THE CENOZOIC ERA
Although chapter five is the most recent in the earth’s history and
lasts up to the present day, evidences of its life and its happenings
are extremely meager in the Grand Canyon region. With the exceptions of
the fresh water deposits formed during the very early part (Bryce Canyon
formations) and of the many volcanoes built in the later stages, no
rocks were formed here during that chapter. This region was then above
sea level and erosion was working continuously. The great level plain
which today forms the plateau surface at Grand Canyon was created by the
wearing away of overlying rocks. The Grand Canyon itself and also Zion
and Bryce Canyons were sculptured. In fact, all of the features of
erosion which today make this desert region so picturesque and fanciful
owe their origin to the various agents of erosion which have been at
work during this most recent chapter of the world’s history.
The “Age of Mammals” is a name often applied to the last era. Creatures
not unlike some of the most advanced forms of life found today lived
even in the early parts of this age. As the era progressed,
nevertheless, a development was noticeable until finally in the very
last part man himself appeared. Though few remains of this interesting
and comparatively recent life have been found in northern Arizona and
southern Utah, still a few elephant tusks, some camel teeth and the more
recent remains of early cliff and pueblo dwellers give evidence of a
thrilling history during parts of this era.
In the following pages will be found brief sketches of some of these
interesting features represented in the Grand Canyon region. The many
activities of erosion such as canyon-forming, the eruption of volcanoes,
influences of the great ice sheets of the north, crustal movements,
fragmentary evidences of early mammals, and lastly early man himself are
all introduced.
BRYCE CANYON FORMATION
(WASATCH: EOCENE EPOCH)
The formation found at Bryce Canyon and at Cedar Breaks in southern Utah
has the distinction of being composed of the most recently formed
sedimentary rocks in this plateau region. It was during the early part
of the last great chapter of history that lime and some sand were
accumulating here in fresh water. They are believed by most geologists
to represent the deposits of ancient lakes and in them are found
freshwater mollusks. Rivers and other agents of deposition probably also
took a part in the forming of these strata as is indicated by the great
irregularity and variety of sand and other sediments. Truly the origin
of these rocks presents an interesting problem.
[Illustration: BRYCE CANYON
AERIAL PHOTO COPYRIGHT FRED HARVEY]
[Illustration: MAP OF THE COLORADO RIVER]
The delicate and beautiful colors of Bryce are due to the white
limestone which in many places retains its creamy color, but in others
has been stained a vivid pink by the drainage from upland washes. The
Canyon itself is almost entirely the result of running water which has
carved and etched its pattern during geologically recent times. Just as
the Grand Canyon and Zion Canyon were made possible by a great elevation
of the land in this region, so also was Bryce affected. The small
streams of the Paunsagunt Plateau were given power to cut into the
sandstones and limestones which form the Pink Cliffs, and due to the
peculiar nature of these rocks the many spires, promontories, and
pinnacles were formed as remnants of erosion in the valleys.
A GREAT EROSION SURFACE
(CENOZOIC AGE)
The level, flat and almost featureless skyline of Grand Canyon is an
outstanding characteristic of the plateau of northern Arizona. This
surface is fascinating to some; monotonous to others. To all, it is one
of the most striking features of the region. The history which it
represents, moreover, is of extreme interest and impressive length. Here
on the top of the great plateau is seen the result of vast erosion. Long
periods of work by water, wind, and other elements have gradually worn
away strata that were once above. Just as erosion is forming the Grand
Canyon today, so it has accomplished this much greater task. Several
thousand feet of materials have been removed from the surface over much
of this entire region.
[Illustration: A GREAT EROSION SURFACE
NATIONAL PARK SERVICE]
South of Grand Canyon, at Red Butte, east in the Painted Desert, and
north in Utah are found remnants of those rocks which once formed a
continuous layer over the present plateau. Red sandstones and shales
representing former sands and muds of shallow water and beach,
pebble-rocks and marls deposited by rivers and containing the remains of
cone-bearing trees, crocodiles, and dinosaurs—all these rocks and
probably others once gave color to this area just as today they lend
brilliance to the Painted Desert and to southern Utah. In those places
high cliffs mark the lines of recession—the stages of the constant
retreat of the rocks from the Grand Canyon region before ever-working
forces of erosion. Red Butte to the south of Grand Canyon, on the other
hand, has been preserved as an isolated remnant of the same rocks by its
hard, resistant cap of lava. Thus we have mute evidence of a
tremendously large and wonderful story of former lands, and of their
later wearing away to leave the great plain which now forms the surface
of the plateau about Grand Canyon.
CRUSTAL MOVEMENT AT GRAND CANYON
(CENOZOIC AGE)
Many visitors to the Grand Canyon are distinctly surprised when they
find numerous seashells, corals, and sponges, beautifully preserved in
the limestone layer upon which they are standing. The idea immediately
occurs that this region was once beneath the sea. Obviously then either
the land has risen or the ocean has receded.
A careful study of the region shows that the rock strata which form the
great plateau of northern Arizona have been bent into a huge arch or
dome. The Santa Fe railway travels steadily up grade to the south rim of
Grand Canyon which is 7,000 feet above sea level. The north rim is a
thousand feet higher, while fifteen miles farther north a high point of
9,000 feet is attained. In southern Utah the limestone layer which forms
the top of Grand Canyon passes beneath the surface at 4,000 feet.
Why crustal movements occur is not definitely known though many theories
have been advanced to explain them. It is significant, nevertheless,
that such movements have gone on in all parts of the world many times in
history, and that in many regions they are taking place today. Parts of
the California coast are known to be rising, while some other parts of
the country are sinking slowly.
The question of whether or not the Grand Canyon region is still rising
today cannot be answered with assuredness, but certain it is that it has
been both above and below sea level at many different times in history.
It is the slow sinking of the region which has made possible great
accumulations of sediments and the building up of rock layers. It is the
rising of the land which has brought about great cycles of erosion such
as apparently have occurred several times in the history of the
Southwest. Since today this region is high above sea level, erosion is
rapid. Not only does this elevation give the Colorado River and its
tributaries speed and power to erode downward, but also it gives them
unusual depth through which to cut and to carve the canyons which are
their valleys. Without the rising of this plateau region, the colossal
gorges, the weird, sculptured forms of erosion, all of the fascinating
and picturesque features of this region could not be.
CUTTING THE GRAND CANYON
(PLIOCENE AND PLEISTOCENE EPOCHS)
“WHAT FORCE HAS FORMED THIS MASTERPIECE OF AWE?
WHAT HANDS HAVE WROUGHT THESE WONDERS IN THE WASTE?
O RIVER, GLEAMING IN THE NARROW RIFT
OF GLOOM THAT CLEAVES THE VALLEY’S NETHER DEEP,
FIERCE COLORADO, PRISONED BY THY TOIL,
AND BLINDLY TOILING STILL TO REACH THE SEA.
THY WATERS, GATHERED FROM THE SNOWS AND SPRINGS
AMID THE UTAH HILLS, HAVE CARVED THIS ROAD
OF GLORY TO THE CALIFORNIA GULF.”
—HENRY VAN DYKE
Very difficult is it for the average human fully to realize, to
comprehend the tremendous power of running water. One does not question
the origin of a wayside gulch cut out by recent storms, nor is it hard
to visualize the formation of some steep-walled glen where a
fast-rushing stream is found at work in its bottom. The vast Grand
Canyon, however, an extreme example of erosion, seems a bit too
large—too wide and deep—to be attributed alone to the power of any river
such as exists today. But the Grand Canyon—the greatest of chasms—is
nothing more than the result of the work of running water over a long
period of history.
[Illustration: CROSS SECTIONS OF GRAND CANYON]
NEAR THE WESTERN END OF NATIONAL PARK. ROCKS OF THE THIRD ERA ALONE HERE
FORM THE CANYON WALLS. THOSE OF THE FIRST ERA ARE PROBABLY NOT FAR BELOW
THE RIVER BED.
CENTRAL OR BRIGHT ANGEL AREA. THE INNER GORGE IS CUT IN HARD VERTICAL
ROCKS OF THE FIRST ERA (ARCHEAN). THE UPPER CANYON WALLS ARE FORMED OF
HORIZONTAL ROCKS OF THE THIRD ERA. THE TILTED STRATA OF THE SECOND ERA
WERE HERE WORN AWAY EXCEPT TO THE LEFT OF THE GORGE.
EASTERN END (DESERT VIEW, CAPE ROYAL). THE FLOOR OF THE CANYON IS HERE
FORMED OF TILTED ROCKS OF THE SECOND ERA. THE UPPER WALLS ARE OF
COMPARATIVELY HORIZONTAL ROCKS OF THE THIRD ERA.
[Illustration: THE GRAND CANYON]
Those who have been to the rocky shores of the Colorado River in Grand
Canyon, who have heard its wild roar, and seen its mad waves rush along
their course, need no further introduction to the power of this stream.
It is a mighty river! In the open stretch above the mouth of Bright
Angel Creek its speed varies between two and a half and ten miles an
hour. Its width at the same place is over one hundred yards and its
depth between twelve and forty-five feet. But the Colorado River alone
would have made but little progress were it not for the many
rocks—boulders, pebbles, and sand grains—all of which act as tools and
are constantly gouging and cutting as they move. Just as sandpaper
rubbing over the same place continuously leaves its groove, so this
combination of power and tools is ever carving its course. The Colorado
River during a vast period has cut almost a mile vertically through all
of the great rock layers now exposed in the walls of Grand Canyon.
The width of the Grand Canyon, an average of about ten miles, has been
brought about by the wearing and washing-in of its sides by natural
processes of erosion. Rain, wind, frost, temperature changes and plant
action have all combined to break down the Canyon walls. The soft rocks
on the slopes are continually being broken and removed; the more
resistant ones in the cliffs are undermined so in time fall down. While
the river has been cutting deeper, the Canyon’s sides have been steadily
receding. The Grand Canyon itself is the valley of the Colorado, and its
narrowness rather than its width is the remarkable feature when compared
with the valleys of other rivers. This present canyon profile has been
brought about as the combined effects of an arid climate and a rapidly
downward cutting river.
Even a distant view of the Colorado River in the Grand Canyon bottom is
sufficient to convince one of the tremendous transporting power of this
stream. Thus it not only does the work of cutting downward, but also
carries off the vast load of sand and silt which is continually emptied
into its waters. It has been aptly described as being “too thick to
drink but too thin to plow.” In this region the river known at its
headwaters as the “Silvery Colorado” bears even a higher percentage of
sediment than does the muddy Mississippi-Missouri. It has been found
from carefully made tests by the United States Geological Survey that
the Colorado River carries past any given point in the Grand Canyon an
average of nearly a million tons of sand and silt every day. Thus has
the Grand Canyon been excavated!
THE FORMING OF ZION CANYON
(PLIOCENE AND PLEISTOCENE EPOCHS)
“A Yosemite Valley in colors” is a very apt description which has often
been applied to Zion Canyon in southern Utah. Sheer-walled with a
beautiful flat valley floor, this canyon is not unlike California’s
glacier-carved fairyland in general size and shape, but in formation it
has a very different history.
[Illustration: ZION CANYON]
The brilliant Vermilion Cliffs which form the bottom two thousand feet
of Zion’s walls and the contrasting White Cliffs which rise an
additional thousand feet are hard, resistant sandstones. Wherever these
rocks are found, they form conspicuous perpendicular cliffs because of
their hardness, yet even they show the results of the constant attacks
of weather and erosion over long periods. From once continuous layers,
they have in many places gradually been cut and dissected by running
water until now numerous canyons expose their secrets.
It was relatively late in the last chapter of the earth’s history
(Cenozoic Era) that the cutting of Zion and associated canyons was made
possible by gradual though tremendous crustal movements in the region.
The then broad, low-lying country was raised several thousand feet to
about its present altitude. This was the means of giving power to the
streams, including the masterstream—the Virgin River. Steadily and
relentlessly these active agents of erosion, heavy-laden with their
tools, the muds, sands, and pebbles, have been cutting notches and then
canyons. Zion Creek itself, which is one of the largest tributaries of
the Virgin River, has cut downward through all of the layers now exposed
in the walls of its canyon, and the rock fragments derived from these
have been the means of grinding and gouging. As the stream has struggled
in its course, these sides have slowly but surely receded through the
combined efforts of rain, wind, frost and plants. They have been
undermined and otherwise attacked, but as yet represent comparatively
little progress in widening. Beautiful Zion Canyon, therefore, has been
created as the result of crustal movements bringing into action the
effective cutting power of running water, assisted by all the
ever-working forces of disintegration and decay.
GLACIERS
(PLEISTOCENE EPOCH)
“What part did glaciers play in cutting the Grand Canyon?” This is a
question asked almost daily on the rim of that great chasm. Everyone has
heard of the mighty ice sheets which somewhere back in geologic history
covered a large part of eastern and midwestern United States. Many
people have seen beautiful Yosemite Valley in the far west, and have
been told how it was carved by the action of glaciers. It is not
altogether strange, therefore, that visitors to the Grand Canyon should
associate the cutting power of ice with that tremendous gash in the
earth’s surface. But geologists agree that the glaciers of the Ice Ages
had no direct part in the story of Grand Canyon. No scratches or gouges
made by ice are to be found on the canyon walls, no great rock piles
formed at a glacier’s front are in evidence, and lastly, the very
V-shape of the canyon itself is vastly different from the usual
flat-bottomed valley scooped out by moving ice.
During the last epoch of geologic history, climatic conditions the world
over altered very materially. Upon five different occasions snow
accumulated in the north to form extensive ice sheets which advanced
steadily toward the equator and then retreated with a later change in
conditions. These were not the only ice ages in history, but they were
of such a comparatively recent date that their influence is strongly
felt today in many parts of the world. At the time of greatest expansion
the glaciers reached New York in the east, Missouri in the mid west, and
Washington in the far west. Contemporaneous with these main ice sheets,
furthermore, were large glaciers throughout the Rocky Mountains and the
Sierra Nevadas. In the mountains of Utah and even in the San Francisco
Peaks, just south of the Grand Canyon, are found evidences of glaciers
of this period. Evidently then, climatic conditions in the Southwest as
elsewhere were greatly different from those of today. It is believed
that there was much more rainfall and less evaporation, as shown by the
extensive lakes which existed in this region at that time. Furthermore,
the later melting of the glaciers must have supplied a vast quantity of
water to the Colorado River causing it to be far larger and more
powerful than today.
SAN FRANCISCO MOUNTAIN VOLCANIC FIELD
(PLIOCENE AND PLEISTOCENE EPOCHS)
[Illustration: VIEW OF VOLCANOES FROM NORTH]
Over a large part of the great plateau of northern Arizona are found
sheets of hard lava and cone-shaped craters. The center of this volcanic
activity is located in the San Francisco Peaks just north of the town of
Flagstaff, but lavas and cones are found westward beyond Williams and to
a considerable extent in every other direction. Looking south from Grand
Canyon these peaks may be seen to rise high above the plateau and are a
very beautiful sight. From Flagstaff and Williams not only the mountains
but also great sheets of lava resting on the limestone surface are
conspicuous.
[Illustration: SAN FRANCISCO MOUNTAIN—PAST AND PRESENT]
It was during the last great era in geological history, and for the most
part after the Colorado River had already started to cut the Grand
Canyon, that molten masses broke through and flowed out on the northern
Arizona plateau. Three great periods of such volcanic activity are
represented by the rocks of this region and they range in age from
probably at least a million to relatively recent years.
The first general period of eruption in the San Francisco Volcanic Field
was characterized by a predominance of lava flows which formed a black
rock known as basalt. These flows had an average thickness of about 50
feet and covered an area of 3,000 square miles. Accompanying them was
the formation of about a hundred small cinder cones.
[Illustration: _San Francisco Mountain Volcanic Field_]
It was during the second period of volcanism that six isolated cones of
large size and a somewhat greater number of small cones were formed by
the eruption of lavas widely ranging in composition. San Francisco Peak,
the largest of these cones and a dominant feature of the region reaches
an elevation of 12,611 feet above sea level, or about 5,000 feet above
the plateau surface. It is composed of five different types, of
lava—mostly red or light colored—which represent a corresponding number
of distinct stages in eruption. Since the termination of its
building-up, the crest of this cone has been eroded and worn away to the
extent of 3,000 feet as estimated from restored cross-sections. Other
large volcanic craters of this period are Bill Williams (9,090 feet),
Kendrick (10,418 feet), O’Leary (8,925 feet) and Sitgreaves (9,240
feet).
Two hundred small cones and about twenty cubic miles of lava were
produced in this same general region during a third and relatively
recent period of volcanic activity. Much of this material overlies that
of the two preceding periods. Probably the most interesting feature of
these cones and flows is their age, at least one cone being so recent
that ash from it buried numerous pithouses built by Pueblo Indians
during the eleventh century, A. D.
[Illustration: SAN FRANCISCO MOUNTAIN]
ELEPHANTS AND CAMELS
(PLEISTOCENE EPOCH)
It was during the fifth and last great era in the earth’s history that
mammals developed and that man made his appearance on earth. In many
places in the world the remains of animals that lived during various
parts of this age have been preserved. In the famous asphalt pits of
California literally hundreds of the bones of large mammals—tigers,
mastodons, wolves and many others—have been brought to light. In the
receding ice of northern Siberia, large mammoths—elephant-like animals
representative of the last era, but unknown today—have come to the
surface with even their skin and flesh preserved. But in the Grand
Canyon region few fossils of the more recent times remain to tell the
story of the life that then roamed over this surface. For long ages this
region has been above the level of the sea, erosion has been continuous,
so sediments have not accumulated and consequently few records of life
have been made.
Recently near the western Navajo Indian agency at Tuba City, Arizona,
however, the remains of several extinct animals were discovered. In a
spring, hidden in a sandstone crevice, were found the tusks of a mammoth
and some teeth which belonged to camels and bison. These were creatures
native to this country not far back in history. They give but a very
fragmentary insight into the more recent geologic history of the region,
but they open up a field for interesting speculation to the imaginative
person.
[Illustration: ELEPHANT AND CAMEL REMAINS]
ADVENT OF MAN IN THE SOUTHWEST
(PLEISTOCENE HISTORIC)
After reviewing the chapters of the earth’s history and witnessing the
procession and the slow but steady development of life through the ages,
it is very natural that one should wonder when man came upon the scene.
Compared with the hundreds of millions of years which have elapsed since
the time of the first plants, or the millions of years following the
first appearance of vertebrate animals, the age of man is as nothing. In
the Old World there is evidence that humans existed before the last
great Ice Ages, more than a million years ago, but in the Americas human
occupation is measured in terms of thousands of years only.
Numerous recent discoveries in widely scattered parts of the Southwest
indicate that man first occupied this region at a time when it was still
inhabited by such animals as the ground sloth, the mammoth and the
camel. Artifacts of stone and bone have been found associated with the
remains of these animals. Early man’s camp sites are located along the
margins of former extensive water bodies that existed throughout this
region at a time when the climate was far more humid than now. Little is
known about the nature or habits of these men, but it is supposed that
they were hunters with no knowledge of agriculture.
In the Grand Canyon region, the earliest human history with a clear,
detailed record goes back only to about 300 A. D. From that time up to
the present, however, the story of a flourishing and rapidly changing
civilization is well recorded. Although no written documents have been
left, abundant reliable information is available as a result of
archeological excavations. Even the dates of many important events have
been accurately determined through an ingenious method of calculating
years on the basis of growth rings in the trees used for house
construction.
[Illustration: ANCIENT INDIAN PETROGLYPHS, HEAD OF BRIGHT ANGEL TRAIL,
GRAND CANYON]
Two distinct cultures are represented in the people who have inhabited
the Grand Canyon region for the past 1,600 years. The earlier and more
primitive was that of a long-headed type of man known as the
Basketmaker. This culture was replaced at about 700 A. D. by another,
probably the result of new people entering the area, mixing with the
older inhabitants and introducing new ideas. A broad-headed type of man
who lived in pueblos and made pottery was the result. In the earliest
stages he built only small one-roomed houses and made relatively crude
pottery, but by 1,200 A. D. his architecture and crafts had developed to
a very high stage as witnessed in the largest cliff-dwellings and
pueblos of the region. Since then the culture has declined. The Hopi
Indians of today who live near the Painted Desert Country to the east of
Grand Canyon are considered to be modern representatives of this group.
In numerous localities throughout southern Utah burials of the early
Farmer Basketmaker period and also pithouses of the later Potter
Basketmaker period have been found. One of the latter has also been
discovered near Clear Creek in Grand Canyon. The remains of
cliff-dwellings and surface houses built by the later Pueblo Indians are
common everywhere throughout the region and show all stages of
development. Those at and in the Grand Canyon are typical of the
intermediate periods and, judging from pottery fragments in them, were
made by the ancestors of the modern Hopi.
GEOLOGICAL BIBLIOGRAPHY OF GRAND CANYON REGION
Including Zion, Bryce, Painted Desert, and Petrified Forest
Allen, V. T., Triassic Bentonite of the Painted Desert: Am. Jour.
Sci., vol. xix, April, 1930.
Baker, A. A. and others, Notes on the Stratigraphy of the Moab Region,
Utah; Bull. Am. Assoc. Petrol. Geol., vol. 11, 1927.
—— and Reeside, J. B., Correlation of the Permian of southern Utah,
northern Arizona, northwestern New Mexico, and southwestern Colorado:
Bull. Am. Assoc. Petrol. Geol., vol. 13, no. 11, Nov., 1929.
——, Dane, C. H., and Reeside, J. B. Jr., Correlation of the Jurassic
Formations of Parts of Utah, Arizona, New Mexico and Colorado: U. S.
Geol. Survey Prof. Paper 183, 1936.
——, Geology of the Monument Valley—Navajo Mountain Region, San Juan
County, Utah: U. S. Geol. Survey Bull. 865, 1936.
Brady, L. F., Preliminary Note on the Occurrence of a Primitive
Theropod in the Navajo: Amer. Jour. Sci., vol. 30, 1935.
Branson, E. B., and Mehl, M. G., Triassic Amphibians from the Rocky
Mountain Region: Univ. Mo. Studies, vol. 4, no. 2, 1929.
Butler, B. S., The Ore Deposits of Utah: U. S. Geol. Survey Prof.
Paper 111, pp. 619-620, 1920.
Bryan, Kirk, Discussion of rock-fill dam, Lees Ferry, Arizona: Am.
Soc. Civ. Eng., Proc., vol. 48, pp. 1615-1627.
——, Wind Erosion near Lees Ferry, Arizona: Am. Jour. Sci., vol. 6, p.
291, 1923.
Camp, Charles L., A Study of the Phytosaurs: Memoirs, Univ. Calif.,
vol. 10, Univ. Calif. Press, 1930.
—— and VanderHoof, V. L., Small Bipedal Dinosaur from the Jurassic of
Northern Arizona: Proc. Geol. Soc. Amer., abstract, pp. 384-5, 1934.
Campbell, Ian, and Maxson, J. H., Some Observations on the Archean
Metamorphics of the Grand Canyon: Proc. Nat. Acad. Sci., vol. 19, no.
9, pp. 806-809, 1933.
Campbell, M. R., and Gregory, H. E., The Black Mesa coal field,
Arizona: U. S. Geol. Survey Bull. 431, pt. 2, 1909.
Carpenter, Frank M., A Fossil Insect from the Lower Permian of the
Grand Canyon: U. S. National Museum Proc. No. 2695, 1927.
Colton, Harold S., Sunset Crater—The Effect of a Volcanic Eruption on
an Ancient Pueblo People: Geogr. Review, vol. 22, no. 4, 1932.
—— Basaltic Cinder Cones and Lava Flows of the San Francisco Mountain
Volcanic Field: Mus. Northern Arizona, Bull. 10, 1937.
Cross and Howe, Redbeds of southwestern Colorado and their
correlation: Geol. Soc. Am. Bull., vol. 16, pp. 486-487, 1905.
Dake, C. L., The pre-Moencopi unconformity of the Colorado Plateau:
Jour. Geology, vol. 28, pp. 61-74, 1920.
Darton, N. H., Reconnaissance of parts of northwestern New Mexico and
northern Arizona: U. S. Geol. Survey, Bull. 435, 84 pp., 17 pls.,
1910.
—— Guidebook of the western United States: Part C, the Santa Fe Route
with a side trip to the Grand Canyon of the Colorado: U. S. Geol.
Survey Bull. 615, pp. 123-131, 1915.
—— A Reconnaissance of parts of northwestern New Mexico and northern
Arizona: U. S. Geol. Surv. Prof. Paper 131, 1922.
—— Resume of Arizona geology: Arizona Bu. of Mines, Bull. 119, 1925.
Daugherty, Lyman H., New Fossil Plants from the Petrified Forest:
Proc. Geol. Soc. Amer., abstract, p. 389, 1934.
Davis, W. M., Notes on the Colorado Canyon district: Am. Jour. Sci.,
4th ser., vol. 10, pp. 251-259, 1900.
—— An excursion to the Grand Canyon of the Colorado: Harvard Coll.
Mus. Comp. Zool., vol. 38, pp. 107-201, 1901.
—— The lessons of the Colorado Canyon: Bull. Am. Geogr. Soc., vol. 41,
1909.
Diller, J. S., Asbestos in 1917: U. S. Geol. Survey Mineral Resources
of U. S. 1917, Pt. 2, pp. 198-199, 1918.
Dutton, E. C., The physical history of the Grand Canyon District: U.
S. Geol. Survey Second Ann. Rept., pp. 47-166, pls. X-XXV, and map,
1882.
—— Tertiary history of the Grand Canyon District: U. S. Geol. Survey
Mon. 2, 264 pp., folio atlas, 1882.
Frech, F., Section in Congress Canyon opposite Point Sublime: Compt.
rend. 5th Sess. Cong. geol. internat., pp. 476-81, 1893.
Gilbert, G. K., Report on the geology of portions of Nevada, Utah,
California, and Arizona, examined in the years 1871, 1872, and 1873,
Report U. S. Geog. Surveys W. 100th Mer. vol. 3, pp. 17-187, 503-567,
1875.
Gilmore, Charles W., Fossil Footprints from the Grand Canyon:
Smithsonian Misc. Collections 77 No. 9, 80 No. 3, 80 No. 8, 1926-7-8.
Gregory, H. E., Geology of the Navajo Country: U. S. Geol. Survey
Prof. Paper 93, 161 pp., map, 1917.
—— The Shinarump conglomerate: Am. Jour. Sci., vol. 35, pp. 424-438,
1913.
—— Reconnaissance of a portion of the Little Colorado Valley: Am.
Jour. Sci., 4th ser., vol. 38, pp. 491-501.
—— Igneous origin of the glacial deposits of the Navajo Reservation:
Am. Jour. Sci., 4th ser., vol. 40, pp. 97-115.
—— The Navajo Country: U. S. Geol. Survey Water-Supply Paper 380, 219
pp., map, 1916.
—— and Moore, R. C., The Kaiparowits Region: U. S. Geol. Surv. Prof.
Paper 164, 161 pp. 31 pls., 1931.
——, Colorado Plateau Region, xvi International Geological Congress,
Guidebook 18, Excursions C-1, C-2, 1933.
Hager, Dorsey, Stratigraphy—northeast Arizona—southeast Utah: Mining
and Oil Bull., vol. 10, pp. 167, 423, 1924.
Hesse, Curtis J., Semionotus cf., gigas, from the Triassic of Zion
Park, Utah: Amer. Jour. Sci., vol. 29, 1935.
Hinds, Norman E. A., Ep-Archean and Ep-Algonkian Intervals in Western
North America: Carnegie Inst. Washington, Publ. No. 463, pp. 1-52,
1935.
—— Uncompahgran and Beltian Deposits in Western North America:
Carnegie Inst. Washington, Publ. No. 463, pp. 53-136, 1936.
Huntington, Ellsworth and Goldthwait, J. W., The Hurricane Fault in
the Toquerville district, Utah: Harvard Coll. Mus. Comp. Zool. Bull.,
vol. 42, 1904.
Iddings, J. P., Pre-Cambrian igneous rocks of the Unkar terrane, Grand
Canyon of the Colorado, Ariz., by C. D. Walcott, with notes on the
petrographic character of the lavas by Iddings U. S. Geol. Survey
Fourteenth Ann. Report, Part 2, pp. 520-24, 1895.
Johnson, D. W., A geological excursion in the Grand Canyon district:
Proc. Boston Soc. Nat. Hist., vol. 34, pp. 135-161, pls. 17-22, 1909.
Knowlton, F. H., The Fossil Forests of Arizona: Amer. For., vol. 9,
1913.
—— A Catalogue of the Mesozoic and Cenozoic plants of North America:
U. S. Geol. Survey Bull. 696, 1919.
Lee, W. T., Geologic reconnaissance of a part of western Arizona: U.
S. Geol. Survey Bull. 352, 96 pp., 11 pls. 1908.
—— Stories in Stone. C. Van Nostrand Co., 1926.
—— The Canyons and Painted Cliffs of Zion National Park and the Story
of their Origin, National Park Service.
Longwell, C. R., Geology of the Muddy Mountains, Nev., with a section
to the Grand Wash Cliffs, in western Arizona: Am. Jour. Sci., 4th
ser., vol. 50, pp. 52-54, 1921.
—— and others, Rock formations in the Colorado Plateau of southeastern
Utah and northern Arizona: U. S. Geol. Survey Prof. Paper 132, pp.
1-23, 1923.
——, The pre-Triassic unconformity in southern Nevada: Am. Jour. Sci.,
5th ser., vol. 10, pp. 93-106, 1925.
—— Structural studies in southern Nevada and western Arizona: Geol.
Soc. Am. Bull., vol. 37, pp. 551-584, pls. 17-20, 1926.
——, Geology of the Muddy Mountains, Nevada, with a section through the
Virgin Range to the Grand Wash Cliffs, Arizona: U. S. Geol. Survey
Bull. 798, 1928.
——, Geology of the Boulder Reservoir Floor: Bull. Geol. Soc. Amer.,
vol. 47, pp. 1393-1476, 1936.
Lucas, F. A., Vertebrates from the Trias of Arizona: Science, new
ser., vol. 14, p. 376, 1901.
—— A New Batrachian and a new reptile from the Trias of Arizona: U. S.
Nat. Mus. Proc., vol. 27, pp. 193, 195, 1904.
Lull, R. S., Fossil Footprints from the Grand Canyon of the Colorado:
Amer. Jour. Sci., vol. 45, 1918.
Marcou, Jules, Resume and field notes: U. S. Pacific Railroad Expl.
vol. 3, pt. 4. Geological Report, 1856.
Matthes, F. E., Bright Angel Quadrangle. U. S. Geol. Survey topo. map
text.
Marvine, A. R., Report on the geology of the route from St. George
Utah, to Gila River, Arizona, examined in 1871: U. S. Geog. Survey W.
of 100th Mer., vol. 3, 1875, pp. 189-225, maps.
Maxson, J. H., and Campbell, Ian, Archean Ripple Mark in the Grand
Canyon: Amer. Jour. Sci., vol. 28, 1934.
McKee, Edwin D., Climates of the Age of Mammals in the Grand Canyon
Region: Museum Notes, Museum of Northern Arizona, Flagstaff, 1932.
——, Arizona Through the Ages: Scientific Monthly, 1932.
—— The Coconino Sandstone—Its History and Origin: Carnegie Institution
Publ. 440, vii, 1934.
—— A Study of the Light-colored, Cross-bedded Sandstones of Canyon de
Chelly, Arizona: Am. Jour. Sci., 5th Ser., vol. 28, pp. 219-233, 1934.
——, Occurrence of Triassic Sediments on the Rim of Grand Canyon: Jour.
Wash. Acad. Sci., vol. 25, no. 4, 1935.
——, A Conularia from the Permian of Arizona: Jour. Paleontology, vol.
9, no. 5, 1935.
——, Triassic Pebbles in Northern Arizona Containing Invertebrate
Fossils: Amer. Jour. Sci., vol. 33, 1937.
——, The Environment and History of the Toroweap and Kaibab formations
of Northern Arizona and Southern Utah: Carnegie Inst. Washington,
Publ. 492, 1938.
Merriam, John C., The Living Past, Charles Scribner’s Sons, 1930.
Miller, W. J., Zion Canyon National Park, Utah: Journal of Geography,
May, 1923.
Moore, R. C., On the Stratigraphy of Northeastern Arizona: Am. Assoc.
Petrol. Geol. Bull., vol. 6, no. 1, pp. 47-49, 1922.
Newberry, J. S., Report upon the Colorado River of the West, explored
in 1857-58 by Lieut. J. C. Ives: Govt. Printing Office, pt. 3,
Geological Report, 1861.
Noble, L. F., The geology of the Shinumo area: Am. Jour. Sci., 4th
ser., vol. 29, pp. 369-386, 497-528, 1910.
——, The Shinumo Quadrangle, Grand Canyon district, Arizona: U. S.
Geol. Survey Bull. 549, 100 pp., 18 pls., 1914.
—— A Section of the Paleozoic formations of the Grand Canyon on the
Bass Trail: U. S. Geol. Survey Prof. Paper 131, pp. 23-73, 1922.
—— and Hunter, J. F., A reconnaissance of the Archean complex of the
Granite Gorge, Grand Canyon, Arizona: U. S. Geol. Survey Prof. Paper
98, pp. 95-113, 1916.
—— A Section of Kaibab Limestone in Kaibab Gulch, Utah: U. S. Geol.
Survey, Prof. Paper 150, 1928.
Powell, J. W., Exploration of the Colorado River of the West and its
tributaries explored in 1869-1872: Smithsonian Inst., 291 pp., 1873.
Ransome, F. L., Pre-Cambrian in Grand Canyon: Science, vol. 27, pp.
667-668, 1908.
—— Some Paleozoic sections in Arizona and their correlations: U. S.
Geol. Survey Prof. Paper 98, pp. 133-166, 1916.
Reagan, Albert B., Some Geological Notes on the Upper Cretaceous of
Black Mesa, Arizona, Transactions of the Kansas Academy of Science,
vol. 35, pp. 232-252, 1932.
—— The Tertiary—Pleistocene of the Navajo Country in Arizona, with a
description of some of its included fossils: Transactions of the
Kansas Academy of Science, vol. 35, pp. 253-259, 1932.
Reeside, J. B., and Bassler, Harvey, Stratigraphic sections in
southwestern Utah and northwestern Arizona: U. S. Geol. Sur. Prof.
Paper, 129-D, 1922.
Robinson, H. H., The San Franciscan volcanic field, Arizona: U. S.
Geol. Survey Prof. Paper 76, 213 pp., 14 pls., 1913.
Schuchert, Charles, On the Carboniferous of the Grand Canyon—The
Cambrian of the Grand Canyon: Am. Jour. Sci., 4th ser., vol. 45, pp.
347-369, 1918.
Shimer, H. W., Permo-Triassic of northwestern Arizona: Geol. Soc. Am.
Bull., vol. 30, 1919.
Stoyanow, A. A., Notes on recent stratigraphic work in Arizona: Am.
Jour. Sci., vol. 12, pp. 311-324, 1926.
——, Correlation of Arizona Paleozoic Formations: Bull. Geol. Soc.
Amer., vol. 47, pp. 459-540, 1936.
Vander Hoof, V. L., The Chinle Formation: Museum Notes, Mus. Northern
Arizona, vol. 6, no. 7, 1934.
Walcott, C. D., The Permian and other Paleozoic groups of the Kanab
Valley, Arizona: Am. Jour. Sci., 3rd ser., vol. 20, pp. 221-225, 1880.
—— Pre-Carboniferous strata in the Grand Canyon of the Colorado,
Ariz.: Am. Jour. Sci., 3rd ser., vol. 26, pp. 437, 442, 484, 1883; U.
S. Geol. Survey Fourth Ann. Rept., p. 47, 1884.
—— Study of a line of displacement in the Grand Canyon in northeast
Arizona: Bull. Geol. Soc. America, vol. 1, pp. 49-64, 1890.
—— Pre-Cambrian igneous rocks of the Unkar terrane, Grand Canyon of
the Colorado, Ariz., with notes on the petrographic character of the
Lavas, by J. P. Iddings: U. S. Geol. Survey Fourteenth Ann. Rept. Pt.
2, pp. 497-524, 1894.
—— Algonkian rocks of the Grand Canyon of the Colorado: Jour. Geology,
vol. 3, pp. 312-330, pls. 6, 1895.
—— Pre-Cambrian fossiliferous formations: Bull. Geol. Soc. America,
vol. 10, pp. 199-244, 1899.
—— Cambrian geology and paleontology: Smithsonian Misc. Coll., vol.
64, no. 5, pp. 373, 374, 1916.
——, Geology of the Little Colorado Valley: Am. Jour. Sci., 4th ser.,
vol. 12, pp. 401-413, 1901.
Ward, L. F., Report on the Petrified Forest of Arizona: Twentieth Ann.
Rept., U. S. Geol. Survey, Pt. II, pp. 324-332, 1900.
—— The Petrified Forest of Arizona: Smith Rept. for 1899, Wash., pp.
289-307, 1901.
White, David, Study of the fossil floras in the Grand Canyon: Carnegie
Inst. Year-Book 26, pp. 366-369, 1927.
—— Flora of the Hermit Shale, Grand Canyon, Ariz., Publication No. 405
Carnegie Institution, 1929.
Williams, Howell, Pliocene Volcanoes of the Navajo-Hopi Country: Bull.
Geol. Soc. Amer., vol. 47, pp. 111-172, 1936.
* * * * * *
Transcriber’s note:
--Obvious typographical errors were corrected without comment.
--Non-standard spellings and dialect were not changed.