It was cut by one of the great rivers of the continent, the Colorado, which enters Arizona from the north and swings sharply west; thence it turns south to form most of Arizona’s western boundary, and a few miles over the Mexican border empties into the head of the Gulf of California. It drains three hundred thousand square miles of Arizona, Utah, Wyoming, and Colorado. It is formed in Utah by the confluence of the Green and the Grand Rivers.
Including the greater of these, the Green River, it makes a stream fifteen hundred miles in length which collects the waters of the divide south and east of the Great Basin and of many ranges of the Rocky Mountain system. The Grand River, for its contribution, collects the drainage of the Rockies’ mighty western slopes in Colorado.
The lower reaches of these great tributaries and practically all of the Colorado River itself flow through more than five hundred miles of canyons which they were obliged to dig through the slowly upheaving sandstone plateaus in order to maintain their access to the sea. Succeeding canyons bear names designating their scenic or geologic character. Progressively southward they score deeper into the strata of the earth’s crust until, as they approach their climax, they break through the bottom of the Paleozoic lime-stone deep into the heart of the Archean gneiss. This limestone trench is known as the Marble Canyon, the Archean trench as the Granite Gorge. The lower part of the Marble Canyon and all the Granite Gorge, together with their broad, vividly colored and fantastically carved upper canyon ten miles across from rim to rim, a mile high from water to rim-level, the climax of the world of canyons and the most gorgeous spectacle on earth, is the Grand Canyon of the Colorado. It lies east and west in the northern part of the State.
To comprehend it, recall one of those ditches which we all have seen crossing level fields or bordering country roads. It is broad from rim to rim and deeply indented by the side washes which follow heavy showers. Its sides descend by terraces, steep in places with gentle’ slopes between the steeps, and on these slopes are elevations of rock or mud which floods have failed to wash away. Finally, in the middle, is the narrow trench which now, in dry weather, carries a small trickling stream. Not only does this ditch roughly typify the Grand Canyon, reproducing in clumsy, inefficient miniature the basic characteristics of its outline, but it also is identical in the process of its making.
Imagining it in cross-section, we find its sides leading down by successive precipices to broad inter-mediate sloping surfaces. We find upon these broad surfaces enormous mesas and lofty, ornately carved edifices of rock which the floods have left standing. We find in its middle, winding snakelike from side to side, the narrow gorge of the river.
The parallel goes further. It is not at all necessary to conceive that either the wayside ditch or the Grand Canyon was once brimful of madly dashing waters. On the contrary, neither may ever have held much greater streams than they hold to-day. In both cases the power of the stream has been applied to downward trenching; the greater spreading sides were cut by the erosion of countless side streamlets resulting temporarily from periods of melting snow or of local rainfall. It was these streamlets which cut the side canyons and left standing between them the bold promontories of the rim. It was these streamlets, working from the surface, which separated portions of these promontories from the plateau and turned them into isolated mesas. It was the erosion of these mesas which turned many of them into the gigantic and fantastic temples and towers which rise from the canyon’s bowl.
Standing upon the rim and overlooking miles of these successive precipices and intermediate templed levels, we see the dark gorge of the granite trench, and, deep within it, wherever its windings permit a view of its bottom, a narrow ribbon of brown river.. This is the Coloradoa rill; but when we have descended six thousand feet of altitude to its edge we find it a rushing turbulent torrent of muddy water. Its average width is three hundred feet; its average depth thirty feet. It is industriously digging the Grand Canyon still deeper, and perhaps as rapidly as it ever dug since it entered the granite.
Developing the thought in greater detail, let us glance at the illustrations of this chapter and at any photographs which may be at hand, and realization will begin. Let imagination dart back a million years or more to the time when this foreground rim and that far rim across the vast chasm are one continuous plain; perhaps it is a pine forest, with the river, no greater than to-day, perhaps not so great, winding through it close to the surface level. As the river cuts downward, the spring floods following the winter snows cave in its banks here and there, forming sharply slanted valleys which enclose promontories between them.
Spring succeeds spring, and these side valleys deepen and eat backward while the promontories lengthen and grow. The harder strata resist the disintegration of alternate heat and cold, and, while always receding, hold their form as cliffs; the softer strata between the cliffs crumbles and the waste of spring waters spreads them out in long flattened slopes. The centuries pass. The ruin buries itself deep in the soft sandstone. The side valleys work miles back into the pine forest. Each valley acquires its own system of erosion; into each, from either side, enter smaller valleys which themselves are eating backward into the promontories.
The great valley of the Colorado now has broad converging cliff-broken sides. Here and there these indentations meet far in the background behind the promontories, isolating island-like mesas.
The rest of the story is simple repetition. Imagine enough thousands of centuries and you will imagine the Grand Canyon. Those myriad temples and castles and barbaric shrines are all that the rains and melting snows have left of noble mesas, some of which, when originally isolated, enclosed, as the marble encloses the future statue, scores of the lesser but mighty structures which compose the wonder city of the depths.
These architectural operations of Nature may be seen today in midway stages. Find on the map the Powell Plateau in the northwest of the canyon. Once it was continuous with the rim, a noble promontory.
It was cut out from the rim perhaps within the existence of the human race. A few hundred thousand years from now it will be one or more Aladdin palaces.
Find on the map the great Walhalla Plateau in the east of the canyon. Note that its base is nearly separated from the parental rim; a thousand centuries or so and its isolation will be complete. Not long after that, as geologists reckon length of time, it will divide into two plateaus; it is easy to pick the place of division. The tourist of a million years hence will see, where now it stands, a hundred glowing castles.
Let us look again at our photographs, which now we can see with understanding. To realize the spectacle of the canyon, let imagination paint these strata their brilliant colors. It will not be difficult; but here again we must understand.
It is well to recall that these strata were laid in the sea, and that they hardened into stone when the earth’s skin was pushed thousands of feet in air. Originally they were the washings of distant highlands brought down by rivers; the coloring of the shales and sand-stones is that of the parent rock modified, no doubt, by chemical action in sea-water. The limestone, product of the sea, is gray.
As these differently colored strata were once continuous across the canyon, it follows that their sequence is practically identical on both sides of the can-yon. That the colors seem confused is because, viewing the spectacle from an elevation, we see the enormous indentations of the opposite rim in broken and disorganized perspective. Few minds are patient and orderly enough to fully disentangle the kaleidoscopic disarray, but, if we can identify the strata by form as well as color, we can at least comprehend without trouble our principal outline; and comprehension is the broad highway to appreciation.
To identify these strata, it is necessary to call them by name. The names that geologists have assigned them have no scientific significance other than identity; they are Indian and local.
Beginning at the canyon rim we have a stalwart cliff of gray limestone known as the Kaibab Limestone, or, conversationally, the Kaibab; it is about seven hundred feet thick. Of this product of a million years of microscopic life and death on sea-bottoms is formed the splendid south-rim cliffs from which we view the chasm. Across the canyon it is always recognizable as the rim.
Below the talus of the Kaibab is the Coconino sandstone, light yellowish-gray, coarse of grain, the product of swift currents of untold thousands of centuries ago. This stratum makes a fine bright cliff usually about four hundred feet in thickness, an effective roofing for the glowing reds of the depths.
Immediately below the Coconino are the splendid red shales and sandstones known as the Supai formation. These lie in many strata of varying shades, qualities, and thicknesses, but all, seen across the can-yon, merging into a single enormous horizontal body of gorgeous red, The Supai measures eleven hundred feet in perpendicular thickness, but as it is usually seen in slopes which sometimes are long and gentle, it presents to the eye a surface several times as broad. This is the most prominent single mass of color in the canyon, for not only does it form the broadest feature of the opposite wall and of the enormous promontories which jut therefrom, but the main bodies of Buddha, Zoroaster, and many others of the fantastic temples which rise from the floor.
Below the Supai, a perpendicular wall of intense red five hundred feet high forces its personality upon every foot of the canyon’s vast length. This is the famous Redwall, a gray limestone stained crimson with the drip of Supai dye from above. Harder than the sloping sandstone above and the shale below, it pushes aggressively into the picture, squared, perpendicular, glowing. It winds in and out of every bay and gulf, and fronts precipitously every flaring promontory. It roofs with overhanging eaves many a noble palace and turns many a towering monument into a pagoda.
Next below in series is the Tonto, a deep, broad, shallow slant of dull-green and yellow shale, which, with the thin broad sandstone base on which it rests, forms the floor of the outer canyon, the tessellated pavement of the city of flame. Without the Tonto’s green the spectacle of the Grand Canyon would have missed its contrast and its fulness.
Through this floor the Granite Gorge winds its serpentine way, two thousand feet deep, dark with shadows, shining in places where the river swings in view.
These are the series of form and color. They occur with great regularity except in several spots deep in the canyon where small patches of gleaming quartzites and brilliant red shales show against the dark granite; the largest of these lies in the depths directly opposite El Tovar. These rocks are all that one sees of ancient Algonkian strata which once over-lay the granite to a depth of thirteen thousand feetmore than twice the present total depth of the canyon. The erosion of many thousands of centuries wore them away before the rocks that now compose the floor, the temples and the precipiced walls of the great can-yon were even deposited in the sea as sand and lime-stone ooze, a fact that strikingly emphasizes the enormous age of this exhibit. Geologists speak of these splashes of Algonkian rocks as the Unkar group, another local Indian designation. There is also a similar Chuar group, which need not concern any except those who make a close study of the canyon.
This is the picture. The imagination may realize a fleet, vivid impression from the photograph. The visitor upon the rim, outline in hand, may trace its twisting elements in a few moments of attentive observation, and thereafter enjoy his canyon as one only enjoys a new city when he has mastered its scheme and spirit, and can mentally classify its details as they pass before him.
To one thus prepared, the Grand Canyon ceases to be the brew-pot of chaotic emotion and becomes the orderly revelation of Nature, the master craftsman and the divine artist.