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                       BUREAU OF ECONOMIC GEOLOGY
                   The University of Texas at Austin
                        Peter T. Flawn, Director


                              Guidebook 8




                 The Geologic Story of Palo Duro Canyon


                                   By
                        William H. Matthews III

    [Illustration: THE UNIVERSITY OF TEXAS AT AUSTIN]

                              August 1969
                            Second Printing
                              August 1983




                                Contents


  Introduction                                                         1
  Acknowledgments                                                      2
  Park history                                                         3
      Ancient man in Palo Duro Canyon                                  3
      Indians of the Plains                                            3
      Advent of the White Man                                          3
  Regional setting                                                     8
  The geologic story                                                  10
      The canyon's rocks and minerals                                 10
      Unraveling earth history                                        10
      The geologic column and geologic time scale                     12
      Geologic formations exposed in Palo Duro Canyon                 16
      Quartermaster Formation                                         17
      Tecovas Formation                                               19
      Trujillo Formation                                              22
      Ogallala Formation                                              23
      Rocks of the Pleistocene                                        28
  How the canyon was carved                                           29
      The geologic work of running water                              29
      Weathering and gravity add the final touch                      30
      Weathering                                                      30
      Mass-wasting                                                    31
      Differential erosion                                            31
  What to do and see at Palo Duro Canyon State Park                   33
      Park Entrance                                                   33
      Coronado Lodge and Observation Point                            33
      The Scenic Drive                                                33
      Pioneer Amphitheatre                                            33
      Sad Monkey Train Ride                                           35
      Triassic Peak                                                   35
      Spanish Skirts                                                  37
      Catarina Cave                                                   37
      Santana's Face                                                  37
      The Sky Ride                                                    37
      The First Water Crossing                                        39
      Colonel Charles Goodnight's Dugout                              39
      The Lighthouse                                                  39
      Capitol Peak                                                    40
      Fortress Cliff                                                  40
      The Rock Garden                                                 40
      The Devil's Slide                                               40
      The Turnaround                                                  41
      Hiking                                                          43
      Horseback riding                                                43
      Camping and picnicking                                          43
      Photography                                                     43
  Panhandle-Plains Historical Museum                                  45
  Selected references                                                 47
  Glossary                                                            48
  Index                                                               50




                              Illustrations


  Figures--                                                         Page
  1. Aerial View of Palo Duro Canyon                        Frontispiece
  2. Place map of Palo Duro Canyon                                   4-5
  3. Indian carving on sandstone boulder                               6
  4. War dress of Comanche Chief Quanah Parker                         7
  5. Generalized geologic map of the Texas Panhandle                   9
  6. Geologic time scale                                              11
  7. Generalized geologic map of Palo Duro Canyon State Park       14-15
  8. Joints and gypsum veins in Quartermaster Formation               17
  9. Syncline in Quartermaster red beds                               18
  10. Reduction halos in Quartermaster shale                          20
  11. Cross-bedded boulder of Trujillo sandstone                      20
  12. Panoramic view of canyon showing major rock units exposed in
          canyon                                                      21
  13. Phytosaur skull                                                 22
  14. Skeleton of _Buettneria_                                        24
  15. Mortar hole made by Indians                                     25
  16. Rock pedestal near the Lighthouse                               25
  17. Outcrop of Ogallala caliche                                     26
  18. Life-sized model of shovel-jawed mastodon                       27
  19. Fossilized carapaces of Pliocene tortoises                      27
  20. Talus slopes and "hoodoo" on Capitol Peak                       31
  21. Entrance to Palo Duro Canyon State Park                         34
  22. Coronado Lodge                                                  34
  23. Pioneer Amphitheatre                                            35
  24. Train on Sad Monkey Railroad track                              36
  25. South face of Triassic Peak                                     36
  26. Spanish Skirts                                                  37
  27. Catarina Cave                                                   38
  28. Santana's Face                                                  38
  29. Picnic area at first water crossing                             39
  30. Colonel Charles Goodnight's Dugout                              40
  31. The Lighthouse                                                  41
  32. Capitol Peak                                                    42
  33. Fortress Cliff                                                  42
  34. The Rock Garden                                                 43
  35. The Devil's Slide                                               44
  36. Campsite in south end of park                                   44
  37. Entrance to Panhandle-Plains Historical Museum                  45

    [Illustration: Fig. 1. Aerial view of Palo Duro Canyon showing
    location of major points of interest: (1) Coronado Lodge; (2)
    Triassic Peak; (3) Timber Mesa; (4) Capitol Peak; (5) Fortress
    Cliff; (6) Prairie Dog Town Fork of Red River; (7) The Turnaround
    (termination of Park Road 5). (Courtesy of Charles A. Wolfin;
    photograph by W. A. Hester.)]




                 The Geologic Story of Palo Duro Canyon


                       William H. Mathews III[1]




                              INTRODUCTION


Like the early Spanish explorers who first saw Palo Duro Canyon, today's
visitor is likely to view the impressive canyon with surprise and awe.
This great depression--it is more than 2 miles wide and as much as 800
feet deep within park boundaries--contains a fascinating assortment of
multicolored geologic formations and erosion-produced rock sculptures of
many shapes, colors, and size. The geographic setting of the canyon
further heightens its impact on the visitor, for it is surrounded by the
level, virtually treeless plains of the Texas Panhandle. (_See_ upper
background area in fig. 1, frontispiece).

It is not surprising that this scenic area has been set aside as a State
park, for Palo Duro Canyon has long been of interest to man. First, as
the hunting grounds of prehistoric Indians who stalked the now-extinct
Ice Age mammoths and bison that roamed the valley floor. Later, the
canyon was frequented by the Comanches, Apaches, Kiowas, and other
Indians of historic time. These tribes, like those before them, found
both food and refuge within the canyon. However, it was not until 1876
that Palo Duro Canyon was inhabited by the white man. It was during this
year that pioneer cattleman Charles Goodnight herded some 1,600 head of
cattle into the canyon and established a camp there (p. 6).

Today's visitor to Palo Duro Canyon can re-live some of the fascinating
history of this interesting area. One can still see a replica of Colonel
Goodnight's primitive dugout, follow the faint trace of the Comanche
Trail, or perhaps find the fossil bones of prehistoric creatures that
lived hundreds of thousands--even millions--of years ago. But most
visitors to Texas' most colorful canyon are not attracted by its
interesting history. They come instead to enjoy the scenery and
recreational opportunities that are present. These are readily
accessible, for a carefully engineered, hard-surface road leads from the
rim of the canyon to the canyon floor. There are campgrounds, picnic
areas, concessions, and even an outdoor theatre (fig. 23). The location
of these facilities and some of the canyon's more interesting geologic
features are shown on the generalized place map of the canyon (fig. 2).

This publication does not attempt to describe the scenic beauty of Palo
Duro Canyon, for this must be seen to be appreciated. Rather, it
discusses the geologic setting and origin of the canyon, the methods by
which some of the more interesting geologic features were formed, and
briefly reviews the history of the area. Hopefully, it will enable the
visitor to understand better the meaning behind the canyon scenery,
thereby enhancing his visit.




                            ACKNOWLEDGMENTS


Many people have assisted in the preparation of _The Geologic Story of
Palo Duro Canyon_, and their help is gratefully acknowledged: Professor
Jack T. Hughes, Dr. Frank W. Daugherty, Dr. Robert C. Burton, Meade
Humphries, and Jim Hughes of the West Texas State University Geology
Department provided much information about the area and assisted in the
field; help was also provided by Mr. Pete Cowart, Mr. Earl Burtz, Mr.
Jerry Tschauner, Mr. Bob Watson, Mr. King, and other park personnel; Mr.
C. Boone McClure, of the Panhandle-Plains Historical Museum, furnished
some of the photographs; Mr. J. Dan Scurlock, Mr. Bill Collins, and Mr.
Harold Allums, of the Texas Parks and Wildlife Department, made
available certain maps and statistical data; Mrs. Ples Harper of Canyon
assisted in assembling information and photographs for the Pioneer
Amphitheatre; and the aerial photograph of Palo Duro Canyon was taken by
Mr. W. A. Hester and made available through the courtesy of Mr. Charles
A. Wolflin of Amarillo.

Drs. Peter T. Flawn, Peter U. Rodda, and Ross A. Maxwell of the Bureau
of Economic Geology read much of the manuscript and offered many helpful
suggestions, and Mr. A. Richard Smith provided special information on
caves in the Palo Duro area. Special thanks are due to Miss Josephine
Casey who edited the manuscript and to Mr. J. W. Macon, cartographer,
who assumed responsibility for preparing the maps. Thanks are due also
to my wife, Jennie, who critically read the manuscript and took a number
of the photographs. Finally, I would like to thank Dr. J. Daniel Powell
of The University of Texas at Arlington for invaluable assistance in the
field and his enthusiastic co-operation throughout the project.




                              PARK HISTORY


Palo Duro Canyon's long and colorful past has created considerable
interest among historians, archeologists, and geologists. Historians
have traced the written history of man and his effect on the Palo Duro
area, but archeologists have delved much further into the past. They
have sought out and studied the more enduring records of the canyon's
early inhabitants--their tools, utensils, and weapons. The geologist,
however, is interested in history that far antedates even the most
primitive human inhabitant of the canyon. The earth scientist has probed
the geologic record of the Palo Duro area, using rocks, minerals, and
fossils as clues to the geologic history and development of the canyon.

Palo Duro Canyon is unique among Texas' State parks because of its many
contributions to history, archeology, and geology. Here the written
record, the artifacts of prehistoric man, and the geologic formations
overlap and complement each other in many respects. Although this
guidebook is primarily concerned with the geologic history of the
canyon, a brief review of its human history is also included.


                    ANCIENT MAN IN PALO DURO CANYON

Archeological studies indicate that the earliest known inhabitants of
Palo Duro Canyon lived in the canyon from about 10,000 to 5,000 B.C.
These early men apparently hunted the bison and now-extinct
elephant-like mammoths that roamed the Palo Duro area during the Ice Age
of Pleistocene time (_see_ geologic time scale, fig. 6). Their stone
weapons and other artifacts have been found in and around the canyon. It
is assumed that these primitive people--like those who came later--were
attracted by the streams and springs that are found in the canyon and by
game that came there to feed. There is also evidence that the Indians
took advantage of certain of the canyon's geologic features. They
fashioned tools, weapons, and utensils from the rocks exposed in the
canyon and used certain of the shallow caves and rock shelters as their
homes.


                         INDIANS OF THE PLAINS

Various tribes of Plains Indians of historic times also used Palo Duro
Canyon as a camping ground. The presence of these Indians is known from
many campsites and burials. In addition, flint chips and stone
artifacts, potsherds, ornaments of shell and bone, grinding slabs, stone
mortars (fig. 15), and a few pictographs (fig. 3) have provided
considerable information about the culture of these people. Among the
tribes believed to have frequented the canyon at various times are the
Apaches, Cheyennes, Arapahos, Kiowas, and Comanches. However, it is the
Comanches who are most closely associated with the Palo Duro area, for
the canyon is located near the center of their last homeland. Indeed it
was here that the Comanches were finally defeated and driven from this
part of the Plains. The battlefield where Colonel Ranald Mackenzie's
troops fought the Comanches is located near the southeast corner of the
park (_see_ fig. 7). This skirmish, which took place in 1874, is
believed to have been the last major Indian battle in Texas.

Although most of the canyon's archeological sites have been picked over
and many of the artifacts removed, important finds are still
occasionally reported. Park visitors who make discoveries of this type
are urged to report them to a park ranger in order that they might be
called to the attention of the proper authorities.


                        ADVENT OF THE WHITE MAN

Although the history of Palo Duro Canyon is rich in Indian lore, it was
the coming of the white man that heralded the development of the area.
Today it is generally believed that Francisco Vasquez de Coronado was
the first white man to view the canyon. Coronado and his men are thought
to have camped here during the winter of 1541, as they crossed the High
Plains in search of the fabled Seven Cities of Cibola.

    [Illustration: Fig. 2. Place map of Palo Duro Canyon.]

Later, during the 17th and 18th centuries, the canyon was a favorite
resting place of the buffalo hunters and Indian traders who frequented
the Plains. The canyon was also popular during the first half of the
19th century, for it was then that it was occupied by the Comanches and
served as a trade center for the Spaniards and Indians who came from New
Mexico. These traders, called _comancheros_, bartered for loot taken by
the Comanches on their raids of early settlements and wagon trains that
passed through the Panhandle-Plains region.

This same era marked the beginning of American interest in the Palo Duro
country. During this period the area was visited by several expeditions
including those of Long and Pike and the Texas-Santa Fe Expedition of
1841. However, the canyon was not fully explored or mapped until 1852.
This important survey was carried out by a party which was under the
supervision of Captain R. B. Marcy.

But it was not until 1876 that the first white man established permanent
residence in Palo Duro Canyon. In 1876--just two years after McKenzie's
rout of the Comanches--Colonel Charles Goodnight herded more than 1,600
head of cattle into the canyon. Here he laid out his first permanent
ranch and lived in a primitive earthen dugout. Not only was Goodnight's
Palo Duro Ranch the first in the canyon, it is also thought to have been
the first commercial cattle ranch in the Texas Panhandle. In later years
Colonel Goodnight formed a partnership with John Adair of Ireland, and
together they developed the famous JA Ranch--a vast spread of some
600,000 acres. Today's visitor to Palo Duro Canyon can visit a partially
restored dugout similar to that occupied by the canyon's early settlers
(fig. 30).

    [Illustration: Fig. 3. The face carved on this boulder can be seen
    along the track of the Sad Monkey Railroad (p. 35). It is believed
    to have been carved by Indians.]

    [Illustration: Fig. 4. The war bonnet, war lance, and head feathers
    of Comanche Chief Quanah Parker can be seen at the Panhandle-Plains
    Historical Museum in Canyon. (Photograph courtesy Panhandle-Plains
    Historical Museum.)]

From the late 1800s until about 1930, the Palo Duro country remained the
domain of the Panhandle-Plains cattleman. It was, nonetheless, a
favorite picnic and camping spot of the residents of nearby towns and
cities. In 1933 the recreational potential of the canyon was finally
recognized and land for the Palo Duro Canyon State Park was purchased by
the State of Texas with money obtained through a public revenue bond
issue. Today, most of the park revenue received through gate admissions,
concession receipts, and mineral leases goes into a fund that pays off
the remaining balance of the revenue bonds. During the initial phase of
the park's development, most of the improvements in the area were made
by members of the Civilian Conservation Corps who worked under the
supervision of the National Park Service.

Currently, Palo Duro Canyon State Park is visited by approximately
300,000 visitors each year and is one of the State's more popular
recreational and scenic areas.




                            REGIONAL SETTING


Palo Duro Canyon State Park is located in the Panhandle of Texas (fig.
5) approximately 13 miles east of Canyon on State Highway 217 (_see_
fig. 7). It is about 12 miles south and 8 miles east of Amarillo via
Ranch Road 1541 which intersects State Highway 217. The park includes
more than 15,000 acres of Palo Duro Canyon, a complexly dissected area
which spreads into Randall, Armstrong, and Briscoe counties.

More specifically, the Palo Duro area is situated on the Llano Estacado
or High Plains area which comprises approximately 20,000 square miles of
Texas and New Mexico (_see_ fig. 5). Generally speaking, the Llano
Estacado is a high isolated plateau or broad mesa, rising above the
surrounding rolling plains in a nearly flat, island-like mass. On the
west, southwest, and south, the Llano Estacado is bounded by the valley
of the Pecos River, while its eastern escarpment is drained by the
headwaters of the Red, Brazos, and Colorado Rivers.

The rim of Palo Duro Canyon is formed by the Eastern Caprock Escarpment.
Caprock is the term used to describe a massive layer of calcareous rock
which supports the High Plains surface (_see_ p. 26). Because it is more
resistant to forces of erosion than the softer, underlying more or less
horizontal strata, the caprock forms an abrupt, precipitous escarpment
at the edge of the High Plains. With the exception of the resistant
caprock, however, the surficial deposits on the High Plains are for the
most part unconsolidated sediments.

The Llano Estacado is essentially devoid of native trees and is
characterized by a sparse, but uniform, covering of grasses. The surface
rocks are of Tertiary and Quaternary age (_see_ geologic time scale,
fig. 6) and have a general easterly to southeasterly slope of about 9½
feet per mile. In the vicinity of Palo Duro Canyon, rocks of Late
Cenozoic age are directly underlain by Permian and Triassic formations.
These Permian and Triassic rocks, which are discussed elsewhere in this
publication, are not normally exposed except in deeply eroded areas such
as the canyon.

    [Illustration: Fig. 5. Generalized geologic map of the Texas
    Panhandle showing location of Palo Duro Canyon.]

  _Showing:_
    Q & T   Pleistocene and Pliocene undifferentiated
    Trdo   Dockum Group (Triassic)
    P   Permian undifferentiated




                           THE GEOLOGIC STORY


                    THE CANYON'S ROCKS AND MINERALS

Palo Duro visitors--regardless of age--seem to have an innate curiosity
about the canyon's rocks. This is not surprising, for most of the
features of the park landscape are composed of or have been sculptured
from solid rock. In short, much of the natural beauty of Palo Duro
Canyon has been derived from the character of its exposed rock
formations and the effect of geologic agents upon them.

Because rocks are the raw materials of geology and the stuff from which
landscapes are formed, it will be helpful for the visitor to know
something about the general characteristics of rocks and their role in
the development of the landscape. Rock is everywhere around us and is
one of the most common objects in the world, yet few people can actually
define a rock. So, at the outset it should be stated that _a rock is a
naturally formed aggregate of minerals_, and _a mineral is a naturally
occurring substance which has a fairly definite chemical composition,
distinctive physical properties, characteristic internal structure, and
which commonly occurs in definite shapes called crystals_. Although not
an exact scientific or legal definition of a mineral, the above
explanation is satisfactory for the purposes of this publication.

Although most visitors show considerable interest in the canyon's rocks
and minerals, few of them know the story behind the rocks. They do not
know how the rocks were formed, of what they are composed, how they
change, and how they differ. More important, they fail to realize the
historical significance of the rocks and how they can be used to
interpret events that occurred in the canyon many millions of years ago.
Thus, before one studies the geologic story of Palo Duro Canyon, it is
helpful to know something about the various kinds of rocks. There are
three major classes of rocks in the earth's crust: _igneous_,
_sedimentary_, and _metamorphic rocks_.

_Igneous rocks_ solidified from an original molten state. Common
examples of igneous rocks include granite, basalt, and volcanic ash.
Although no igneous rocks are found in Palo Duro Canyon, they are widely
exposed in parts of West and Central Texas.

_Metamorphic rocks_ were originally igneous or sedimentary in origin.
However, these rocks have undergone such great physical and chemical
change that they have been transformed into a different kind of rock.
Thus, metamorphic changes alter limestone to marble or sandstone to
quartzite. No metamorphic rocks crop out in the canyon, but, like the
igneous rocks, they are common in some parts of the State.

All of the geologic formations exposed in Palo Duro Canyon are composed
of _sedimentary rocks_. These are rocks that have been formed by the
compaction and cementation of rock and mineral fragments called
_sediments_, or by the precipitation of material from solution.
Sandstone, conglomerate, shale, and caliche (_see_ p. 26) are examples
of sedimentary rocks that are exposed in the canyon.

Sedimentary rocks are typically _stratified_, that is, they occur in
layers or beds called _strata_. In addition, sedimentary
rocks--especially those of marine origin--commonly contain _fossils_.
These fossils are traces or evidence of prehistoric plants and animals
that have been preserved in the rocks, and they may provide clues as to
the age of rocks and the manner in which they were formed. Fossil
remains have been found at a number of places in the park and these are
discussed later.


                        UNRAVELING EARTH HISTORY

In order to understand better the geologic history and development of
the canyon, one should also have some knowledge of the basic principles
of earth history and should be familiar with the geologic time scale
(fig. 6).

    [Illustration: Fig. 6. Geologic time scale. Reproduced from
    _FOSSILS: An Introduction to Prehistoric Life_, William H. Matthews
    III, Barnes and Noble, Inc., 1962.]

  GEOLOGIC TIME SCALE
  ERA
    PERIOD
      EPOCH
        SUCCESSION OF LIFE
  CENOZOIC   "RECENT LIFE"
    QUATERNARY   0-1 MILLION YEARS
      Recent
      Pleistocene
    TERTIARY   62 MILLION YEARS
      Pliocene
      Miocene
      Oligocene
      Eocene
      Paleocene
  MESOZOIC   "MIDDLE LIFE"
    CRETACEOUS   72 MILLION YEARS
    JURASSIC   46 MILLION YEARS
    TRIASSIC   49 MILLION YEARS
  PALEOZOIC   "ANCIENT LIFE"
    PERMIAN   50 MILLION YEARS
    CARBONIFEROUS
      PENNSYLVANIAN   30 MILLION YEARS
      MISSISSIPPIAN   35 MILLION YEARS
    DEVONIAN   60 MILLION YEARS
    SILURIAN   20 MILLION YEARS
    ORDOVICIAN   75 MILLION YEARS
    CAMBRIAN   100 MILLION YEARS
  PRECAMBRIAN ERAS
    PROTEROZOIC ERA
    ARCHEOZOIC ERA
      APPROXIMATE AGE OF THE EARTH MORE THAN 4 BILLION 550 MILLION YEARS

The geologist has learned that the earth's physical features have not
always been as they are today. It is known, for example, that mountains
now occupy the sites of ancient seas. Coal is now being mined where
swamps existed many millions of years ago. Furthermore, the earth's
plants and animals have also been subject to great change. The trend of
this organic change is, in general, toward more complex and advanced
forms of life. However, some forms have remained virtually unaltered
while others have become extinct at different points in geologic time.

In order to interpret earth history, the earth scientist gathers
evidence of the great changes in climate, geography, and life that took
place in the geologic past. He does this by studying the rock
formations, the structural relationships of these formations, and the
landforms of the area. The record of ancient events is pieced together
by studying the stony layers of the earth as one might study a giant
history book. Indeed, the sedimentary rocks are the rocky "pages" of
earth history, for in them we find the tracks and trails, and bones and
stones, which reveal the intriguing story of life long ago.

Much of the basic information which the geologist uses to reconstruct
the geologic history of a region comes from his examination and
interpretation of _bedrock outcrops_. _Bedrock_ is the solid unweathered
rock which underlies loose earth material such as soil, sand, and
gravel. An _outcrop_, or _exposure_, is a place where bedrock is exposed
at the surface.

The first chapter of earth history begins with the most ancient rocks
known. Because they were formed early in geologic time, these rocks are
normally found deeply buried beneath younger rocks which have been
deposited on top of them. It is for this reason that earth history is
read from the bottom up, for the earliest formed rock layers correspond
to the opening chapter in our earthen history book. The later chapters
are found in the upper younger rocks which are located nearer the
surface. Thus, in "reading" the geologic history of Palo Duro Canyon we
start with the oldest "chapter" which is recorded in the Quartermaster
Formation (p. 17) of Permian age, for these are the oldest rocks exposed
in the canyon.

But deciphering earth history is not as simple as it might appear. In
many areas the rock layers are not always found in the sequence in which
they were originally deposited. In places, great structural disturbances
have caused some of the rocky "pages" to become shuffled and out of
place; others may be missing completely. Many rocks have been destroyed
by weathering and erosion or greatly altered by metamorphism. As a
result, the story recorded in these particular rocks is lost forever.
These missing "pages" make the ancient story even more difficult to
interpret so the geologist must then depend on other evidence that will
permit him to "fill in the blanks."

The record revealed in the rocks indicates that our planet is at least
4½ billion years old and that life has been present for more than 3
billion years. During this vast span of time the earth and its
inhabitants have undergone many changes.


              THE GEOLOGIC COLUMN AND GEOLOGIC TIME SCALE

The _geologic column_ refers to the total succession of rocks, from the
oldest to the most recent, that are found in the entire earth or in a
given area. For example, the geologic column of Texas includes all rock
divisions known to be present in the State. By the same token, the
geologic column of Palo Duro Canyon consists of the geologic formations
exposed there. Thus, by referring to the geologic column previously
determined for a specific area, the geologist can determine what type of
rock he might expect to find in that particular region.

The _geologic time scale_ (fig. 6) is composed of named intervals of
geologic time during which were deposited the rocks of the geologic
column. These time intervals bear the same names that are used to
distinguish the various units of the geologic column. For example, one
can speak of Permian _time_ (referring to the geologic time scale) or of
Permian _rocks_ (referring to rock units of Permian age in the geologic
column).

Both the geologic column and the geologic time scale are based upon the
_principle of superposition_. This basic geologic concept states that
unless a series of sedimentary rock has been overturned, a given rock
layer is older than the strata above it, and younger than all of the
layers below it. Thus, the field relationship of the rocks plus the type
of fossils (if present) give the geologist some indication of the
_relative_ age of the rocks. Relative age does not imply age in years;
rather, it fixes age in relation to other events that are recorded in
the rocks.

Within recent years, however, it has become possible to assign ages in
years to certain rock units. This is accomplished by a system of rock
dating based on very precise measurements of amounts of radioactive
elements (such as uranium). When present in the rocks, radioactive
minerals change or decay at a known rate so that they are natural
"clocks." This method of dating has made it possible to devise a time
scale in years which gives some idea of the tremendous amount of time
that has passed since the oldest known rocks were formed. It has also
been used to verify the previously determined relative ages of the
various rock units.

The largest unit of geologic time is an _era_, and each era is divided
into smaller time units called _periods_. A period of geologic time is
divided into _epochs_, which, in turn, may be subdivided into still
smaller units. The geologic time scale might be roughly compared to the
calendar in which the year is divided into months, months into weeks,
and weeks into days. Unlike years, however, geologic time units are
arbitrary and of unequal duration, and the geologist cannot be positive
about the exact length of time involved in each unit. The time scale
does, however, provide a standard by which he can discuss the age of
fossils and their surrounding rocks. By referring to the time scale it
may be possible, for instance, to state that a certain event occurred
during the Paleozoic Era in the same sense that one might say that
something happened during the American Revolution.

There are five eras of geologic time, and each has been given a name
that is descriptive of the degree of life development that characterizes
that era. Hence, Paleozoic means "ancient-life" and the era was so named
because of the relatively simple and ancient stage of life development.

The eras, a guide to their pronunciation, and the literal translation of
each name is shown below.

    Cenozoic (SEE-no-zo-ic)--"recent-life"
    Mesozoic (MES-o-zo-ic)--"middle-life"
    Paleozoic (PAY-lee-o-zo-ic)--"ancient-life"
    Proterozoic (PRO-ter-o-zo-ic)--"earlier-life"
    Archeozoic (AR-kee-o-zo-ic)--"beginning-life"

Archeozoic and Proterozoic rocks are commonly grouped together and
referred to as Precambrian in age. In most places Precambrian rocks have
been greatly contorted and metamorphosed, and the record of this portion
of earth history is most difficult to interpret. Precambrian time
represents that portion of geologic time from the beginning of earth
history until the deposition of the earliest fossiliferous Cambrian
strata. Precambrian time probably represents as much as 85 percent of
all geologic time.

The _oldest_ era is at the _bottom_ of the time scale because this part
of geologic time transpired first and was then followed by the
successively younger eras which are placed above it. This is, of course,
the order in which the various portions of geologic time occurred and
during which the corresponding rocks were formed.

As mentioned above, each of the eras has been divided into periods, and
most of these periods derive their names from the regions in which the
rocks of each were first studied. For example, the Pennsylvanian rocks
of North America were first studied in the State of Pennsylvania.

    [Illustration: Fig. 7. Generalized geologic map of Palo Duro Canyon
    State Park.]

  EXPLANATION
    Q & T   Pleistocene and Pliocene undifferentiated
    Rdo   Dockum Group
    P   Permian undifferentiated

The Paleozoic Era has been divided into seven periods of geologic time.
With the oldest at the bottom of the list, these periods and the source
of their names are:

    Permian (PUR-me-un)--from the Province of Perm in Russia
    Pennsylvanian (pen-sil-VAIN-yun)--from the State of Pennsylvania
    Mississippian (miss-i-SIP-i-un)--from the Upper Mississippi Valley
    Devonian (de-VO-ni-un)--from Devonshire, England
    Silurian (si-LOO-ri-un)--for the Silures, an ancient tribe of
          Britain
    Ordovician (or-doe-VISH-un)--for the Ordovices, an ancient tribe of
          Britain
    Cambrian (KAM-bri-un)--from the Latin word _Cambria_, meaning Wales

The Carboniferous Period in Europe includes the Mississippian and
Pennsylvanian Periods of North America. Although this classification is
no longer used in the United States, the term Carboniferous is found in
many of the earlier geological publications and on many of the earlier
geologic maps.

The periods of the Mesozoic Era and the source of their names are:

    Cretaceous (cre-TAY-shus)--from the Latin word _creta_, meaning
          chalky
    Jurassic (joo-RAS-ik)--from the Jura Mountains of Europe
    Triassic (try-ASS-ik)--from the Latin word _triad_, meaning three

The Cenozoic periods derived their names from an old outdated system of
classification which divided all of the earth's rocks into four groups.
The two divisions listed below are the only names of this system which
are still in use:

    Quaternary (kwah-TUR-nuh-ri)
    Tertiary (TUR-shi-ri)

Although the units named above are the major divisions of geologic time
and of the geologic column, the geologist generally works with smaller
units of the column called _geologic formations_. A geologic formation
is a unit of rock that is recognized by certain physical and chemical
characteristics. A formation is generally given a double name which
indicates both where it is exposed and the type of rock that makes up
the bulk of the formation. For example, the Beaumont Clay is a formation
consisting of clay deposits that are found in and around Beaumont,
Texas. For convenience in study, two or more successive and adjoining
formations may be placed together in a group. Thus, the Tecovas and
Trujillo Formations have been placed in the Dockum Group. Likewise, a
formation may be subdivided into smaller units such as members, which
may also be given geographic or lithologic (rock type) names.


            GEOLOGIC FORMATIONS EXPOSED IN PALO DURO CANYON

As noted above, all of the rocks which crop out in Palo Duro Canyon are
sedimentary in origin. They represent four different geological periods:
the Permian, Triassic, Tertiary, and Quaternary (fig. 12).

Although these rock formations differ considerably in composition and
age, they do not tell the whole geologic story of the area. Long spans
of geologic time are not represented by rock units because the region
was undergoing erosion or no sediments were being deposited during
certain portions of geologic time. Rocks that had formed during one
geologic period were removed by erosion during a later period. Thus,
segments of the geologic record were destroyed or never recorded. For
this reason, much of the geologic history of the Palo Duro area is
unrecorded and must be inferred from fragmentary evidence borrowed and
pieced together from adjacent areas. Even so, an interesting story can
be assembled from the rocks that remain in the canyon today.

In general, the following descriptions of the formations exposed in Palo
Duro Canyon State Park follow the procedure that most geologists use in
presenting the results of their geologic investigations. The more
distinctive characteristics of the rock units are described in order
that they may be more easily recognized, and the ways in which the rocks
were formed are also considered. With this background it is then
possible to review the geologic history recorded in the bedrock of the
canyon. A simplified geologic map is presented in figure 7; this shows
the distribution of the major rock types in the canyon. The reader will
find it helpful to refer to this map when reading the descriptions of
the various formations.


Quartermaster Formation.--

The oldest formation exposed in the canyon is the Quartermaster
Formation of Permian age (_see_ fig. 6) which is named from exposures
along the banks of Quartermaster Creek in Roger Mills County, Oklahoma.
One of the more colorful formations in the park, the Quartermaster is
composed primarily of brick-red to vermilion shales which are
interbedded with lenses of gray shales, clays, mudstones, and
sandstones. Averaging about 60 feet thick where exposed in the park, the
Quartermaster forms the floor and lower walls of the canyon.

The rocks of this formation are easily examined at many places
throughout the canyon and in them can be seen a number of interesting
geologic phenomena. Probably the most noticeable of these features are
the shining white veins of _gypsum_ that lace the face of the red shale
outcrops (fig. 8). A soft, transparent to translucent mineral that can
be scratched by a fingernail, gypsum is hydrous calcium sulfate
(CaSO_{4}·2H_{2}O). Three varieties of gypsum are found in the canyon:
(1) _satin spar_, a fibrous variety with a silky sheen; (2) _selenite_,
a colorless, transparent variety which commonly occurs in sheet-like
masses; and (3) a fine-grained massive variety called _alabaster_. Satin
spar is the most common variety of gypsum present and it commonly occurs
in thin bands interbedded with the mudstones and sandstones. It is much
more noticeable in the shales, however, for it is typically seen in
narrow veins which criss-cross the surface of the outcrop and intersect
the bedding planes at various angles. Although normally white, some of
the satin spar has a soft pink or bluish hue due to the presence of
impurities in the mineral.

    [Illustration: Fig. 8. Veins of selenite gypsum (top arrow) in
    Quartermaster Formation. Notice diagonal joint to left of
    geologist's hand (lower arrow).]

The presence of gypsum in the Quartermaster red beds is of special
significance to the geologist, for it provides valuable information
about the geologic history of the Palo Duro area. It is known, for
example, that when a landlocked body of sea water in an arid climate
becomes separated from the ocean, one of the most common salts to
precipitate is hydrous calcium sulfate, or gypsum. Gypsum may also be
precipitated when a lake without an outlet evaporates in an arid
climate. Geologic evidence suggests that the sediments which gave rise
to the rocks of the Quartermaster Formation were deposited in a
landlocked arm of the sea during the latter part of the Permian Period.
As evaporation continued and the sea water was reduced to approximately
one-third of its original volume, gypsum was precipitated. There must
have been periodic influxes of silt- and mud-bearing waters entering the
ancient Permian sea, for layers of shale and mudstone are interbedded
with the gypsum.

It is believed that much of the satin spar and selenite gypsum was
originally _anhydrite_ (CaSO_{4}). Unlike gypsum, anhydrite does not
contain water, but it can be changed to gypsum in the presence of
moisture. There are two lines of evidence that indicate an anhydrite
origin for the Quartermaster gypsum. First, microscopic examination of
gypsum samples reveals the presence of residual anhydrite crystals
embedded in the gypsum. Second, many of the gypsum beds have been
squeezed into rather gentle _folds_. These consist of small
_anticlines_, upfolds or arches, and _synclines_, downfolds or troughs
(fig. 9). It has been suggested that this folding took place as the
anhydrite underwent _hydration_, or took on water. As hydration occurred
and the anhydrite was converted to gypsum, the gypsum expanded, thereby
exerting both lateral and vertical pressure on the beds around it. This
produced the crumpled, wave-like folding so characteristic of certain of
the gypsum beds. However, there is not complete agreement that the
folding in the gypsum is due to the hydration of anhydrite. Certain
geologists attribute this deformation to slumping caused by solution
cavities, for gypsum is relatively easily dissolved in water. As the
gypsum was dissolved and carried away in solution, the removal of the
supporting layers of gypsum permitted slumping and consequent
deformation in the overlying shales and mudstones. Although some
geologists believe that the folds were caused by expansion due to the
hydration of anhydrite and others support deformation related to the
removal of soluble gypsum, there is general agreement that the folding
is local and not related to regional or widespread deformation.

    [Illustration: Fig. 9. Sagging beds of Quartermaster Formation have
    produced this gentle syncline, or downfolding, in the rocks. The
    "dome" on Capitol Peak can be seen in the background.]

Not all of the red Quartermaster shales are uniformly colored. Some of
them contain gray-green, circular spots called _reduction halos_ (fig.
10). These spots, which in places give the red shales a distinctive
polka-dot appearance, have been produced as the result of chemical
change of certain minerals within the shale.

As noted earlier, sediments are usually laid down in horizontal layers.
However, in certain environments, sediments may be deposited in such a
way that the layers are inclined at angle to horizontal (fig. 11). This
structure, called _cross-bedding_ or _cross-stratification_, is found in
certain sandstones and other coarse-grained or fragmental sedimentary
rocks. Cross-bedding typically consists of rather distinct inclined
layers separated by _bedding planes_ (the surface of demarcation between
two individual rock layers). Bedding of this type commonly occurs in
sedimentary rocks formed in rivers, deltas, and along the margins of
lakes or oceans. The cross-bedding in the Quartermaster and certain of
the Triassic formations is believed to have been developed under similar
conditions. Although cross-bedding is also common in certain rocks of
_eolian_ origin (deposited by wind) none of the cross-bedding in the
canyon's rocks is due to the action of wind.

In addition, some of the Quartermaster strata have _ripple marks_ on
their surfaces. These features are common in certain sedimentary rocks
and were formed when the surface of a bed of sediment was agitated by
waves or currents. The size, shape, and cross section of the ripple
marks can be used to tell whether the marks were produced by waves or
currents. The ripple marks in the Quartermaster appear to have been
formed by the action of waves on a shallow sea floor.

A number of interesting geologic features in the canyon have been formed
in part in the Quartermaster Formation. These include the multi-hued
Spanish Skirts (fig. 26), the Devil's Slide (fig. 35), Capitol Peak
(fig. 32), and Catarina Cave (fig. 27). The latter is a rather unusual
cave in that it has developed in a large mass of landslide debris
divided by projecting bedrock of the Spanish Skirts. The cave has been
formed by _suffosian_, a process whereby water enters the landslide
debris on the upper slopes and follows buried channels in the landslide
removing rock debris as it passes through. The flood water exits at the
base of the landslide by means of Catarina Cave. The plan of the cave
closely resembles the drainage patterns of surface gullies.


Tecovas Formation.--

Rocks of the Triassic System (fig. 6) are well represented in Palo Duro
Canyon and consist of the _Tecovas_ and _Trujillo_ Formations. These
formations are part of the Dockum Group of Late Triassic age.

Having a total thickness of about 200 feet, the Tecovas (which is named
from exposures found on Tecovas Creek in Potter County, Texas) consists
largely of multicolored shales. Also present are thin layers of soft
sandstone, which are disseminated throughout the shales, and a more
prominent bed of white sandstone, which marks the middle of the
formation. The Tecovas shales overlie the Quartermaster Formation, and
the lower zone of lavender, gray, and white shales forms a relatively
smooth slope that is easily distinguished from the steeper slopes of
gullied red-and-white-banded shales beneath them (fig. 12).

    [Illustration: Fig. 10. Chemical reactions in certain of the red
    Quartermaster shales have produced reduction halos (p. 19) which
    give the rocks a polka-dot appearance.]

    [Illustration: Fig. 11. This boulder, located near the foot of
    Triassic Peak along the Sad Monkey Railroad track, exhibits the
    cross-bedding typical of the Trujillo sandstones.]

But the contact zone between the Tecovas and Quartermaster shales
involves more than a mere change in color. Here is one of the missing
"chapters" in the geologic history of the canyon, for part of the Late
Permian record and all of the record of Early and Middle Triassic time
are missing from the geologic column. Such gaps in the column are
represented by _unconformities_ in the rocks. Here the unconformity is
an ancient erosional surface between the Tecovas Formation of Late
Triassic age and the Late Permian Quartermaster Formation, and there are
many millions of years of earth history represented in this missing
"chapter" in the geologic story of Palo Duro Canyon. During this vast
span of time, thousands of feet of sediments were probably deposited,
converted into rock, and then later removed by erosion.

Near the middle of the Tecovas Formation there is a bed of white,
crumbly (friable) sandstone. Averaging about 15 feet in thickness, this
sandstone contains many _joints_ (small crack-like fractures) along
which no appreciable movement has taken place (fig. 8). There are two
distinct sets of these joints which intersect each other at right
angles. The distinctive joint patterns, the color, and the friability of
this sandstone clearly differentiate it from the harder, darker, and
more coarse-grained sandstones of the overlying Trujillo Formation (p.
22).

The upper part of the Tecovas consists of a layer of orange shale which
overlies the middle sandstone unit and is in contact with the lower part
of the Trujillo Formation.

    [Illustration: Fig. 12. Taken from the northwest rim near Coronado
    Lodge, this photograph shows the four major rock units exposed in
    the park: (1) The Quartermaster Formation which forms the lower wall
    and canyon floor; (2) Tecovas Formation; (3) Trujillo Formation
    which caps the mesas; and (4) Ogallala Formation.]

The fossils which have been found in the Tecovas Formation suggest that
these rocks were derived from sediments deposited in swamps and streams.
Unlike the _marine_ deposits of the Quartermaster, the rocks of the
Tecovas were formed from _continental_ deposits laid down on the land.
Fossils found in the canyon include the bones and teeth of the extinct
semi-aquatic reptiles known as _phytosaurs_ (fig. 13) and bone and skull
fragments of a primitive amphibian called _Buettneria_ (fig. 14).
_Coprolites_ (the fossilized excrement of animals), pieces of petrified
wood, and the teeth and bones of lungfish have also been reported from
the Tecovas.

    [Illustration: Fig. 13. The skull of this crocodile-like creature
    called a phytosaur is typical of the reptiles that inhabited the
    Palo Duro area during the Triassic Period. (Photograph courtesy
    Panhandle-Plains Historical Museum.)]

A number of minerals including _hematite_, an iron mineral, and
_psilomelane_, a barium-magnesium oxide, occur in the Tecovas. Hematite
is an ore of iron and psilomelane a manganese ore, though neither of
these is present in commercial quantities in the canyon.

The Tecovas also contains a number of _concretions_ which range from a
fraction of an inch to as much as 6 inches in diameter. These spherical
masses are generally harder than the fine-grained shaly sands in which
they are found and were thus left behind when the surrounding rock was
eroded away. Some of these concretions are marked by cracks or veins
filled with the mineral _calcite_. Concretions bearing this type of
structure are called _septaria_, or _septarian concretions_.

_Geodes_ are also found in the Tecovas Formation. These are rounded
concretionary rocks with a hollow interior that is frequently lined with
mineral crystals. Well-formed crystals of clear calcite have been found
in many of the geodes from the Tecovas.

Among park landmarks that are characterized by the multi-hued Tecovas
strata are the middle portion of Triassic Peak (fig. 25), the upper part
of the Spanish Skirts (fig. 26), Capitol Peak (fig. 32), and the Devil's
Slide (fig. 35).


Trujillo Formation.--

Named from rock exposures on Trujillo Creek in Oldham County, Texas, the
Trujillo is easy to distinguish from the underlying Tecovas Formation.
The contact is quite distinct and lies between the top of the orange
Tecovas shale and the base of the massive-bedded, cliff-forming Trujillo
sandstone (fig. 25). Although generally fine grained and thickly bedded,
there are local concentrations of pebble-sized rock fragments in the
Trujillo. The weathered surface of the lower sandstone is stained red or
dark brown by iron oxides. However, a fresh, unweathered surface is
typically gray or greenish gray in color, and careful examination of the
unweathered rock reveals the presence of tiny flakes of mica.

The basal Trujillo sandstone is one of the most conspicuous rock units
in the canyon and forms many of the prominent benches and mesas so
typical of the Palo Duro landscape. In places the sandstone is
cross-bedded (p. 20) and contains channel deposits of coarse sand which
suggest that the sediments from which it was derived were deposited in
ancient stream beds.

Red, maroon, and gray shales overlie the basal sandstone member of the
Trujillo, and these shales are overlain by cross-bedded, coarse-grained
sandstone. Another interval of varicolored shales separates the middle
sandstone bed from the upper sandstone member. The middle sandstone unit
is a conspicuous ledge- or cliff-forming rock and is medium to coarse
grained and commonly cross-bedded. In most localities, the upper
sandstone is overlain by a section of red and green shales which mark
the uppermost limits of the Trujillo Formation. In places, however, this
shale section has been removed by erosion and rocks of Tertiary age
directly overlie the sandstone.

Although fossils are not common, the remains of _Buettneria_ (fig. 14),
leaf imprints, pieces of mineralized wood, and the scattered teeth and
bone fragments of reptiles and amphibians have been found. Phytosaur
remains, especially teeth, have also been collected from the Trujillo
sandstones.

The Indians who formerly inhabited the Palo Duro area (p. 3) put the
rocks of the canyon to a number of uses. This appears to be especially
true of the rather coarse-grained Trujillo sandstones, which were
commonly used for constructing primitive rock shelters. The abrasive
surface of the sandstone was especially well suited for grinding grain,
and mortar holes have been found in a number of places. One of these
(fig. 15) can be seen along the tracks of the Sad Monkey Railroad (p.
35) near the foot of Triassic Peak. The Indians also used the clays of
the Quartermaster, Tecovas, and Trujillo Formations to make pottery, and
iron and copper minerals such as hematite and malachite were used to
make red and green pigments for decoration and war paint.

The Trujillo shales and sandstones can be seen in a number of Palo
Duro's more spectacular geological oddities. These erosional remnants
are best developed where blocks of erosion-resistant sandstone protect
underlying pedestals of softer shale (fig. 15). This type of
differential weathering (p. 31) has produced a number of interesting and
unusually shaped pedestal rocks or "hoodoos" (figs. 16 and 20). The most
spectacular erosional remnant--and one that has come to be the
"trademark" of Palo Duro Canyon--is the Lighthouse (fig. 31). The great
jumble of boulders called the Rock Garden (fig. 34) is also composed
largely of massive blocks of dislodged Trujillo sandstone. These
boulders accumulated on the canyon floor as a result of landslides. In
addition, the rock profile known as Santana's Face (fig. 28) is a
naturally sculptured profile in the Trujillo sandstone that forms the
cap of Timber Mesa.


Ogallala Formation.--

The Ogallala Formation is named from exposures around Ogallala in Keith
County, Nebraska. There is a major unconformity between the Trujillo
Formation of the Triassic and the overlying Ogallala Formation of
Pliocene (Late Tertiary) age. Missing here is the geologic evidence for
what may have been some of the more exciting chapters in the canyon's
history. There is no record, for example, of the Jurassic and Cretaceous
Periods which together encompass almost 120 million years of earth
history. Also missing is any evidence of what transpired during more
than 90 percent of the Tertiary Period, for no rocks of Paleocene,
Eocene, Oligocene, or Miocene age are exposed in the canyon. Together
these four epochs comprise approximately 47 million years of earth
history. It is impossible, of course, to determine how many geologic
formations may have been formed and later eroded during the 167 million
years represented by this unconformity. However, our knowledge of
present-day deposition and erosion suggests that the missing geologic
record undoubtedly represents many thousands of feet of rock.

    [Illustration: Fig. 14. The skeleton of _Buettneria_, a large
    amphibian, found in Upper Triassic strata in the canyon. (Photograph
    courtesy Panhandle-Plains Historical Museum.)]

The lower portion of the Ogallala Formation is composed of a
reddish-brown, fine- to medium-grained sandstone that contrasts sharply
with the underlying red and green shales that are exposed in the top of
the Trujillo Formation. Much of this sandy rock is characterized by
pebbles consisting of a variety of igneous, sedimentary, and metamorphic
rocks. Because it consists of rock and mineral fragments of varied
composition and size, this kind of sedimentary rock is called a
_conglomerate_. The type of rock fragments found in basal Ogallala
conglomerates suggests that they were transported to the
Panhandle-Plains area by streams flowing southeastward from the Rocky
Mountains. As these streams deposited their loads, they left behind a
wide spread blanket of sand, gravel, and mud which formed an extensive
alluvial plain that extended from western Nebraska to northwest Texas.
Although it is less than 100 feet thick in Palo Duro Canyon, in places
this great mantle of _fluvial_ (stream-deposited) sediments is as much
as 900 feet thick.

    [Illustration: Fig. 15. The depression in this boulder is a mortar
    hole believed to have been used by the Indians for grinding corn.]

    [Illustration: Fig. 16. This pedestal rock, located near the
    Lighthouse, is capped by a slab of weather-resistant Trujillo
    sandstone.]

Most of the Ogallala Formation consists of a mixture of diverse rock
types such as conglomerate, sandstone, siltstone, clay and marl. But the
upper part of the formation is characterized by thick _caliche_
deposits. A dull, earthy calcite deposit, caliche typically forms in
areas of scant rainfall. It is believed to originate when ground
moisture, containing dissolved calcium bicarbonate, moves to the surface
where the moisture steadily evaporates leaving a calcium carbonate crust
on or near the surface (fig. 17).

Caliche, which derives its name from the Latin _calix_, meaning "lime,"
may be firm and compact or loose and powdery. It is also commonly found
mixed with other materials such as clay, sand, or gravel. Caliche
commonly occurs in the Trans-Pecos, southwestern Gulf Coastal Plain, and
the High Plains area of Texas (_see_ fig. 5, p. 8). In the latter area
it typically makes up the "caprock." Caliche is commonly quarried in
these parts of Texas where it is used as road material and as an
aggregate.

Good exposures of Ogallala caliche can be seen on the surface around the
overlook at Coronado Lodge on the northwest rim of the canyon (fig. 17).
Ogallala strata also crop out along the upper reaches of Park Road 5 as
it starts to descend into the canyon. But probably the most spectacular
exposures of the Ogallala are exposed in the precipitous face of the
Fortress Cliff (fig. 33) which forms part of the eastern rim of the
canyon.

Also located within the Ogallala Formation is a very important
_aquifer_--a porous, water-bearing rock formation. This fine-to
coarse-grained sandstone is very porous and permeable and is the most
important single water-producing formation in the Panhandle-Plains area.

    [Illustration: Fig. 17. The white surface in the right foreground
    consists of caliche (p. 26) in the Ogallala Formation. Coronado
    Lodge can be seen in the right background.]

Opal and chert are locally abundant in the Ogallala conglomerates. The
opal, which is found in small cavities in the conglomerate is not of the
gem variety but it does _fluoresce_. Minerals that exhibit
_fluorescence_ emit visible colors when exposed to ultraviolet light.
For this reason, the Ogallala opal is sought after by rock and mineral
collectors. The chert, a flint-like variety of quartz, occurs as nodules
in the conglomerate and in a well-developed layer near the base of the
formation. Both of these _siliceous_ (silica-bearing) rocks were
apparently prized by the Indians, who used them to fashion knives,
scrapers, projectile points, and other artifacts. The Indians also
learned that flat slabs of caliche were ideal for lining fireplaces and
to construct primitive rock shelters.

A number of Pliocene vertebrates have been found in the Palo Duro area.
Known as the "Age of Mammals," the Tertiary Period was characterized by
mammals as diverse as were the reptiles of the Mesozoic Era. Among these
unusual creatures were such now-extinct species as the saber-tooth cat
and the elephant-like shovel-jawed mastodon (fig. 18). The remains of
these as well as bones of giraffe-like camels, pony-sized horses, and
sloths have been found in the vicinity of the canyon. The grassy plains
of Pliocene time were also inhabited by large tortoises which reached
lengths of up to 3 feet (fig. 19). Dioramas showing how these animals
might have looked, as well as their actual remains, are on display in
the Hall of Pre-History in the lower floor of the Panhandle-Plains
Historical Museum in Canyon, 13 miles west of the park (p. 35).

    [Illustration: Fig. 18. This life-size model of a shovel-jawed
    mastodon is typical of the now-extinct, elephant-like creatures that
    lived in this area during the Pliocene Epoch. (Photograph courtesy
    Panhandle-Plains Historical Museum.)]

    [Illustration: Fig. 19. The carapaces of giant tortoises as much as
    3 feet long have been collected from Pliocene rocks in the Palo Duro
    area. (Photograph courtesy Panhandle-Plains Historical Museum.)]


Rocks of the Pleistocene.--

The youngest rocks in Palo Duro Canyon State Park were formed during the
Pleistocene Epoch of the Quaternary Period of the Cenozoic Era (_see_
geologic time scale, p. 11). Pleistocene rocks are rather widespread in
much of the Panhandle-Plains area and they are mostly composed of
sediments which were deposited in stream valleys, in lakes or ponds, or
by the wind. Most of the Pleistocene strata in the park area consist of
loose deposits of silt and sand which were deposited by wind action.
Known locally as "blow sand," this reddish-brown, silty sand overlies
the Ogallala caliche at most points along the canyon's rim.




                       HOW THE CANYON WAS CARVED


The visitor seeing Palo Duro Canyon for the first time may find it
difficult to believe that this yawning chasm began as a simple gully.
But to the _geomorphologist_--the geologist who studies the origin and
development of landscapes--Palo Duro Canyon is but a gully magnified
many times over. This is evident because the shape of the canyon, the
nature of its tributaries, and the character of its walls indicate that
it has been deepened and lengthened by the downcutting of a stream and
widened by other geologic processes.


                   THE GEOLOGIC WORK OF RUNNING WATER

Palo Duro Canyon is a classic example of a land-form that has been
created by the geologic work of _running water_. Undoubtedly the most
important single agent of erosion, running water probably does more to
wear away the land than all the other geologic agents combined. This is
not surprising considering the fact that the earth's annual
precipitation (such as rain and snow) equals about four billion tons of
water. Although the amount of precipitation varies greatly from place to
place, the average annual precipitation on land is about 40 inches of
water. Of this, roughly 25 percent runs off from the land to form
streams.

When one drives through the park and fords the normally gently flowing
waters of the Prairie Dog Town Fork of the Red River he may well wonder
if this unimposing stream actually is the geologic agent that is
responsible for this deep gorge. But the visitor who happens to be
present during a severe rainstorm will soon be convinced, for during
heavy rains this gentle stream becomes a raging torrent. As the river
increases in size it also becomes a more effective land-shaping tool,
for the larger and swifter the stream, the more rock material it can
carry. Thus, when flowing at peak capacity, this branch of the Red River
becomes a moving ribbon of sandpaper whose load of sand, silt, and
gravel has cut and scoured the canyon walls and floor for hundreds of
thousands of years. How long has it taken the river to carve this
remarkable chasm? Although there is no way of knowing for sure, geologic
evidence indicates that the canyon has formed during the last one
million years--a relatively short time, geologically speaking.

The work of the river is made still more effective by water and sediment
which it receives from its tributaries; this added water substantially
increases the volume and velocity of the river. Although many of the
tributary streams are dry throughout much of the year, they carry large
quantities of water during heavy rains. Moreover, because most of these
streams flow over rock surfaces which are not protected by thick soil or
vegetation, their waters are quickly transported to the master stream.
Thus, the volume and velocity of the Prairie Dog Town Fork of the Red
River make it possible--especially during flood periods--for the river
to carry a large load of rock particles which effectively erodes the
stream channel. Where does this rock debris come from? Most of it is
eroded from the sides and bottom of the river's channel.

The river carries its load in a number of ways. Material such as salt
and other soluble matter is transported in a dissolved state or in
_solution_. Still more, for example, silt and fine sand, is carried in
_suspension_. These sediments are suspended between the surface of the
water and the bottom of the stream channel. Those particles that will
not dissolve in water and are too heavy to be carried in suspension,
constitute the _bottom load_ of the stream. These larger sediments, such
as gravel, cobbles, and boulders, roll, bounce, or slide along the
stream bed.

As flash floods course through Palo Duro Canyon, the river uses its load
to erode further the rocks over which it passes. Each moving rock
fragment literally becomes a cutting tool for _abrasion_ as the loose
rock particles slowly wear away the banks and bed of the stream.
Eventually the abraded rock fragments become smooth and rounded and the
stream channel is gradually worn down to a lower level; it is also
widened.

The river also erodes by _hydraulic action_ as loose rock fragments are
lifted and moved by the force of the stream's current. This process is
similar to the effect produced when soil is churned up and washed away
when water from a garden hose is sprayed on loose earth. The effects of
hydraulic action have played an important role in widening the canyon,
for recession of the cliffs away from the middle of the canyons has been
caused in part by undercutting. Thus, as the soft shale and gypsum beds
were removed by the stream, the overlying sandstone formations gradually
broke off and fell into the canyon. Once on the canyon floor, most of
the slabs and blocks of sandstone were eventually broken up and carried
away by the streams as sand and mud. Not all of the boulders have been
destroyed in this manner; in places (for example, the Rock Garden)
similar boulders are seen today (fig. 34).


               WEATHERING AND GRAVITY ADD THE FINAL TOUCH

Most of the energy of the river has been expended in downcutting, for
the canyon has apparently been deepened more rapidly than it has been
widened. But as the stream gouged its channel deeper into the bedrock,
an ever-increasing expanse of canyon wall was exposed to other agents of
erosion. Slowly--almost imperceptibly--the walls of the canyon have been
eroded by the processes of weathering and mass-wasting.


Weathering.--

Wherever rocks are exposed on the earth's surface, they are attacked by
the agents of _weathering_. They are dissolved by rainwater, pried apart
by frost and ice, and blasted by windblown sand. Some of the changes
produced by weathering are purely mechanical, that is, the rock is
simply reduced to smaller fragments without being broken down chemically
or undergoing any change in its mineral composition. This _mechanical
weathering_, or _disintegration_, takes place in a number of ways.
Changes are especially noticeable in rocks that are subjected to large
daily temperature variations. If a crack in these rocks becomes filled
with water and the temperature drops below freezing, ice forms. When
water freezes it expands by about 10 percent of its volume--this is the
reason why water pipes often split open during the winter. Just as in a
water pipe, the pressure of the expanding ice is commonly great enough
to widen and deepen the crack in the rock. This process, called _frost
wedging_, may ultimately cause the rock to split and fall apart. The
cumulative effects of frost wedging have probably played a significant
role in prying off large blocks of rocks from the walls and rim of the
canyon.

Animals and plants may also hasten rock disintegration. Plant roots
commonly grow in rock crevices and as the roots become larger they wedge
the rock apart. Burrowing animals such as rabbits, gophers, and ground
squirrels also promote rock disintegration. Although they do not attack
the rocks directly, their digging exposes new rock surfaces to
weathering processes. The holes these creatures make also permit water
and air to enter the earth more easily, thereby hastening rock
destruction.

Man, of course, promotes more rock disintegration than all other animals
combined. Thus, as one explores the canyon's trails and climbs its
walls, he will not only see evidence of the various types of mechanical
weathering, he will also be contributing to the further wearing away of
the rocks.

_Decomposition_, or _chemical weathering_, works hand in hand with
mechanical weathering. But unlike disintegration, decomposition produces
rock materials that are basically different from the original
unweathered rock. These changes are brought about as the result of
chemical reactions between minerals in the rocks and water, carbon
dioxide, and oxygen. Although the arid climate and severe winters of the
Panhandle generally facilitate mechanical weathering, some of the red
shales and gypsum deposits show the effect of oxidation, hydration, and
other forms of chemical weathering (fig. 10).


Mass-wasting.--

_Mass-wasting_, the erosional process by which rock and soil move
downslope in response to the force of gravity, has also been
instrumental in shaping Palo Duro Canyon. This type of erosion has been
especially active on the walls of the canyon, for here the slopes are
steep enough to promote downward movement of earth materials. In a few
places there have been landslides which have moved large quantities of
rock in a short span of time. But most mass movements have been
imperceptibly slow as masses of _talus_ (accumulations of rock debris)
on steeper slopes have inched slowly downhill because of their own
weight. Talus deposits produced in this way can be seen at the foot of
most of the cliffs and erosional remnants throughout the canyon (fig.
20).


Differential erosion.--

Even the most casual observer will soon note that not all of the
canyon's rocks have been equally affected by erosion. Indeed, it is the
nature of this _differential erosion_ that gives Palo Duro Canyon the
rugged sculptured appearance that accounts for much of its beauty.

Visitors to Palo Duro Canyon commonly ask why the rock formations are so
diversely shaped. The answer to this question lies in the rocks
themselves. Because the various rock strata are of unequal hardness,
they erode at different rates of speed. Hence, the harder, more
resistant rocks, such as the sandstones and conglomerates of the
Trujillo Formation, form the shelves, ledges, and "caps" of the rock
sculptures. The Lighthouse (fig. 31) and other pedestal rocks (fig. 16)
are good examples of land-forms produced by differential erosion. The
"hoodoos" mentioned earlier are also the products of this type of
erosion (figs. 16 and 20).

    [Illustration: Fig. 20. Talus slopes (arrow) are well developed on
    the east side of Capitol Peak and in places obscure the
    Quartermaster red beds. Note the "hoodoo" at the south (left) end of
    the structure.]

Softer rocks like shales and clay are more readily eroded and they
normally form slopes rather than cliffs or ledges (fig. 12). Grooves,
recesses, and caves have also developed in some of the less resistant
rocks such as the shales and gypsum beds of the Quartermaster Formation.
Catarina Cave (fig. 27) which has formed in the red and white shales of
the Spanish Skirts (fig. 26) is a good example of this type of feature.
Caves of this type afforded protection to both man and wild animals
since the dawn of history, for their remains have been found in a number
of similar caves.

Thus, within a relatively short time--geologically speaking--the
familiar land-shaping processes described above have joined forces to
provide Texas with one of its most remarkable natural attractions. But
interestingly enough, the same geologic processes that created these
unusual formations are busily at work destroying them. As time passes
and erosion progresses, the caps of the pedestals are worn away and the
underlying shales crumble and are washed into the valley below. Yet even
as the old land-forms are being destroyed, wind, water, ice, and man are
attacking the canyon walls to produce still more of these interesting
erosional remnants.




           WHAT TO DO AND SEE AT PALO DURO CANYON STATE PARK


The visitor to Palo Duro Canyon can choose from a number of recreational
and educational activities. Moreover, regardless of whether one visits
for a few hours to picnic along the banks of the river, or spends a week
at one of the well-kept campgrounds, the visit will probably be both
pleasant and rewarding. In the pages that follow there is a brief
description of certain of the park landmarks and some of the more
popular attractions within the canyon. The numbers in parentheses refer
to numbers which designate these places on the map of Palo Duro Canyon
(fig. 2, pp. 4-5). Hopefully, this information will help one to plan his
visit to the canyon and thereby make his stay more enjoyable and
worthwhile.


_Park Entrance_ (1).--

The first stop in the park is the gate at the ranger station (fig. 21).
Here one pays a modest admission fee and receives literature and
information about the park. The park is open every day of the year, but
the entrance gates close at sundown.


_Coronado Lodge and Observation Point_ (2).--

The overlook at Coronado Lodge (fig. 22), located about half a mile from
the Park Entrance, is a good place to start one's visit. Situated on a
ledge of Ogallala caliche (p. 26), the Lodge is an attractive, rustic
structure constructed of blocks of Trujillo sandstone (p. 22). Its
picture windows and outdoor overlook provide a matchless view of the
canyon and make it possible to become oriented for the descent to the
canyon floor. Large, coin-operated telescopes permit close-up views of
distant parts of the canyon, and there are museum cases containing
objects of historical and geological interest from the Palo Duro area.
If possible one should visit the Coronado Observation Point more than
once during the visit, preferably at different times of the day. Because
of shifting clouds and changing lighting conditions, the canyon presents
a continually changing panorama from sunrise to sunset. Open year-round,
the Lodge offers a complete line of souvenirs, film, and camping
supplies. There is also a snack bar where coffee, sandwiches, and cold
drinks can be purchased.


_The Scenic Drive_ (1-16).--

After viewing the canyon from Coronado Lodge, one should take the scenic
drive on Park Road 5. This paved, all-weather road descends the
northwest rim of the canyon and continues on to the turnaround at Cow
Camp, a distance of about 8 miles. Although the present scenic drive was
completed in 1951, the path that it follows is essentially that which
was laid out by Colonel Charles Goodnight when he established Palo Duro
ranch in 1876. The road descends to the canyon floor in a series of
well-engineered turns, but because it drops some 800 feet in little more
than a mile it is wise to use second or low gear on the descent. One
should also observe the posted speed limits (10 to 20 miles per hour)
and keep to the right side of the road at all times.

In the 800-foot drop from rim to floor, the complete geologic section of
the canyon is traversed, as one passes from the Pleistocene sands
through the Ogallala, Trujillo, and Tecovas Formations, before reaching
the Quartermaster Formation which is exposed in the canyon floor. Each
of these geologic formations is discussed elsewhere in this publication
(pp. 16-28).


_Pioneer Amphitheatre_ (3).--

Upon reaching the canyon floor, Park Road 5 flattens out and from this
point it is but a short distance to the Pioneer Amphitheatre, one of the
canyon's newest and most popular attractions. Here, located at the foot
of a colorful 600-foot cliff, is a remarkable 1500-seat outdoor theatre
of latest design (fig. 23). Each evening during a ten-week summer
season, a symphonic drama portraying the history of the Texas Panhandle
is presented in the amphitheatre. Information about these productions
can be obtained at the Park Entrance, Coronado Lodge, and other points
within the park.

    [Illustration: Fig. 21. The entrance gate to Palo Duro Canyon State
    Park.]

    [Illustration: Fig. 22. Coronado Lodge on the canyon's northwest rim
    affords panoramic views of the canyon.]


_Sad Monkey Train Ride_ (4).--

The Sad Monkey Railroad begins--and ends--at Sad Monkey, Texas, a small
"community" that lies at the foot of Triassic Peak (fig. 24). Unlike
most miniature railroads, the Sad Monkey Special is not a "kiddie" ride.
Instead, this 2-mile journey provides an opportunity to get away from
the road for a closer look at the geologic formations exposed along the
track. There are especially good views of the Spanish Skirts (fig. 26),
Catarina Cave (fig. 27), and Triassic Peak (fig. 25). These, and other
features of geologic interest, are pointed out by an experienced
lecturer who also presents a brief review of the geologic history of the
area.


_Triassic Peak_ (5).--

Long used by Indians and ranchers as a Palo Duro landmark, the canyon
visitor will find Triassic Peak to be equally useful as a geologic
landmark. When viewed from the Sad Monkey Railroad Terminal, the south
face of Triassic Peak clearly reveals three of the four major geologic
formations of the canyon (fig. 25).

    [Illustration: Fig. 23. Located on the canyon floor, Pioneer
    Amphitheatre is a modern outdoor theatre where symphonic dramas are
    presented each summer. (Courtesy Mrs. Ples Harper, Texas Panhandle
    Heritage Foundation, Inc.; photograph by Ron Horn.)]

The lower one-third of the peak consists of deeply furrowed, red and
white banded shales of the Quartermaster Formation (p. 17). Overlying
the Permian red beds are the brightly colored, multi-hued Tecovas shales
of Triassic age (p. 19). The composition of the Tecovas is such that the
lower shales tend to weather into relatively gentle slopes with rather
smooth surfaces. Triassic Peak is capped by a weather-resistant layer of
Trujillo sandstone, and this durable cliff-forming sandstone has served
as a protective covering to impede the erosion of the softer rocks of
the Tecovas and Quartermaster Formations. Although it has withstood the
ravages of time exceedingly well, the large blocks of Trujillo sandstone
which litter the flanks and foot of Triassic Peak clearly indicate that
weathering and mass-wasting have exacted their toll in the geologic
past.

    [Illustration: Fig. 24. A trip on the Sad Monkey Railroad is a good
    place to learn more about the canyon's geology and get a closer look
    at the rocks.]

    [Illustration: Fig. 25. Excellent exposures of the Quartermaster
    Formation of Permian age (1) and the Triassic Tecovas (2) and
    Trujillo (3) Formations can be seen in the south face of Triassic
    Peak. The feature known as the Sad Monkey is indicated by the
    arrow.]

Sad Monkey, Texas derives its name from the prominent mass of Trujillo
sandstone at the southern extremity of Triassic Peak. When viewed in the
proper perspective--and with the proper amount of imagination--this
massive block of sandstone bears a striking resemblance to an aged and
saddened monkey.


_Spanish Skirts_ (6).--

Few of the canyon's features are as well-named as the gaudy Spanish
Skirts (fig. 26). The lower part of this multi-colored bluff consists of
alternating layers of red and white Quartermaster shale, capped by the
colorful maroon and lavender Tecovas shales. Located on the north flank
of Timber Mesa, the Spanish Skirts and nearby Catarina Cave can be
reached by an easy half-mile path. The trail begins on the west side of
Park Road 5, just beyond the Timber Creek bridge located several hundred
feet from the Sad Monkey Station.


_Catarina Cave_ (7).--

A short distance west of the Spanish Skirts lies Catarina Cave. This
depression has been washed out of the relatively soluble Permian shales
(fig. 27).


_Santana's Face_ (8).--

Like Triassic Peak, Timber Mesa is capped by a thick layer of massively
bedded Trujillo sandstone. On the eastern tip of the mesa the sandstone
has been eroded in such a fashion that it resembles the profile of an
Indian (fig. 28). This feature, called Santana's Face, is best seen from
the park road shortly after leaving Sad Monkey Station.

    [Illustration: Fig. 26. The gaudy Spanish Skirts are a colorful
    expanse of Quartermaster and Tecovas strata exposed on the north
    flank of Timber Mesa. Note the contrast in weathering in the lower,
    gullied Quartermaster Formation and the smooth slopes of the Tecovas
    shales above it. Catarina Cave (arrow) is at the right.]


_The Sky Ride_ (9).--

The Sky Ride, located near the first water crossing on Park Road 5,
transports visitors from the canyon floor to the top of Timber Mesa
(fig. 28). The 300-foot ascent is made in ski-lift chairs that are
comfortable and safe. The observation area atop the mesa offers an
unusually fine view of most parts of the canyon.

    [Illustration: Fig. 27. Catarina Cave (arrow) is easily reached by a
    half-mile trail from Park Road 5.]

    [Illustration: Fig. 28. Santana's Face (left arrow) has been
    sculptured from the Trujillo sandstone cap of Timber Mesa. The cable
    for the Sky Ride (p. 37) passes through the notch indicated by arrow
    at right.]


_The First Water Crossing_ (10).--

As it winds through the canyon, the park road crosses the Prairie Dog
Town Fork of the Red River seven times in a distance of about 4 miles.
These fords, or water crossings as they are called locally, are paved
and are normally safe to pass through. They should, however, be avoided
during times of heavy rains and flash flooding. Because of stream
erosion, especially fine exposures of the Quartermaster Formation are
revealed in the stream banks near several of the crossings.

The first of these crossings (fig. 29) is about 1 mile from the Sad
Monkey Station and is one of the more popular picnic areas in the park.
This area was also popular with earlier residents of the park, for it is
believed to have been the campgrounds of both the Kiowa and Comanche
Indians.


_Colonel Charles Goodnight's Dugout_ (11).--

As mentioned earlier (p. 6) Colonel Charles Goodnight entered the canyon
in 1876 with more than 16,000 head of cattle. Although he later
established more comfortable quarters, Col. Goodnight first lived in a
primitive dugout similar to the one shown in figure 30. A replica of
this early shelter has been constructed of mud, stone, and logs and can
be seen on the west side of the park road just beyond the first water
crossing (_see_ fig. 29).

    [Illustration: Fig. 29. Now a popular picnic spot, the wooded area
    near the first water crossing through the Prairie Dog Town Fork of
    the Red River was a favorite Indian campground.]


_The Lighthouse_ (12).--

The unpaved road to the Lighthouse enters Park Road 5 about two-tenths
of a mile beyond the first water crossing. Although considered by many
to be the canyon's best-known landmark, the Lighthouse is actually not
within park boundaries. It is located in Little Sunday Canyon about 3
miles west of the road and is not easily accessible to the average
visitor. Like many of the park's natural attractions, the Lighthouse is
an erosional remnant of colorful Trujillo shales and sandstones (fig.
31). A similar pedestal rock, the Devil's Tombstone, can be reached by
means of a trail which leaves the Lighthouse road and enters Sunday
Canyon.

    [Illustration: Fig. 30. When Colonel Charles Goodnight settled in
    the canyon in 1876 he lived in a primitive dugout similar to the one
    shown here.]


_Capitol Peak_ (13).--

Capitol Peak (figs. 20 and 32) is a rather imposing geologic feature
that can be seen from a number of points along Park Road 5. There are
especially good views in the vicinity of the second water crossing if
one will look to the west of the road. Just beyond the crossing an
unimproved road leads to the foot of Capitol Peak. The lower part of
this feature is composed of Quartermaster shales of Permian age and the
upper section consists largely of Triassic Tecovas shales. When viewed
from the proper angle, the silhouette of Capitol Peak is thought to
resemble the prostrate form of a human (fig. 32). For this reason it has
also been called the Sleeping Indian.


_Fortress Cliff_ (14).--

The Ogallala Formation of Pliocene age (p. 23) forms the upper rim of
the canyon and is well exposed in impressive Fortress Cliff (fig. 33).
Although this precipitous cliff dominates the eastern rim of the canyon
along most of the scenic drive, especially good views are afforded
between the second and third water crossings.


_The Rock Garden_ (15).--

Shortly after fording the river at the fifth water crossing, there is a
jumbled pile of boulders on the west side of the road (fig. 34). This
accumulation of Trujillo sandstone blocks has been named the Rock
Garden. Many boulders such as these have accumulated on the floor of the
canyon in ages past. However, most of these have been destroyed by
weathering and their fragments removed by the canyon's streams.


_The Devil's Slide_ (16).--

The Devil's Slide can be reached by an unimproved road that leads
southwest from the scenic drive for a distance of about half a mile.
Composed of upper Quartermaster and lower Tecovas shales, the surface of
this eroded spur is laced with many trails and "slides" that have been
made by previous visitors (fig. 35).

    [Illustration: Fig. 31. The Lighthouse, an erosional remnant and the
    "trademark" of Palo Duro Canyon, exhibits well the geologic
    phenomenon of differential erosion (p. 31).]


_The Turnaround_ (17).--

A loop marks the end of Park Road 5 and the conclusion of the scenic
drive. Located in this area are a number of fine camping areas, picnic
grounds, the old stone cottages called the "Cow Cabins," and rest rooms
with shower facilities (fig. 36).

    [Illustration: Fig. 32. The "dome" on Capitol Peak is a well-known
    canyon landmark. Composed of the Tecovas and Quartermaster
    Formations, the profile of Capitol Peak is referred to as the
    Sleeping Indian. (The "Indian's" head can be seen in the right
    background.)]

    [Illustration: Fig. 33. Fortress Cliff is a prominent feature on the
    eastern rim of the canyon. Seen here are the precipitous cliffs
    developed in the Ogallala caliche (p. 26) and the sandstones and
    shales of the Trujillo Formation.]

    [Illustration: Fig. 34. The Rock Garden is a jumbled mass of
    Trujillo sandstone boulders that mark the site of an ancient
    landslide.]


_Hiking._--

There are a number of established trails for the visitor who is
interested in hiking. The more popular trails include those to the
Spanish Skirts and Catarina Cave (p. 37), the Devil's Tombstone, the
Lighthouse (p. 39), and the Devil's Slide (p. 40). Park rangers will be
glad to provide more complete information about these and other trails
within the canyon.


_Horseback riding._--

Saddle horses can be rented at the stables located east of the road near
the Pioneer Amphitheatre. There are a number of trail rides that can be
taken on well-trained horses accustomed to the rugged terrain of the
canyon. Additional information may be obtained from the attendants at
the stable.


_Camping and picnicking._--

An ample number of well-developed camping and picnic areas are scattered
throughout the canyon. Most are located adjacent to or a short distance
from Park Road 5; they are equipped with outdoor fireplaces and tables.
Running water, rest rooms, and showers are provided in certain areas.
Campsites are available on a first-come first-served basis, and there is
a 10-day limit on overnight camping. Detailed information on camping
regulations and camping areas is available from a park ranger or at the
Entrance Station.


_Photography._--

Palo Duro Canyon offers many opportunities for both amateur and
professional photography. The multi-colored rock formations, erosional
land-forms, and plants and animals offer limitless possibilities to the
creative and imaginative photographer. Color shots are especially
effective, but a haze filter will be helpful when photographing distant
objects. Morning and afternoon are the best times for picture taking as
the mid-day sun is "flat" and lends little perspective to the canyon
scene.

    [Illustration: Fig. 35. The Devil's Slide in the south end of the
    park is an eroded spur of Tecovas shales. Some of the "slides" made
    by visitors are indicated by the arrow.]

    [Illustration: Fig. 36. Outcrops of the Quartermaster (1) and
    Tecovas (2) Formations provide a geological backdrop for this
    campsite near the turnaround at the end of Park Road 5.]




                   PANHANDLE-PLAINS HISTORICAL MUSEUM


    [Illustration: Fig. 37. Located on the campus of West Texas State
    University in Canyon, the Panhandle-Plains Historical Museum has
    many exhibits of historical and geological interest that will
    enhance one's visit to Palo Duro Canyon State Park. (Courtesy
    Panhandle-Plains Historical Museum.)]

The visitor to Palo Duro Canyon State Park would do well to start his
visit at the Panhandle-Plains Historical Museum located on the campus of
West Texas State University in Canyon (fig. 37). Here all phases of
history--recent, archeologic, and geologic--are depicted in the various
halls. In the Hall of Pre-History are the fossilized remains and
reconstructions of ancient animals that were entombed in the canyon
walls as long as 200 million years ago. Elsewhere there are exhibits and
dioramas that portray human history in the Palo Duro area. Beginning
with the oldest known evidence of human occupation about 12,000 years
ago, there is a succession of displays that tell the story of man in the
Palo Duro--High Plains region. These exhibits follow man from the early
Indians living in stone shelters, to the horse-using nomadic plains
Indians who relied heavily on the great herds of bison and who fought a
desperate but losing battle to save their homeland from invasion by the
white man. Here, too, is the story of the coming of the Spanish
conquistadores, the _comancheros_ (_see_ p. 6), and the advent of the
anglican settler. All are portrayed by means of artifacts that represent
the different cultures of the region's colorful past.

The major theme of the Museum is the history of the High Plains during
the period of the cattle industry of the open range. One entire hall is
devoted to the display of saddles, spurs, lariats, barbed wire, branding
irons, a chuck wagon, and a life size model of a typical cowboy of the
Old West. The Museum also houses one of the nation's finest collections
of guns of the Old West, the Old World, and guns of today. Other
highlights include scale models depicting scenes of the Old West,
exhibits of typical rooms from pioneer homes furnished with furniture of
that era, a fine assortment of antique vehicles, and famous collections
of Western art.

The Panhandle-Plains Historical Museum is easily reached from any of the
major highways that pass through Canyon. It is open from 9:00 a.m. to
5:00 p.m. weekdays and from 2:00 p.m. to 6:00 p.m. Sundays.




                         SELECTED REFERENCES[2]


Brand, J. P. (1956) Triassic System, _in_ Eastern Llano Estacado and
    adjoining Osage Plains: West Texas Geol. Soc. and Lubbock Geol.
    Soc., Guidebook, Spring Field Trip, April 6-7, 1956, pp. 8-9.

Cummins, W. F. (1890) The Permian of Texas and its overlying beds: Texas
    Geol. Survey 1st Ann. Rept. (1889), pp. 183-197.

---- (1893) Notes on the geology of northwestern Texas: Texas Geol.
    Survey 4th Ann. Rept. (1892), pt. 1, pp. 177-238.

Drake, N. F. (1892) Stratigraphy of the Triassic formations of northeast
    Texas: Texas Geol. Survey 3rd Ann. Rept. (1891), pp. 225-247.

Evans, G. L. (1949) Upper Cenozoic of the High Plains: West Texas Geol.
    Soc. and New Mexico Geol. Soc., Guidebook for Field Trip No. 2,
    November 9, 1949, pp. 1-9.

*----, and Meade, G. E. (1945) Quaternary of the Texas High Plains, _in_
    Contributions to Geology, 1944: Univ. Texas Pub. 4401, pp. 485-507.

*Frye, J. C., and Leonard, A. B. (1957) Studies of Cenozoic geology
    along eastern margin of Texas High Plains, Armstrong to Howard
    counties: Univ. Texas, Bur. Econ. Geol. Rept. Inves. No. 32, 62 pp.

*----, and ---- (1959) Correlation of the Ogallala Formation (Neogene)
    in western Texas with type localities in Nebraska: Univ. Texas, Bur.
    Econ. Geol. Rept. Inves. No. 39, 46 pp.

*----, and ---- (1964) Relation of Ogallala Formation to the southern
    High Plains in Texas: Univ. Texas, Bur. Econ. Geol. Rept. Inves. No.
    51, 25 pp.

*Girard, R. M. (1959) Bibliography and index of Texas geology: Univ.
    Texas Pub. 5910, 238 pp.

*---- (1964) Texas rocks and minerals: Univ. Texas, Bur. Econ. Geol.
    Guidebook No. 6, 109 pp.

Gould, C. N. (1902) The geology and water resources of the eastern
    portion of the Panhandle of Texas: U. S. Geol. Survey Water-Supply
    Paper 154, 64 pp.

---- (1907) The geology and water resources of the western portion of
    the Panhandle of Texas: U. S. Geol. Survey Water-Supply Paper 191,
    70 pp.

*Matthews, W. H., III (1960) Texas fossils: An amateur collector's
    handbook: Univ. Texas, Bur. Econ. Geol. Guidebook No. 2, 123 pp.

*Patton, L. T. (1923) The geology of Potter County [Texas]: Univ. Texas
    Bull. 2330, 180 pp.

*Reed, L. C., and Longnecker, O. M. (1932) The geology of Hemphill
    County, Texas: Univ. Texas Pub. 3231, 98 pp.

*Sellards, E. H., Adkins, W. S., and Plummer, F. B. (1933) The geology
    of Texas, Vol. I, Stratigraphy: Univ. Texas Bull. 3232 (August 22,
    1932), 1007 pp.

West Texas State University Geological Society (1964) Palo Duro Field
    Trip Guidebook: West Texas State Univ. Geol. Soc., Canyon, 18 pp.

---- (1960) Geology of Palo Duro Canyon State Park and the Panhandle of
    Texas: West Texas State Univ. Geol. Soc., Guidebook for 1966 SASGS
    Annual Field Trip, April 15-17, 1966, 58 pp.

Smith, A. R. (1967) Caves of Palo Duro Canyon: The Texas Caver, Abilene,
    Texas, vol. 12, pp. 145-148.




                                GLOSSARY


Abrasion--erosion of rock material by friction of solid particles moved
    by water, ice, wind, or gravity.

Absolute time--geologic time measured in years. Compare with relative
    time.

Amphibians--cold-blooded four-footed animals which have gills in youth
    and lungs in maturity (e.g., frog).

Anhydrite--the mineral calcium sulfate, CaSO_{4}. _See_ Gypsum.

Anticline--an arch-like fold in the rocks, with the beds dipping in
    opposite directions on the two sides.

Aquifer--a water-bearing layer of porous and permeable rock.

Aragonite--a form of calcium carbonate (CaCO_{3}).

Archeozoic--the oldest known geological era; early Precambrian.

Bedding plane--the plane of demarcation between two individual rock
    layers or strata.

Calcite--a mineral composed of calcium carbonate, CaCO_{3}.

Caliche--an accumulation of calcium carbonate, commonly white in color,
    in the soil profile.

Cenozoic--the latest era of geologic time, containing the Tertiary and
    Quaternary Periods and continuing to the present time.

Chert--dense, hard rock of very fine-grained silica, usually in nodular
    form. This material is also called flint.

Concretion--a concentration, usually spherical, of mineral matter in
    sedimentary rocks, produced by deposits from solution; it is harder
    than the surrounding rock.

Conglomerate--a sedimentary rock composed of rounded, water-worn gravel,
    usually mixed with sand, and cemented together by another mineral
    substance.

Coprolite--the fossilized excrement of animals.

Eolian--pertaining to the erosion and the deposits resulting from wind
    action and to sedimentary rocks composed of wind-transported
    material.

Epoch--a subdivision of a geologic period, such as the Pliocene Epoch of
    the Tertiary Period.

Era--a major division of geologic time. All geologic time is divided
    into five eras: the Archeozoic, Proterozoic, Paleozoic, Mesozoic,
    and Cenozoic Eras.

Fluorescence--luminescence of a mineral during exposure to radiation
    (such as from ultraviolet or X-rays).

Fluvial deposit--sediment deposited by streams.

Formation--a rock unit useful for mapping and distinguished primarily on
    the basis of lithologic character.

Fossil--any remains or traces of plants or animals preserved in deposits
    of a past geologic age.

Geode--a hollow stone, usually lined or filled with mineral matter.

Geologic age--the age of an object as stated in terms of geologic time
    (e.g., a Pennsylvanian fern, Cretaceous dinosaur).

Geologic time--all time which has elapsed since the first known rocks
    were formed and continuing until recent, or modern, times.

Geologic time scale--record of the divisions of earth history.

Gypsum--a mineral, hydrated calcium sulfate (CaSO_{4}·2H_{2}O). _See_
    Anhydrite.

Hoodoo--a form produced by erosion of rock.

Ice age--the Pleistocene Epoch of the Quaternary Period, Cenozoic Era; a
    time of extensive glaciation.

Igneous rock--rocks which have solidified from lava or molten rock
    called magma.

Joint--a fracture in a rock along which there has been no displacement
    on opposite sides of the break.

Joint System--a series of two or more sets of joints passing through a
    rock mass and separating it into blocks of more or less regular
    pattern.

Mass-wasting--erosion caused chiefly by gravity.

Mesozoic--the geologic era between the Paleozoic and Cenozoic Eras; the
    "Age of Reptiles."

Metamorphic rock--rock formed from igneous or sedimentary rocks that
    have been subjected to great changes in temperature, pressure, or
    chemical environment.

Metamorphism--the process whereby rocks are changed physically by heat,
    pressure, or chemical environment into different kinds.

Mineral--a naturally occurring inorganic substance possessing definite
    chemical and physical properties.

Nodule--rounded lump of rock or mineral.

Outcrop--the area where a particular rock formation comes to the
    surface.

Paleontology--the science which deals with the study of fossils.

Paleozoic--that era of geologic time following the Proterozoic and
    preceding the Mesozoic.

Period--a basic unit of the geologic time scale into which the eras are
    divided, such as the Pennsylvanian Period of the Paleozoic Era.

Permian--the seventh and last period of the Paleozoic Era.

Pleistocene--the first of the two epochs of the Quaternary Period, and
    that which precedes modern time, known as the Great Ice Age.

Pliocene--last and youngest epoch of the Tertiary Period of the Cenozoic
    Era.

Proterozoic--youngest era of the Precambrian; follows the Archeozoic Era
    and precedes the Cambrian Period of the Paleozoic Era.

Red beds--a general term for red sandstone, shales, etc., which appear
    to characterize arid periods in the past.

Ripple marks--wave-like corrugations produced in unconsolidated
    materials by wind or water.

Rock--any natural aggregate of mineral matter, usually consisting of a
    mixture of two or more minerals.

Sandstone--sedimentary rock composed of cemented sand grains, usually
    quartz.

Sediment--material that has been deposited by settling from a
    transportation agent such as water or air.

Sedimentary rock--rocks formed by the accumulation of sediments.

Shale--a sedimentary rock formed by the hardening of mud and clay and
    usually tending to split into thin sheets or layers.

Silica--an oxide of silicon (SiO_{2}).

Siliceous--containing or pertaining to silica.

Silt--fine muddy sediment consisting of particles intermediate in size
    between clay particles and sand grains.

Siltstone--a very fine-grained sedimentary rock composed of silt grains,
    and intermediate between shale and sandstone.

Stratified rocks--sedimentary rocks; those formed in beds, layers, or
    strata.

Stratum--an individual layer of rock formation. (Plural, _strata_.)

Superposition, law of--in an undisturbed sequence of rocks younger beds
    overlie older beds.

Syncline--a trough-like fold in the rocks, with the beds dipping inward
    on either side. _See_ Anticline.

Talus--a mass of rock debris commonly on slopes or at the base of a
    steep mountain or cliff.

Topography--the configuration of a land surface.

Unconformity--a break in the sequence of rock formations which separates
    younger strata from older ones; caused primarily by removal of older
    rocks by erosion before those of a later sequence were laid down.

Weathering--any natural process, mechanical or chemical, whereby rocks
    are disintegrated or decomposed into smaller particles and
    ultimately into clay and soil.




                                 Index


                                   A
  abrasion: 30
  Adair, John: 6
  "Age of Mammals": 27
  alabaster: 17
  ancient man in Palo Duro Canyon: 3
  anhydrite: 18
  anticlines: 18
  Apaches: 1, 3
  aquifer: 26
  Arapahos: 3
  Archeozoic rocks: 13


                                    B
  "blow sand": 28
  bottom load: 29
  Brazos River: 8
  _Buettneria_: 22, 23, 24


                                    C
  calcite: 22
  caliche: 26
  camels: 27
  camping and picnicking: 43
  Canyon, Texas: 45
  Capitol Peak: 1, 18, 19, 31, 40, 42
  Carboniferous Period: 16
  Catarina Cave: 19, 37, 38
  chemical weathering: 30
  chert: 26
  Cheyennes: 3
  Civilian Conservation Corps: 8
  Colorado River: 8
  _comancheros_: 6, 46
  Comanches: 1, 3
  concretions: 22
  conglomerate: 24
  coprolites: 22
  Coronado, Francisco Vasquez de: 3
  Coronado Lodge: 1, 21, 26, 33, 34
  "Cow Cabins": 41
  cross-bedding: 19, 20
  cross-stratification: 19


                                    D
  decomposition: 30
  Devil's Slide: 19, 40, 44
  Devil's Tombstone: 40
  differential erosion: 31, 41
  disintegration: 30
  dugout, Col. Charles Goodnight's: 39, 40


                                    E
  earth history: 10-12
  Eastern Caprock Escarpment: 8
  erosion, differential: 31, 41


                                    F
  flash floods: 29
  fluorescence: 26
  fluvial sediments: 24
  Fortress Cliff: 1, 40, 42
  fossils: 10
  frost wedging: 30


                                    G
  geodes: 22
  geologic column: 12
  geologic time scale: 11, 12
  geomorphologist: 29
  Goodnight, Colonel Charles: 1, 39, 40
  gypsum: 17


                                    H
  Harper, Mrs. Ples: 35
  hematite: 22
  Hester, W. A.: 1
  High Plains: 8
  hiking: 43
  history of park: 3-8
  "hoodoos": 23, 31
  Horn, Ron: 35
  horseback riding: 43
  horses: 27
  hydration: 18, 31
  hydraulic action: 30


                                    I
  Ice Age: 3
  igneous rocks: 10
  Indian campground: 39
  Indians of the Plains: 3


                                    J
  JA Ranch: 6


                                    K
  Kiowas: 1, 3


                                    L
  Lighthouse, The: 23, 25, 39, 41
  Little Sunday Canyon: 39
  Llano Estacado: 8


                                    M
  Mackenzie, Colonel Ranald: 3
  mammals: 27
  Marcy, Captain R. B.: 6
  mass-wasting: 31
  mastodon, shovel-jawed: 27
  mechanical weathering: 30
  metamorphic rocks: 10
  mortar hole: 25


                                    O
  Observation Point: 33
  Ogallala Formation: 21, 23-27, 42
  opal: 26
  oxidation: 31


                                    P
  Paleozoic Era: 13
  Palo Duro Canyon State Park: 7, 14, 45
  Panhandle-Plains Historical Museum: 2, 27, 45-46
  Park Entrance: 33
  park history: 3-8
  Park Road 5: 33, 38, 50
  Parker, Chief Quanah: 7
  Pecos River: 8
  pedestal rock: 25
  petrified wood: 22
  photography: 43
  phytosaurs: 22
  picnicking and camping: 43
  Pioneer Amphitheatre: 33-34
  Plains Indians: 3
  Pleistocene rocks: 28
      time: 3
  Pliocene Epoch: 27
  Prairie Dog Town Fork of the Red River: 1, 29, 39
  Precambrian rocks: 13
  principle of superposition: 13
  Proterozoic rocks: 13
  psilomelane: 22


                                    Q
  Quartermaster Formation: 12, 17-19, 20, 21, 31, 36, 37, 42, 44


                                    R
  Red River: 8, 29
  reduction halos: 19, 20
  ripple marks: 19
  Rock Garden, The: 23, 40, 43
  Rocky Mountains: 24


                                    S
  saber-tooth cat: 27
  Sad Monkey, Texas: 36
      Railroad: 6, 20, 23, 35
  Santana's Face: 23, 37, 38
  satin spar: 17
  Scenic Drive, The: 33
  sedimentary rocks: 10
  sediments: 10
  selenite: 17
  septaria: 22
  septarian concretions: 22
  shovel-jawed mastodon: 27
  Sky Ride, The: 37
  Sleeping Indian: 40, 42
  sloths: 27
  siliceous rocks: 27
  solution: 29
  Spanish Skirts: 19, 37
  suffosian: 19
  Sunday Canyon: 40
  superposition, principle of: 13
  suspension: 29
  synclines: 18


                                    T
  talus: 31
  talus slopes: 31
  Tecovas Formation: 19-22, 36, 37, 42, 44
  Texas Panhandle: 9
  Texas Panhandle Heritage Foundation, Inc.: 35
  Texas Parks and Wildlife Department: 2
  Texas-Santa Fe Expedition: 6
  Timber Mesa: 1, 23, 37, 38
  time scale, geologic: 11, 12
  tortoises: 27
  Triassic Peak: 1, 35
  Trujillo Formation: 20, 21, 22-23, 36, 38, 42, 43
  Turnaround, The: 1, 41, 44


                                    U
  unconformities: 21


                                    W
  water crossings: 39
  weathering: 30
  West Texas State University: 45
  Wolfin, Charles A.: 1




                                Footnotes


[1]Professor of Geology, Lamar State College of Technology, Beaumont,
    Texas.

[2]Entries marked with asterisk are published by the Bureau of Economic
    Geology, The University of Texas at Austin. Those not out of print
    are distributed at nominal sale price; list sent on request.


    [Illustration: Cover image, Aerial view of Palo Duro Canyon]




                          Transcriber's Notes


--This book, published without copyright notice, is in the public
  domain.

--Silently corrected a few palpable typos.

--Added links to glossary entries.