in the Alps, beginning with those which are highest in the animal
kingdom. Chief among these is the brown bear, still occasionally
found, but it is exceedingly rare, except in the Grisons and in the
districts of the Tyrol and Italy bordering on the canton, where it
still carries on its ravages.[18] Some also believe that it still
lingers in the rocky fastnesses of the Jura Mountains, to the east of
the Alps. There is properly only one species of bear in Switzerland,
but the hunters generally speak of three,--the great black, the
great grey, and the small brown. The second of these is merely an
accidental variety of the first; but between the grey and the small
brown bears there is a good deal of difference. They assert that
the black bear is not only considerably larger than the brown, but
is also different in its habits. It is less ferocious and prefers a
vegetable diet,--feeding on herbs, corn, and vegetables, with the
roots and branches of trees. It has a way of plundering bee-hives and
also ants' nests; it delights in strawberries and all kinds of fruit,
plundering the orchards, and even making raids on the vineyards,
but always retreating before dawn. As a rule it does not attack
human beings. The brown bear is much more formidable, prowling by
night about the sheepfolds, and causing the sheep by their fright to
fall down precipices. Goats, when alarmed, leap on the roofs of the
châlets, and bleat, in order to arouse the shepherds; so that when
Bruin rears himself up against the wall he often meets his death.
There are many stories on record of fierce fights for life between
man and bear. The bear passes the winter in a torpid state, and eats
little or nothing then.

  [18] We are again indebted to Professor Bonney's "Alpine Regions
  of Switzerland" for the information here given.

The wolf, though still lingering in several lonely parts of the
Alps, is rapidly becoming rare. It is most frequent in the districts
about the Engadine and in the Jura Mountains. Only in winter-time,
when hard pressed by hunger, does it approach the haunts of man. It
takes almost any kind of prey it can get,--foxes, hares, rats, mice,
birds, lizards, frogs, and toads. Sheep and goats are its favourite
prey. The wolf is an affectionate parent, and takes his turn in
looking after the nurslings, which is a necessary precaution, as his
friends and relations have a way of eating up the babies.

The fox is common in many parts of the Alps, but not often seen
by travellers. Instead of taking the trouble to burrow, he
frequently manages by various cunning devices to take possession
of a badger's hole. As Tschudi quaintly observes, "He has far too
much imagination and poetic sentiment to like so monotonous and
laborious an occupation as burrowing." Like the wolf, the mountain
fox eats whatever he can catch, even beetles, flies, and bees. Those
in the valleys live more luxuriously than their relations on the
mountains,--plundering bee-hives and robbing orchards. As it was in
Judæa in the days of Solomon, so it is now in Switzerland among the
vineyards; and a peasant might well say, "Take us the foxes, the
little foxes that spoil the vineyards."

The lynx is only occasionally found in the Alps, which is fortunate
for the shepherds, for they can play terrible havoc with the sheep.

Wild-cats still linger in the most unfrequented parts. Their fur is
valuable, and the flesh is sometimes eaten. The badger is far from
common, though rarely seen by day. It is very cunning in avoiding
traps, and so is generally either dug out of its hole drawn by
dogs, or pulled out by a pole with nippers or a hook at the end.
Passing on to less ferocious beasts, we find the otter common along
the borders of rivers and lakes. The polecat, weasel, and stoat
are often too abundant for keepers of poultry. The squirrel is
common enough in the forests, but varies greatly in colour. It is
doubtful whether the beaver still lingers by some lonely Alpine
stream. It is last mentioned in a list of Swiss mammals, published
in 1817, as found, though rarely, in some lonely spots. Rabbits are
common, but hares rather scarce; of these there are, as in Scotland,
two varieties,--the brown hare, which is seldom found at heights
greater than four thousand to five thousand feet, and the blue
hare, which ranges up to nine thousand feet. The latter changes
colour: its fur in summer is of a dull bluish-grey, and in winter it
becomes perfectly white, and so affords a striking illustration of
"protective mimicry," for with snow lying on the ground it would be
very hard to see the creature.

The marmot is common in all the higher Alpine regions. These
interesting little creatures are very watchful, and easily scent
danger. When an intruder approaches, a sentinel marmot utters a
long shrill whistle, which is often repeated two or three times,
and then they all make for their burrows; but it is not easy to
distinguish them from the grey rocks among which they live. The fur
is a yellowish or brownish grey, with black on the head and face,
and a little white on the muzzle; the tail is short and bushy with a
tipping of black. They have different quarters for summer and winter.
The summer burrows are in the belt of rough pasture between the
upper limits of trees and the snows; towards the end of autumn they
come down to the pastures which the herdsmen have just abandoned
and there make their winter burrows, which are much larger than the
summer ones. Like rabbits, they frequently make a bolt-hole, by which
they may escape from an intruder. In winter the holes are plugged up,
and the marmots, rolling themselves up in a ball, go to sleep for six
months or more. Sometimes hunters dig them out; but so soundly do
they sleep that, according to De Saussure, they may often be taken
out, placed in the game-bag, and carried home without being aroused.
They wake up about April.

The chamois, a very favourite subject with the wood-carvers, is the
only member of the antelope family in Western Europe; it is found
in almost every part of the Alps, but is now much rarer than it was
formerly. A full-grown chamois in good condition weighs about sixty
pounds. The hair is thick, and changes colour with the season, being
a red yellowish-brown in summer and almost black in winter. The
horns, which curve backwards, rise from the head above and between
the eyes to a height which rarely exceeds seven inches. When the
kid is about three months old, the horns make their appearance, and
at first are not nearly as hook-shaped as they afterwards become.
When full-grown, it stands at the shoulder about two feet from the
ground. The hind-legs being longer than the fore-legs, its gait is
awkward on level ground, but they are admirably suited for mountain
climbing. When at full speed, it can check itself almost instantly,
and can spring with wonderful agility. Its hoofs are not well adapted
for traversing the ice, and therefore it avoids glaciers as far as
possible. Having a great fear of concealed crevasses, it is very
shy of venturing on the upper part of a glacier; and the tracks
which it leaves in these places often show by their windings and
sudden turnings that the animal has exercised great caution. And so
travellers often use this as a useful clue to getting safely over
a glacier. Its agility is something extraordinary. It can spring
across chasms six or seven yards wide, and "with a sudden bound leap
up the face of a perpendicular rock, and merely touching it with its
hoofs, rebound again in an opposite direction to some higher crag,
and thus escape from a spot where, without wings, egress seemed
impossible. When reaching upwards on its hind-legs, the fore-legs
resting on some higher spot, it is able to stretch to a considerable
distance, and with a quick spring bring up its hind-quarters to a
level with the rest of the body, and with all four hoofs together,
stand poised on a point of rock not broader than your hand."[19] The
chamois feed on various mountain herbs, and on the buds and sprouts
of the rhododendron and latschen (a pine). At night they couch among
the broken rocks high upon the mountains, descending at daybreak
to pasture, and retreating, as the heat increases, towards their
fastnesses. When winter comes, they are forced down to the higher
forests, where they pick up a scanty subsistence from moss, dead
leaves, and the fibrous lichen which hangs in long yellowish-grey
tufts from the fir-trees and bears the name of "chamois-beard."
While browsing on this, they sometimes get their horns hooked in a
bough, and so, being unable to disentangle themselves, perish with
hunger. The senses of hearing, smell, and sight are exceedingly
acute; so that the hunter must exercise all his craft to approach
the animals. Pages might be filled with the hair-breadth escapes and
fearful accidents which have befallen hunters; and yet they find the
pursuit so fascinating that nothing will induce them to abandon it. A
young peasant told the famous De Saussure (the pioneer of Alpine
explorers) that though his father and grandfather before him had met
their death while out on the hunt, not even the offer of a fortune
would tempt him to change his vocation. The bag which he carried with
him he called his winding-sheet, because he felt sure he would never
have any other. Two years afterwards he was found dead at the foot of
a precipice.

  [19] Bonar on Chamois-hunting in Bavaria.

The bouquetin, or steinbock, once abundant throughout the greater
part of the Alps, is now confined to certain parts where it is
preserved by the King of Italy. De Saussure observes that in his
time they had ceased to be found near Chamouni. Its whole build is
remarkably strong, giving it quite a different appearance from the
slender and graceful chamois.

  [Illustration: RED DEER. AFTER ANSDELL.]

The roe, the fallow deer, and the red deer have, it is said, quite
disappeared from the French and Swiss Alps, but all of them occur in
the Bavarian and Austrian highlands. They frequent the forests which
clothe the lower slopes, and do not often wander into the more rocky
districts. The wild boar only now and then appears across the Rhine,
although it is common in the Subalpine forests farther east; but we
can hardly consider it a true Alpine quadruped.

Passing on to the birds which frequent the Alps, we must first notice
the bearded vulture, the lämmergeier of the Germans, which once was
common, but now only holds its own here and there in some lonely
mountain fastness. Although preferring living prey to carrion, still
in many ways it is closely allied to the true vulture. The upper part
of the body is a greyish-brown hue, the under side white, tinged with
reddish brown. The nest, built on a high ledge of rock, consists of
straw and fern, resting on sticks, on which are placed branches lined
with moss and down. It is a rare thing for the traveller to obtain
a view of this monarch of the Alpine birds. Like the true vulture,
its digestive powers are marvellous. According to Tschudi ("Les
Alpes"), the stomach of one of these birds was found to contain five
fragments of a cow's rib, a mass of matted wool and hair, and the
leg of a kid perfect from the knee downwards. Another had bolted a
fox's rib fifteen inches long, as well as the brush, besides a number
of bones and other indigestible parts of smaller animals, which
were slowly being eaten away by the gastric juice. Sheep, goats,
full-grown chamois, and smaller quadrupeds are eagerly devoured by
this voracious bird. It is said to be bold enough to attack a man,
when it finds him asleep or climbing in any dangerous place. Tschudi,
in his book on the Alps, gives several instances of young children
being carried off. One of these happened in the Bernese Oberland, as
follows: Two peasants, making hay upon the pastures, had taken with
them their daughter Anna, a child about three years old. She quickly
fell asleep on the turf near the hay châlet; so the father put his
broad-brimmed hat over her face, and went to work some little way
off. On his return with a load of hay the child was gone; and a brief
search showed that she was nowhere near. Just at this time a peasant
walking along a rough path in the glen was startled by the cry of a
child, and going towards the place whence it came, saw a lämmergeier
rise from a neighbouring summit and hover for some time over a
precipice. On climbing thither in all haste, he found the child
lying on the very brink. She was but little injured; some scratches
were found on her hands and on the left arm, by which she had been
seized; and she had been carried more than three quarters of a mile
through the air. She lived to a good old age, and was always called
the Geier-Anna, or Vulture's Annie, in memory of her escape. The
particulars are inscribed in the registers of the parish of Habkeren.

The golden eagle is not uncommon in most parts of the Alps, although
travellers rarely obtain a near view. It is said to be very fond
of hares, chasing and capturing them very cleverly. As in Great
Britain, it is accused of carrying off children; but this is at least
doubtful. The kite, buzzard and falcon are occasionally seen. There
are at least ten species of owls, among which is the magnificent
eagle-owl. The raven is found in the lonelier glens, and is often
tamed. Its thieving propensities are very amusing. Alpine birds
of prey correspond very closely with British. The jackdaw is also
common. It would be impossible within our short limits to give
a complete list of Swiss birds, but we may mention among others
the nutcracker, the jay, the white-breasted swift, the wheatear,
the common black redstart, the beautiful wall-creeper, and the
snow-finch, which mounts to the borders of the snow. Of game-birds
we may mention the capercailze, the black grouse, and the hazel
grouse, all of which are common in many of the forests. The ptarmigan
haunts the stony tracts on the borders of perpetual snow. In winter
it turns white, and in summer greyish-brown, though a good deal of
white remains.

Pheasants and partridges cannot be said to be Alpine birds; but the
Greek partridge may be so considered.

Numbers of the mountain streams and tarns contain excellent trout,
and most of the larger lakes are well stocked with fish. Some of the
trout of the Swiss and Italian lakes are of great size. The pike
frequently weigh twelve to fifteen pounds.

Reptiles are not numerous. The common frog, which is said to be found
as high as ten thousand feet above the sea, swarms in some parts of
the Rhone Valley. Of true lizards, five species have been recognized.
The blind-worm (which is not a snake), so common on many of our
English heaths, is often met with. Among the true snakes we find the
English ringed snake--quite harmless--and two adders. The common
adder is found at a height of seven thousand feet above the sea.

Lower forms of life not possessing a backbone (invertebrates) abound
in this region; but they are far too numerous to be considered here.
Butterflies and moths are abundant; and many of those which are rare
in England are common in the Alps, so that the entomologist finds
a happy hunting-ground. The beautiful swallowtail and the handsome
apollo, coppers, painted ladies, fritillaries, and many other
Lepidoptera thrive in these regions, and are less easily frightened
than at home in England.




PART II.

HOW THE MOUNTAINS WERE MADE.




Part II.

HOW THE MOUNTAINS WERE MADE.




CHAPTER V.

HOW THE MATERIALS WERE BROUGHT TOGETHER.

    These changes in the heavens, though slow, produce
    Like change on sea and land.

    MILTON


Probably every mountain climber, resting for a brief space on a loose
boulder, or seeking the shade of some overhanging piece of rock, has
often asked himself, "How were all these rocks made?" The question
must occur again and again to any intelligent person on visiting a
mountain for the first time, or even on seeing a mountain-range in
the distance. He may well ask his companions how these great ramparts
of the earth were built up. But unless he possesses some knowledge
of the science of geology, which tells of the manifold changes which
in former ages have taken place on the earth, or unless, in the
absence of such knowledge, he chance to meet with a geologist, his
question probably remains unanswered. Such questions, however, can
be very satisfactorily answered,--thanks to the labours of zealous
seekers after truth, who have given the best part of their lives
to studying the rocks which are found everywhere on the surface of
the earth, and the changes they undergo. Geology is a truly English
science; and Englishmen may well cherish gratefully the memories of
its pioneers,--Hutton, Playfair, Lyell, and others, who have made the
way so clear for future explorers.

The story of the hills as written on their own rocky tablets and on
the very boulders lying loose on their sloping sides, and interpreted
by geologists, is a long one; for it takes us far back into the dim
ages of the past, and like the fashionable novel, may be divided into
three parts, or volumes. To those who follow the stony science it
is quite as fascinating as a modern romance, and a great deal more
wonderful, thus illustrating the force of the old saying, "Truth is
stranger than fiction."

The three parts of our story may be best expressed by the three
following inquiries:

   I. How were the materials of which mountains are built up
   brought together and made into hard rock?

   II. How were they raised up into the elevated positions in
   which we now find them?

   III. How were they carved out into all their wonderful and
   beautiful features of crag and precipice, peaks and passes?

A mountain group, with its central peak or spire, its long ridges,
steep walls, towers, buttresses, dark hollows, and carved pinnacles
standing out against the sky, has well been compared to a great
and stately building such as a cathedral or a temple. Mountains
are indeed "a great and noble architecture, giving first shelter,
comfort, and rest, but covered also with mighty sculpture and painted
legend;" and to many they are Nature's shrines, where men may offer
their humble praises and prayers to the great Architect who reared
them for His children. We have introduced this illustration because
it will help us in our inquiry. Suppose we were standing in front of
some great cathedral, such as Milan, with all its marble pinnacles,
or Notre Dame, with its stately towers, or the minsters of York or
Durham in our own country, and trying to picture to ourselves how
it was built. No one has lived long enough to watch the completion
of one of these great buildings; but for all that, we know pretty
well how it was made, even by watching the builder's operations for
a short time, or by following, as we often may, the various stages
in the construction of a small house. So it is with Nature's work.
We cannot, in our little lives, witness the rearing of a great
mountain-chain, or even the carving of a single hill; but we can
observe for ourselves the slow and continuous operations which in the
course of thousands and thousands of years produce such stupendous
results. We may learn how the building operations are conducted,
though the final results will only be manifested in the far-distant
future.

But to return to our cathedral. If we try to picture to ourselves
the long years during which it was covered with scaffolding and
surrounded by a busy army of workers, we shall soon perceive that
the operations may be broadly divided into three heads. _First_, we
must inquire how the separate stones of which it is composed were
brought together into one place, and we shall at once picture to
ourselves groups of men working in stone-quarries,--perhaps a long
way off,--busy with their crowbars and hammers, breaking off large
blocks of stone, and following the natural divisions of the rock
that their rough labour may be lessened; for all rocks will split
more easily along certain lines than along others. Sometimes it is
easier to follow the "bedding," or natural layers in which the rock
was formed; at other times the "joints," or cracks subsequently
formed as the rocky materials hardened and contracted in bulk, afford
easier lines for the workmen to follow. Others are busily engaged in
placing the stony blocks on trollies drawn by horses, that they may
be borne along the roads leading from the quarry to the site of the
future cathedral. And so, taking a bird's-eye view, we seem to see
horses and carts slowly moving on from many a distant quarry, but
all converging like the branches of a river to one main channel, and
finally depositing their burdens in the stone-yard where the masons
are at work. Perhaps bricks are partly employed, in which case we can
easily picture to ourselves the brickyards, where some are digging
out the soft clay, others moulding it into bricks with wooden moulds,
while others again lay them down in rows on the ground to dry, before
they are baked in the ovens. And when the bricks are ready for
use, the same means of transportation are employed; and cart-loads
of them are borne along the country roads until they so reach their
destination.

Now, all this may be summed up in the one word "transportation;"
and we shall presently inquire how the rocky matter of which the
mountains are built was transported.

_Secondly._ We have to inquire how the bricks and stones were raised
up. The analogy is not quite perfect in this case; for the mountains
were raised up _en bloc_, not bit by bit and stone by stone, as in
the case of the cathedral. Still they have been raised somehow.
Analogies are seldom complete in every detail; but for all that, our
illustration serves well enough, and will help us in following the
various processes of mountain building. In these days, the raising of
the stones is mostly effected by steam-power applied to big cranes
and pulleys. In old days they used cranes and pulleys, but the ropes
were pulled by hand-power. In either case the work proceeds slowly;
and we can easily picture to ourselves the daily raising of the
stones of which the cathedral is composed. "What were the forces
at work which slowly raised the mountains?" This question we will
endeavour to answer later on (see next chapter). This work may be
included in the one word, "elevation."

_And lastly._ We must inquire how the carving of the stately building
was effected, how its pinnacles received their shape, and how all
those lovely details received their final forms; how the intricate
traceries of its windows were made, and the statues carved which
adorn its solemn portals. This question is easily answered, for we
are all more or less familiar with what goes on in a stone-mason's
yard. Under those wooden sheds we see a number of skilled labourers
at work, busy with their chisels and mallets, cutting out, according
to the patterns made from the architect's detailed drawings, the
portions of tracery for windows, or the finials, crockets, and other
features of the future building. In another part of the yard may be
seen the stone-cutters, working in pairs and slowly pulling backwards
and forwards those long saws which, with the help of water and sand,
in time cut through the biggest blocks. All this work then may be
summed up under the one word, "ornamentation," for it includes the
cutting and carving of the stone.

Our three lines of inquiry may now be summed up in these three words,
which are easily remembered:--

    _Transportation_,
    _Elevation_,
    _Ornamentation_.

Taking the first of these subjects for consideration in the present
chapter, we have now to inquire into the nature of the materials of
which mountains are composed and the means by which they have been
brought together and compacted into hard rock.

First, with regard to the nature of the materials which Mother Earth
uses to build her rocky ramparts: they are the same as the ordinary
rocks of which the earth's crust is composed; and the greater part of
them have been formed by the action of water. These are the ordinary
"stratified" rocks, which in one form or another meet us almost
everywhere, and may be said to be aqueous deposits, or sediments
formed in seas and inland lakes. They are always arranged in layers,
known to geologists as "strata," because they have been gently laid
down, or strewn (Latin, _stratum_), at the bottom of some large body
of water. There were pauses in the deposition of the materials,
during which each layer had time to harden a little before the next
one was formed. This accounts for the stratification. In this way
great deposits of sandstone, clay, and limestone, with their numerous
varieties, have been in the course of ages gradually piled up, till
they have attained to enormous thickness, which at first sight seem
almost incredible; but the bed of the seas in which they formed was
probably undergoing a slow sinking process that kept pace with the
growth of these deposits, otherwise the sea might have been more or
less filled up.

And these processes are still going on. In fact, it is entirely by
watching what goes on now that geologists are able to explain what
took place a very long time ago when there were no human beings on
the earth to record the events that took place. And so we argue
from the present to the past, from the known to the unknown. In
other words, geology is based upon physical geography, which tells
us of the changes now in progress on the earth. Thus, sandstone,
as frequently met with in different parts of Great Britain, and
largely used for building purposes, such as the familiar old red
sandstone[20] of South Wales, Hereford, and the north of England and
different parts of Scotland, was once soft sand in no way at all
different from the sand of the seashore at the present day, or of the
sandy bed of the North Sea. In process of time it became hardened,
and acquired its characteristic red colour, which is due to oxide of
iron. In some places numerous fossil fishes have been discovered in
this interesting formation, so intimately associated with the name
of Hugh Miller, who first thoroughly explored it; these and other
remains entombed therein tell us of the strange forms of life which
flourished on the earth during that very old-fashioned period of
the world's history; and by putting together all kinds of evidences
derived from the rock itself, geologists are able to form a very good
idea of the way in which this rock-deposit was accumulated, always,
however, basing their conclusions on a thorough knowledge of what
goes on at the present day in seas, rivers, and inland lakes.

  [20] The reader will find an account of the old red sandstone in
  the writer's "Autobiography of the Earth" (Edward Stanford, 1890).

In the great series of stratified rocks forming what is commonly
called the crust of the earth (an unfortunate term which has survived
from the time when the interior of the earth was generally believed
to be in a fiery molten condition, and covered by a thin coating of
solid rock at the surface), there are besides the sandstones, of
which we have just spoken, great deposits of dark-coloured clays,
shales, and slates. All these can be accounted for by the geologist.
They are simply different states of what was once soft mud. The
slates tell us that they have been subjected to very severe pressure,
which squeezed their particles till they were elongated and all
arranged in one direction, and this is the reason why they split up
into thin sheets.

Others, again, represent vast deposits of carbonate of lime,
thousands of feet thick and now occupying hundreds of square miles
of the earth's surface. Limestone rocks are as abundant in our own
country as the sandstones, shales, or slates. The chalk of which
the North and South Downs are composed is a familiar example. It is
seen again forming Salisbury Plain, in Hampshire and the Isle of
Wight, and then it may be traced running up the country in a long
band through the counties of Oxford, Cambridge, Lincoln, until it
reaches the coast at Flamborough Head in Yorkshire. Then we have the
Bath Oölites so much used in building, for they form an admirable
"freestone" that can be easily carved and cut in any direction (hence
the term "freestone"); and lastly, the great mountain limestone so
well developed in South Wales, Yorkshire, and the Lake country. All
these were slowly built up at the bottom of the seas which existed
in past ages; great beds of gravel formed at the mouths of rivers,
and long banks of pebbles and rounded stones collected on the shore
of primeval seas, and were ground against each other as now by
the action of the waves, until all their corners were rubbed off.
Pebble-beds, called by geologists conglomerates, are met with among
the stratified rocks; and their story is easily read by studying
what takes place at the present day on our seashores.

  [Illustration: CHALK ROCKS, FLAMBOROUGH HEAD. FROM A PHOTOGRAPH
  BY G. W. WILSON.]

Now, the sandstones, clays, gravels, and pebble-beds all represent,
as will presently be explained, so much material worn away from the
surface of the land and swept into the ocean (or in some cases into
inland seas and lakes) by streams and rivers, which are the great
transporting agents of the world. Hence such deposits of débris,
supplied by the constant wear and tear of all rocks exposed to the
atmosphere, are truly sedimentary and have a purely mechanical
origin. But it is not so with the limestones. The latter were never
transported, but grew at the bottom of the sea in very wonderful
ways. They have nothing to do with the wear and tear of the land to
which the others owe their existence, but represent vast quantities
of carbonate of lime extracted from sea water. Sea water contains
a certain amount of this substance in a dissolved state, or "in
solution," as a chemist would say; and the way in which this is
extracted by the agency of various creatures, such as coral polypes
and little microscopic creatures that build their shells of
carbonate of lime, of great beauty, forms one of the most interesting
subjects presented to the student of physical geography. Hence,
since limestone can only be accounted for by the agency of living
organisms,[21] it is rightly termed an _organic deposit_, and the
others are said to be _mechanical deposits_. But both are called
"aqueous rocks," because they are formed under water. It is important
to distinguish clearly between these two very different methods of
rock-formation.

  [21] The flints usually found in limestone are also of organic
  origin.

But although water plays such a very important part in the making of
the common rocks around us, yet there are others which have quite a
different origin,--rocks which have come up from below the surface of
the earth in a heated and molten condition, such as the lavas that
flow from volcanoes in active eruptions and the showers of ashes
and fine volcanic dust which often attend such eruptions (see chap.
viii., pp. 271-272). Some highly heated rocks, though they never rise
to the surface to form lava-flows, are forced up with overwhelming
pressure from below, and wedge themselves into the sedimentary rocks
that overlie them, thus forming what are known as volcanic dykes, and
intrusive masses or sheets of once molten rock. In this category we
include such rocks as basalt, felstone, pitchstone, and other rocks
of fiery origin that have flowed from volcanoes as lava, as well as
those like granite, which have cooled and become solid _below_ the
surface, and are Plutonic, or deep-seated, igneous rocks. Granite
may be exposed to the surface of the earth when the rocks which once
overlaid it have been worn away or "denuded." It is frequently seen
in the central regions of mountain-chains, where a vast amount of
erosion has been effected. Thus we see that heat has played its part
in the making of rocks; and for this reason such rocks as we have
just mentioned are called _igneous_. Fire and water are therefore
very important geological agents; but we should say heat rather than
fire, because the latter word might convey a false impression. No
rocks can be burned except coal, which may be considered rather as a
mineral deposit than as a rock. Some rocks may be heated, and undergo
many and various changes in their mineral composition; but they are
not capable of combustion.

So far, then, we have learned that the rocks exposed to view on
the surface of the earth may be divided into two classes; that is,
aqueous and igneous. There is yet a third class, which, though of
aqueous origin, has in course of time suffered considerable from
the internal heat of the earth and the enormous pressure due to the
weight of overlying rocks. Such rocks have been greatly changed
from their original condition, both in appearance and in mineral
composition, and are said to be "metamorphic," a word which implies
change. Thus chalk, or other limestone rock, has been metamorphosed
into marble; shales and slates into various kinds of "schists,"[22]
such as mica-schist, and even into gneiss, which closely resembles
granite. And it is quite possible that even granite may in some cases
be the result of the melting and consolidation under great pressure
of certain familiar stratified rocks. It is quite conceivable that
slate might be converted into granite, for their chemical composition
is similar, only the minerals of which it is composed would require
to be rearranged and grouped into new compounds. This would seem
quite possible; but at present we have no direct proof of such a
change having taken place. Even igneous rocks are found in some
places to have suffered very considerable change.

  [22] Schists are so named from their property of splitting into
  thin layers. Their structure is crystalline; and the layers, or
  folia, consist usually of two or more minerals, but sometimes
  of only one. Thus mica-schist consists of quartz and mica, each
  arranged in many folia, but it splits along the layers of mica.

In some inland seas, like the Caspian Sea, deposits of rock salt and
gypsum may be formed by chemical precipitation, owing to evaporation
from the surface.

The various kinds of rock known to geologists may be conveniently
arranged as follows:

                    {                 { Clay, shale, slate, etc.
                    { I. Sedimentary. { Sandstones.
                    {                 { Conglomerates.
                    {
    Rocks of        {                 { Limestones.
    aqueous         { II. Organic.    { Flint.
    origin.         {                 { Coal.
                    {
                    { III. Chemical.  { Rock salt.
                    {                 { Gypsum, etc.

                    { I. Volcanic.    { Lavas.
    Rocks of        {                 { Volcanic ashes, etc.
    igneous origin. {
                    { II. Plutonic.   { Basalt.
                    {                 { Granite.

    Metamorphic rocks                 { Marbles.
    of aqueous and                    { Various kinds of schists.
    igneous origin.                   { Gneiss, etc.

So far we have only attempted to state very briefly the different
kinds of rocks, and to point out that they were formed in various
ways. We must now consider the question of rock-making more closely,
and see what we can learn about the wonderful ways in which rocks are
made; and it may be instructive to glance at the conflicting opinions
on this subject which learned men held not very long ago.

At the end of the last century a great controversy took place on
the question of the origin of rocks, and the learned men of the day
were divided into two parties. One of these parties, following the
teaching of Werner, professor of mining at Freyburg, who inspired
great enthusiasm among his disciples, declared that all rocks were
formed by the agency of water. This was a very sweeping and of course
rash conclusion. But whenever they examined rocks, they found so many
clear evidences of the action of water that a powerful impression
of the importance of this agency was naturally made on their minds.
They found rocks uniformly arranged in great layers which extended
for long distances, and containing the remains of animals which must
undoubtedly have lived in the seas or estuaries. These layers were
further divided into smaller layers, such as clearly were formed
by the slow settling down of sand and mud. Others again contained
gravels and rounded pebbles, testifying in no uncertain way to
the action of water. Even the little grains of sand are obviously
water-worn. This teaching was quite sound so long as they confined
their attention to clays, sandstones, and limestones; but when they
came to basalt and granite, a blind adherence to the views of their
master caused them to shut their eyes to the clear evidences of the
action of heat, presented by such rocks. The crystalline structure
of such rocks; their irregular arrangement, often so different
from the uniform disposition of the stratified rocks (although it
must be admitted that ancient lava-flows often lie very evenly
between aqueous rocks), and the way in which they burst through
overlying rocks, thus proving their former molten condition; the
signs of alteration exhibited in the aqueous rocks into which they
intruded themselves (changes which are obviously due to the action
of heat),--these and other evidences were entirely overlooked, and
Werner declared that basalt had been found as a sediment under water.

This school of geologists, believing so strongly in the all-powerful
influence of Father Neptune, received the not inappropriate title of
"Neptunists."

On the other hand, the party who happened to be in districts where
granite, basalt, and such igneous rocks abounded were equally
impressed with the importance of the powerful agency of heat. To
them nearly every rock they met with seemed to show some signs of
its action. And since Pluto was the classical deity of the lower
regions, and the earth shows evidences in places of greater heat
below the surface, this party received the title of "Plutonists;"
and so the battle raged hotly for some time between the Neptunists,
with their claims for cold water, and the fiery Plutonists of the
rival school of Edinburgh, with their subterranean heat. Fire and
water are never likely to agree; and they did not do so in this case.
But now that the battle is over, and both sides are found to have
been partly right and partly wrong,--though the Neptunists have the
advantage,--we can afford to smile at the fierceness of the contest,
and wonder how it was that each side thought they were so entirely in
the right.

Let us now consider the aqueous rocks, and see if we can gain a clear
idea of the ways in which they were formed; and first, we will take
those of a purely sedimentary origin,--the sandstones, pebble-beds,
gravels, and clays. These, as the reader has already probably
guessed, have all been transported by means of streams and rivers,
and settled down quietly in seas at the mouths of rivers or in inland
lakes. There is no trace of the action of heat in the forming of
these rocks, though they often show signs of having suffered more or
less change from contact with highly heated igneous rocks of later
date which forcibly intruded themselves from below; and if the change
thus effected were considerable, we should call the rocks so altered
metamorphic. But we are now dealing with their original state and how
they were made; and of that there is no possible doubt whatever. So
for the time being we may call ourselves Neptunists.

Streams and rivers are the great transporting agents whereby the
never-failing supply of débris from the waste of the land is
unceasingly brought down from the mountains and hills, through the
broad valleys and along the great plains, until finally it is flung
into the sea. The sea is the workshop where all the sedimentary
rocks are slowly manufactured from the raw material brought to it
by the rivers. But for the present we must confine our attention to
the question of transport. Referring back to our illustration of the
cathedral, we may say that streams and rivers play the part of cart
and horses. They bring the materials down from the quarry to the
scene of action,--the workshop where they are wanted. The quarries,
in this case, may be said to be almost everywhere. For wherever rocks
and soil are exposed to the action of wind and weather, there is
certain to be more or less decay and crumbling away. But it is among
the hills and in the higher parts of the mountains that the forces
of destruction are most active. How this is brought about will be
discussed in the seventh chapter, on the carving of the hills. The
frequent slopes covered with loose stones are sufficient evidence of
the continual destruction that takes place in these regions.

The transporting powers of rivers are truly prodigious. Looking at
a stream or river after heavy rain, we see its waters heavily laden
with mud and sand; but it is difficult to realise from a casual
glance the vast amount of material that is thus brought down to lower
levels. If we could trace the sediment to its source, we must seek it
among the rocks of mountains far away. Step by step we may trace it
up along the higher courses of the river, then along mountain streams
rushing over their rocky beds, tumbling in cascades over broken
rocks, or leaping in waterfalls over higher projections of rock,
until we come to the deep furrows on the sides of mountains along
which loose fragments of rock come tumbling down with the cascades of
water that run along these steep channels after heavy rain, leaving
at the base of the mountain great fan-shaped heaps of stones.

    "Oft both slope and hill are torn
    Where wintry torrents down have borne,
    And heaped upon the cumbered land
    Its wreck of gravel, rocks, and sand."

These accumulations are gradually carried away by the larger mountain
streams, which in hurrying them along cause a vast amount of wear
and tear; so that their corners are worn off, and they get further
and further reduced in size, becoming mere round pebbles lining
the bed of the stream, and finally by the time they reach the large
slow-moving rivers of the plains are mainly reduced to tiny specks
of mud or grains of sand. So then the rivers and streams not only
transport sediment, but they manufacture it as they go along. And
thus they may be considered as great grinding-mills, where large
pieces of stone go in at one end, and only fine sand and mud come out
at the other.

The amount of land débris thus transported depends partly on the
carrying power of rivers, which varies with the seasons and the
annual rainfall; partly on the size of the area drained by a river;
and again, partly on the nature of the rocks of which that area is
composed.

A stream, moving along at the rate of about half a mile (880 yards)
an hour, which is a slow, rate, can carry along ordinary sandy soil
suspended in a cloud-like fashion in the water; when moving at the
rate of two thirds of a mile (about 1,173 yards) an hour, it can roll
fine gravel along its bed; but when the rate increases to a yard
in a second, or a little more than two miles an hour, it can sweep
along angular stones as large as an egg. But streams often flow much
faster than this, and so do rivers when swollen by heavy rain.

A rapid torrent often flows at the rate of eighteen or twenty miles
an hour, and then we may hear the stones rattling against each other
as they are irresistibly rolled onward; and during very heavy floods,
huge masses of rock as large as a house have been known to be moved.

These are the two principal ways in which streams and rivers act as
transporting agents: they carry the finer materials in a suspended
state (though partly drifting it along their beds); and they push
the coarser materials, such as gravel, bodily along. But there
is one other way in which they carry on the important work of
transportation, which, being unseen, might easily escape our notice.
Every spring is busily employed in bringing up to the surface mineral
substances which the water has dissolved out of the underground
rocks. This invisible material finds its way, as the springs do, to
the rivers, and so finally is brought into that great reservoir, the
sea. Rain and river water also dissolve a certain amount of mineral
matter from rocks lying on the surface of the earth. Now, the
material which is most easily dissolved is carbonate of lime. Hence
if you take a small quantity of spring or river water and boil it
until the whole is evaporated, you will find that it leaves behind
a certain amount of deposit. This, when analysed by the chemist,
proves to be chiefly carbonate of lime; but it also contains minute
quantities of other minerals, such as common salt, potash, soda,
oxide of iron, and silica, or flint. All these and other minerals are
found to be present in sea water.

The waters of some of the great rivers of the world have been
carefully examined at different times, in order to form some idea of
the amount of solid matter which they contain, both dissolved and
suspended; and the results are extremely important and interesting,
for they enable us to form definite conclusions with regard to their
capacity for transport. This subject has been investigated with great
skill by eminent men of science. The problem is a very complicated
one; but it is easy to see that if we know roughly the number of
gallons of water annually discharged into the sea by a big river,
and the average amount of solid matter contained in such a gallon
of water, we have the means of calculating, by a simple process
of multiplication, the amount of solid matter annually brought
down to the sea by that river. But we must also add the amount of
sand, gravel, and stones pushed along its bed. This may be roughly
estimated and allowed for. These are some of the results:

The amount of solid matter discharged every year by that great river,
the Mississippi, if piled up on a single square mile of the bed of
the sea,--say, in the Gulf of Mexico, where that river discharges
itself,--would make a great square-shaped pile 268 feet high. But the
Gulf Stream, sweeping through this gulf, carries the materials for
many and many a mile away; so that in course of time it gradually
sinks and spreads itself as a fine film or layer over part of the
great Atlantic Ocean. The mud brought down by the great river
Amazon spreads so far into the Atlantic Ocean as to discolour the
water even at a distance of three hundred miles. The Ganges and the
Brahmapootra, flowing into the Bay of Bengal, discharge every year
into that part of the Indian Ocean 6,368,000,000 cubic feet of solid
matter. This material would in one year raise a space of fifteen
square miles one foot in height. The weight of mud, etc., that these
rivers bring down is sixty times that of the Great Pyramid of Egypt,
or about six million tons.

Or, to put the matter in another way, if a fleet of more than eighty
"Indiamen," each with a cargo of fourteen hundred tons of solid
matter, sailed down every hour, night and day, for four months, and
discharged their burdens into the waters of the Indian Ocean, they
would only do what the mighty Ganges does quietly and easily in the
four months of the flood season.

It is probable that even the Thames, a small river compared to
those just mentioned, manages to bring down, in one way or another,
fourteen million cubic feet of solid matter. These few figures may
suffice to give the reader some idea of the enormous amount of
rock-forming materials brought down to the seas at the present day.

Of course they are spread out far and wide by the numerous ocean
currents, some of which flow for hundreds of miles; and so the bed of
the sea can only be very slowly raised by their accumulation. Still
the geologist can allow plenty of time, for there is no doubt that
the world is immensely old; and if we allow thousands of years, we
may easily comprehend that deposits of very considerable thickness
may in this way accumulate on the floors of the oceans. Also the
coasts of continents and islands suffer continual wear and tear at
the hands of sea waves; and thus the supply of sediment is increased.

When the geologist comes to study the great rock-masses--hundreds,
and even thousands, of feet in thickness--of which mountain-ranges
are composed, he finds all those kinds of rock which we have
just been considering,--sandstones, shales (or hardened clays),
pebble-beds, and limestones,--and endeavours to picture to himself
their gradual growth in the ways we have described. In so doing, he
is driven to the conclusion that many thousands of years must have
been occupied in their construction.

We must now say a few words about those other aqueous rocks which
have an organic origin, of which limestone is the chief. It is indeed
a startling conclusion that deposits of great thickness, and ranging
for very many miles over the earth's surface, have been slowly built
up through the agency of marine animals extracting carbonate of lime
from the sea. Yet such is undoubtedly the case. Of this important
process of rock-building coral reefs are the most familiar example.
The great barrier reef along the northeast coast of Australia is
about 1,250 miles long, from ten to ninety miles in width, and rises
at its seaward edge from depths which in some places certainly exceed
eighteen hundred feet. It may be likened to a great submarine wall.
Now, all this solid masonry is the work of humble coral polypes (not
"insects"), building up their own internal framework or skeleton
by extracting carbonate of lime from sea water. Then the breakers
dashing against coral reefs produce, by their grinding action, a
great deal of fine "coral-sand" and calcareous mud, which covers the
surrounding bed of the sea for many miles.

Now, geologists find that some limestone formations met with in the
stratified rocks have certainly been formed in this way; for example,
certain parts of the great "mountain limestone." This is proved by
the fossil corals it contains, and by tracing the old coral reefs;
but it is also largely formed by the remains of other graceful
calcareous creatures known as encrinites, or "sea-lilies," with long
branching arms that waved in the clear water. Such creatures still
exist in some deeper parts of the sea, and look more like plants
than animals. In former ages they existed in great abundance, and so
played an important part as rock-formers,--for their stems, branches,
and all are made of little plates of carbonate of lime, beautifully
fitting together like the separate bones, or vertebræ, composing
the backbone of a fish; and when the creatures died, these little
plates no longer held together, but were scattered on the floor
of the sea-bed. Shell-fish abounded too, and their shelly remains
accumulated into regular shell-beds in some places. But at times mud
and sand would come and cover over all these organic deposits.

But of all rocks that have an organic origin, chalk is the most
interesting. Geologists were for a long time puzzled to know how this
rock could have been formed; but some soundings made in the Atlantic
Ocean previous to the laying of the first Atlantic cable led to a
very important discovery, which at once threw a flood of light on
the question. Samples of the mud lying on the bed of this ocean at
considerable distances from the European and American coasts, and
at depths varying from one thousand to three thousand fathoms, were
brought up by sounding apparatus.

Little was it thought that the dull grey ooze covering a large part
of the Atlantic bed would bring a message from the depths of the sea,
and furnish the answer to a great geological problem. Yet such was
the case; for under the microscope this mud was seen to be chiefly
composed of very minute and very beautiful shells, now known as
_foraminifera_, and much prized by microscopists. These tiny shells
are found at or near the surface of the sea; and after the death of
the creatures that inhabit them (which are only lumps of protoplasm
with no organs of any kind), the shells slowly sink down to the bed
of the ocean. Now, these creatures multiply at so inconceivable a
rate that a continuous shower of dead shells seems to be taking
place, and the result is the slow accumulation over vast areas of the
Atlantic and Pacific oceans of a great deposit of calcareous ooze,
which if raised above the sea-level would harden into a rock very
similar to chalk.

  [Illustration: MICROPHOTOGRAPHS ILLUSTRATING ROCK FORMATION.

  I. Foraminifera. II. Section of Granite. III. Nummulitic
  Limestone.]

But this process only takes place in the deeper parts of our seas,
far removed from land, where the supply of land-derived materials
fails,--for even the finest mud supplied by rivers probably all
settles down before travelling two or three hundred miles from its
native shores.

Thus we learn that when one agency fails, Nature makes use of another
to take up the important work of rock-building. How the other rocks
which we mentioned in our list were formed,--such as granite, basalt,
and the metamorphic rocks,--we must explain in a future chapter
dealing with volcanoes and their work.




CHAPTER VI.

HOW THE MOUNTAINS WERE UPHEAVED.

   The notion that the ground is naturally steadfast is an
   error,--an error which arises from the incapacity of our senses
   to appreciate any but the most palpable, and at the same time
   most exceptional, of its movements. The idea of _terra firma_
   belongs with the ancient belief that the earth was the centre
   of the universe. It is, indeed, by their mobility that the
   continents survive the increasing assaults of the ocean waves,
   and the continuous down-wearing which the rivers and glaciers
   bring about.--PROFESSOR SHALER.


We have found out the quarries which supplied the rocky framework of
mountains, and have learned how the work of transporting these vast
quantities of stone was accomplished by the agency of ever-flowing
glaciers, rivers, and streams.

We must now consider the second stage of the work, and inquire how
the mountains were raised up. Referring back to our illustration
of the cathedral (see pages 143-147), it will be remembered that
this work was included under the head of _Elevation_. But perhaps
some one might ask: "How do you know that the mountains have been
elevated or upheaved? Is it not enough to suppose that they owe their
height entirely to the fact that they are composed of harder rock,
and so have been more successful in resisting the universal decay and
destruction?" Now, such an objection contains a good deal of truth,
for mountains _are_ formed of hard rocks; but at the same time we
know that the agents of denudation are more active among them than on
the plains below, so that, in the higher mountain regions at least,
the work of demolition may actually proceed faster than it does on
low ground.

Mountains are higher than the rest of the world, not merely because
they are built of more lasting material, but also because they have
been uplifted for thousands of feet above the level of the sea; and
the evidence of their upheaval is so plain as to be entirely beyond
doubt.

Let us inquire into the nature of this evidence. We have seen that
the rocks of which mountains are composed were for the most part
formed at the bottom of the sea. When the geologist finds, as he
frequently does, buried in mountain rocks the fossil remains of
creatures that must have lived in the sea (and often very similar to
those living there now), he is compelled to think of the gigantic
upheavals that must have taken place before those remains could
arrive at their present elevated position.

Numerous examples might be given; but we will only mention three. In
the Alps marine fossils have been detected at a height of 10,000 feet
above sea-level, in the Himalayas at a height of 16,500 feet, and in
the Rocky Mountains at a height of 11,000 feet.

Again we must take it for granted that all the stratified or
sedimentary rocks (see pages 148-149) with some trivial exceptions,
such as beds of shingle and conglomerates, have been formed in
horizontal layers. This is one of the simple axioms of geology to
which every one must assent.

Now, if we find in various parts of the continents, and especially
among the mountains, such strata sloping or "dipping" in
various directions, sometimes only slightly, but sometimes very
steeply,--nay, even standing up on end,--the conclusion that they
have been upheaved and pushed or squeezed into these various
positions by some subsequent process is irresistible. But this is
not all; for in every mountain region we find that the rocks have
been crumpled, twisted, and folded in a most marvellous manner. Solid
sheets of limestone may be seen, as it were, to writhe from the
base to the summit of a mountain; yet they present everywhere their
truncated ends to the air, and from their incompleteness it is easy
to see what a vast amount of material has been worn away, leaving,
as it were, mere fragments behind. The whole geological aspect of
the Alps (for example) is suggestive of intense commotion; and they
remain a marvellous monument of stupendous earth-throes, followed by
prolonged and gigantic denudation (see diagrams, chap. ix., p. 307).

There are certain features found in all mountain-chains which must
be carefully borne in mind, especially when we are considering the
explanations that have been suggested with regard to their upheaval.
These may be briefly stated as follows:--

   1. Mountain-chains tend to run in straight or gently curving
   lines.

   2. Their breadth is small compared to their length, and their
   height smaller still.

   3. They rise sharply and are clearly marked off from the
   country on either side.

   4. They form the backbones of continents.

   5. The rocks of which they are composed have been greatly
   disturbed, folded, and contorted.

   6. There is often a band of crystalline rocks (granite, gneiss,
   etc.) running along the centre of a high range.

   7. They are connected with lines of volcanoes.

   8. They are frequently affected by earthquakes.

Having arrived at the conclusion that the mountains show evident
signs of upheaval, let us proceed to inquire whether any movements,
either upward or downward, are taking place now on the earth, or can
be proved to have done so within comparatively recent times. On this
question there is ample evidence at our disposal.

More than one hundred and thirty years ago, Celsius, the Swedish
astronomer, was aware, from the unanimous testimony of the
inhabitants of the sea-coasts, that the Gulf of Bothnia was
constantly diminishing both in depth and extent. He resorted to
measurements in order to prove (as he thought) that the waters of
the Baltic were changing their level. This was a mistaken idea; and
we now understand that the level of the sea does not change, except
under the influence of the daily rise and fall of the tide, which is
easily allowed for. However, that was the idea then; and it survived
for some time. But if the sea-level were continually sinking, the
water, which, owing to the influence of gravitation, must always
remain horizontal, would equally retreat all round the Scandinavian
peninsula and on all our seashores. But this is not the case. Again,
it would be impossible on this theory to explain the curious fact
that in some parts of the world the sea is gaining on the land, while
in other places it is as surely retreating; for we cannot believe
that in one part the sea-level is rising, while in another (not far
off in some cases) it is sinking. No body of water could behave in
this irregular fashion; and the sea could not possibly be rising and
falling at the same time.

Hence we may take it for granted that any change that we may notice
in the relative level of land and sea _must_ be due to upward or
downward movements in the land.

But to return to Celsius. Old men pointed out to him various points
on the coast, over which during their childhood the sea was wont to
flow, and besides, showed him the water-lines which the waves had
once traced out farther inland. And besides this, the names of places
which implied a position on the shore, former harbours or ports now
abandoned and situated inland, the remains of boats found far from
the sea, and lastly, the written records and popular songs, left no
doubt that the sea had retreated; and it seemed both to themselves
and to the astronomer that the waters were sinking. In the year 1730
Celsius, after comparing all the evidence he had collected, announced
that the Baltic had sunk three feet, four inches, every hundred
years. In the course of the following year, in company with Linnæus,
the naturalist, he made a mark at the base of a rock in the island
of Leoffgrund, not far from Jelfe, and thirteen years afterwards was
able to prove, as he thought, that the waters were still subsiding
at the same rate, or a little faster. In reality, he had proved, not
that the sea was sinking, but that the land was rising.

Similar observations show that nearly the whole of Scandinavia is
slowly rising out of the sea. At the northern end of the Gulf of
Bothnia the land is emerging at the rate of five feet, three inches,
in a century; but by the side of the Aland Isles it only rises three
and one quarter feet in the same time. South of this archipelago it
rises still more slowly; and farther down, the line of shore does not
alter as compared with the level of the sea.

But it is a curious fact that the extreme southern end of this
peninsula is subsiding, as proved by the forests that have been
submerged. Several streets of some towns there have already
disappeared, and the coast has lost on the average a belt of land
thirty-two yards in breadth.

The upward movement of the Scandinavian peninsula must have been
going on for a long time, if we assume that it was always at the same
rate as at present; for we find beds of seashells of living species
at heights of six or seven hundred feet above the level of the sea.
Great dead branches of a certain pink coral, found in the sea at a
depth of over one hundred and fifty to three hundred fathoms, are
now seen in water only ten or fifteen fathoms deep. It must have
been killed as it was brought up into the upper and warmer layers of
water. This is striking testimony.

The pine woods too, which clothe the hills, are continually being
upheaved towards the lower limit of snow, and are gradually withering
away in the cooler atmosphere; and wide belts of forest are composed
of nothing but dead trees, although some of them have stood for
centuries.

Geologists have proved that the Baltic Sea formerly communicated
by a wide channel with the North Sea, the deepest depressions of
which are now occupied by lakes in the southern part of Sweden; for
considerable heaps of oyster-shells are now found in several places
on the heights commanding these great lakes. Then we have in Denmark
the celebrated "kitchen-middens," heaps of rubbish also largely
composed of oyster-shells which the inhabitants, in the "Stone
Age," collected from the bottoms of the neighbouring bays. At the
present day the waters of the Baltic, into which rivers bring large
quantities of fresh water, do not contain enough salt for oysters to
grow there; but the oyster-shells prove that the Baltic Sea and these
inland lakes were once as salt as the North Sea is now. This can only
be explained by supposing that the Baltic was not so shut in then as
it is in these days. The bed of the old wide channel has risen, and
what once was sea is now land.

Again, it is very probable that the great lakes and innumerable
sheets of water which fill all the granite basins of Finland have
taken the place of an arm of the sea which once united the waters of
the Baltic to those of the great Polar Ocean. And so there must have
been upheaval here as well.

The old sea-beaches, now above the level of the highest tides, that
are found in many parts of the Scandinavian, Scottish, and other
coasts, furnish plain evidence of upheaval.

At the present day, between the lines of high tide and low tide, the
sea is constantly engaged in producing sand and shingle, spreading
them out upon the beach, mingling them with the remains of shells
and other marine animals, and sometimes piling them up, sometimes
sweeping them away. In this way a beach often resembles a terrace.
When the land is upheaved rapidly enough to carry up this line
of beach-deposits before they are washed away by the waves, they
form a flat terrace, or what is known as a "raised beach." The old
high-water mark is then inland; its sea-worn caves become in time
coated with ferns and mosses; the old beach forms an admirable
platform on which meadows, fields, villages, and towns spring up; and
the sea goes on forming a new beach below and beyond the margin of
the old one.

The Scottish coast-line, on both sides, is fringed with raised
beaches, sometimes four or five occurring above each other, at
heights of from twenty-five to seventy-five feet above the present
high-water mark. Each of these lines of terrace marks a former lower
level at which the land stood with regard to the sea; and the spaces
between them represent the amount of each successive rise of the
land. Each terrace was formed during a pause, or interval, in the
upward movement, during which the waves had time to make a terrace,
whereas, while the land kept on rising, they had no time to do so.
Thus we learn that the upheaval of the country was interrupted by
considerable pauses.

Sometimes old ports and harbours furnish evidence of upheaval. Thus,
the former Roman port of Alaterva (Cramond) in Scotland, the quays of
which are still visible, is now situated at some distance from the
sea, and the ground on which it stands has risen at least twenty-four
feet. In other places the scattered débris shows that the coast has
risen twenty-six feet. And by a remarkable coincidence, the ancient
wall of Antoninus, which in the time of the Romans stretched from sea
to sea, and served as a barrier against the Picts, comes to an end at
a point twenty-six feet above the level of high tides. In the estuary
of the Clyde there are deposits of mud, containing rude canoes and
other relics of human workmanship, several feet above the present
high-water mark.

Raised beaches are found on many parts of the coast of Great Britain.
Excellent examples occur on the coasts of Devon and Cornwall. On the
sides of the mountainous fiords of Norway similar terraces are found
up to more than six hundred feet above the sea; and as some of these
rise to a greater height at a distance of fifty miles inland, it
seems that there was a greater upward movement towards the interior
of Norway than on the coasts.

There is a celebrated raised beach on the side of a mountain in
North Wales, known as Moel Tryfaen, where the writer gathered a
number of marine shells at a height of 1,357 feet.

But Scandinavia and Great Britain are not the only parts of Europe
where an upward movement has taken place, for the islands of Nova
Zembla and Spitzbergen show evidence of the same kind; and the coast
of Siberia, for six hundred miles to the east of the river Lena, has
also been upraised. On the banks of the Dwina and the Vega, 250 miles
to the south of the White Sea, Murchison found beds of sand and mud
with shells similar to those which inhabit the neighbouring seas, so
well preserved that they had not lost their colours.

Again, the ground of the Siberian _toundras_ is to a large extent
covered with a thin coating of sand and fine clay, exactly similar
to that which is now deposited on the shores of the Frozen Ocean.
In this clay, the remains of the mammoth, or woolly elephant, now
extinct, are preserved in great numbers.

Parts of Northern Greenland have also risen; while at the southern
end of this frozen land a downward movement is still taking place.

The best-known example of these slow movements within historic times
is the so-called Temple of Serapis in the Bay of Baie, near Naples.
The ruins of this building, which was probably a Roman bath, consist
of a square floor paved with marble, showing that it possessed a
magnificent central court. This court, when perfect, was covered with
a roof supported by forty-six fine columns, some of marble, others
of granite. There is still a hot spring behind, from which water was
conducted through a marble channel. All the columns but three were
nearly buried in the soil which covered the whole court, when the
ruins were first discovered. Now, each of the three marble columns
that are still standing shows clear evidence of having been depressed
below the sea-level, for they all exhibit a circular row of little
holes bored by a certain marine shell-fish, known as _Lithodomus
dactylus_, at a height of twelve feet from the floor; each row is
about eight feet broad. The shells may still be seen inside the
little pear-shaped holes which the shell-fish bored for themselves;
and the same shell-fish still live in the waters of the Mediterranean
and bore holes in the limestone rocks.

It is therefore quite clear that these columns must have been under
water to a depth of twenty feet or so, and also that they must have
remained under water for some considerable time, during which the
shell-fish made these borings. Then an upheaval took place whereby
the whole building was elevated to its present level. But underneath
the present floor, at a depth of five feet, were discovered the
remains of an older floor. This probably belonged to an earlier
building which had in like manner been depressed below sea-level. We
thus learn that the land in this spot had been sinking for a long
time, and that at some subsequent time it rose. The fallen columns
suggest the idea that they were thrown down by earthquakes. At the
present time the land here is again sinking at the rate of one inch
in three or four years.

But the first example of upheaval within comparatively recent times,
and one which is instructive as throwing some light on the subject of
the present chapter,--namely, the upheaval of mountain-chains,--is to
be found along the western mountainous coast of South America. Here
we have the magnificent ranges of the Andes running along the whole
length of this continent. The illustrious Charles Darwin, during
his famous trip in the "Beagle," discovered numerous raised beaches
along this coast, and at once perceived their importance to the
geologist. The terraces are not quite horizontal, but rise towards
the south. On the frontier of Bolivia, they are seen at heights of
from sixty-five to eighty feet above sea-level; but nearer the higher
mass of the Chilian Andes they are found at one thousand feet, and
near Valparaiso, in Chili, at thirteen hundred feet above the sea.
Darwin also discovered that some of the upheavals thus indicated took
place during the human period; for he found in one of the terraces
opposite Callao, in Peru, at a height of eighty feet, shells with
bones of birds, ears of wheat, plaited reeds, and cotton thread,
showing that men had lived on the terrace. These relics of human
industry are exactly similar to those that are found in the _huacas_,
or burial-places, of the ancient Peruvians. There can be no doubt
that the island of San Lorenzo, and probably the whole of the coast
in its neighbourhood, have risen eighty feet or more since the Red
Man inhabited the country.

Callao probably forms the northern limit of the long strip of coast
that has been upheaved, and the island of Chiloe the southern limit;
but even thus the region of elevation has a length from north to
south of about 2,480 miles.

We noticed in the case of Scandinavia that the upward movement is
greater in the interior of the mountain-range than at or near the
coast; and it is interesting to find that the same difference has
been observed in the case of the Andes. The upheaving force, whatever
its nature, acts with more energy under the Chilian Andes than under
the rocks of the adjacent coast.

In New Zealand we have also evidences of upheaval; and if we trace
out on the map a long line from the Friendly Isles and Fiji, through
the Eastern Archipelago, and then on through the Philippine Islands,
and finally to Japan and the Kurile Islands, we shall find scattered
regions of elevation all along this great line, which is probably a
mountain-chain, partly submerged, and along which numerous active
volcanoes are situated.

Putting together all the evidence that has been gathered on this
subject, of which only a very small part is here given, we are
warranted in concluding that taking the world generally, regions
where active volcanoes exist are generally regions where upheaval is
taking place. There is also a very interesting connection between
mountain-chains and lines of volcanic action. From this it seems to
follow, if lines of volcanic action are also lines of upheaval, that
mountain-chains are undergoing upheaval at the present time. This
is a conclusion in favour of which a good deal may be said. It is
certainly true in the cases of the Scandinavian range, and also of a
very large part of the Andes, to which we have already referred. The
Highlands of Scotland and Scandinavia form the northern end of an old
line of volcanic action running down the Atlantic Ocean through the
Azores, Madeira, Cape Verde Islands, Ascension, St. Helena, right
down to Tristan d'Acunha.

In many other parts of the world we have evidences from submerged
forests, the positions of certain landmarks with regard to the sea,
and in some cases submerged towns, that movements of a downward
nature are taking place.

It is important to distinguish from these evidences the changes that
take place where the waves of the sea are rapidly washing away the
coast-line. Putting aside these cases, however, it has been clearly
proved that in many regions a slow sinking of the land is going on.

The eastern side of South America has not been so thoroughly observed
as its western side; but there is still good reason to believe that
a large part of this coast is sinking. So it appears that a see-saw
movement is affecting South America, and that while one side is going
up, the other is going down; and it is interesting to observe other
examples of the same thing,--such as are afforded by Greenland and
Norway.

  [Illustration: THE SKAEGGDALFORS, NORWAY.

  FROM A PHOTOGRAPH BY J. VALENTINE.]

Again, while part of Labrador is rising, parts of the eastern coast
of North America, as far down as Florida, are slowly sinking. Thus
along the New England coast between New York and Maine, and again
along the Gulf of St. Lawrence, we find numerous submerged forests
with quantities of trees standing upright with their roots in old
forest-beds, but with the tops of their stumps some feet below the
level of high tide. In the case of New Jersey the subsidence is
probably taking place at the rate of two feet in a hundred years.

Before passing on to consider upward movements of a more rapid
nature, such as are frequently caused by earthquakes, we may pause
for a few moments to consider certain very slight, but nevertheless
very interesting little movements, such as _slight pulsations_ and
tremors, which have been observed to take place in the earth's crust
(as it is called), and which of late years have been carefully
studied.

Professor Milne, a great authority on earthquakes, has noticed slight
swayings of the earth, which though occupying a short time--from a
few seconds to a few hours--are still too slow to produce a shock of
any kind. These he calls "earth pulsations." They have been observed
by means of delicate spirit-levels, the bubbles of which move with
very slight changes of level at either end of the instrument. At
present only a few experiments of this kind have been made; but they
tell us that the surface of the earth (which is apparently so firm
and immovable) is subject to slight but frequent oscillations. Some
think that they depend upon changes in the weight of the atmosphere.
If this is so, the balance between the forces at work below the
earth's surface and those that operate on its surface must be
very easily disturbed. Still we cannot see that this is a serious
objection; on the contrary, there is much reason to think that any
slight extra weight on the surface, such as might be caused by an
increase of the pressure of the atmosphere, and still more by the
accumulation of vast sedimentary deposits on the floor of the ocean,
may be quite sufficient to cause a movement to take place. Moreover,
Mr. G. H. Darwin has shown that the earth's crust daily heaves up and
down under the attraction of the moon in the same kind of way that
the ocean does; so that we must give up all idea of the solid earth
being fixed and immovable, and must look upon it as a flexible body,
like a ball of india-rubber (see chap. ix., pp. 314-315).

Slight movements of rather a different kind have been noticed, to
which the name of "earth-tremors" has been given. These are very
slight jarrings or quiverings of the earth, too slight to be observed
by our unaided senses, but rendered visible by means of very delicate
pendulums and other contrivances. Now wherever such observations
have been made it has been discovered that the earth is constantly
quivering as if it were a lump of jelly. In Italy, where this subject
has been very carefully studied, the tremors that are continually
going on are found to vary considerably in strength; for instance,
when the weather is very disturbed and unsettled, the movements of
the pendulum are often much greater. Again, before an earthquake the
instrument shows that the tremors are more frequent and violent.

Another way of observing these curious little movements is by burying
microphones in the ground. The microphone is a little instrument
invented of late years which is capable of enormously magnifying the
very slightest sounds, such as our ears will not detect. By its means
one can hear, as some one said, "the tramp of a fly's foot," if he
will be so obliging as to walk over it. It has thus been proved in
Italy that the earth sends forth a confused medley of sounds caused
by little crackings and snappings in the rocks below our feet.

In this way it will be possible to predict a serious earthquake,
because it will give warning some days before, by the increase of the
little tremors and sounds; and it is to be hoped that by this simple
means human lives may be saved.

Now, these disturbances are of precisely the same nature as
earthquakes,--in fact, we may call them microscopic earthquakes. To
the geologist they are of great interest, as they seem to afford
some little insight into the difficult question of the upheaval of
mountains, and to show us something of the constant _working_ of
those wonderful forces below the surface of the earth by means of
which continents are raised up out of the sea, and mountain-chains
are elevated thousands of feet. It is probable that both are due to
the working of the same forces, and are accomplished by the same
machinery.

We now pass on to consider those more violent movements of the solid
land known as earthquakes. This kind of disturbance is such as might
be produced by a sudden shock or blow given below the ground, from
which waves travel in all directions. First comes a rumbling noise
like the roar of distant artillery; then come the earthquake waves
one after another, causing the ground to rise and fall as a ship does
on the waves of the sea; the ground is frequently rent asunder, so
that chasms are formed, into which in some cases men and animals
have been hurled alive. In the case of a very violent earthquake
the waves travel long distances. Thus the great earthquake by which
Lisbon was destroyed in the year 1755 disturbed the waters of Loch
Lomond in Scotland. In this fearful catastrophe sixty thousand human
beings perished. If the disturbance takes place near the sea, great
sea waves are formed, which cause fearful destruction to life and
property. This happened in the case of the Lisbon earthquake; and
in the year 1868, when Ecuador and Peru were visited by a fearful
earthquake, a great sea wave swept over the port of Arica, and in a
few minutes every vessel in the harbour was either driven ashore or
wrecked, and a man-of-war was swept inland for a quarter of a mile.

Earthquakes bring about many changes on the surface of the earth. For
example, on mountain-slopes forests are shattered, and large masses
of soil and débris are shaken loose from the rock on which they
rested, and hurled into the valleys; streams are thus choked up, and
sometimes lakes formed, either by the damming up of a river or by
the subsidence of the ground.

It is frequently found after an earthquake that the level of
the ground has been permanently altered; and this effect of
earthquakes is important in connection with the subject we are now
considering,--namely, how mountains are upheaved. Sometimes, it is
true, the movement is a downward one; but more generally it takes
place in an upward direction. As an example of this, we may mention
the Chilian earthquake of 1835, which was very violent, and destroyed
several towns on that coast, from Copiapo to Chile. It was afterwards
found that the land in the Bay of Conception had been raised four or
five feet. At the island of Santa Maria, to the southwest of this
bay, the land was raised eight feet, and in one part ten feet; for
beds of dead mussels were seen at that height above high water, and
a considerable rocky flat that formerly was covered by the sea now
became dry land. It was also proved by means of soundings that the
sea round the island was shallower by about nine feet.

Now the question arises, "How are earthquakes caused?" Various
suggestions have been made; but it is pretty clear that all
earthquakes are not produced in the same way. For instance, volcanic
eruptions are frequently attended by earthquakes. Violent shocks of
this nature generally precede and accompany a great eruption, as is
frequently the case before an eruption of Mount Vesuvius.

Steam plays a very important part in all volcanic eruptions; and
these earthquakes are probably caused by great quantities of pent-up
steam at a high pressure struggling to escape. It is also possible
that when molten rock is forcibly injected into the crevices and
joints of overlying rocks earthquake shocks may be produced by
the concussion. The old Roman poet and philosopher, Lucretius,
endeavoured to solve this problem, and concluded that "the shakings
of the surface of the globe are occasioned by the falling in of
enormous caverns which time has succeeded in destroying." But
though the explanation might possibly apply to a few cases of small
earthquakes, it is not a satisfactory one, for it is not at all
likely that many large cavities exist below the earth's surface,
because the great weight of the overlying rock would inevitably crush
them in.

We have already pointed out that earthquakes frequently happen in
mountainous regions; and this fact alone suggests that perhaps the
same causes which upheave mountains may have something to do with
earthquakes. But there are other reasons for believing that the same
force which causes earthquakes also upheaves mountain-chains. The
reader will remember the case of the Chilian earthquake that raised
part of the Andes a few feet in height.

Now, it is quite clear that the rocks of which mountains are composed
have suffered a great deal of disturbance. We have only to look at
the crumbled and contorted strata to see that they have been forced
into all kinds of positions, sometimes standing bolt upright (see
diagrams, chap. ix., p. 307). And as we cannot believe, for many
reasons, that these movements were of a very sudden or violent kind,
we must consider that they took place slowly on the whole; but
besides being folded and twisted, the rocks of mountains frequently
exhibit clear signs of having been split and cracked. The fractures
are of all sizes, from an inch or more up to hundreds or even
thousands of feet. They tell us plainly that the rocks were once
slowly bent, and that after a certain amount of bending had taken
place, the strain put upon them became greater than they could bear,
and consequently they snapped and split along certain lines. This is
just what might be expected. For instance, ice on a pond will bend a
good deal, but only up to a certain amount; after that, it cracks in
long lines with a remarkably sharp and smooth fracture. But suppose
the pressure came from below instead of from above, as when a number
of people are skating on a pond. Should we not see the ice forced
up in some places, so that some sheets stood up above the others
after sliding past their broken edges? This is just what the rocks
in different places have frequently done. After a fracture has taken
place the rock on one side has slid up over the other, and the two
surfaces made by the fracture--like two long walls--are no longer
seen at the same level. One has been pushed up, while the other has
gone down (see diagram of the ranges of the Great Basin, chap. viii.,
p. 273).

Now, it is almost impossible to conceive of these tremendous
fractures taking place in the rocks below our feet without causing
sudden jars or shocks. Here, then, we seem to have a clue to the
problem. Even if the movements took place only a few inches or a few
feet at a time, that does not spoil our theory, but rather favours
it; for in that case the upheaval of a mountain-chain will have
taken a very long time (which is almost certain), and may have been
accomplished bit by bit. Hundreds and thousands of earthquake shocks,
some slight, and others severe, may have attended the upheaval of a
mountain-range.

This explanation is accepted by many authorities. It does not exactly
imply that mountains were upheaved by earthquakes; but it means that
the same forces that elevate continents, heaving them up out of the
sea into ridges and very low arches, have been at work to crumple and
fold their rocks in some places into stupendous folds, such as we now
find form part of the general structure of mountains; and that in so
doing they caused fearful strains, too great for the rocks to bear,
so that they split over and over again, and in so doing produced jars
and shocks that must have been very similar to, if not identical
with, earthquake shocks as we know them at the present day.

Such an explanation is in striking harmony with what we have
already learned about the operations of Nature. It was from the
long-continued operation of rain and rivers that the materials now
forming mountains were transported to the seas in which they were
slowly formed. It was also by the ordinary operations of frost,
heat and cold, snow and ice, streams, rain, and rivers that the
mountains received their present shapes (see chapters v. and vii.).
And now we learn that the gigantic work of upheaval took place in a
tolerably quiet and uniform manner,--with perhaps only an occasional
catastrophe of a more violent kind, but still according to the same
law of uniformity which is the very basis of modern geology, and by
means of which so much can be explained.

We could give other proofs of the gradual elevation of mountains
if they were wanted. But at least enough has been said to give
the reader a glimpse into the methods employed by geologists in
endeavouring to explain how mountains were upheaved; and to show that
it is only by a careful study of all that is taking place now on the
earth that we can ever hope to solve the difficult questions that
present themselves to all who study those stony records on which the
earth has written for our enlightenment the chapters of her ancient
history.

In conclusion, it may be asked what is the nature of the force that
accomplishes all this titanic work of upheaval. Although the question
has been much discussed, and some very ingenious suggestions brought
forward, we cannot say that any of them are entirely satisfactory.
But we know that the earth is a cooling body which loses so much heat
every year; and it may be that the shrinking that takes place as it
cools, by leaving the crust of the earth in some places unsupported,
causes it to settle down, to adapt itself to a smaller surface below,
and in so doing it would inevitably throw itself into a series of
folds, or wrinkles, like those on the skin of a dried apple. Many
think that mountain-ranges may be explained in this way.




CHAPTER VII.

HOW THE MOUNTAINS WERE CARVED OUT.

            And surely the mountain fadeth away,
    And the rock is removed out of its place,
    The waters wear away the stones:
    The overflowings thereof wash away the dust of the earth.

    _Job xiv. 18._


The mighty fortresses of the earth, which seem so imperishable, so
majestic in their strength, and have from time immemorial received
their title of "the everlasting hills," are nevertheless undergoing
constant change and decay. They cannot abide for ever. Those waste
leagues around their feet are loaded with the wrecks of what once
belonged to them; they are witnesses to the victory of the hostile
forces that are for ever contending with them, and pledges of a final
triumph. To those who will read their story, mountains stand like old
dismantled castles, mere wrecks of ruined masonry, that have nearly
crumbled away, telling us of a time when all their separate peaks
and crags were one solid mass, perhaps an elevated smooth plateau
untouched by the rude hand of time.

Let us now inquire how the work of destruction is accomplished.
Referring back to our illustration of the cathedral, given in chap.
v., pp. 143-147, the question we have now to consider is, how the
mountains were carved out into all these wonderful features of crag
and precipice, peak and pass, which are such a source of delight
to all who care for scenery. This work we included in the one word
"ornamentation." What, then, are the tools which Nature uses in this
work of carving out the hills? What are her axes and hammers, her
chisels and saws?

This question, like many others, must be answered by observing what
takes place at the present day. It is scarcely necessary to say that
mountains and mountain-ranges are not simply the result of upheaval,
though they have been upheaved. If that were so, they would probably
appear as long smooth, monotonous ridges, with no separate mountain
masses, no peaks, no glens or valleys; in some cases they might
appear as simply elevated and smooth plateaux. Such mountains, if
we may so call them, would be almost as uninteresting as the roof
of a gabled house down which the rain finds its way in one smooth
continuous sheet.

Mountains, reaching as they do into the higher regions of the
atmosphere, where the winds blow more fiercely than on the plains
below, storms rage more violently, and the extremes of heat and cold
are more severe,--in fact, where every process of change and decay
seems quickened,--suffer continually at the hands of the elements.

   "Death must be upon the hills, and the cruelty of the tempests
   smite them, and the thorn and the briar spring up upon them;
   but they so smite as to bring their rocks into the fairest
   forms, and so spring as to make the very desert blossom as the
   rose."[23]

  [23] Modern Painters.

Nature never leaves them alone, never gives them a brief armistice in
the long war that she wages against them. She is a relentless enemy,
ever on the move, and ever varying her methods of attack. Now she
assails them openly with her storm-clouds, and pelts them furiously
with driving rain; now we hear the thunder of her artillery, as she
pierces their crests with strange electric darts of fire; now she
secretly undermines their sides with her hidden sources of water,
till whole villages are destroyed by some fearful fall of overhanging
rocks (see chapter iii., pages 96-101). Her winds and gentle breezes
are for ever at work on their surfaces, causing them to crumble into
dust much in the same way as iron turns to rust.

Again, she heats them by day and then chills them suddenly at night,
under the cold starry sky, so that they crack under the strain of
expanding and contracting. Now she splits them with her ice-wedges;
now she furrows their sides with the dashing torrents and running
streams; and yet again she wears them gently down with her glaciers,
and carries away their débris--the token of her triumph--on those icy
streams, as conquering armies carry the spoils in procession.

This is, briefly, her mode of warfare; these are some of her tools,
_wind_, _rain_, _frost_, _snow_, _heat_ and _cold_, _streams_,
_rivers_, and _glaciers_. Lightning does occasionally break off
portions of a cliff or a mountain-peak; but compared to the others,
this agent is not very important.

Let us first inquire into the effects produced by the atmosphere.
The air around us is composed mainly of two well-known gases;
namely, oxygen and nitrogen. There is also a small proportion (about
one in ten thousand) of carbonic acid gas; a variable quantity of
water-vapour, and in the neighbourhood of towns, traces of other
noxious gases, such as sulphurous acid and chlorine.

Now, the nitrogen plays a very unimportant part, as it merely
serves to dilute the powerful gas, oxygen, which has such important
life-sustaining properties. We live by breathing oxygen; so do all
animals; and the more pure air we can contrive to get into our
lungs, the better. But undiluted oxygen would be too strong for us,
and so its strength is diminished by being mixed with four parts of
nitrogen; that is to say, the air only contains about one fifth by
volume, or bulk, of oxygen and four fifths of nitrogen.

Now, oxygen, being always ready to combine chemically with some other
element, is a great agent of change and decay. It attacks all the
metals except gold and platinum. Iron, we all know, oxidises, or
rusts, only too quickly; but copper, lead, silver, and other metals
are more or less attacked by it. So it is with all the rocks exposed
at or near the surface of the earth. Oxygen will, if it can, pick
out something to combine with and so bring about chemical changes
which lead to decay. But a much more powerful agent is the carbonic
acid gas in the atmosphere; although there is so little of it, there
is enough to play a very important part in causing rocks to crumble
away, and in some cases to dissolve them entirely. The supply of this
gas is continually being renewed, for all living animals breathe out
carbonic acid, and plants give it out by night. Under the influence
of sunlight plants give out oxygen, so that gas is supplied to the
air by day.

Both oxygen and carbonic acid gas are dissolved by rain as it falls
through the air; and so we cannot separate the effects of the dry
air by itself from those of rain and mist, which are more important
agents. The action of rain is partly mechanical, partly chemical, for
it not only beats against them, but it dissolves out certain mineral
substances that they contain.

All rocks are mixtures of two or more kinds of minerals, the
particles of each being often invisible to the naked eye. Thus
granites are essentially mixtures of felspar, quartz, and mica;
ordinary volcanic rocks ("trap-rocks") of felspar and augite;
sandstones consist mainly of particles of silica; limestones of
carbonate of lime; shales and slates of silicate of alumina, the
principal substance in clay. These grains are usually joined together
by a cement of some mineral differing more or less from the other
particles. Lime is found in many of the rocks as the cement that
binds their particles together; while oxide of iron and silica serve
this purpose in many other instances. Now, if the lime or iron or
silica is dissolved by water, the rock must tend to crumble away. Any
old building shows more or less manifold signs of such decay, and
this process is called "weathering." All this applies merely to the
surfaces of rocks; and if there were no other forces at work, their
rate of decay would be very slow.

But there are other forces at work. In the first place, sudden
changes of temperature have a destructive influence. If the sun
shines brightly by day, the rocks--especially in higher mountain
regions--are considerably expanded by the heat they receive; and if
a hot day is followed by a clear sky at night, the free radiation of
heat into space (see chap. ii., p. 39) causes them to become very
cold, and in cooling down they contract. In this way an internal
strain is set up which is often greater than they can bear, and so
they split and crack. Thus small pieces of rock are detached from a
mountain-side. An Alpine traveller told the writer that one night
when sleeping on a mountain-side, he heard stones rattling down at
frequent intervals. Livingstone records in his journal that when
in the desert he frequently heard stones splitting at night with a
report like that of a pistol. But sometimes the expansion by day is
sufficient to cause fragments of rock to be broken off.

Frost, however, is responsible for a vast amount of destruction among
rocks. When water freezes, it expands with tremendous force; and this
is the reason why water-pipes so frequently burst during a frost,
though we don't find it out until the thaw comes,--followed by long
plumbers' bills. Rocks, being traversed in several directions by
cracks, allow the water to get into them, and this in freezing acts
like a very powerful wedge; and so the rocks on the higher parts of
the mountains are continually being split up by Nature's ice-wedge.

The amount of rock broken up in this way every year is enormous.
Stone walls and buildings often suffer greatly from this cause during
a long frost, especially if the stone be of a more than usually
porous kind, that can take up a good deal of rain water.

Where trees, shrubs, etc., grow on rocks, the roots find their way
into its natural divisions, widened by the action of rain soaking
down into them; and as they grow, they slowly widen them, and in time
portions are actually detached in this manner. Moreover, the roots
and rootlets guide the rain water down into the cracks, or joints, as
they are called. Even the ivy that creeps over old ruined walls has a
decidedly destructive effect.

At the base of every steep mountain may be seen heaps of loose
angular stones; sometimes these are covered with soil, and form long
slopes on which trees and shrubs grow. Every one of the numerous
little gullies that furrow the mountain-sides has at its lower
end a similar little heap of stones. Sometimes a valley among the
mountains seems half choked with rocky fragments; and if these were
all removed, the valley would be deeper than it is. In some hot
countries, where the streams only flow in winter, this is especially
the case; for example, every valley, or "wady," in the region of
Mount Sinai and Mount Horeb is more or less choked up with boulders
and stones of every size, because the stones come down faster than
they can be carried away.

But the main work of carving out the hills and mountains of the
world is done by streams, rivers, and glaciers; and so we now pass
on to consider how they perform their tasks. Water by itself, even
when flowing fast, would be powerless to carve gorges and valleys
in the solid rock; but the stones which torrents and streams carry
along give them a marvellous grinding power, for with such material
a stream continually wears away its rocky bed. Moreover, the stones
themselves are all the while being rubbed down by each other, until
finally they are ground down to fine sand and mud, which help in the
work of erosion.

Every mountain stream or torrent runs in a ravine or valley of some
sort; and any traveller who will take the trouble to watch what goes
on there may easily convince himself that the ravine, gorge, or
valley has been carved out by the stream, aided by the atmospheric
influences to which we have already alluded.

But perhaps some may be inclined to look upon the ravine as a chasm
produced by some violent disturbance from below, whereby the rocks
were rent asunder, and that the stream somehow found its way into the
rent. A little inquiry will dispel this idea. In the first place,
such catastrophes are quite unknown at the present day; and as we
have more than once pointed out, the geologist's method is to apply
a knowledge of processes now in operation to the phenomena of the
rocks, in order to read their history. Secondly, no conclusion can be
accepted which is not supported strongly by evidence.

If such a rending of the rocks had taken place, there would assuredly
be some evidence of the fact. We should expect to find a great crack
running all along the bed of the stream; but of this there is no
sign. Go down in any weather when the stream is low, and look at
the rocks over which it flows, and you will search in vain for such
evidence. Instead of being broken, the rocks extend continually
across. You would also expect to find the strata "dipping," or
sloping away from the stream on each side, if they had been rent
by such an upheaval; but here again we are met by a total want of
evidence. Thirdly, a crack might be expected to run along more or
less evenly in one direction. But look at the ravine, follow it
up for some miles, and you will see that it winds along in a very
devious course, not in a straight line.

For these reasons, then, we must conclude that the ravine or
valley has been carved out by the stream; but perhaps the most
convincing arguments are afforded by the furrows and miniature
ravines so frequently met with on the sides of all mountains; and
it is impossible to examine these without concluding that they have
in every case been cut out of the solid rock by the little rapid
torrents that run along them after heavy rain. If we are fortunate
enough to see them on a thoroughly rainy day, we may derive much
instruction from watching the little torrents at work as they run
down the mountain-side, here and there dashing over the rocks in
little cascades, and bringing down to the base of the hill much of
the débris that forms higher up. In this way Nature gives us an
"object lesson," and seems to say: "Watch me at work here, and learn
from such little operations how I work on a larger scale, and carve
out my ravines and big valleys. Only give me plenty of time, and I
can accomplish much greater feats than this."

The question of time is no longer disputed; and all geologists are
willing to grant almost unlimited time, at least periods of time that
seem to us unlimited. Most streams have been flowing for thousands
of years; and when once we grant that, we find no difficulty in
believing that all valleys are the work of rain and rivers. Surely
no one would argue that the furrows on a mountain-side are all rents
which have been widened by the action of water; for if they were
rents, each must have been caused by some disturbance of the rocks
composing the mountain, and we should of course be able to see the
cracks for ourselves, and to find that the rocks had in some way been
disturbed and rent open.

Even the rain which falls on the road in a heavy shower teaches the
same simple but important lesson, as it runs off into the gutters
on each side; and we may often find the road furrowed by little
miniature rivers, that carve out for themselves tiny valleys as they
run off into the gutter, bringing with them much débris in the form
of mud and sand.

Sometimes a stream encounters in its course a layer of rock that is
harder than the rock underlying it. In this case the softer rock
is worn away faster, and the hard layer forms a kind of ridge at a
higher level; the result is a waterfall. Waterfalls are frequently
found in mountain streams. In this case, it is easy to trace the
ridge of harder rock running unbroken across the path of the stream,
showing clearly that it has not been rent in any way. First it showed
merely as a kind of step, but gradually the force of the falling
water told with greater effect on the softer rock below, wearing it
away more rapidly than that above, and so the depth of the waterfall
went on increasing year by year; and at the same time the hard layer
was slowly worn away until the stream sawed its way through.

Some river valleys are steep and narrow; others are broad, with
gently sloping sides. A careful study of the different valleys in
any large country such as Great Britain, shows that their forms vary
according to the nature of the rocks through which rivers flow. Where
hard rocks abound, the valleys are steep and narrow; where soft rocks
occur, the valleys are broad and low. This is only what might be
expected, for hard rocks are not easily worn away; a river must cut
its way through them, leaving cliffs on either side that cannot be
wasted away by rain. But in a district where clay or soft sandstone
occurs, the rain, as it finds its way to the valley, will wash them
away and give a smooth gentle slope to the sides of the valley.

It is very instructive to notice how the scenery of any district
depends on the nature of its prevailing rocks. Hard rocks give bold
scenery with steep hills and rocky defiles; while soft rocks make the
landscape comparatively flat and tame, though often very beautiful
in its way, especially where a rich soil abounds, so that we see
pleasant woods, rich pasture-land, and heavy crops in the fields.

Compare, for instance, the scenery of Kent or Surrey with that
of the Lake District or the west of Yorkshire. The difference
is due chiefly to the fact that in Kent and Surrey we have rocks
that succumb more easily to the action of rain and rivers, and
consequently are worn away more rapidly than the harder rocks in the
north country. Geologists have a word to express the effects of this
wear and tear; namely, "denudation," which means a stripping off, or
laying bare.

In Kent and Surrey the agents of denudation (rain and rivers, aided
by the effects of the air, of heat and cold, and so on) wear away the
whole surface of the county in a tolerably even and uniform manner,
because there are no hard rocks for them to contend with. In this
case rain washes away the sides of the valleys faster than the river
can carve its bed, consequently the valleys are shallow compared to
their width. And so the streams have broad valleys, while the hills
are smooth and gently rounded. Chalk, clay, and soft sandstone abound
there. The two latter rocks are washed away with comparative ease,
and the chalk is dissolved; whereas in the Lake District we have very
much harder and older rocks, that require to be split up and broken
by the action of frost, while every stream carves out for itself a
steep valley, and great masses of hard rock stand out as bold hills
or mountains, that seem to defy all the agents of denudation. Here
the opposite is the case, and the valleys are deepened faster than
they are widened. But for all that, a vast amount of solid rock has
been removed from the surface there, of which the mountains are, as
it were, but fragments that have escaped the general destruction.
Moreover, the rocks in this region have been greatly disturbed and
crumpled since they were first formed, and thereby thrown into
various shapes that give certain peculiar structures more or less
capable of resisting denudation.

Very effective illustrations of the power of rain by itself are
afforded by the "earth pillars" of the Tyrol, and "cañons" of
Colorado. The material of which they consist is called conglomerate,
because it is composed of stones and large blocks of rock with stiff
earth or clay between. All the taller ones have a big stone on the
top which protects the softer material below from being washed away
by heavy rains; and it is easily perceived that each pillar owes its
existence to the stone on the top, which prevents the soft materials
below it from being washed away. When, after a time, the weathering
of the soft strata diminishes the support of the capping boulders,
these at last topple over, and the pillar, thus left unprotected,
becomes an easy prey to the rain, and is rapidly washed away. Some
of the pillars are over a hundred feet in height. But it is only in
places where heavy rains fall that these interesting monuments of
denudation are to be seen.

By way of contrast we may turn now to a district in which very little
rain falls, but where the streams have a considerable slope, and so
can wear away, or erode, their valleys much faster than rain and
frost, etc., can bring down the rocks of which the sides are composed.

The river Colorado of the West, which runs from the Rocky Mountains
to the Gulf of California, flows for nearly three hundred miles at
the bottom of a profound chasm, or cañon, being hemmed in by vertical
walls which in some places are more than a mile in depth. The
tributary streams flowing into the river run through smaller ravines
forming side cañons; and there is no doubt that these wonderful
chasms have been, in the course of ages, slowly carved out by the
river Colorado and its numerous tributary streams. Sometimes the
walls of the cañon are not more than fifty yards apart, and in height
they vary from three thousand to six thousand feet.

Far above the level of the highest floods patches of gravel are found
here and there on the sides, which must have been left there by the
river when it had not cut its way so far down. These cañons afford
striking testimony to the erosive power of running water, of which
they are the most wonderful illustration in the world.

But water, even when in the form of ice, has more or less power to
wear away solid rock; and the glaciers that we see in Switzerland,
Norway, and other countries must slightly deepen the rocky valleys
down which they flow. Let us see how this can be accomplished.

The snow that falls in the High Alps, impelled by the weight of fresh
layers of snow overlying it, and by the slope of the mountain-sides,
gradually creeps down into the valleys. Owing to the pressure thus
put upon it, and partly to the melting power of the sun's rays, it
assumes the form of ice; and glaciers are composed of solid ice. The
downward motion is so slow that a glacier appears quite stationary;
and it is only by putting in stakes and watching them change their
positions that it can be shown to be moving.

In all respects except speed, glaciers flow like rivers, for ice is
a viscous body, behaving partly like a fluid and yet partly like
a solid substance; but it will not endure a sharp bend without
snapping. Hence, a glacier in traversing a valley frequently gets
split. The cracks thus formed widen by degrees until they expand
into chasms, or "crevasses." Like rivers, glaciers transport a large
amount of rocky matter to lower levels, and at the same time wear
away and deepen their rocky channels.

Let us see how they do this twofold work of transportation and
erosion. In the first place, a large amount of débris falls onto the
sides of a glacier from the peaks, precipices, and mountain-side
along which it flows. Some stones, however, fall down crevasses, and
so reach the bottom, where they become cemented in the ice. In this
way they are slowly carried down over the rocky floor of the valley,
until at last they reach the end of the glacier, where in the warmer
air the ice melts just as fast as it creeps down; and there they will
be left to form a heap of stones, sand, and mud.

Large blocks of stone, quite different from the rocks on which they
lie, are very numerous, and are called "erratics," since they are
evidently wanderers from a distance. Sometimes such blocks can be
proved to have been brought many miles from their home among the
higher peaks. The long lines of stones and mud seen on the sides of
a glacier are called "moraines," and at the end of every glacier we
find a big heap known as a "terminal moraine." But the stones of
which they are composed are probably not to be entirely accounted
for in this way. Can we not conceive that the weight and pressure of
a descending glacier may be sufficient to break off many protruding
portions of the rocky bed over which it flows, and then to drag them
along with it? This seems reasonable. Let us therefore consider
the materials of which moraines are composed to be derived partly
from the rocks beneath and partly from those above the glacier. But
whatever their origin, such materials must inevitably find their way
to the end of the glacier and be added to the big heap there. The
work of transportation is then taken up by the stream which always
flows from the end of a glacier. Such streams are in summer-time
laden with fine sediment, which gives them a milky and turbid
appearance.

Thus a glacier wears away the rocks over which it flows; rock
fragments become embedded in the ice, and these are the tools with
which a glacier does its work. It must be granted that the downward
movement of a great mass of ice is irresistible, and consequently
that as the moving glacier slowly creeps along, it must inevitably
cause the stones which it thus holds to grind over the surface of
the rock. It is easy to imagine the effects of this grinding action.
If sand-paper, rubbed for a minute or two over wood, wears down and
smooths its surface, what must be the result of all these stones,
together with sand and mud, grinding over the rocky bed?

The answer to this question is found in examining the rocks over
which glaciers once flowed. Now, the Swiss glaciers once extended
far beyond their present limits; and the rocks in the lower parts of
their present valleys, now free from ice, show unmistakable signs
of having been considerably worn down. The corners and angles of
projecting pieces of rock have been worn away until the once rugged
outline has become wavy and round, so much so as to produce more or
less resemblance to the backs of sheep lying down. Hence the name
_roches moutonnées_, by which rocks of this shape are known. They
frequently retain on their surface peculiar markings, such as long
scratches and grooves which must have been made as the old glacier,
with its embedded angular fragments of rock, slowly ground over
their surfaces. Such markings are called "striæ." But besides these
glacial records graven on the rocks, we have other evidence, in the
form of great moraines in some of the valleys of Switzerland, and
especially at those places where side valleys open out into a main
valley. Any one may learn by a little observation to recognise these
peculiar heaps of stones, mud, and sand, deposited long ago by the
old glaciers of Switzerland.

It will be perceived that the evidence for the erosive power of
glaciers is of two kinds,--first, there is the testimony of the
smoothed and striated rocks, which is very convincing; secondly,
the equally strong proofs from the moraines, both great and small.
These old rubbish heaps give us a very fair idea of the amount of
wear and tear that goes on under a glacier, for there we see the rock
fragments that tumbled down the mountain-side onto the surface of the
glacier (together with those which the glacier tore off its rocky
bed), all considerably smoothed, worn down, and striated. But a still
better idea of the work done is afforded by the gravel, mud, and sand
in which these stones are embedded. All this finer material must have
been the result of wear and tear. This kind of action may well be
compared to what takes place on a grindstone as one sharpens an axe
on it. The water poured on the stone soon becomes muddy, owing to the
presence of countless little grains of sand worn off the grindstone.
But a good deal of the mud thus formed is carried away by the little
stream that runs out from the end of every glacier; so that there is
more formed than we see in the moraine.

  [Illustration: THE MER DE GLACE AND MONT BUET. FROM A PHOTOGRAPH
  BY MR. DONKIN.]

We have already alluded in former chapters to the "Ice Age" in
Britain, when great glaciers covered all our high mountains, and
descended far and wide over the plains. Now, the evidence for the
former existence of these glaciers is of the same kind as that which
we have just described. In Wales and Scotland we may soon learn
to recognise the _roches moutonnées_, the old moraine heaps, and
the erratic boulders brought down by these old glaciers. Besides
these proofs, there is also the evidence of the arctic plants now
flourishing in the highlands (see chapter iv., pages 123-124).

There can be no doubt, then, that glaciers have an erosive action,
and therefore must be regarded as agents of denudation. But it is
important to bear in mind that their powers in this direction are
limited; for it is manifest that a mountain stream is a much more
powerful agent, and will deepen its little valley much more rapidly,
than a cumbrous, slow-moving glacier, advancing at the rate of a
few inches a day. It has been found by careful measurements that
the Mer de Glace of Chamouni moves during summer and autumn at the
average daily rate of twenty to twenty-seven inches in the centre,
and thirteen to nineteen and one half inches near the side, where
friction somewhat impedes its course. This seems very slow compared
to the rapid movement of a mountain stream; but then, a glacier
partly makes up for this by its great weight.

In considering a glacier as an agent of erosion, we must not forget
that probably a good deal of water circulates beneath glaciers. If
this is so, the water must have a considerable share in producing the
effects to which we have already alluded. It would be extremely rash
to conclude, as some students of glaciers have done, that valleys
can be carved out _entirely_ by glaciers; and we must be content
with believing that they have been somewhat deepened by ice-action,
and their features more or less altered, but no more. The valleys of
Switzerland, of Wales, and Scotland, were probably all in existence
before the period of the "Ice Age," having been carved out by streams
in the usual way; but the glaciers, as it were, put the final touches
and smoothed their surfaces.

Having learned how the three agents of denudation--namely, rain,
rivers, and glaciers--accomplish their work, let us now take a wider
view of the subject and consider the results of their united efforts
both in the present and in the past.

We have already alluded to the enormous amount of solid matter
brought down to the sea every year by rivers (see chap. v., pp.
166-168), and we pointed out that all this represents so much débris
swept off the land through which the rivers flow; also that it comes
down in three ways, one part being suspended in the water as fine
mud, another part being pushed along the river-bed as gravel, etc.,
while a third part is the carbonate of lime and other mineral matter
in a dissolved state, and therefore invisible.

Now, it is quite plain that rain and rivers, in sweeping away so much
solid matter from the surface of the land, must tend in the course
of time to lower its general level; and it therefore seems to follow
that after the lapse of ages any given continent or large island
might be entirely washed away, or in other words, reduced to the
level of the sea. This would certainly happen were it not that the
lands of the world seem to be slowly rising, so that the denudation
going on at the surface appears to be counterbalanced by continued
upheaval.

But, supposing no upheaval took place, how long would it take for
rain and rivers to wear away a whole continent? Let us see if there
is any way of answering this difficult question, for if it can be
even partially solved, it will help us to realise the enormous length
of time that must have been required to bring about the results of
denudation that we see all around us.

Although the calculations that have been made on this subject are
very complicated, yet the principle on which they are based is quite
simple. For an answer to our question we must go to the rivers again,
and measure the work they do in transporting solid matter down to
the sea. Let us take the Mississippi as a typical big river, for
it has been more carefully studied than any other, and it drains a
very extensive area, embracing many varieties of climate, rock, and
soil. As the result of many observations carried on continuously at
different parts of the river for months together, the engineers who
conducted the investigation found that the annual discharge of water
by this river is about nineteen thousand millions of cubic feet,
and that on the average the amount of sediment it contains is about
a 1/1500th part by weight. But besides the matter in suspension,
they observed that a large amount of sand, gravel, and stones is
being constantly pushed along the bottom of the river. This they
estimated at over seven hundred and fifty millions of cubic feet.
They also calculated that the Mississippi brings down every year
more than eight hundred thousand million pounds of mud. Putting the
two together, they found (as before stated) that the amount of solid
matter thus transported down to the Gulf of Mexico may be represented
by a layer 268 feet high, covering a space of one square mile; that
is, without allowing for what is brought down dissolved in the water,
which may be neglected in order to prevent any exaggeration.

Now, it is quite clear that all this débris must have come from the
immense area that is drained by the Mississippi. It could not have
been supplied by any rivers except those that are its tributaries.
And so if we can find out what is the extent of this area, it is not
difficult to calculate how much its general surface must have been
lowered, or in other words, how much must have been worn away from
it in order to supply all the material. This area is reckoned at
1,147,000 square miles; and a very simple calculation tells us that
the general surface would thus be lowered to the extent of 1/6000th
part of a foot. That of course means that one foot would be worn away
in six thousand years. On high ground and among mountains the rate of
denudation would of course be much greater; but we are now dealing
with an average for the whole surface.

The next thing we require to finish this calculation is the average
or mean height of the American continent. This was reckoned by the
celebrated Humboldt at 748 feet. Now if we may assume that all this
continent is being worn down at the same rate of one foot in six
thousand years (which is a reasonable assumption), we find, by a
simple process of multiplication, that it would require about four
and a half millions of years for rain and rivers to wash it all away
until its surface was all at the sea-level (with perhaps a few little
islands projecting here and there as relics of its vast denudation).
This is a very interesting result; and if the above measurements are
reliable, they afford us some idea of the rate at which denudation
takes place at the present time.

By a similar process it has been calculated the British Isles might
be levelled in about five and a half millions of years. Geologists
do not pretend to have solved this problem accurately; that is
impossible with our present knowledge. But even as rough estimates
these results are very valuable, especially when we come to study
the structure of the land in different countries, and to find out
therefrom, by actual measurement, how much solid rock has been
removed. We will now give some examples of this; but perhaps a simple
illustration will make our meaning clearer.

Suppose we picked up an old pair of boots, and found the soles worn
away in the centre. It would be easy to find out how much had been
worn away over the holes by simply measuring the thickness of leather
at the sides, where we will suppose that they were protected by
strong nails. Geologists apply a very similar kind of method in order
to find out how much rock has been removed from a certain region of
the earth. One of the simplest cases of this kind is that of the area
known as the Weald of Kent, Surrey, and Sussex (see illustration,
Fig. 1). A great deal of denudation has taken place here, because
there is ample evidence to prove that the great "formation" known
as the Chalk (now seen in the North and South Downs) once stretched
right across; and below this came the lower greensand and Weald clay.
They spread over this area in a low arch of which we now only see the
ruins.

  [Illustration: Fig. 1. SECTION ACROSS THE WEALD OF KENT AND
  SURREY.]

  [Illustration: Fig. 2. THE HIGHLANDS OF SCOTLAND ON A TRUE SCALE
  (after GEIKIE).]

The dotted lines in the figure show us their former extent; but
the vertical height is exaggerated, for otherwise the hills would
scarcely be seen.

These lines simply follow out the curves taken by the strata at each
end of the denuded arch, and therefore rightly indicate its former
height. By making such a drawing on a true scale, geologists can
easily measure the former height of the surface of this old arch,
or "anticline," of chalk, greensand, and other strata, just as an
architect might restore the outlines of an old traceried window from
a few portions left at the sides.

This very useful and instructive method is much employed in drawing
sections through mountain-chains, in order to gain some idea of the
amount of denudation which they have suffered.

Let us see how much has been removed from the present surface of
the Weald. First there is the chalk, which we may put down at six
hundred feet at least; then there is the lower greensand, say, eight
hundred feet; and below that, and forming the lowest ground in the
Weald, is the Weald clay, which is one thousand feet thick, and being
softer, was more rapidly borne away. Along the centre runs a ridge
of Hastings sand, forming higher ground on account of its greater
hardness, but this formation is not much denuded. However, adding
together the thicknesses of the others, we arrive at the conclusion
that about twenty-four hundred feet of chalk and other strata has
been removed from the present surface of the Weald. And all this
denudation has probably been effected by rain and rivers, for it is
very doubtful whether the sea had any share in this work.

But in other parts of our own country we find proofs of denudation
on a much grander scale than this; for example, in North Wales there
are rocks now lying exposed at the surface which are of a very much
greater antiquity than any that may be seen in the Wealden area,
belonging to the very ancient periods known as the Cambrian and
Silurian. These have evidently been exposed for a much longer time
to the action of denuding forces; and the Welsh hills, as we now
see them, are but fragments of what they once were. After carefully
mapping out the rocks in the neighbourhood of Snowdon, noting their
thickness, the directions in which they slope, or "dip," so that
the structure of this region might be ascertained, as in the case
of the Weald, it was found, on drawing sections of the rocks there,
and putting in dotted lines to continue the curves and slopes of the
strata as known at or near the surface, that from fifteen thousand
to twenty thousand feet of solid rock must have been removed (see
diagrams, chapter ix., p. 307). Applying the same method to the Lake
District, it has been calculated that the amount of denudation which
that beautiful country has suffered may be represented by twenty-six
thousand feet. Turning to the other side of the Atlantic, we find
the American geologists estimate that a thickness of five miles has
been removed from a large part of the Appalachian chain of mountains
(near their east coast), and that at least one mile has been eroded
from the entire region between the Rocky and Wahsatch Mountains (see
chapter ix.).

In conclusion, we must bear in mind that mountains, in spite of the
enormous erosion they have suffered, are more capable of resisting
the ever active agents of denudation than the softer rocks that form
the plains and lowlands, and consequently stand out in bold relief
from other features of the earth's surface. This truth has been
beautifully expressed in the following passage:--

   " ... In order to bring the world into the form which it now
   bears, it was not mere sculpture that was needed; the mountains
   could not stand for a day unless they were formed of materials
   altogether different from those which constitute the lower
   hills and the surfaces of the valleys. A harder substance had
   to be prepared for every mountain-chain, yet not so hard but
   that it might be capable of crumbling down into earth, fit to
   nourish the Alpine forest and the Alpine flowers; not so hard
   but that in the midst of the utmost majesty of its enthroned
   strength there should be seen on it the seal of death, and the
   writing of the same sentence that had gone forth against the
   human frame, 'Dust thou art and unto dust thou shalt return.'
   And with this perishable substance the most majestic forms were
   to be framed that were consistent with the safety of man, and
   the peak was to be lifted and the cliff rent as high and as
   steeply as was possible, in order yet to permit the shepherd
   to feed his flocks upon the slope, and the cottage to nestle
   beneath their shadow."[24]

  [24] Modern Painters.




CHAPTER VIII.

VOLCANIC MOUNTAINS.

    'Tis said Enceladus' huge frame,
    Heart-stricken by the avenging flame,
    Is prisoned here, and underneath
    Gasps through each vent his sulphurous breath;
    And still as his tired side shifts round,
    Trinacia echoes to the sound
    Through all its length, while clouds of smoke
    The living soul of ether choke.

    VIRGIL: _Æneid iii._


In some parts of the world we meet with mountains of a very different
kind from any we have yet considered,--mountains that are known
at times to send forth fiery streams of glowing lava, and to emit
with terrific force great clouds of steam. Such mountains have
long been known, in popular but unscientific language, as "burning
mountains,"[25]--a term which is unfortunate, because they do not
burn in the proper sense of the word, like candles or gas-jets. They
are better known as volcanoes. There are about three hundred and
fifty known active volcanoes; and if we include all mountains that
once were in that state, the number is about one thousand.

  [25] See papers by the writer on Volcanoes and Volcanic Action
  in "Knowledge" for May and June, 1891, on which this chapter is
  partly based.

Such mountains are connected in a curious way with those upheaved
ridges of the world known as mountain-chains (see chap. vi., p.
191). And not only are many mountains more or less penetrated and
intersected by rocks of an igneous origin (see chap. v., p. 155),
but some have been largely formed by the action of old volcanoes.
In fact, there are hills in Great Britain and parts of Europe, in
America, and other countries, that once were actual volcanoes (see
page 277).

We must briefly consider these strange mountains so different from
others, and see what we can find out about them. Let us first inquire
how a volcano is made, then consider what a volcano does; that is, we
must view it as a geological agent that has a certain definite part
to play in the economy of the world. And lastly, we may glance at
some of the old volcanoes, and see what they were doing in those long
ages of the world during which the great series of the stratified
rocks were formed,--which rocks are, as it were, the book in which
the earth has written her autobiography.

In old days volcanoes were regarded with superstitious awe; and any
investigation of their actions would have been considered rash and
impious in the highest degree. Mount Etna, as Virgil tells us, was
supposed to mark the spot where the angry gods had buried Enceladus,
one of the rebellious giants. Volcano, a certain "burning mountain"
in the Lipa Islands, was likewise called the forge, or workshop,
of Vulcan (or Volcan), the god of fire. And so it comes about that
all "burning mountains" take their name from this one Mediterranean
island, and at the same time tell us of the mythological origin of
the word. It has been said that words are "fossil thoughts;" and we
have here an old and very much fossilised thought,--a kind of thought
long since extinct among civilised peoples, and one which is never
likely to come to life again.

A volcanic mountain consists of alternating sheets of lava and
volcanic ashes, mantling over each other in an irregular way,
and all sloping away from the centre. In the centre is a pit or
chimney, widening out towards the top so as to resemble a funnel or
cup; hence the name "crater," which means a cup. In the centre of
this crater a very small cone ("minor cone") is frequently found;
and it is interesting to find that many of the moon's volcanic
craters possess these "minor cones." A number of cracks or fissures
intersect the volcano. These frequently spread out from the centre
of the mountain in all directions, like the spokes of a wheel.
They generally get filled with lava that wells up from below, thus
forming "dykes," which may be regarded as so many sheets of igneous
rock, such as basalt, that have forced their way while still liquid
in among the layers of lava and ashes. The word "ash" is used by
geologists in a special sense; and volcanic ash is not, as might
be supposed, a deposit of cinders, but mostly of dust of various
degrees of fineness, and sometimes it is very fine indeed. Pieces
of pumice-stone may be embedded in a layer of volcanic ash, and
sometimes great blocks of stone that have been shot out of the
volcano as from a big gun, but these only form a small part of the
layer. Dykes strengthen the mountain, and tend to hold it together
when violently shaken during an eruption.

The shape and steepness of a volcano depend on the nature of the
materials ejected. The finer the volcanic ash, the steeper and more
conical is the mountain. The building up of a volcano may be fairly
illustrated by the little cone of sand formed in an hourglass as the
sand-grains fall. These settle down at a certain slope, or angle,
at which they can remain, instead of falling down to the bottom, as
they do directly this slope is exceeded. Some volcanoes are built up
almost entirely of volcanic ash and its embedded blocks. Vesuvius,
Teneriffe, Jorullo, in Mexico, and Cotopaxi, in the Andes, are
examples of steep volcanic cones built up in this way. Others, less
steep and more irregular in shape, are chiefly formed of successive
lava-flows. Little minor cones are frequently formed on the side of
a volcano; and these during an eruption give rise to small outbursts
of their own. They are easily accounted for by the dykes which are
mentioned just now; for when molten rock forces its way through
fissures, it sometimes finds an outlet at the surface, and being full
of steam, as soda-water is full of gas, it gives rise to an eruption.
The great opening in the centre of a volcano, with its molten lava,
is like a very big dyke that has reached the surface and so succeeded
in producing an eruption.

The opening of a soda-water bottle not infrequently illustrates a
volcanic eruption; for when the pent-up carbonic acid cannot escape
fast enough, it forces out some of the water, even when the bottle is
held upright.

Every volcano has been built up on a platform of ordinary stratified
rocks; and at some period _after_ these had been laid down in water
and raised up into dry land, molten rock found its way through them,
and so the volcano was built up by successive eruptions during many
years. It is probable that earthquake shocks, preceding the first
eruption, cracked up these strata, and so made a way for the lava to
come up.

The main point we wish to emphasize is that _volcanoes are never
formed by upheaval_. In this way they differ from all other
mountains. They have not been made by the heaving up of strata, but
have been gradually piled up, something like rubbish heaps that
accumulate in the Thames barges as the dustmen empty their carts into
them, only in the case of volcanoes the "rubbish" comes from below.
It is not necessary to suppose that the reservoir down below, from
which the molten rock is supplied, exists at any very great depth
below the original land surface on which the volcano grows up.

The old "upheaval theory" of volcanoes, once advocated by certain
authorities, instead of being based on actual evidence or on
reasoning from facts, was a mere guess. Moreover, if the explanation
we have given should not be sufficiently convincing, there is good
proof furnished by the case of a small volcano near Vesuvius, the
building of which was actually witnessed. It is called Monte Nuovo,
or the New Mountain. It is a little cone 430 feet high, on the bank
of Lake Averno, with a crater more than a mile and a half wide at the
base. It was almost entirely formed during a single night in the year
1538, A. D. We have two accounts of the eruption to which it owes
its existence; and each writer says distinctly that the mountain was
formed by the falling of stones and ashes.


One witness says,--

   "Stones and ashes were thrown up with a noise like the
   discharge of great artillery, in quantities which seemed as if
   they would cover the whole earth; and in four days their fall
   had formed a mountain in the valley between Monte Barbaro and
   Lake Averno, of not less than three miles in circumference, and
   almost as high as Monte Barbaro itself,--a thing incredible
   to those who have not seen it, that in so short a time so
   considerable a mountain should have been formed."


Another says,--

   "Some of the stones were larger than an ox. The mud (ashes
   mixed with water) was at first very liquid, then less so, and
   in such quantities that with the help of the afore-mentioned
   stones a mountain was raised one thousand paces in height."

(The writer's astonishment led him greatly to exaggerate the height.)

These accounts are important as showing how in a much longer time
a big volcano may be built up. From such small operations we learn
how Nature works on a large scale. The great volcano in Mexico known
as Jorullo was probably built up in a very similar way. There is a
tradition among the natives that it was made in two or three days;
but we can hardly believe that. Volcanoes, as they get older, tend
to grow taller and bigger; but every now and then a large portion may
be blown away by some great eruption, and they have, as it were, to
begin again.

  [Illustration: THE ERUPTION OF VESUVIUS IN 1872. FROM AN
  INSTANTANEOUS PHOTOGRAPH.]

Let us now consider volcanoes as geological agents, and see what
they do. A volcanic eruption may be described in a general way
as follows: Its advent is heralded by earthquakes affecting the
mountain and the whole country round; loud underground explosions
are heard, resembling the fire of distant artillery. The vibrations
are chiefly transmitted through the ground; the mountain seems
convulsed by internal throes, due, no doubt, to the efforts of the
imprisoned steam and liquid rock to find an opening. These signs are
accompanied by the drying up of wells and disappearance of springs,
since the water finds its way down new cracks in the rocks, caused
by the frequent shocks and quiverings. When at last an opening has
been made, the eruption begins,--generally with one tremendous
burst that shakes the whole mountain down to its foundations. After
this, frequent explosions follow with great rapidity and increasing
violence, generally from the crater. These are indicated by the
globular masses of steam which are to be seen rising up in a tall
column like that which issues from the funnel of a locomotive. But
sometimes the whole mountain seems to be more or less engaged in
giving out steam, and thus to be partly enveloped in it. This is
illustrated by our engraving from an instantaneous photograph of
Vesuvius in eruption in the year 1872. The steam and other gases, in
their violent ascent, hurl up into the air a great deal of solid rock
from the sides of the central opening, after first blowing out the
stones which previously stopped up the orifice.

Blocks of stone falling down meet with others coming up; and so a
tremendous pounding action takes place, the result of which is that
great quantities of volcanic dust and ashes are produced, generally
of extreme fineness. Winds and ocean currents transport these light
materials for long distances. The observations made during the
famous and fruitful voyage of H. M. S. "Challenger" showed that
fine volcanic dust is carried by wind and marine currents to almost
all parts of the oceans. The darkness so frequently mentioned in
accounts of eruptions--sometimes at a very great distance from the
volcano--is entirely caused by clouds of volcanic dust hiding the
light of the sun. Perhaps the best example of this is the case of the
eruption of Krakatoa (in the Strait of Sunda, between Sumatra and
Java) in 1883. Its explosions were heard in all directions for two
thousand miles, and a perceptible layer of volcanic dust fell at all
places within one thousand miles; while the finest dust and vapour,
shot up fifteen or twenty miles high, were spread all over the globe,
causing, while still suspended in the atmosphere, the peculiar red
sunsets noticed in all parts of the world for some months after the
eruption.

Again, those very curious deposits of "red clay" found in the very
deepest parts of the Pacific and Atlantic oceans (at depths of about
four thousand fathoms, or twenty-four thousand feet) have been shown
to be chiefly composed of volcanic dust, their red colour being due
to oxidised iron.

But there is another way in which a good deal of fine volcanic dust
is made; and it is this: the lava is so full of steam intimately
mixed up with it that the steam, in its violent effort to escape,
often blows the lava into mere dust.

Another interesting phenomenon may be thus described: Portions of
liquid, or half liquid, lava are caught up by the steam and hurled
into the air. These assume a more or less round form, and are known
as "bombs." At a distance they give rise to the appearance of
flames. And here we may remark that the flaring, coloured pictures
of Etna or Vesuvius in eruption, which frequently may be seen, are
by no means correct. The huge flames shooting up into the air are
quite imaginary, but are probably suggested by the glare and bright
reflection from glowing molten lava down in the crater.

So great is the force of the pent-up steam trying to escape that it
frequently blows a large part of the volcano bodily away; and in some
cases a whole mountain has been blown to pieces.

Finally, torrents of rain follow and accompany an eruption,--a result
which clearly follows from the condensation of large volumes of
steam expanding and rising up into the higher and cooler layers of
the atmosphere. Vast quantities of volcanic ash are caught up by the
rain, and in this way very large quantities of mud are washed down
the sides of the mountain.

Sometimes the mud-flows are on a large scale, and descending with
great force, bury a whole town. It was mostly in this way that the
ancient cities of Herculaneum and Pompeii were buried by the great
eruption of Vesuvius in the year 79 A. D., in which the elder Pliny
lost his life. The discoveries made during excavations at Pompeii are
of very great interest as illustrating old Roman life. The Italians
give the name _lava d'acqua_, or water-lava, to flows of this kind,
and they are greatly dreaded on account of their great rapidity. An
ordinary lava-stream creeps slowly along, so that people have time
to get out of the way; but in the case of mud-flows there is often
no time to escape. No lava-stream has ever reached Pompeii since it
was first built, although the foundations of the town stand upon an
old lava-flood. Herculaneum is nearer to Vesuvius, and has at times
been visited by lava-streams. Mud-lavas, ashes, and lava-streams have
accumulated over this city to a depth of over seventy feet.

Lava-streams vary greatly in size; in some cases the lava, escaping
from craters, comes to rest before reaching the base of the slopes of
the volcano; in other cases a lava-flow not only reaches the plains
below, but extends for many miles over the surrounding country.
Hence lava-streams are important geological agents. Let us look at
some famous instances. The most stupendous flow on record was that
which took place from Skaptar Jökull in Iceland, in the year 1783.
In this case a number of streams issued from the volcano, flooding
the country far and wide, filling up river gorges which were in some
cases six hundred feet deep and two hundred and fifty feet broad, and
advancing into the alluvial plains in lakes of molten rock twelve to
fifteen miles wide and one hundred feet deep. Two currents of lava
which flowed in nearly opposite directions spread out with varying
thickness according to the nature of the ground for forty and fifty
miles respectively. Had this great eruption taken place in the south
of England, all the country from the neighbourhood of London to
that of Gloucester might have been covered by a flood of basalt of
considerable thickness.

Sometimes, when the lava can only escape at a point low down on the
mountain, a fountain of molten rock will spout high into the air.
This has happened on Vesuvius and Etna. But in an eruption of Mauna
Loa, in the Sandwich Islands, an unbroken fountain of lava, from two
hundred to seven hundred feet high and one thousand feet broad, burst
out at the base of the mountain; and again in April, 1888, the same
thing happened on a still grander scale. In this case four fiery
fountains continued to play for several weeks, sometimes throwing
the glowing lava to a height of one thousand feet in the air. Surely
there can be no more wonderful or awful sight than this in the world.

The volcanoes of Hawaii, the principal island in the Sandwich
Islands, often send forth lava-streams covering an area of over
one hundred square miles to a depth of one hundred feet or more;
but they are discharged quite quietly, like water welling out of a
spring. Repeated flows of this kind, however, have in the course of
ages built up a great flat cone six miles high from the floor of the
ocean, to form this lofty island, which is larger than Surrey; and
it is calculated that the great volcanic mountain must contain enough
material to cover the whole of the United States with a layer of rock
fifty feet deep.

But it is not only on the surface of the land that volcanic eruptions
take place; for in some cases the outbreak of a submarine eruption
has been witnessed, and it is highly probable that in past geological
ages many large eruptions of this nature have taken place. In the
year 1783, an eruption took place about thirty miles off the west
coast of Iceland. An island was built up from which glowing vapour
and smoke came forth; but in a year or less the waves had washed
everything away, leaving only a submerged reef. The island of
Santorin, in the Greek Archipelago, is a partly submerged volcano.

But in some cases enormous outpourings of lava have taken place,
not from volcanoes, but from openings of the ground here and there,
and more usually from long fissures or cracks in the rocks lying at
the surface. In many cases so much lava has quietly welled out in
this way that the old features of the landscape have been completely
buried up, and wide plains and plateaux formed over them. Sir A.
Geikie says,--

   "Some of the most remarkable examples of this type of volcanic
   structure occur in western North America. Among these that of
   the Snake River plain in Idaho may be briefly described.

   "Surrounded on the north and east by lofty mountains, it
   stretches westward as an apparently boundless desert of sand
   and bare sheets of black basalt. A few streams descending into
   the plain from the hills are soon swallowed up and lost. The
   Snake River, however, flows across it, and has cut out of its
   lava bed a series of picturesque gorges and rapids.

   "The extent of country which has been flooded with basalt in
   this and adjoining regions of Oregon and Washington has not
   yet been accurately surveyed, but has been estimated to cover
   a larger area than France and Great Britain combined. Looked
   at from any point on its surface, one of these lava plains
   appears as a vast level surface, like that of a lake bottom.
   This uniformity has been produced either by the lava rolling
   over a plain or lake bottom, or by the complete effacement of
   an original, undulating contour of the ground under hundreds of
   feet of lava in successive sheets. The lava, rolling up to the
   base of the mountains, has followed the sinuosities of their
   margin, as the waters of a lake follow its promontories and
   bays."

A few further examples of mud-lavas may be mentioned here. Cotopaxi,
a great volcano in Ecuador, South America, with a height of 17,900
feet, reaches so high into the atmosphere that the higher parts are
capped with snow. In June, 1877, a great eruption took place, during
which the melting of snow and ice gave rise to torrents of mud and
water, which rushed down the steep sides of the mountain, so that
large blocks of ice were hurried along. The villages around to a
distance of about seventy miles were buried under a deposit of mud,
mixed with blocks of lava, ashes, pieces of wood, etc.

Sometimes a volcano discharges large quantities of mud directly
from the crater. In this case the mud is not manufactured by the
volcano itself, but finds its way through fissures and cracks from
the bed of the neighbouring sea or rivers to the crater. Thus, in
the year 1691, Imbaburu, one of the Andes of Quito, sent out floods
of mud containing dead fish, the decay of which caused fever in the
neighbourhood. In the same way the volcanoes of Java have often
buried large tracts of fertile country under a covering of volcanic
mud, thus causing great devastation.

Vast quantities of dust are produced, as already explained, by the
pounding action that takes place during an eruption, as portions
of rock in falling down meet others that are being hurled into the
air. Striking instances of this have occurred not far from Great
Britain. Thus in the year 1783, during an eruption of Skaptar Jökull,
so great was the amount of dust thus created that the atmosphere in
Iceland was loaded with it for several months. Carried by winds, it
even reached the northern parts of Scotland, and in Caithness so
much of it fell that the crops were destroyed. This is remarkable,
considering that the distance was six hundred miles. Even in Holland
and Norway there are traces of this great shower of dust from the
Icelandic volcano.

During the fearful eruption of Tomboro, a volcano in the island of
Sumbawa, in the Eastern Archipelago, in 1815, the abundance of ashes
and dust ejected caused darkness at midday at Java, three hundred
miles away, and even there the ground was covered to a depth of
several inches. In Sumbawa itself the part of the island joining
the mountain was entirely desolated, and all the houses destroyed,
together with twelve thousand inhabitants. Trees and herbage were
overwhelmed with pumice and volcanic dust. The floating pumice on the
sea around formed a layer two feet, six inches thick, through which
vessels forced their way with difficulty. From such facts as these
it is clear that if in past ages volcanoes have been so powerfully
active as they are now, we should expect to find lava-flows, dykes,
and great deposits of volcanic ash deposited in water among the
stratified rocks; and such is the case. Many large masses of rock
familiar to the geologist, and often forming parts of existing
mountains, are to be accounted for either as great lava-flows, or
dykes that have forced their way in among the strata, or as extensive
deposits of volcanic ash.

But perhaps the reader would like to know what the inside of a
volcanic crater is like during an eruption. Let us, then, take a peep
into that fearful crater of Kilauea, in the Sandwich Islands. For
this purpose we cannot do better than follow Miss Bird's admirable
description of her adventurous expedition to this crater:--

   "The abyss, which really is at a height of four thousand feet,
   on the flank of Mauna Loa, has the appearance of a pit on
   a rolling plain. But such a pit! It is quite nine miles in
   circumference, and at its lowest area--which not long ago fell
   about three hundred feet, just as ice on a pond falls when
   the water below is withdrawn--covers six square miles. The
   depth of the crater varies from eight hundred to one thousand
   feet, according as the molten sea below is at flood or ebb.
   Signs of volcanic activity are present more or less throughout
   its whole depth, and for some distance round its margin, in
   the form of steam-cracks, jets of sulphurous vapour, blowing
   cones, accumulating deposits of acicular crystals of sulphur,
   etc., and the pit itself is constantly rent and shaken by
   earthquakes. Grand eruptions occurred with circumstances
   of indescribable terror and dignity; but Kilauea does not
   limit its activity to these outbursts, but has exhibited its
   marvellous phenomena through all known time in a lake or lakes
   on the southern part of the crater three miles from this side.

   "This lake--the _Hale-mau-mau_, or 'House of Everlasting Fire,'
   of the Hawaiian mythology, the abode of the dreaded goddess
   Pele--is approachable with safety, except during an eruption.
   The spectacle, however, varies almost daily; and at times the
   level of the lava in the pit within a pit is so low, and the
   suffocating gases are evolved in such enormous quantities, that
   travellers are unable to see anything. There had been no news
   from it for a week; and as nothing was to be seen but a very
   faint bluish vapour hanging round its margin, the prospect was
   not encouraging.... After more than an hour of very difficult
   climbing, we reached the lowest level of the crater, pretty
   nearly a mile across, presenting from above the appearance
   of a sea at rest; but on crossing it, we found it to be an
   expanse of waves and convolutions of ashy-coloured lava, with
   huge cracks filled up with black iridescent rolls of lava only
   a few weeks old. Parts of it are very rough and ridgy, jammed
   together like field-ice, or compacted by rolls of lava, which
   may have swelled up from beneath; but the largest part of the
   area presents the appearance of huge coiled hawsers, the ropy
   formation of the lava rendering the illusion almost perfect.
   These are riven by deep cracks, which emit hot sulphurous
   vapours....

   "As we ascended, the flow became hotter under our feet, as well
   as more porous and glistening. It was so hot that a shower of
   rain hissed as it fell upon it. The crust became increasingly
   insecure, and necessitated our walking in single file with the
   guide in front, to test the security of the footing. I fell
   through several times, and always into holes full of sulphurous
   steam so malignantly acid that my strong dogskin gloves were
   burned through as I raised myself on my hands.

   "We had followed the lava-flow for thirty miles up to the
   crater's brink, and now we had toiled over recent lava for
   three hours, and by all calculation were close to the pit; yet
   there was no smoke or sign of fire, and I felt sure that the
   volcano had died out for once for our special disappointment....

   "Suddenly, just above, and in front of us, gory drops were
   tossed in the air, and springing forwards we stood on the brink
   of _Hale-mau-mau_, which was about thirty-five feet below
   us. I think we all screamed. I know we all wept; but we were
   speechless, for a new glory and terror had been added to the
   earth. It is the most unutterable of wonderful things. The
   words of common speech are quite useless. It is unimaginable,
   indescribable; a sight to remember for ever; a sight which
   at once took possession of every faculty of sense and soul,
   removing one altogether out of the range of ordinary life.
   Here was the real 'bottomless pit,' 'the fire which is not
   quenched,' 'the place of Hell,' 'the lake which burneth with
   fire and brimstone,' 'the everlasting burnings,' 'the fiery
   sea whose waves are never weary.'[26] There were groanings,
   rumblings, and detonations, rushings, hissings, splashings,
   and the crashing sound of breakers on the coast; but it was
   the surging of fiery waves upon a fiery shore. But what can
   I write? Such words as jets, fountains, waves, spray, convey
   some idea of order and regularity, but here there was none.
   The inner lake, while we stood there, formed a sort of crater
   within itself; the whole lava sea rose about three feet; a
   blowing cone about eight feet high was formed; it was never the
   same two minutes together. And what we saw had no existence
   a month ago, and probably will be changed in every essential
   feature a month hence.... The prominent object was fire in
   motion; but the surface of the double lake was continually
   skimming over for a second or two with a cooled crust of a
   lustrous grey-white, like frosted silver, broken by jagged
   cracks of a bright rose-colour. The movement was nearly always
   from the sides to the centre; but the movement of the centre
   itself appeared independent, and always took a southerly
   direction. Before each outburst of agitation there was much
   hissing and throbbing, internal roaring, as of imprisoned
   gases. Now it seemed furious, demoniacal, as if no power on
   earth could bind it, then playful and sportive, then for a
   second languid, but only because it was accumulating fresh
   force.... Sometimes the whole lake ... took the form of mighty
   waves, and surging heavily against the partial barrier with
   a sound like the Pacific surf, lashed, tore, covered it, and
   threw itself over it in clots of living fire. It was all
   confusion, commotion, forces, terror, glory, majesty, mystery,
   and even beauty. And the colour, 'eye hath not seen' it! Molten
   metal hath not that crimson gleam, nor blood that living
   light."[27]

  [26] Perhaps these Scripture phrases were suggested long before
  the Bible was written, by the sight of some crater in active
  eruption.

  [27] The Hawaiian Archipelago.

Continued observation of volcanoes, together with evidence derived
from history, teaches that there are different stages of volcanic
action. There are three pretty well-marked phases. First, the state
of permanent eruption; this is not a dangerous state, because the
steam keeps escaping all the time: the safety-valve is at work, and
all goes smoothly. The second state is one of moderate activity, with
more or less violent eruptions at brief intervals; this is rather
dangerous, because at times the safety-valve does not work.

And thirdly, we have paroxysms of intense energy, alternating with
long periods of repose sometimes lasting for centuries. These
eruptions are extremely violent, and cause widespread destruction;
the safety-valve has got jammed, and so the boiler bursts.

No volcano has been so carefully watched for a long time as Vesuvius.
Its history illustrates the phases we have just mentioned. The first
recorded eruption is that of A. D. 79, a very severe one of the
violent type, by which Herculaneum, Pompeii, and Stabiæ were buried.
We have an interesting account by the younger Pliny. Before this
great eruption took place, Vesuvius had been in a state of repose
for eight hundred years, and if we may judge from the Greek and Roman
writings, was not even suspected of being a volcano. Then followed
an interval of rest until the reign of Severus, the second eruption
taking place in the year 203. In the year 472, says Procopius, all
Europe was covered more or less with volcanic ashes. Other eruptions
followed at intervals, but there was complete repose for two
centuries; that is, until the year 1306. In 1500 it was again active,
then quiet again for one hundred and thirty years. In 1631 there took
place another terrific outburst. After this many eruptions followed,
and they have been frequent ever since. Vesuvius is therefore now in
the second stage of moderate activity.

But geologists can take a wider view than this. They can sum up the
history of a volcanic region of the earth; and the result is somewhat
as follows: Volcanoes, like living creatures, go through different
periods or phases, corresponding roughly to youth, middle age, old
age, and finally decay. The invasion of any particular area of the
earth's surface by the volcanic forces is heralded by underground
shocks, or earthquakes. A little later on cracks are formed, as
indicated by the rise of saline and hot springs, and the issuing of
carbonic acid and other gases at the surface of the earth. As the
underground activity becomes greater, the temperature of the springs
and emitted gases increases; and at last a visible rent is formed,
exposing highly heated and glowing rock below. From the fissure thus
formed, the gas and vapours imprisoned in the molten rocks escape
with such violence as to disperse the latter in the form of pumice
and volcanic ash, or to cause them to pour out as lava-streams.

The action generally becomes confined to one or more points along the
line of action (which is a line of fissures and cracks). In this way
a chain of volcanoes is formed, which may become the seat of volcanic
action for a long time.

When the volcanic energies have become somewhat exhausted, so that
they cannot raise up the lava and expel it from the volcanic crater,
nor rend the sides of the volcano and cause minor cones to grow up
on their flanks, small cones may be formed at a lower level in the
plains around the great central chain. These likewise are fed from
fissures.

Later on, as the heated rock below cools down, the fissures are
sealed up by lava that has become solid; and then the volcanoes
fall, as it were, into the "sere and yellow leaf," and remain in a
peaceful, quiet state befitting their old age.

After this they begin to suffer from long exposure to the atmospheric
influences of decay, and rain and rivers wash them away more or less
completely.

But still the presence of heated rocky matter at no great depth
below is proved by the outbursts of gases and vapours, the forming
of geysers and ordinary hot springs. Gradually, however, even these
signs of heat below disappear; and the cycle of volcanic phases is at
an end. Such a series of changes may require millions of years; but
by the study of volcanoes in every stage of their growth and decline
it is possible thus to sketch out an outline of their history.

It must be confessed that in the present state of scientific
knowledge no full and complete explanation of volcanic action is
possible. Geologists and others are as yet but feeling their way
cautiously towards the light which, perhaps before long, will
illumine the dark recesses of this mysterious subject. Many theories
and ideas have been put forward, but in the opinion of the writer the
most promising explanation is one that may be briefly expressed as
follows:

There are below the crust of the earth large masses of highly
heated rock that are _kept solid_ by the enormous pressure of the
overlying rocks, or otherwise they would melt,--for it is a known
fact that pressure tends to prevent the melting of a solid body. But
when earth-movements taking place within the earth's crust--such
as the upheaving of mountain-chains--take off some of the weight,
the balance between internal heat and the pressure from above is no
longer maintained; and so these highly heated rocks run off into
the liquid state, and finding their way to the surface through the
fissures mentioned above, give rise to volcanic action. There is
much to be said in favour of this view. It rightly connects volcanic
action with movements of upheaval, with mountain-chains and lines of
weakness in the earth's crust.

There is very good reason to believe that the earth was once in a
highly heated state, and has been slowly cooling down for ages. The
increase of temperature observed in penetrating mines tells us that
it still retains below the surface some of its old heat. We need not
therefore be surprised at the existence of heated masses of rock down
below, or seek, as some have done, an entirely different source for
the origin of volcanic heat than that which remains from the earth's
once molten condition. It would take too long to state the reasons
on which this idea of the former state of our planet is based, and
moreover, it would bring us into the region of astronomy, with which
we are not concerned at present.

In various parts of Great Britain and Ireland we meet with old
volcanic rocks,--lavas, intrusive dykes, and sheets of basalt, etc.,
together with vast deposits of volcanic ash, which, sinking into
the old neighbouring seas, became stratified, or arranged in layers
like the ordinary sedimentary rocks. In some cases we see embedded
in these layers the very "bombs" that were thrown out by the old
volcanoes (see page 253). And besides these purely volcanic rocks, we
often meet in these areas with great bosses of granite, which must
have been in some way connected with the old volcanoes, and probably
were in many cases the source from which much of the volcanic rock
was derived. But more than this, in a few instances we have the site
of the old volcano itself marked out by a kind of pipe, or "neck,"
now filled with some of its volcanic débris in the shape of coarse,
rounded fragments (see page 277).

During a very ancient period, known to geologists as the Silurian
Period, great lava-flows took place from volcanoes situated where
North and South Wales and the Lake District now are; and by their
eruptions a vast amount of volcanic ash was made, which fell into
the sea and slowly sank to the bottom, so that the shell-fish living
there were buried in the strata thus formed, and may now be seen in a
fossilised condition.

  [Illustration: Fig. 1. THE RANGES OF THE GREAT BASIN, WESTERN
  STATES OF NORTH AMERICA, SHOWING A SERIES OF GREAT FRACTURES AND
  TILTED MASSES OF ROCK.]

  [Illustration: Fig. 2. SECTION THROUGH SNOWDON.]

Thus Snowdon, Cader Idris, the Arans, Arenig Mountain, and others,
are very largely made up of these ancient volcanic materials. The
writer has picked up specimens of fossil shell-fish near the summit
of Snowdon from a bed of fine volcanic ash that forms the summit.
Fig. 2 represents a section through Snowdon, from which it will be
seen that we have first a few sedimentary strata, _S_, then a great
lava-flow, _L_; and that volcanic ashes accumulated on the top of
this, of which _A A_ are patches still left. _B_ is an intrusive dyke
of a basaltic rock that forced its way through afterwards. Again, in
the Lake District there is a well-known volcanic series of stratified
rocks of the same age, consisting mostly of lavas and ashes, the
total thickness of which is about twelve thousand feet (known as the
"Green Slates and Porphyries"), so that a large part of some of the
mountains there have also been built up by volcanic action; but no
traces of the old volcanoes remain.

Going farther north we find abundant proof that volcanic action on
a prodigious scale took place in Scotland during the very ancient
period of the Old Red Sandstone, with which the name of Hugh Miller
will always be associated. In Central Scotland we see lava-flows and
strata formed of volcanic ash, with a thickness of more than six
thousand feet, fragments of which, having escaped the destructive
agents of denudation, now form important chains of hills, such
as the Pentland, Ochil, and Sidlaw ranges. Nor was the volcanic
action confined to this region. In the district of the Cheviot
Hills similar volcanic rocks are to be seen. But here again the old
volcanoes have long since been swept away, leaving us only portions
of their outpourings buried in the hills.

There can be no doubt that the present area of the Grampian Hills was
once the site of a considerable number of volcanoes, only at a much
higher level than their present surface, elevated though that is to
the region of the clouds; but in this case subsequent denudation has
been so enormous that the old mountain surface has been planed away
until all we can now see is a series of separate patches of granite,
that were once in a fused and highly heated state far below the
surface, and formed part of the subterranean reservoirs from which
the volcanoes derived their great supplies of lava and steam. It is
indeed difficult to imagine the enormous amount of denudation which
has taken place in the Highlands of Scotland, and to realise that the
magnificent range of the Cairngorms, for instance, has been for ages
worn down until now they are but a remnant of what they once were.

In this region we see the once boiling and seething masses of
rock which fed the old volcanoes, now no longer endowed with
life-like power by the force of steam, but lying in deathlike cold
and stiffness, with their beautiful crystals of mica and felspar
sparkling in the sun. The volcanic fires have died out; but the
traces of their work are unmistakable, among which we must not forget
to reckon the beautiful minerals made by the action of heated water
upon the surrounding rocks.

The beautiful cairngorm stones are still sometimes found on the
mountain from which they take their name, and in all volcanic regions
minerals are plentiful.

The well-known hill called Arthur's Seat, close to Edinburgh, marks
the site of an old volcano. The "neck," or central opening, may be
seen at the top of the hill, but choked up with volcanic rocks and
débris. The crater has long since disappeared, but Salisbury Craigs
and St. Leonard's Craigs are formed of a great sheet of basalt that
intruded itself among the stratified rocks that had been formed
there, and so belong really to a great intrusive dyke. In the Castle
Rock we see the same basalt again.

During a much later age, known as the Miocene Period (see chap. x.,
p. 324), enormous outpourings of lava took place in Western Europe,
covering hundreds of square miles. Of these the most important is
that which occupies a large part of the northeast of Ireland, and
extends in patches through the Inner Hebrides and the Faröe Islands
into Iceland. These eruptive rocks, unlike those above referred to,
must have poured out at the surface, and have taken the form of
successive sheets, such as we now see in the terraced plateaux of
Skye, Eigg, Canna, Muck, Mull, and Morven. These, then, are patches
of what once formed a great plain of basalt. During later times
this volcanic platform has been so greatly cut up by the agents of
denudation that it has been reduced to mere scattered fragments;
thousands of feet of basalt have been worn away from it; deep and
wide valleys have been carved out of it; and in many cases it has
been almost entirely stripped off from the wide areas it once
covered. Where, as in the Isle of Eigg, the lava has been piled up
in successive sheets, with some layers of volcanic ash between, the
latter has been worn away rather faster than the hard layers of
basalt, and each lava-flow is clearly marked by a terrace. These
volcanic eruptions have thus had a great influence in moulding the
scenery of this region. In Ireland the old basalts are well seen at
the Giant's Causeway, and on the Scottish coast we see them again at
the well-known Fingal's cave at Staffa. This island, like the others,
is just a patch of the old lava-streams.

Its curious six-sided columns illustrate a fact with regard to the
subsequent cooling of lava-flows. Some internal forces, analogous to
that which regulates the shapes of crystals, have caused it to crack
along three sets of lines, so placed with regard to each other as to
produce six-sided columns.

In Ireland the basalts attain a thickness of nine hundred feet; in
Mull they are about three thousand feet thick. It has been clearly
proved that Mull is the site of one of the old volcanoes of this
period, but very few others have as yet been detected. Perhaps the
eruptions took place mainly from large fissures, instead of from
volcanic cones, for it is known that the ground below the lava-sheets
has been rent by earthquakes into innumerable fissures, into which
the basalt was injected from below.

In this way a vast number of "dykes" were formed. These have been
traced by hundreds eastwards from this region across Scotland,
and even the north of England. In this case the molten rock was
struggling to get through the overlying rocks and escape at the
surface; but apparently it did not succeed in so doing, for we do not
find lava-flows to the east and south. These basalt dykes are found
as far south as Yorkshire, and can be traced over an area of one
hundred thousand square miles.

It is thus evident that in the Miocene Period a great and extensive
mass of molten basalt was underlying a large part of the British
Isles, and probably the weight of the thick rocks overlying it was
sufficient to prevent its escape to the surface. If it had succeeded
in so escaping and overflowing, how different the scenery of much of
Scotland and Northern England might have been!

  [Illustration: COLUMNAR BASALT AT CLAMSHELL CAVE, STAFFA. FROM A
  PHOTOGRAPH BY J. VALENTINE.]




CHAPTER IX.

MOUNTAIN ARCHITECTURE.

    The splendour falls on castle walls
      And snowy summits old in story;
    The long light shakes across the lakes,
      And the wild cataract leaps in glory.
    Blow, bugle, blow, set the wild echoes flying;
    Blow, bugle; answer, echoes, dying, dying, dying.

    TENNYSON.


The dying splendours of the sun slowly sinking and entering the
"gates of the West" may well serve as a fitting emblem of the
mountains in their beautiful old age, awaiting in silent and calm
dignity the time when they also must be brought low, and sink in the
waters of the ocean, as the sun appears daily to do. Yes, they too
have their day. They too had their rising, when mighty forces brought
them up out of their watery bed. Many of them have passed their
hey-day of youth, and their midday; while others, far advanced in old
age, are nearing the end of their course.

But as the sun rises once more over eastern seas to begin another
day, so will the substance of the mountains be again heaved up after
a long, long rest under the sea, and here and there will rise up from
the plains to form the lofty mountain-ranges of a distant future.

Everywhere we read the same story, the same circle of changes. The
Alpine peak that proudly rears its head to the clouds must surely
be brought low, and finally come back to the same ocean from which
those clouds arose. It is in this way that the balance between land
and water is preserved. In passing through such a great circle of
changes, the mountains assume various forms and shapes which are
determined by:--

   1. Their different ages and states of decay.

   2. The different kinds of rocks of which they are composed, and
   especially by their "joints," or natural divisions.

   3. The different positions into which these rocky layers have
   been squeezed, pushed, and crumpled by those stupendous forces
   of upheaval of which we spoke in chapter vi.

Let us therefore glance at some of these external forms, and then
look at the internal structure of mountains.

In so doing we shall find that we have yet a good deal more to learn
about mountains and how they were made; and also we shall then be in
a better position to realise not only how very much denudation they
have suffered, but also how greatly they have been disturbed since
their rocks were first made.

Every one who knows mountains must have observed how some are smooth
and rounded, others sharp and jagged, with peaks and pinnacles
standing out clearly against the sky; some square and massive, with
steep walls forming precipices; others again spread out widely at
their base, but the sloping sides end in a sharp point at the top,
giving to the mountain the appearance of a cone. Their diversities of
shape are so endless that we cannot attempt to describe them all.

First, with regard to the general features of mountains. Looked
at broadly, a mountain-range is not a mere line of hills or
mountains rising straight up from a plain on each side, such as
school-boys often draw in their maps; very far from it. Take the
Rocky Mountains, for instance. "It has been truly said of the Rocky
Mountains that the word 'range' does not express it at all. It is a
whole country populous with mountains. It is as if an ocean of molten
granite had been caught by instant petrifaction when its billows were
rolling heaven high."[28]

  [28] "The Crest of the Continent," by Ernest Ingersoll, Chicago,
  1885.

It has often been observed by mountain climbers that when they get
to the top of a high mountain, and take a bird's-eye view of the
country, all the mountain-tops seem to reach to about the same
height, so that a line joining them would be almost level. For this
reason, perhaps, writers so often compare them to the waves of an
ocean. This feature is very conspicuous in the case of the Scotch
Highlands.

Sir A. Geikie has well described what he saw from the top of Ben
Nevis:--

   "Much has been said and written about the wild, tumbled sea of
   the Highland Hills. But as he sits on his high perch, does it
   not strike the observer that there is after all a wonderful
   orderliness, and even monotony, in the waves of that wide
   sea? And when he has followed their undulations from north to
   south, all round the horizon, does it not seem to him that
   these mountain-tops and ridges tend somehow to rise to a
   general level; that, in short, there is not only on the great
   scale a marked similarity of contour about them, but a still
   more definite uniformity of average height? To many who have
   contented themselves with the bottom of the glen, and have
   looked with awe at the array of peaks and crags overhead, this
   statement will doubtless appear incredible. But let any one get
   fairly up to the summits and look along them, and he will not
   fail to see that the statement is nevertheless true. From the
   top of Ben Nevis this feature is impressively seen. Along the
   sky-line, the wide sweep of summits undulates up to a common
   level, varied here by a cone and there by the line of some
   strath or glen, but yet wonderfully persistent round the whole
   panorama. If, as sometimes happens in these airy regions, a
   bank of cloud with a level under-surface should descend upon
   the mountains, it will be seen to touch summit after summit,
   the long line of the cloud defining, like a great parallel
   ruler, the long level line of the ridges below. I have seen
   this feature brought out with picturesque vividness over the
   mountains of Knoydart and Glen Garry. Wreaths of filmy mist had
   been hovering in the upper air during the forenoon. Towards
   evening, under the influence of a cool breeze from the north,
   they gathered together into one long band that stretched for
   several miles straight as the sky-line of the distant sea,
   touching merely the higher summits and giving a horizon by
   which the general uniformity of level among the hills could be
   signally tested. Once or twice in a season one may be fortunate
   enough to get on the mountains above such a stratum of mist,
   which then seems to fill up the irregularities of the general
   platform of hill-tops, and to stretch out as a white phantom
   sea, from which the highest eminences rise up as little islets
   into the clear air of the morning.... Still more striking
   is the example furnished by the great central mass of the
   Grampians, comprising the Cairngorm Mountains and the great
   corries and precipices round the head of the Dee. This tract
   of rugged ground, when looked at from a distance, is found to
   present the character of a high, undulating plateau."[29]

  [29] Scenery of Scotland page 130, new edition.

This long level line of the Highland mountain-tops may be seen very
well from the lower country outside; for example, from the isles of
Skye and Eigg, where one may see the panorama between the heights of
Applecross and the Point of Ardnamurchan showing very clearly the
traces of the old table-land.

How are we to explain this curious fact, so opposed to our first
impressions of a mountain region? It is quite clear that the
old plateau thus marked out cannot be caused by the arrangement
or position of the rocks of which the Highlands are composed. If
these rocks were found to be lying pretty evenly in flat layers,
or strata, undisturbed by great earth-movements, we could readily
understand that they would form a plateau. But the reverse is the
case: the rocks are everywhere thrown into folds, and frequently
greatly displaced by "faults;" yet these important geological
features have little or no connection with the external aspect of the
country. It is therefore useless to look to internal structure for
an explanation. We must look outside, and consider what has been for
ages and ages taking place here.

As already pointed out, an enormous amount of solid rock has been
removed from this region--thousands and thousands of feet. It was
long ago planed down by the action of water, so that a table-land
once existed of which the tops of the present mountains are isolated
fragments. No other conclusion is possible. To the geologist every
hill and valley throughout the whole length and breadth of the
Highlands bears striking testimony to this enormous erosion. The
explanation we are seeking may therefore be summed up in one word,
"denudation." The valleys that now intersect the table-land have been
carved out of it. If we could in imagination put back again onto
the present surface what has been removed, we should have a mental
picture of the Highlands as a wide, undulating table-land; and this
rolling plain would suggest the bottom of the sea. The long flat
surfaces of the Highland ridges, cut across the edges of inclined
or even upright strata, are the fragments of a former base-line of
erosion; that is, they represent the general submarine level to which
the Highlands were reduced after exposure to the action of "rain and
rivers," and finally of the sea. As the sea gradually spread over it,
it planed down everything that had not been previously worn away, and
so reduced the whole surface to one general level like the sea-bed of
the present day. But it is not necessary to suppose that the whole
region was under water at the same time, and it is probable that
there were separate inland seas or lakes. In these the rocks of the
Old Red Sandstone were formed; and they in their turn have suffered
so much denudation that only patches and long strips of them are left
on the borders of the Highlands.

Before we speak of individual mountains and their shapes, it is
important to bear in mind another fact about mountain-chains;
namely, that they are very low in proportion to their breadth and
length. The great heights reached by some mountains produce such a
powerful impression on our senses that we hardly realise how very
insignificant they really are. It is only by drawing them on a true
scale that we can realise this. The surface of the earth is so vast
that even the highest mountains are in proportion but as the little
roughnesses on the skin of an orange. Fig. 2 (see chap, vii., p. 236)
represents a section through the Highlands, drawn on the same scale
for height as for length.


What has been said about the Highland plateau applies equally well
to many other mountain-ranges. Mr. Ruskin observed something rather
similar in the Alps. He says,--

   "The longer I stayed in the Alps, and the more closely I
   examined them, the more I was struck by the one broad fact of
   there being a vast Alpine plateau, or mass of elevated land,
   upon which nearly all the highest peaks stood like children set
   upon a table, removed, in most cases, far back from the edge
   of the plateau, as if for fear of their falling; ... and for
   the most part the great peaks are not allowed to come to the
   edge of it, but remain like the keeps of castles, withdrawn,
   surrounded league beyond league by comparatively level fields
   of mountains, over which the lapping sheets of glaciers writhe
   and flow, foaming about the feet of the dark central crests
   like the surf of an enormous sea-breaker hurled over a rounded
   rock and islanding some fragment of it in the midst. And the
   result of this arrangement is a kind of division of the whole
   of Switzerland into an upper and a lower mountain world,--the
   lower world consisting of rich valleys, bordered by steep but
   easily accessible, wooded banks of mountain, more or less
   divided by ravines, through which glimpses are caught of the
   higher Alps; the upper world, reached after the first steep
   banks of three thousand or four thousand feet in height have
   been surmounted, consisting of comparatively level but most
   desolate tracts of moor and rock, half covered by glacier, and
   stretching to the feet of the true pinnacles of the chain."

He then points out the wisdom of this arrangement, and shows how it
protects the inhabitants from falling blocks and avalanches; and
moreover, the masses of snow, if cast down at once into the warmer
air, would melt too fast and cause furious inundations.

All the various kinds of rocks are differently affected by the
atmospheric influences of decay, and so present different external
appearances and shapes, so that after a little experience the
geologist can recognize the presence of certain rocks by the kind
of scenery they produce; and this knowledge is often of great use
in helping him to unravel the geological structure of a difficult
region. Thus granite, crystalline schists, slates, sandstones, and
limestones, all "weather" in their own ways, and moreover split up
differently, because their joints and other natural lines of division
run in different ways.

Thus granite is jointed very regularly, some of the joints running
straight down and others running horizontally, so that the rain and
atmosphere seize on these lines and widen them very considerably; and
thus the granite is weathered out either in tall upright columns,
like those seen at Land's End, or else into great square-shaped
blocks with their corners rounded off, presenting the appearance
of a number of knapsacks lying one over the other. In this way
we can account for the well-known "Tors" of Devonshire, and the
"Rocking Stones." Granite weathers rapidly along its joints, and
its surfaces crumble away more rapidly than might be expected,
considering how hard a rock it is; but the felspar which is its chief
mineral constituent is readily decomposed by rain water, which acts
chemically upon it. The deposits of China clay in Devonshire are
the result of the decomposition and washing away of the granite of
Dartmoor.

Granite mountains are generally rounded and "bossy," breaking now
and then into cliffs, the faces of which are riven by huge joints,
and present a very different appearance from those composed of
crystalline schists with their sharp crests and peaks. Ben Nevis and
the Cairngorms are partly composed of granite.

Gneiss is a rock composed of the same minerals as granite; namely,
mica, quartz, and felspar. And yet mountains composed of this rock
have quite a different aspect, and sometimes, as in the Alps, produce
very sharp and jagged pinnacles. The reason of this is that gneiss
splits in a different way from granite, because its minerals are
arranged in layers, and so it is more like a crystalline schist.

Mica-schist is another rock very abundant in mountain regions. This
rock is composed of quartz and mica arranged in wavy layers. The
mica, which is very conspicuous, lies in thin plates, sometimes
so dovetailed into each other as to form long continuous layers
separating it from those of the quartz; and it readily splits along
the layers of mica. This mineral is easily recognised by its bright,
shiny surface. There are, however, two varieties,--one of a light
colour and the other black.

Mica-schist and gneiss are often found in the same region, and are
the materials of which most of the highest peaks in Europe are
composed. We find them abounding in the district of Mont Blanc; and
all the monarch's attendant _aiguilles_, with the splintered ridges
enclosing the great snowfields in the heart of the chain, consist
mostly of these two rocks. The Matterhorn, Weisshorn, Monte Viso, the
Grand Paradis, the Aiguille Verte and Aiguille du Dru are examples of
the wonderful forms produced by the breaking up and decay of these
two rocks.

The different varieties of slate split in a very marked way. Slates
are often associated with the schists, and exert their influence in
modifying the scenery.

Limestone ranges, though less striking in the outlines of their
crests than those composed of slates and crystalline schists, and not
reaching to such heights, are nevertheless not at all inferior in the
grandeur of their cliffs, which frequently extend for miles along the
side of a valley in vast terraces, whose precipitous walls are often
absolutely inaccessible. The beauty of limestone mountains is often
enhanced by the rich pastures and forests which clothe their lower
slopes. The dolomitic limestone of the Italian Tyrol, being gashed by
enormous vertical joints and at the same time having been formed in
rather thin layers which break up into small blocks, produces some
very striking scenery. But wild as these mountainous ridges may be,
their forms can never be confounded with those of the crystalline
schists; for however sharp their pinnacles may appear at first sight,
careful examination will always show that their outline is that
of ruined masonry, suggesting crumbling battlements and tottering
turrets, and not the curving, flame-like crests and splintered peaks
of the crystalline schists.[30]

  [30] Bonney.

It has already been explained that all sedimentary rocks have been
formed under water in layers or strata, and it must be obvious
that the stratification of such rocks has an important influence
on scenery; and very much depends on whether the strata have been
left undisturbed, with perhaps just a slight slope, or whether they
have been folded and crumpled; for the position of the strata, or
"bedding," as it is called,--whether flat, inclined, vertical, or
contorted,--largely determines the nature of the surface. Undoubtedly
the most characteristic scenery formed by stratified rocks is to be
seen in those places where the "bedding" is horizontal, or nearly so,
and the strata are massive. A mountain constructed of such materials
appears as a colossal pyramid, the level lines of stratification
looking like great courses of masonry. The joints that cut across the
strata allow it to be cleft into great blocks and deep chasms; so
that, as in the case of the dolomitic limestone above mentioned, we
find a resemblance to ruined buildings.

We cannot find a better example of this in our own country than the
mountains of sandstone and conglomerate (of the Cambrian age) that
here and there lie on the great platform of old gneiss in the west of
Sutherland and Ross. Sir A. Geikie says,--

   "The bleak, bare gneiss, with its monotonous undulations,
   tarns, and bogs, is surmounted by groups of cones, which for
   individuality of form and independence of position better
   deserve to be called mountains than most of the eminences to
   which that name is given in Scotland. These huge pyramids,
   rising to heights of between two thousand and four thousand
   feet, consist of dark red strata, so little inclined that
   their edges can be traced by the eye in long, level bars on
   the steeper hillsides and precipices, like lines of masonry.
   Here and there the hand of time has rent them into deep rifts,
   from which long 'screes' (slopes of loose stones) descend into
   the plains below, as stones are detached from the shivered
   walls of an ancient battlement. Down their sides, which have in
   places the steepness of a bastion, vegetation finds but scanty
   room along the projecting ledges of the sandstone beds, where
   the heath and grass and wildflowers cluster over the rock in
   straggling lines and tufts of green; and yet, though nearly as
   bare as the gneiss below them, these lofty mountains are far
   from presenting the same aspect of barrenness. The prevailing
   colour of their component strata gives them a warm red hue,
   which even at noon contrasts strongly with the grey of the
   platform of older rock.... These huge isolated cones are among
   the most striking memorials of denudation anywhere to be seen
   in the British Isles. Quinag, Canisp, Suilven, Coulmore, and
   the hills of Coygoch, Dundonald, Loch Maree, and Torridon are
   merely detached patches of a formation not less than seven
   thousand or eight thousand feet thick, which once spread
   over the northwest of Scotland. The spaces between them were
   once occupied by the same dull red sandstone; the horizontal
   stratification of one hill, indeed, is plainly continuous with
   that of the others, though deep and wide valleys, or miles
   of low moorland, may now lie between. While the valleys have
   been worn down through the sandstone, these strange pyramidal
   mountains that form so singular a feature in the landscapes of
   the northwest highlands have been left standing, like lonely
   sea-stacks, as monuments of long ages of waste."[31]

  [31] Scenery of Scotland, page 201, new edition.

Again, the vast table-lands of the Colorado region illustrate on
a truly magnificent scale, to which there is no parallel in the
Old World, the effects of atmospheric erosion on undisturbed and
nearly level strata. Here we find valleys and river gorges deeper
and longer than any others in the world; great winding lines of
escarpment, like ranges of sea cliffs; terraced slopes rising at
various levels; huge buttresses and solitary monuments, standing like
islands out of the plains; and lastly, great mountain masses carved
out into the most striking and picturesque shapes, yet with their
lines of "bedding" clearly marked out.

On the other hand, where, as is almost always the case in
mountain-ranges, the stratified rocks have been folded, crumpled,
twisted, and fractured by great "faults," we find a very different
result. In these cases the rocks have generally been very much
altered by the action of heat. For here we find crystalline schists,
gneiss, granite, and other rocks in the formation of which heat has
played an important part; and very often the igneous rocks have
forced their way through those of sedimentary origin and altered them
into what are called metamorphic rocks (see chapter v., page 156).
Thus they have lost much of their original character and structure.

The repeated uplifts and subsidences of the earth's crust, by which
the continents of the world have been raised up out of the sea
to form dry land, have, broadly speaking, thrown the rocky strata
into a series of wave-like undulations. In some extensive regions
these undulations are so broad and low that the curvature is quite
imperceptible, and the strata appear to lie in horizontal layers, or
to slope very slightly in a certain direction. This is, in a general
way, the position of the strata of which plains and plateaux are
composed.

But in the longer and comparatively narrow mountain regions that
traverse each of the great continents, forming, as it were, backbones
to them, the undulations are very much more frequent, narrower, and
higher. Sometimes the rocks have been thrown into huge open waves, or
the folds are closely crowded together, so that the strata stand on
their ends, or are even completely overturned, and thus their proper
order of succession is reversed, and the older ones actually lie on
the top of the newer ones.

As we approach a great mountain-chain we observe many minor ridges
and smaller chains running roughly parallel with it, and, as it
were, foreshadowing the great folds met with in the centre of the
chain and among its highest peaks. These small folds become sharper
and closer the nearer we get to the main chain, and evidently were
formed by the same movements that uplifted the higher ranges beyond;
but the force was not so great. Thus we find the great Alpine chain
flanked to the north by the smaller ranges of the Jura Mountains; and
on the south, side of the Himalayas we find similar smaller ranges of
hills.

Ruskin thus describes his impression of the Jura ranges, which he
very aptly compares with a swell on the sea far away from a storm,
the storm being represented by the wild sea of Alpine mountains:--

   "Among the hours of his life to which the writer looks back
   with peculiar gratitude, as having been marked with more
   than ordinary fulness of joy or clearness of teaching, is
   one passed, now some years ago, near time of sunset, among
   the masses of pine forest which skirt the course of the Ain,
   above the village of Champagnole, in the Jura. It is a spot
   which has all the solemnity, with none of the savageness, of
   the Alps; where there is a sense of a great power beginning
   to be manifested in the earth, and of a deep and majestic
   concord in the rise of the long low lines of piny hills,--the
   first utterance of those mighty mountain symphonies, soon to
   be more loudly lifted and wildly broken along the battlements
   of the Alps. But their strength is as yet restrained; and the
   far-reaching ridges of pastoral mountain succeed each other,
   like the long and sighing swell which moves over quiet waters
   from some far-off stormy sea.

   "And there is a deep tenderness pervading that vast monotony.
   The destructive forces and the stern expression of the central
   ranges are alike withdrawn. No frost-ploughed, dust-encumbered
   paths of ancient glacier fret the soft Jura pastures; no
   splintered heaps of ruin break the fair ranks of her forests;
   no pale, defiled, or furious rivers rend their rude and
   changeful ways among her rocks. Patiently, eddy by eddy, the
   clear green streams wind along their well-known beds; and under
   the dark quietness of the undisturbed pines there spring up,
   year by year, such company of joyful flowers as I know not the
   like among all the blessings of the earth."

Long faults, or fractures, where the strata have been first bent
and then broken, and afterwards have been forced up or have slid
down hundreds or even thousands of feet, are very numerous in
mountain-ranges; and by suddenly bringing quite a different set of
rocks to the surface, these faults cause considerable difficulty to
the geologist, as he goes over the ground and endeavours to trace the
positions of the different rocks.

In these vast folds it sometimes happens that portions of older (and
lower) strata are caught up and so embedded among those of newer
rocks. It will therefore be readily perceived that to unravel the
geological structure of a great mountain-chain is no easy task.
We need not then be surprised if in some cases the arrangement of
the rocks of mountains is not thoroughly understood. The wonder
is, when we think of the numerous difficulties which the geologist
encounters,--the arduous ascents, the precipices, glaciers,
snowfields obscuring the rocks from his view, the overlying soil
of the lower parts, and the steep crests and dangerous ridges that
separate the snowfields,--that so much has already been discovered in
this difficult branch of geology.

However, the general arrangement of the rocks of which many
mountain-chains are composed has been satisfactorily made out in not
a few cases. Let us look into some of these and see what has been
discovered.

You will remember the structure of the Weald, described in chap.
vii., pp. 235-238, and how we showed that a great low arch of chalk
strata has been entirely removed over that area, so that at the
present time only its ends are seen forming the escarpments of the
North and South Downs. This area, then, is now a great open valley,
or rather a gently undulating plain enclosed by low chalk hills. Now,
an arch of this kind is called an "anticline," and it might have been
expected that it would have remained more or less unbroken to the
present day. Why, then, has it suffered destruction?

In the first place, chalk is a soft rock, and one that rain water can
dissolve; but more than that, its arch-like structure was against it,
and its chance of preservation was decidedly small. In architecture
the arch is the most firm and stable structure that can be made; but
not so with strata, and this is the reason. Such an arch was not made
of separate blocks, closely fitting and firmly cemented together;
on the contrary, the arch was stretched and heaved up from below.
It therefore must have been more or less cracked up; for rocks are
apt to split when bent, although when deeply buried under a great
thickness of overlying rocks, they will bend very considerably
without snapping. But this was not the case here. And so the forces
of denudation set to work upon an already somewhat broken mass of
rock. Try to picture to yourself this old low arch of chalk as it was
when it first appeared as dry land. Probably some of it had already
been planed away by the waves of the sea, and what was left was by
no means well calculated to withstand the action of the agents of
denudation. If you look back to the figure, you will see the dotted
lines showing the former outline of this anticline, or arch, and you
perceive at once that the strata must have been sloping outwards away
from the middle. Now, this one fact greatly influenced its fate, for
an anticline cannot be regarded as a strong or stable arrangement
of strata. It is easy to see why; suppose a little portion were cut
away on one side at its base by some stream. It is clear that a kind
of overhanging cliff would be left, and blocks of chalk would sooner
or later come rolling down into the valley of the little stream.
When these had fallen, they would leave an inclined plane down which
others would follow; and this would continue to take place until the
top of the arch was reached. The same reasoning applies to the other
side. It is very seldom that arches, or anticlines, can last for a
long time. The outward slope of the strata and their broken condition
are against them.

But when the rocks dip _inwards_, to form a kind of trough or basin,
it is just the opposite. Such basins are known as "synclines;" and
a structure of this kind can be shown to be much more stable and
permanent than an anticline. The strata, instead of being stretched
out and cracked open, have been squeezed together.

It is very important to bear this in mind, and to remember how
differently anticlines and synclines are affected; for this simple
rule is illustrated over and over again in mountain-ranges:--

   Anticlines, being unstable, are worn away until they become
   valleys.

   Synclines, being stable, are left and frequently form mountains.

Now look at the section through the Appalachian chain (see Fig.
1), and you will see that each hill is a syncline, and the valleys
between them are anticlines. This happens so frequently that almost
every range of mountains furnishes examples; but as every rule has
its exceptions, so this one has, and we may find an example in the
case of the Jura Mountains outside the Alps.

It will be seen from the section that the ridges are formed by
anticlines, and the valleys by synclines. But on looking a little
more closely, we see that the tops of the former have suffered a
considerable amount of erosion (as indicated by the dotted lines).
Now, the reason why they have not been completely worn down into
valleys is that these rocks were once covered by others overlying
them, so that this outer covering of rocks had first to be removed
before they could be attacked by rain and rivers. These wave-like
ridges of the Jura are being slowly worn down; and the time must
come when they will be carved out into valleys, while the synclines
between them will stand out as hills. It is simply a question of
time. But many mountain-chains have a far more complicated structure
than that of the Appalachians, and consist of violently crumpled and
folded strata (see section of Mont Blanc, Fig. 3).

  [Illustration: SECTIONS OF MOUNTAIN-RANGES, SHOWING THEIR
  STRUCTURE AND THE AMOUNT OF ROCK WORN AWAY.]

It might naturally be asked how such sections are made, considering
that we cannot cut through mountains in order to find out their
structure; but Nature cuts them up for us, gashing their sides with
ravines and valleys carved out by streams and rivers, and in steep
cliffs and precipices we find great natural sections that serve our
purpose almost equally well. Sometimes, however, we get considerable
help from quarries and railway-cuttings.

Take, for example, one of the synclinal folds in the Appalachian
chain. Its structure is ascertained somewhat as follows. Suppose you
began to ascend the hill, armed with a good map, a pocket-compass, a
clinometer,--a little instrument for measuring the angles at which
strata dip or slope,--and with a bag on your back for specimens
of rocks and fossils. At the base of the hill you might notice at
starting a certain layer of rock--say a limestone--exposed by the
side of the stream. It will be so many feet thick, and will contain
such-and-such fossils, by means of which you can identify it; and
it will dip into the interior of the hill at a certain angle, as
measured by the clinometer. As you rise higher, this rock may be
succeeded by sandstone of a certain thickness, and likewise dipping
into the hill; and so with the other rocks that follow, until you
reach the summit.

By the time you have reached the top of the hill, you know the nature
of all the rocks up that side, and the way they dip; and all your
observations are carefully recorded in a notebook. Then you begin
to descend on the other side, and in so doing you find the same set
of rocks coming out at the surface all in the same order; only this
order is now reversed, because you are following them downwards
instead of upwards. Of course they are hidden in many places by soil
and loose stones; but that does not matter, because at other places
they are exposed to view, especially along ravines, carved out of
the mountain-side. Also rocks "weather" so differently that they can
often be distinguished even at a distance.

In this kind of way you can find out the structure of a mountain,
and draw a section of it when you get home, by following out and
completing the curves of the strata as indicated at or near the
surface; and you find they fit in nicely together.

Fig. 3 (see page 307) represents what is believed to be the general
arrangement of the rocks of Mont Blanc. The section is greatly
simplified, because many minor folds and all the faults, or
dislocations, are omitted. Now, in this case we have an example of
what is known as the "fan-structure." It will be seen at once that
the folds have been considerably squeezed together; and the big fold
in the centre indicated by dotted lines has been so much compressed
in the lower part--that is, in what is now Mont Blanc--that its sides
were brought near to each other until they actually sloped inwards
instead of outwards.

You may easily imitate this structure by taking a sheet of paper,
laying it on the table, and then, putting one hand on each side of
it, cause it to rise up in a central fold by pressing your hands
towards each other. Notice carefully what happens. First, you get a
low arch, or anticline, like that of the Weald. Then as you press it
more, the upward fold becomes sharper and narrower; then continue
pressing it, and you will find the fold bulging out at the top, but
narrowing in below until you get this fan-structure.

This is just what has happened in the case of the Alps. A tremendous
lateral pressure applied to the rocks heaved them up and down
into great and small folds, and in some places, as in Mont Blanc,
fan-structure was produced. Imagine the top of the fan removed, and
you get what looks like a syncline, but is really the lower part of a
very much compressed anticline.

Now, it is believed that all mountain-ranges have been enormously
squeezed by lateral pressure; and the little experiment with the
sheet of paper furnishes a good illustration of what has happened. A
table-cloth lying on a smooth table will serve equally well. You can
easily push it into a series of folds; notice how they come nearer
as you continue pushing. You see also that in this way you get long
narrow ridges with valleys between. These represent the original
anticlines and synclines of mountain-ranges, which in course of time
are carved out, as explained above, until the synclines become hills
and the anticlines valleys.

Every mountain-chain must originally have had long ridges like these,
which in some cases determined the original directions of the streams
and valleys; and it is easy to see now why mountain-chains are long
and narrow, why their strata have been so greatly folded, and why
we get in every mountain-chain long ranges of hills roughly parallel
with each other (see chapter vi., pages 177-178).

The reason why granite, gneiss, and crystalline schists are
frequently found in the central and highest peaks of mountain-ranges
is that we have the oldest and lowest rocks exposed to the surface,
on account of the enormous amount of denudation that has taken place.
There may be great masses of granite underlying all mountain-chains;
but it is only exposed to view when a very great deal of overlying
rock has been removed.

It was thought at one time that granite was the oldest of all rocks,
and that mountain-chains had been upheaved by masses of granite
pushing them up from below; but we know now that both these ideas
are mistaken. Some granites are certainly old geologically, but
others are of later date; and it is certain that granite was not the
upheaving agent, but more likely it followed the overlying rocks as
they were heaved up by lateral pressure, because the upward bending
of the rocks would tend to relieve the enormous pressure down below,
and so the granite would rise up.

  [Illustration: MONT BLANC. SNOWFIELDS, GLACIERS. AND STREAMS.]

We now pass on to a very different example, where mountains are the
result of huge fractures and displacements; namely, the numerous
and nearly parallel ranges of the Great Basin, of Western Arizona,
and Northern Mexico. The region between the Sierra Nevada and the
Wahsatch Mountains, extending from Idaho to Mexico, is composed
of very gently folded rocks deeply buried in places by extensive
outflows of lava.

Now, in this case the earth-movements caused great cracks, or splits,
doubtless attended by fearful earthquakes. We find here a series of
nearly parallel fractures, hundreds of miles long, and fifteen to
thirty miles apart. These traverse the entire region, dividing the
rocks into long narrow blocks. There is evidence to show that the
whole region was once much more elevated than it is now, and has
subsided thousands of feet. During the subsidence along these lines
of fracture, or faults, the blocks were tilted sideways; and the
uptilted blocks, carved by denudation, form the isolated ranges of
this very interesting region (see illustration, chap. viii., p. 273,
Fig. 1). The faults are indicated by arrows pointing downwards; and
the dotted lines indicate the erosion of the uptilted blocks.

But this must be regarded as a very exceptional case, for we do not
know of any other mountain-range formed quite in the same way. Why
the strata, although only slightly bent, should have snapped so
violently in this case, while in other mountain-ranges they have
suffered much more bending without so much fracture and displacement,
we cannot tell, but can only suggest that possibly it was because
they were not buried up under an enormous thickness of overlying
rocks, which would exert an enormous downward pressure, and so tend
to prevent fracturing.

There are many other deeply interesting questions with regard to the
upheaval of mountains which at present cannot be answered.

We have already learned to alter our preconceived ideas about the
stability and immovable nature of the earth's crust, and have seen
that it is in reality most unstable, and is undergoing continual
movements, both great and small. But here we have an equally
startling discovery, which quite upsets all our former ideas of the
hard and unyielding nature of the rocks composing the earth's crust;
for we find that not only can they be bent into innumerable folds
and little puckerings, but that in some cases they have been drawn
out and squeezed as if they were so much soft putty. The imagination
almost fails to grasp such facts as these.

Of late years geologists in Switzerland and in Great Britain have
discovered that in some parts of mountains rocks have been enormously
distorted and crushed, so that they have assumed very different
states from those in which they were made, and curious mineral
changes have taken place under the influence of this crushing.

In the very complicated region of the Northwest Highlands of
Sutherland and Ross, the structure of which has only lately been
explained, some wonderful discoveries of this nature have been
made. Certain of the crystalline schists found there have been
formed by the crushing down and rearrangement of older rocks that
once presented a very different appearance. In this district,
where the rocks have been squeezed by enormous lateral pressure,
the dislocations sometimes have assumed the form of inclined or
undulating planes, the rocks above which have been actually pushed
over those below, and in some cases the horizontal displacement
amounts to many miles.

Not only have the rocks been ruptured, and older, deep-seated masses
been torn up and driven bodily over younger strata (that once were
_above_ them), but there has been at the same time such an amount
of internal shearing as to crush the rocks into a finely divided
material, and to give rise to a streaky arrangement of the broken
particles, closely resembling the flow-structure of a lava. In the
crushed material new minerals have been sometimes so developed as to
produce a true schist.[32]

  [32] Geikie.




CHAPTER X.

THE AGES OF MOUNTAINS, AND OTHER QUESTIONS.

    O Earth, what changes hast thou seen!

    TENNYSON.


It might naturally be asked at what period in the world's primeval
or geological history some particular mountain-range was upheaved;
whether it is younger or older than another one perhaps not very
far away; and again, whether the mountain-chains of the world have
been uplifted all at once, or whether the process of elevation was
prolonged and gradual?

Questions such as these are deeply interesting, and present to the
geologist some of the most fascinating problems to be met with in the
whole range of this science. And though at first sight they might
seem hopelessly beyond our reach, yet even here the prospect is by no
means unpromising; and it is quite possible to show that they can be
answered to some extent. Here we shall find our illustration of the
cathedral (see chapter v., pages 143-147) holds good once more.

It is perhaps hardly necessary to explain that by looking at a
Gothic cathedral one can say at what period or periods it was built.
Perhaps it has a Norman nave, with great pillars and rounded arches.
Then the chancel might be Early English, with pointed windows and
deep mouldings, and other features that serve to mark the style of
the building, and therefore its date,--because different styles
prevailed at different periods. Other parts might contain work easily
recognised as belonging to the "Perpendicular" period.

Now, as there have been periods in the history of architecture and
art, so there have been periods in the history of our earth. What
these periods were, and how we have learned to recognise them, we
must first very briefly describe.[33]

  [33] For a fuller account see the writer's "Autobiography of the
  Earth."

There are two simple rules by which the age of an ordinary
sedimentary rock may be ascertained. This is fixed (1) By its
position with regard to others; (2) By the nature of its embedded
animal or vegetable remains, known as fossils.

These rules may easily be illustrated by a reference to the methods
of the antiquary. For instance, suppose you were going to build
a house, and the foundations had just been dug out; you might on
examining them find several old layers of soil, showing that the site
or neighbourhood had been formerly occupied. You might find in one
layer stone implements, in another Roman or early British pottery,
and yet again portions of brick or stonework, together with tools
or articles of domestic use, belonging, say, to the time of Queen
Elizabeth. Now, which of these layers would be the oldest? It is
quite clear that the lowest layers must have been there the longest,
because the others accumulated on the top of them.

The explorations made of late years under Jerusalem have led to the
interesting discovery that the modern city is built up on the remains
of thirteen former cities of Jerusalem, all of which have been
destroyed in one way or another. Here, again, it is quite clear that
the oldest layer of débris must be that which lies at the bottom, and
the newest will be the one on the top.

Again, you know that the "Stone Age" in Britain came before the Roman
occupation. Those old stone implements were made by a barbarous race,
who knew very little of agriculture or the arts of civilisation. Then
in succeeding centuries various arts were introduced, many relics of
which are found buried in the soil; and hence, since different styles
of art and architecture prevailed at different periods, the works of
art or industry embedded in any old layers of soil serve to fix the
date of those layers.

These layers of soil and débris correspond to the layers or strata of
the sedimentary rocks, in which the different chapters of the world's
history are recorded. Geology is only another kind of history; and
the same principles which guide the archæologist searching buried
cities also guide the geologist in reading the stony record. As the
illustrious Hutton said, "The ruins of an older world are visible
in the present state of our planet." The successive layers of ruin
in this case are to be seen in the great series of the stratified
rocks; and we may lay it down as an axiom that the lowest strata are
the oldest, unless by some subsequent disturbance the order should
have been reversed, which, fortunately, is a rare occurrence, though
examples are to be found in some mountain-chains with violent
foldings.

But it often happens that neither the strata which should come
above nor those that lie below can be seen. Then our second rule
comes in: We can determine the age of the rock in question by its
fossils. The reason of this has perhaps already been guessed by the
reader. It is that as different kinds of plants and animals have
prevailed at different periods of the world's history, so there have
been "styles," or fashions, in creation, as well as in art. At one
geological period certain curious types of fishes flourished which
are now almost extinct, only a few old-fashioned survivals being
found in one or two out-of-the-way places. At another period certain
types of reptiles flourished vigorously, and were the leaders in
their day; but they have altogether vanished and become extinct. So
one type after another has appeared on the scene, played its humble
part in the great drama of life; and then--"exit!" another takes its
place.

In the oldest and lowest of the series of rocks we find no certain
trace of life at all. In the next series we find only lowly
creatures, such as shell-fish, corals, and crab-like animals that
have no backbone. In a higher group of rocks fishes appear for the
first time. Later on, we come across the remains of amphibious
creatures for the first time. Then follows (after a long unrecorded
interval) an era when reptiles and birds existed in great numbers.
After another long interval we come to strata containing many and
diverse remains of mammals or quadrupeds. So we have an "Age of
Fishes," an "Age of Reptiles," and an "Age of Mammals." Some tribes
of these creatures died out, but others lived on to the present day.
Thus we see that there has been a continuous progress in life as the
world grew older, for higher types kept coming in.

To the geologist fossils are of the greatest possible use, since they
help him to determine the age of a particular set of strata, for
certain kinds of fossils belong to certain rocks, and to them only.

But the classification of the stratified rocks has been carried
farther than this. Practical geologists, working in the field, use
fossils as their chief guide in working out the subdivisions of a
group of rocks, for certain genera and species of old plants and
animals are found to belong to certain small groups of strata. In
this way a definite order of succession has been established once
for all; and, except in the case of inverted strata already alluded
to, this order is invariably found to hold good.

This great discovery of the order of succession of the British
stratified rocks, established by their fossil contents, is due to
William Smith, the father of English geology. After exploring the
whole of England, he published in 1815 a geological map, the result
of his extraordinary labours. Before then people had no idea of a
definite and regular succession of rocks extending over the country,
capable of being recognised to some extent by the nature of the
rocks themselves,--whether sandstones, clays, or limestones, etc.,
but chiefly by their own fossils. They thought the different kinds
of rocks were scattered promiscuously up and down the face of the
country; but _now_ we know that they do not show themselves in this
haphazard way, but have definite relations to each other, like the
many volumes of one large book.

By combining the two principles referred to above, geologists have
arranged the great series of British stratified rocks into certain
groups, each indicating a long period of time. First, they are
roughly divided into three large groups, marking the three great eras
into which geological time is divided. Secondly, these eras are
further divided into certain periods. These periods are again divided
into epochs, indicated by local divisions of their rocks. In this way
we have something like a historical table. Omitting the small epochs
of time, this table is as follows, in descending order:--

_Table of the British Stratified Rocks._

       ERA.         PERIOD.           PREVAILING TYPE.

               { Recent.
    Cainozoic, { Pleistocene,
       or      {    or
    Tertiary.  { Quaternary.          Mammals.
               { Pliocene.
               { Miocene.
               { Eocene.

               { Cretaceous.
    Mesozoic,  { Neocomian.
       or      { Jurassic.            Reptiles.
    Secondary. { Triassic.
               { Permian.

               { Carboniferous.       Fishes.
               { Devonian, and
    Palæozoic, { Old Red Sandstone.
       or      { Silurian.            Creatures without
    Primary.   { Cambrian.            a backbone
               { Archæan,[34]          (invertebrates).
               {    or
               { Pre-Cambrian.

  [34] The Archæan rocks are frequently placed in a separate group
  below the Palæozoic.

The total thickness of all these rocks has been estimated at about
one hundred thousand feet, or not far from twenty miles. These
names have been given partly from the region in which the rocks
occur, partly from the nature of the rocks themselves, and partly
for other reasons. Thus the Old Red Sandstone is so called, because
it generally, though not always, appears as a dark red sandstone.
But the Silurian rocks, which we find in North Wales, receive
their name from the Silures, an ancient Welsh tribe; the Cambrian
rocks take theirs from Cambria, the old name for North Wales. The
Cretaceous rocks are partly composed of chalk, for which the Latin
word is _creta_; and so on. The terms "Palæozoic," "Mesozoic," and
"Cainozoic" mean "ancient life," "middle life," and "recent or new
life," thus indicating that as time went on the various types of
life that flourished on the earth became less old-fashioned, and
more like those prevailing at the present time. These used to be
called "Primary," "Secondary," and "Tertiary;" but the terms were
unfortunate, because the primary rocks, as then known, were not the
first, or oldest. We have therefore included the Archæan rocks,
since discovered, in this primary group. Only one fossil has been
found in these rocks, and that is a doubtful one; hence they are
sometimes called "Azoic," that is, "without life." The Mesozoic rocks
are, as it were, the records of the "middle ages" in the world's
history; while the Palæozoic take us back to a truly primeval time.

We have now learned how the geological age of any group of rocks
may be determined. Thus, if a series of rocks of unknown age can be
shown to rest on undoubtedly Silurian rocks in one place, and in
another place to be overlaid or covered by undoubtedly Carboniferous
rocks, they will probably belong to the Old Red Sandstone Period. If
afterwards we find that they contain some of the well-known fossils
of that period, the question of their age is settled at once. But we
want more evidence than this. Suppose, now, we find somewhere on the
flanks of a mountain-range a series of Permian and Triassic rocks,
resting almost horizontally on disturbed and folded Carboniferous
strata. Does not that at once prove that the upheaval took place
before the Permian Period? Clearly it does, because the Permian rocks
have evidently _not_ been disturbed thereby. So now we can fix the
date of our range of hills; namely, after the Carboniferous Period
and before the Permian Period.

It is by such reasoning that the age of our Pennine range of hills,
extending from the north of England into Derbyshire, has been fixed;
for the Permian and Triassic strata lie undisturbed on the upheaved
arch of Carboniferous rocks of which this chain is composed. Its
structure is that of a broken and much denuded anticline, which
stands up to form a line of hills only because the Carboniferous
limestone is so much harder than the "coal measures," or coal-bearing
rocks, on each side of it, that it has not been worn away so fast. In
time, this great anticline will be entirely worn away like that of
the Weald. It is called the Great Mountain Limestone, because it so
often rises up to form high ground. The Mendip Hills in Somersetshire
are of about the same date, and they too are largely composed of this
great limestone formation.

Of course, a certain amount of up and down movement took place after
the hills were upheaved, otherwise the Permian and Triassic rocks
could not have been deposited on their sides; but these movements
were slight and of a more general kind than those by which strata are
thrown into folds.

The main upheaval, by which the rocks now forming the Highlands of
Scotland were lifted up and contorted, took place after the Lower
Silurian Period, and before that of the Old Red Sandstone; and there
is clear evidence that even before the latter period they had not
only been greatly altered, or "metamorphosed," by subterranean heat,
but that they had suffered enormous denudation. And the work of
carving out these mountains has gone on ever since; for even in Old
Red Sandstone times they were probably not entirely covered by water.
The Highland Mountains are therefore older than the Pennine range.

Geologically Scotland belongs in great part to Scandinavia; and
the long line of Scandinavian Mountains is a continuation of the
Highlands, and so is of the same age.

Mountain-chains and hill-ranges have been upheaved at various
geological periods; and some are very old, while others are much
younger.

Turning to the southeast of England, we find the ranges of chalk
hills forming the North and South Downs (see page 237). As explained
previously, these owe their existence to the upheaval and subsequent
denudation of the low arch, or anticline, of the Weald. They are
called "escarpments," because they are like lines of cliffs that are
being gradually cut back. Now, it is clear that these hills are much
newer than either of those we have just considered. Look at the table
on page 324, and you will see that the Cretaceous rocks (chalk, etc.)
belong to the Mesozoic era. The chalk was the last rock formed during
the Cretaceous Period.

So the Wealden arch must have been heaved up after the chalk was
formed; that is, ages and ages later than the date of the Pennine
range or the Scotch Highlands. From other evidences it has been shown
that this anticline was heaved up in the early part of the Cainozoic
Era, perhaps during the Miocene Period.

Let us now take the case of the Alps. And here we have an instructive
example of a great mountain system formed by repeated movements
during a long succession of geological periods. We cannot say
that they were entirely raised up at any one time in the world's
past history. In the centre of this great range we find a series
of igneous and metamorphic rocks, such as granite, gneiss, and
crystalline schists. Some of these may belong to the very oldest
period,--namely, the Archæan; others are probably Palæozoic and
Cainozoic deposits greatly altered by heat and pressure.

The ground from Savoy to Austria began to be an area of disturbance
and upheaval towards the close of the Palæozoic Era, if not before;
so that crystalline schists and Carboniferous strata were raised
up to form elevated land around which Permian conglomerates and
shingle-beds were formed,--as on the seashore at the present day.

During the early part of the Mesozoic Era local fractures and certain
up and down movements occurred. After this there was a long period
of subsidence, during which a series of strata known as Oölites and
Cretaceous were deposited on the floor of an old sea.

Towards the close of this long era, a fresh upheaval took place along
the present line of the Alps,--an upheaval that was prolonged into
the Eocene Period. It was during this latter period that a very
extensive formation known as the "Nummulitic limestone" was formed in
a sea that covered a large part of Europe and Asia. We have already
referred (see chap. v., pp. 169-171) to the way in which limestones
have been formed. Nummulites are little shells that were formed by
tiny shell-fish.

But after this, the greatest upheaval and disturbance took place,--an
upheaval to which the Alps as we now see them are chiefly due. By
this means the older Cainozoic strata, once lying horizontally on the
floor of the sea, were raised up, together with older rocks, to form
dry land, and not only raised up, but crumpled, dislocated, and in
some cases turned upside down.

So intense was the compression to which the Eocene rocks were
subjected that they were converted into a hard and even crystalline
state. It seems almost incredible that these highly altered rocks
which look so ancient are of the same date as our London clay and
the soft Eocene deposits of the south of England; but in our country
the movement that raised up those strata was of the most feeble and
gentle kind compared to the violent disturbances that took place in
Switzerland.

And here we may point out that the Alps are only a portion of a
vast chain of mountains stretching right across Europe and Asia in
a general east and west direction, beginning with the Pyrenees and
passing through the Alps, the Carpathians, the Caucasus, and the
range of Elbruz to the Hindoo-Koosh and the high plateau of Pamir,
called "the roof of the world," which stands like a huge fortress,
fifteen thousand feet high. Thence it passes to the still higher
tracts of Thibet, great plains exceeding in height the highest
summits of the Alps, being enclosed between the lofty ramparts of
the Himalayas on the south and the Kuen-Lun Mountains on the north;
and thence the mountain wall is prolonged in the Yuen-Ling, In-Shan,
Khin-Gan, and other ranges till it finally passes to the Pacific
Ocean at Behring's Strait.

All these ranges are, as it were, the backbone of the great
continental plateau of the Old World, and doubtless are chiefly due
to those earth-movements by means of which the Alps were upheaved.
The last grand movement, which raised the Mont Blanc range, was
probably rather later, and seems to have taken place as late as the
Pliocene Period.

At the present day no great movements are taking place in the Alps;
but now and then earthquakes visit this region, and serve to remind
us that the process of mountain-making is still slowly going on.

Probably there have been times in the history of all these
mountain-ranges when movements took place of a more violent and
convulsive kind than anything with which we are familiar at the
present day; and the age we live in may be one of comparative
repose. This is of course somewhat a matter of speculation; and we
only allude to it because there has been a tendency on the part of
some to carry the theory of uniformity in all geological operations
much farther than Hutton or Lyell ever intended. But at the same
time there is no need to go back to the old teaching of sudden
catastrophes and violent revolutions. We only wish to avoid either of
these two extremes and to take a safe middle course.

How rapidly some of these great earth-movements took place it is
impossible at present to say; but in several cases it can be shown
that they were quite slow, as indicated by the testimony of the
rivers. Thus, the rise of the great Uintah Mountains of the Western
States was so slow and gradual that the Green River, which flowed
across the site of the range, so far from being turned aside as they
rose up, has actually been able to deepen its cañon as fast as the
mountains were upheaved. So that the two processes, as it were, kept
pace with each other, and the river went on cutting out its gorges
at the same time that the ground over which it flowed was gently
upheaved; and as the land rose the river flowed faster, and therefore
acquired more power to cut and deepen its channel. This is a valuable
piece of evidence; but in this case we have only a few big broad
folds, instead of the violent folding seen in the Alps. However,
certain Pliocene strata lying on the southern flanks of the Himalayas
show that the rivers still run in the same lines as they occupied
before the last great upheaval took place.

We have seen how the substance of the mountains was slowly
manufactured by means of such quiet and gentle operations as may
be witnessed at the present day; how the rivers of old brought
down their burdens as they do now, and flung them into the sea; how
the sea spread them out very slowly and compacted them into level
layers, to form, in process of time, the hard rocky framework of
the plateaux, hills, and mountains of the world; how vast marine
accumulations were also slowly manufactured through the agency of
countless generations of humble organisms, subtracting carbonate of
lime from sea water to form the limestones of future ages; how by
slow earth-movements these marine deposits were reared up into dry
land; how they have frequently been penetrated by molten rocky matter
from below, which occasionally forced its way up to the surface
and gave rise to various volcanic eruptions, by means of which the
sedimentary rocks were often considerably baked and hardened, and new
fissures filled up with valuable metallic ores and precious stones;
how lava-flows and great deposits of volcanic ash were mingled with
these sedimentary rocks.

Then we endeavoured to follow the history of these rocky layers after
their upheaval, and learn how they are affected by the ceaseless
operations of rain and rivers and other agents of destruction, so
that finally the upheaved ridges of the lands are carved out into all
those wonderful features of crag and pinnacle and precipice that give
the mountains their present shapes and outlines. All this we were
able to account for, without the aid of any imaginary or unnatural
causes.

And, lastly, we have seen that even where such causes might seem
at first almost indispensable,--when mountains tell us of mighty
internal forces crumpling, folding, and fracturing their rocky
framework,--yet even there we can account for what we see without
supposing them to have been torn and tossed about by any very violent
convulsions.

  [Illustration: MOUNTAIN IN THE YOSEMITE VALLEY.]

Although the question of the cause, or causes, of earth-movements,
whereby continents are upheaved, and the contorting, folding, and
crumpling of the rocks of mountains produced, is not at present
thoroughly explained, it may perhaps be worth our while to consider
briefly some of the views that have been put forward on this
difficult subject. The words "upheaval" and "elevation," in reference
to movements of the earth's surface, are somewhat misleading, but are
used for want of better terms. They would seem to imply that the
force which produced mountains was a kind of upward push; whereas, in
most cases, and perhaps in all, the force, whatever it was, did not
act in an upward direction. So it should be understood that we employ
these terms only to indicate that the rocks have somehow been carried
up to a higher level, and not as suggesting _how_ the force acted by
which they were raised.

It seems pretty clear that in the case of mountain-chains, at least,
the force acted in a horizontal direction, as a kind of side-thrust.

This we endeavoured to illustrate in chapter ix. by means of a simple
experiment with a sheet of paper; and it was shown how folds similar
to those of which Mont Blanc is composed could be imitated by simply
pressing the sides of a sheet of paper inwards with one's two hands
as it lies on a table. Such lateral pressure, it is thought by many,
must be caused by the shrinking of the lower and hotter parts of the
earth's crust as they cool, leaving the outer crust unsupported, so
that it gradually settles down onto a smaller surface below, and in
so doing must inevitably be wrinkled and throw itself into a series
of folds (see chapter vi., page 204).

The interior of the earth is hotter than the outside; and since there
is good reason to think that the whole earth was once upon a time in
a highly heated and perhaps half molten condition, we are compelled
to believe that it always has been, and still is, a cooling globe.
Now, almost all known substances are found to contract more or less
on cooling; and so if the materials of which the earth is mainly
composed are at all similar in their nature and properties to those
which we find on its surface, it follows that the earth must be
contracting at the same time that it is cooling, just as a red-hot
poker will contract on being taken out of the fire.

Moreover, we find that hot bodies contract faster than those that are
merely warm, so that a red-hot poker contracts more during the first
few minutes after it is taken out of the fire than it does after
it has passed the red-hot stage. Hence it is easy to see that the
interior portions of the earth, which are hotter, must be contracting
at a greater rate than its external parts, for they evidently have
very little heat to lose. This may seem rather puzzling to the reader
at first; for it might be argued that the heat from below _must_ pass
through the external layers, or crust, as it is often called. But it
should be remembered that this is not the only way in which the earth
loses heat. Think of the vast amount of heat given out from the earth
every year by volcanic eruptions, and you will see at once that much
of the cooling takes place in this way, and not as a direct flow of
heat from the interior, as in the case of the poker. A single big
lava-stream flowing out from a volcano, and cooling on the surface
of the earth, represents so much heat lost forever; and so do the
clouds of steam emitted during every eruption; so, again, do even the
hot springs that are continually bringing up warm water. If, then,
the lower portions of the earth are slowly contracting, they must
tend to leave the outer portions of the crust unsupported, so that
they would be compelled by their own enormous weight to settle down.
Now, we know that something like this happens in coal mines; and as
long passages are hollowed out below, the ground begins to "creep,"
or slowly sink. Think what would be the effect of a slow sinking of
any portion of the earth down towards the centre; it would inevitably
be curved up and down into numerous folds, as it endeavoured to get
itself onto a smaller space, much in the same way that a table-cloth,
when thrown onto a table in a kind of arch, settles down in a series
of waves, or folds. And this, it is thought, is the way in which
it happens that the pressure comes, as we said just now, sideways,
instead of from below upwards. It is on this theory that many
geologists account for the enormous side-pressure to which rocks have
in many cases been subjected.

The evidences of such pressure are many. In some cases fossils
have been thereby pulled out of shape and appear considerably
distorted; in others, even hard quartz pebbles have been considerably
elongated (see chap. ix., pp. 315-316). Then again, we have the
little crumplings of all sizes so frequently seen in mica-schists.
And lastly, the peculiar property that slates possess of splitting
up into thin sheets is found to be due to the same cause; namely,
lateral pressure. Slates were originally formed of soft dark mud, and
on being subsequently squeezed, by earth-movements, have assumed
a structure known as "cleavage," whereby their tiny mud-particles
were elongated, and all assumed the same direction, thus giving to
the rock this peculiar property of splitting. It can be proved that
the pressure came in a direction opposite to that of the planes
of cleavage; and it is found that the direction of the cleavage
corresponds in a general way with the direction, or trend, of a
mountain-chain which is composed partly of slates, as in North Wales.
And this discovery helps and harmonises with what we have already
said about the cause of the folds in mountain-chains, for the same
force, acting sideways, produced the cleavage and the folding, etc.

It has been already stated that in a large number of cases a
mountain-range has a central axis, or band, of granite or other
crystalline rock. This led some people to suppose that the granite
had been driven up from below, and in so doing had thrust up the
overlying rocks seen on either flank of the chain; in other words,
they believed granite to have been the upheaving agent. And even now
we often find unscientific writers speaking of the volcanic forces of
upheaval.

Having very little idea of the true structure of mountains, they
believed them to consist of a kind of core, or axis, of this igneous
rock, with sedimentary rocks sloping away from it on each side.
This was a very simple theory of mountain-chains, but unfortunately
it will not bear examination. It takes no notice of the folding
which is so characteristic of mountain strata, and is quite out of
agreement with the facts of the case; so it must be buried among the
archives of the past. Mountain-chains are now known to have a much
more complicated structure than this,--thanks to the labours of many
subsequent observers.

That illustrious astronomer, the late Sir John Herschel, threw out
a bold suggestion on this subject, which in the light of recent
discoveries with regard to the delicate adjustment between the
internal and external forces affecting the earth's surface, is
worthy of careful consideration. His idea was that the mere weight
of a thick mass of sediment resting on any portion of the earth's
crust might cause a certain amount of sinking; and that this would
cause portions on either side to swell up. It is certain that as
great deposits of sedimentary materials accumulate on the floor of
an ocean, that floor slowly sinks, otherwise the sea would become
choked up, and dry land would take its place. Now, it is found that
every great mountain-chain consists of many thousands of feet of
strata thus formed; and more than this: it turns out that a greater
thickness of such materials has been formed in regions where we
now see mountain-chains than in those continental regions that lie
farther away from them. This is an important fact, which was not
known in Sir John Herschel's time. One striking example may be
mentioned here. In the complicated region of the Appalachian chain
the strata are estimated to have a total thickness of eight miles;
while in Indiana, where the same strata are nearly horizontal, they
are less than one mile thick. Hence it is not impossible that in the
mere accumulation, through long periods of time, of vast masses of
strata many thousands of feet thick, we may find a potent cause of
earth-movements.

The marginal regions of oceans, where most deposition takes place,
seem to undergo slow subsidence, while the continents seem in most
places to be as slowly rising. Modern geologists are inclined to
think that as denudation wears down a continental surface, removing
from it a great quantity of solid rocky matter (see chap. v., pp.
161-163), the pressure below is somewhat lessened, or in other words,
so much weight is taken off; but that, on the other hand, as this
extra amount of material accumulates on the bed of a neighbouring
ocean the pressure is increased by a corresponding amount, and so the
balance between internal and external forces is upset, and movements
consequently take place. We have already seen that the external parts
of the earth are much more subject to movements than might have been
expected; and for our part, we are willing to believe that in this
simple way upheaving forces might be called into play sufficient to
account for even the elevation of mountain-chains. For suppose a
great mass of strata to continue sinking as they were formed, for
long periods of time; what seems to follow? The downward movement
would go on until a time would come when the strata, in endeavouring
to settle down at a lower level, would (as by the contraction
theory above explained) be forced to fold themselves into ridges,
and in this way long strips of them might even be elevated into
mountain-ranges.

Another ingenious idea was suggested by the late Mr. Scrope, whose
work on volcanoes is well known. His idea was that when a large
amount of sedimentary material has accumulated on any large area
of the bed of the ocean, it somewhat checks the flow of heat from
within, and therefore the temperature of the rocks forming part of
the earth's crust below will be increased, much in the same manner as
a glove checks the escape of heat from the hand and keeps it warm.
The consequence of this would be expansion; and as such expansion
would be chiefly in a horizontal direction, the area would bulge
upwards and cause elevation of the strata resting on it. But there
are several difficulties which this theory fails to explain.

And lastly, Professor Le Conte, holding that the contraction theory
is unsatisfactory, accounts for earth-movements of all kinds by
supposing that some internal parts of the earth cool and contract
faster than others. Those parts that cool fastest, according to this
theory, are those that underlie the oceanic basins or troughs; while
the continental areas, not cooling so rapidly, are left standing up
in relief. This theory, which does not seem very satisfactory, is
based upon the idea that some parts of the earth's interior may be
capable of conducting heat faster than others. We know that some
substances, like iron, are good conductors of heat, while others are
bad conductors; and it is therefore conceivable that heat may be
flowing faster along some parts of the earth than along others; and
if so, there would be differences in the rate of contraction.


There are various theories with regard to the nature of the earth's
interior. One of these already referred to, but now antiquated,
supposes our planet to consist of a thin, solid crust lying on a
molten interior, so that the world would be something like an egg
with its thin shell and liquid, or semi-liquid, interior. Now, there
are grave reasons for refusing to accept this idea. In the first
place, a certain slow movement of the earth known as "precession,"
because it causes the precession of the equinoctial points on the
earth's orbit, could not possibly take place as it does if the
earth's interior were in this loose and molten condition. That is
a matter decided by mathematical calculation, on which we will not
dwell further. Secondly, we obtain some very valuable evidence on
this abstruse subject from the well-known daily phenomenon of the
tides, caused, as the reader is probably aware, by the attractions of
the sun and moon; but much more by the moon, because she is nearer,
and so exerts a greater pull on the ocean as each part of the world
is brought directly under her by the earth's daily rotation on its
axis. The waters of our oceans rise up twice each day as they get
in a line with the moon, and then begin to fall again. Thus we get
that daily ebb and flow seen on our shores. Now, it has been clearly
proved by Sir William Thomson, and others, that if any considerable
portion of the interior of the earth were in a fluid condition, it
too would rise and fall every day as the ocean does. So we should in
that case have a tide _below_ the earth as well as on its surface,
and the one would tend to neutralise the other, and the ocean tide
ought to appear less than it actually is. Even if the earth's crust
were made of solid steel, and several hundreds of miles thick, it
would yield so much to the enormous pulls exerted by both the sun
and moon that it would simply carry the waters of the ocean up and
down with it, and we should therefore see no appreciable rise and
fall of the water relatively to the land. As a matter of fact, there
_is_ a very slight tide in the solid earth below our feet, but so
slight that it does not practically affect the tide which we see
every day in the ocean. But we wish to show that were the interior of
the earth in anything approaching, to a fluid or molten condition,
the phenomena of the tides would be very different from what they
actually are.

All geologists are therefore agreed that we must consider our earth
as a more or less solid body, and not as being something like an
india-rubber ball filled with water.

The only question is whether it is entirely solid throughout. Some
authorities consider this to be the case. But others venture to think
that while the great mass of the globe is solid, there may be a thin
liquid layer lying somewhere below the surface. Sir William Thomson
calculates that there must be a solid crust at least two thousand or
twenty-five hundred miles thick (the diameter of the earth is about
eight thousand miles) and that the mass of the earth "is on the whole
more rigid certainly than a continuous solid globe of glass of the
same diameter."


One other question with regard to the earth's interior may be
mentioned in conclusion. Astronomers have calculated the weight of
our planet, and the result is curious; for it turns out to be _at
least twice as heavy as the heaviest rocks that are found on or near
the surface_. It is about five and a half times as heavy as a globe
of water of the same size would be, whereas most rocks with which
we are acquainted are about two and a half, or at most three times
heavier than water. This fact seems to open out curious consequences;
for instance, it is quite possible that metals (which are of course
much heavier than water) may exist in the earth's interior in
considerable quantities. The imagination at once conjures up vast
quantities of gold and silver. What is the source of the gold and
silver, and other metals found in mineral veins? This question cannot
as yet be fully answered. Very small quantities of various metals
have been detected in sea-water; and so some geologists look upon the
sea as the source from which metals came. But it is possible that
they were introduced from below,--perhaps by the action of steam and
highly heated water during periods of volcanic activity,--and that
their source is far down below in the depths of the earth.

But perhaps we have already wandered too far into the regions of
speculation.

Such are some of the interesting problems suggested by the study of
mountains, and they add no small charm to the science of geology.

And as we leave the mountains behind us, refreshed by their bracing
air, and strengthened for another season of toil and labour by
a brief sojourn among their peaks and passes, we come away with
a renewed sense of the almost unlimited power of the unhasting
operations of Nature, and the wisdom and beneficence of the Great
Architect of the Universe, who made and planned those snowcapped
temples as symbols of His strength, who was working millions of years
ago as He is working to-day, and to whom a thousand years are as one
day.




INDEX.


    Agents of transportation, 161.

    Ages of strata, how determined, 317-333.

    Air, composition of, 209.

    Alpine animals, 124. plants, 103, 114.

    Alps, the history of, 330.
      (See also Ruskin.)

    Ancients, the, their dread of the mountains, 3.

    Andes, the, elevation of, 189.

    Animals, behaviour of, before an avalanche or earthquake, 95.

    "Anticline," 237, 303, 327.

    Appalachian Mountains, denudation of the, 239, 305-309.

    Aqueous rocks, 154.

    Archæan Era, 324.

    Arctic flora, 121.

    "Arthur's Seat," 277.

    Ashes, volcanic, 245, 251, 260.

    Atlantic ooze, 172.

    Atmosphere, effects produced by the, 209.
      rarefaction of, 79.

    Avalanches, 89.


    Badger, the, in Alps, 128.

    Baltic Sea, changes in, 182.

    Barrier reef, of Australia, 170.

    Basalt, of Hebrides, 278.
      of Snowdon, 272.

    Basin, the Great, of United States, 313.

    Bear, brown, 125.
      black, 126.

    Beaver, the, in Alps, 128.

    Bergfalls, 97.

    Bernina, the, fall of rocks from, 98.

    Bird, Miss (Mrs. Bishop), on eruption of Kilauea, 262.

    Birds, of Alps, 134.

    Blueness of the sky, 75.

    Bombs, volcanic, 253.

    Bonney, Prof., on mountain legends, 23.
      on effects of the Alps in Europe, 48.
      on wind on mountain-tops, 84.
      on Alpine plants, 115.
      on forms of mountains, 294.

    Boulders, erratic, 225.

    Bouquetin, the, in Alps, 133.

    Britain, Great, rainfall of, 42.

    Building up of mountains, 174.

    Butterflies, in Alps, 138.

    Buzzard, the, in Alps, 136.


    Cader Idris, volcano rocks of, 272.

    Cainozoic Era, 324.

    Callao, 189.

    Cambrian rocks, 296, 324.

    Canisp Mountain, 297.

    Cañons of Colorado, 221.

    Carbonic acid in atmosphere, 210.

    Carboniferous Period, 324.

    Catastrophes, 215.

    Caves, human remains, etc., in, 31.

    Celsius, on elevation of Gulf of Bothnia, 178.

    Chalk, Cretaceous rocks composed of, 325.
      origin of. See Limestones.

    Challenger, H. M. S., expedition of, 251.

    Chamois, the, in Alps, 130.

    Characteristics of mountain races, 14.

    China clay, 292.

    Classification of rocks, 157.

    Cleavage of slates, 151, 340.

    Coniferous trees, region of, 111.

    Contortions in strata, 298, 311.

    Contraction and expansion of rocks, 208.

    Contraction theory of earth-movements, 338.

    Coral reefs, 170.

    Cotopaxi, 259.

    Crystalline schists, 312.


    Darwin, Charles, on elevation of the Andes, 189.

    Deciduous trees, mountain region of, 110.

    Dent de Mayen, 99.

    Dent du Midi, fall of rock from, 98.

    Denudation, 220, 229, 288, 312.

    Devonian rocks, 324.

    Diablerets, fall of rock from, 98.

    Dislocations of mountain rocks, 313, 315.

    Dust, volcanic, 245, 260.

    Dykes, 245.


    Eagle, the golden, 136.

    Earth-pillars in Tyrol, 221.

    Earthquakes, 95, 102, 196.
      effects of, 198, 336.
      causes of, 198, 200.
      Lucretius on, 199.

    Earth-tremors, 194.

    Elevation of mountains, 146, 200, 202, 299, 336.
      continents, 298-299.

    Encrinites, 171.

    Eocene Period, 324.

    Equador and Peru, earthquake of, 197.

    Eras, geological, 324.

    Eruptions, volcanic, 247.


    Fairies, 5.

    Falcon, the, in Alps, 136.

    "Fan-structure," 310.

    "Faults" and fractures, 200, 313.

    Features characteristic of mountains, 177.

    Ferns, 118.

    Fishes, Age of, 322.

    Fissures, 268.

    Föhn, the, 84.

    Foraminifera, 172.

    Fox, the, in Alps, 127.

    Frog, the, in Alps, 137.

    Frost, effects of, on mountain rocks, 212.


    Game-birds, in Alps, 137.

    Ganges and Brahmapootra, 167.

    Geikie, Sir A., on influence of Scottish scenery, 21.
      on the Highland plateau, 284.
      on the mountains of West Sutherland, 296.

    Giant's Causeway, basalt of, 279.

    Glace, Mer de, 229.

    Glacial drifts, 227.

    Glacial region of vegetation in Alps, 116.

    Glaciers, erosive power of, 228.

    Glare from snow in Alps, 76.

    Gneiss, 156, 292.

    Gold and silver in mountains, 61.
      in the earth, 350.

    Grampians, 276.

    Granite, 210.
      weathering of, 291.
      in mountain-chains, 312.

    Greenland, elevation of, 186.

    Green slates and porphyries, 275.

    Gulf Stream, 42.


    Hare, the, in Alps, 128.

    Hawaii, 256.

    Heat, effects of, on rocks, 154, 156, 160.
      underground, of the earth, 338, 345.

    Hebrides, former volcanic action in, 278.

    Height, influence of, on vegetation, 107.

    Herculaneum, 254.

    Highest cluster of houses in the world, 79.

    Highlands of Scotland, 284.

    Himalayas, description of, 6.

    Hutton, 142, 320.


    Iberian, or pre-Celtic race, 30.

    Ice Age, the, 65, 123.

    Ice, as a geological agent, 223.

    Igneous rocks, 155.

    Imbaburu, eruption of mud from, 259.

    Implements of stone, 31.


    Jackdaw, the, in Alps, 136.

    Jura Mountains, 300, 306.

    Jurassic rocks, 324.


    Kilauea, eruption of. (See Bird, Miss.)

    Kite, the, in Alps, 136.

    Krakatoa, 252.


    Labrador, elevation of, 192.

    Lake District, denudation of, 220.
      volcanic rocks of, 275.

    Lakes, origin of, 47.

    Lateral pressure, applied to mountains, 310, 315, 337.

    Lichens and mosses. (See Ruskin.)

    Limestones, origin of, 151, 153, 169.

    Lisbon, earthquake at, 197.

    Livingstone, on splitting of rocks, 212.

    Lizard, the, in Alps, 137.

    Lyell, Sir Charles, 333.

    Lynx, the, in Alps, 128.


    Mal de montagne, 80.

    Mammals, age of, 322.

    Marmot, the, in Alps, 129.

    Mauna Loa, eruption of, 256.

    Mendip Hills, 327.

    Mer de Glace. (See Glace.)

    Metals, precious, 60.
      in the earth, 349.

    Metamorphic rocks, 156, 157, 298, 330.

    Mica-schist, 156, 293.

    Miller, Hugh, 150.

    Milne, Prof., on earth-pulsations, 193.

    Minor cones of volcanoes, 246.

    Miocene Period, 278, 324.

    Mississippi, denudation by the, 232.

    Moel Tryfaen, raised beach in, 186.

    Mont Blanc, 310.

    Monte Conto, downfall of, in 1618, 101.

    Monte Nuovo, 248.

    Moraines, 225.

    Mountain limestone, 152.

    Mountains, as barriers between nations, 26.
      as reservoirs of water, 43.
      human wants supplied by, 58.
      influence of, on climate, 62.
      causing movements in the atmosphere, 65.
      as backbones of continents, 67.
      floras of, 103-124.
      forms of, how determined, 282.
      general features of, 177, 283.
      structure of, how determined, 308.
      elevation of, 174, 313.
      formed by huge dislocations, 313.
      Ruskin on uses of, 68.
        " on a scene on the Jura, 300.
        " on flowers of, 107.

    Mud-flows from volcanoes, 259.


    "Needles," the, of Colorado, 221.

    Neptunists and Plutonists, 160.

    New England, elevation of, 192.

    New Zealand, elevation of, 190.

    Nummulites, 331.


    Old Red Sandstone, 150, 324.

    Olive region, the, 107.

    Organically formed rocks, 157.

    Ornamentation of mountains, 147.

    Oxygen, in air, 209.


    Palæozoic Era, 324.

    Permian rocks, 324.

    Pleistocene rocks, 324.

    Pliocene, 324.

    Plutonists, 160.

    Pompeii, buried up, 254.

    Precious stones in mountains, 277.

    Primary Era, 324.

    Pulsations of the earth. (See Milne.)


    Quinag, 297.


    Rabbit, the, in Alps, 128.

    Raised beaches, 185.

    Raven, the, in Alps, 136.

    Red clay, of Atlantic Ocean, 252.

    Reptiles, Age of, 323.

    Righi Mountain, fall of rock from, 99.

    Rivers, transporting power of, 161-168.

    Roches Moutonnées, 227.

    "Rocking Stones," 292.

    Ross and Sutherland, mountains of, 315.

    Rossberg, the, fall of rock from, 99-101.

    Ruskin, on effect of tourists in Switzerland, 21.
      on effects of scenery on mythology, 22.
      on uses of mountains, 50.
      on formation of soil, 55.
      on lichens and mosses, 119.
      on the Alps, 289.
      on a scene in the Jura Mountains, 300.


    Santorin, island of, 257.

    Scandinavia, elevation of, 180.

    Scenery, influence of rocks on, 219.

    Schists. (See Mica-schist.)

    Scotland, former volcanic action in, 275.

    Sea-beaches, 183.

    Sea-level, constancy of, 179.

    Secondary Era, 324.

    Serapis, Temple of, 187.

    Silurian Period, 324.
      volcanic rocks of, 272.

    Shearing of rocks in mountains, 316.

    Skaptar Jökull, lava-flow from, 255, 260.

    Smith, William, 323.

    Snake River Plain, 258.

    Snow, lambent glow of, 77.

    Snowdon, volcanic rocks of, 272.
      denudation of, 239.

    Spectre of the Brocken, the, 78.

    Stability of the earth, 174, 314.

    Stanley, Dean, on capture of Canaan, 32.

    Stone Age, 31.

    Storms on mountains, 81.

    Stratified rocks, table of, 324.
      how formed, 148, 176.

    Striæ, glacial, 227.

    Submerged forests, 192.

    Suilven Mountain, 297.

    Sunsets, 71.

    Sutherland, West, mountains of, 296.


    Taurentum, destroyed by downfall of rocks, 97.

    Thames, solid matter transported by, 168.

    Thunder-storms, in Alps, 86.

    Tomboro, eruption at, 260.

    "Tors," 292.

    Tourmente, the, 83.

    Transportation by rivers, 161, 166-169.
      by glaciers, 224.

    Triassic Period, 324.

    Types of plants and animals at different periods, 106.


    Upheaval theory of mountains, 247.

    Uses of mountains, 33.


    "Valleys, how carved out, 214-230.

    Vesuvius, history of, 250.

    Vines, the region of, in Alps, 109.

    Volcanoes, number of active, 242.
      old ideas about, 244.
      structure of, described, 244.
      volcanic rocks of Great Britain, 271.

    Vulture, the bearded, 134.


    Wall of Antoninus, 185.

    Waterfalls, origin of, 218.

    Water-vapour, in air, 34.
      condensation of, by mountains, 34.

    Waves of population, 30.

    Weald, the denudation of, 235-239.
      structure of, 303.

    Werner, 158.

    Wild-cat, in Alps, 128.

    Wolf, the, in Alps, 126.


    Zones of climate on the earth, 63.

Transcriber's note:
    A "List of Illustrations II" has been added to the text, for the
    convenience of the reader, to display Illustrations that were
    not included in the original "Illustrations" section. The original
    spelling of words, especially for place names, has been retained.





End of Project Gutenberg's The Story of the Hills, by H. N. Hutchinson