Edwin D. McKee

“ Red sandstones and shales representing former sands and muds of shallow water and beach, pebble-rocks and marls deposited by rivers and containing 33 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. ”

“ The lure of a desert with its drifting sands, its scattered oases, and its broad extent has ever been great. Today in the Southwest, cut off from the moist ocean breezes of the west by the lofty Sierra Nevadas and further isolated by the Rocky Mountains to the east, is America’s great desert region. Here the winds and the rains are constantly at work tearing down and sculpturing the great land masses, while in places the wind is piling up the sand and debris to form dunes and new lands. ”

“ In that country the grey and red hills of clay, the cliffs of sand and the many brightly colored layers of hardened mud represent a part of the ancient landscape in which lived the “terrible lizards.” Furthermore, life definitely inserts itself into this picture when a person sees in the rocks the very three-toed tracks left by the dinosaur. Who can deny the story of life when he can place his fingers in the foot impressions and measure the strides of these animals—many of them—both large and small? ”

“ Point at Grand Canyon are all monuments of the Jurassic Age. These high walls are of sandstone—formed from sand steeply piled at varying angles. They have been aptly called “cliffs of fossil sand dunes.”
While desert winds and a burning sun were playing a prominent part in the Grand Canyon region, during the Jurassic Age, other sections of the country were favored with a moist climate and luxuriant vegetation. Dinosaurs and other reptiles waded about in swamps and developed to tremendous sizes. The country teemed with life, very different from that of today, yet none the less interesting. ”

“ 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. ”

“ 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. ”

“ 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. ”

“ The oldest forms of life represented in rocks of Grand Canyon are found in strata of the Second, or Algonkian, Era. Certain layers of limestone showing peculiar structural patterns on their surfaces are interpreted as being the reefs built up through the activities of primitive one-celled plants known as algae. Similar structures are being formed today by plants of this type. Near Harper’s Ferry, West Virginia, for example, algae are building up limestone layers almost identical to the fossil ones found in the Algonkian rocks of Grand Canyon. ”

“ At the Grand Canyon, although we are impressed by the depth of the dark Archean rocks, beneath the plateau surface approximately a mile, yet we marvel even more when we contemplate their great age and the important series of events whose history they partially record. Built up originally as great horizontal deposits of sand and mud, they were bent by mighty crustal movements until high mountains, probably comparable to the present Alps, were formed. ”

“ As will be seen in the succeeding pages, some of these rocks are sandstones formed from the sands of early beaches or sand dune areas, others are shales—the hardened muds of ancient river deltas—and still others are limestones built up by accumulations of plant and animal remains on sea bottoms. All are rocks formed by the deposition of sediments by wind and water during vast intervals of time. In them have been hidden and preserved many forms of life. Seashells, footprints, fern impressions, and various other traces of early plants and animals remain to tell the story of these ancient times. ”

“ Along Bright Angel Canyon and in several other places in the Grand Canyon, rocks of Algonkian age, representing accumulations of sediments several thousand feet in thickness, are found. Below and to the north of Desert View (southeast of Cape Royal on the North Rim) they form the open floor of the Canyon. Everywhere the most conspicuous layer of this series is a mud rock of brilliant vermilion color. However, the rocks also include a conglomerate or 6 pebble layer, a dark limestone formed principally by plants, and a purple quartzite made by the consolidation of the grains of a sandstone. ”

“ 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. ”

“ Thirty-five species of plants are at present known from the Hermit Shale of Grand Canyon. Many of these have not been found elsewhere in the world, though some were representatives of European plants, and others had their closest relations in central Asia, India, Australia, Africa, and South America. This fossil flora consists principally of ferns and small cone-bearing plants, all of which were relatively dwarfed in size and appear less dense than those of corresponding age found in eastern America. ”

“ In several parts of the world traces of great ice sheets—glaciers which scratched and eroded the surface—are found preserved in Algonkian rocks. In other places, including the Grand Canyon, ancient flows of lava are found where they gushed out upon the surface of an old land mass. Among the rocks below Desert View (Navajo) Point and bordering on the Colorado River may readily be seen several black cliffs formed by the volcanic activity of this early age. ”

“ 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.
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. ”

“ Great accumulations of vegetable matter, buried beneath sediments brought down by streams, eventually formed the many layers of coal which today are found in various places in Utah, Arizona, and New Mexico. In the last named state some extensive and valuable coal beds are found in rocks of this age near Gallup. Impressions of leaves and pieces of fossil wood are also numerous among these rocks and they indicate that there was a warm, moist climate during that period in which they grew. ”

“ 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. ”

“ Everywhere the rounding off of corners takes place.
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The origin of the Redwall Limestone is as interesting as its form. The purity of the lime indicates that it was built up in a relatively wide and quiet sea. Its composition represents a vast accumulation of the skeletons of ancient plants and animals. Seashells are found in great numbers, some of them preserved in delicate detail. These and other forms of ocean life clearly indicate that a great sea connection then existed between this region and that of western Canada to the north. ”

“ Dinosaur means “terrible lizard.” Everyone has heard this name and attaches to it at least a vague conception of a creature of peculiar shape and tremendous size. In the dim far-away past these giant reptiles lived, developed and died in many parts of this country, but to most of us, they are only fantastic creatures in literature—not live or moving animals.
DINOSAUR TRACKS. PAINTED DESERT
The reality of the dinosaur should become apparent to those who travel through the Painted Desert region of 25 Arizona. ”

“ 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. ”

“ 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. ”

“ 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. ”

“ They are not highly altered or completely changed in form and structure as are those of the oldest era, but are largely free from such changes and, for the most part, similar to rocks which are seen in the process of formation today. Furthermore, they are known to contain definite traces of plant life, though no certain forms of animal life have yet been found in them. ”

“ A large majority of the fossil trees in Petrified Forest National Monument represent a pine-like species belonging to a group now extinct in the northern hemisphere. Some individuals of this type 24 have diameters as great as ten feet and heights of more than 200 feet. ”

“ It is composed of relatively pure lime so rain and other waters have a chemical action upon it—they leach and dissolve it. Waters all tend to drain toward curving centers, and so increase this curving. ”