CHAPTER XV. THE GRAND CANYON.
The Grand Canyon is a gorge 217 miles in length, through which flows a great river with many storm-born tributaries. It has a winding way, as rivers are wont to have. Its banks are vast structures of adamant, piled up in forms rarely seen in the mountains.
Down by the river the walls are composed of black gneiss, slates, and schists, all greatly implicated and traversed by dikes of granite. Let this formation be called the black gneiss. It is usually about 800 feet in thickness.
Then over the black gneiss are found 800 feet of quartzites, usually in very thin beds of many colors, but exceedingly hard, and ringing under the hammer like phonolite. These beds are dipping and unconformable with the rocks above; while they make but 800 feet of the wall or less, they have a geological thickness of 12,000 feet. Set up a row of books aslant; it is 10 inches from the shelf to the top of the line of books, but there may be 3 feet of the books measured directly through the leaves. So these quartzites are aslant, and though of great geologic thickness, they make but 800 feet of the wall. Your books may have many-colored bindings and differ greatly in their contents; so these quartzites vary greatly from place to place along the wall, and in many places they entirely disappear. Let us call this formation the variegated quartzite.
Above the quartzites there are 500 feet of sandstones. They are of a greenish hue, but are mottled with spots of brown and black by iron stains. They usually stand in a bold cliff, weathered in alcoves. Let this formation be called the cliff sandstone.
Above the cliff sandstone there are 700 feet of bedded sandstones and limestones, which are massive sometimes and sometimes broken into thin strata. These rocks are often weathered in deep alcoves. Let this formation be called the alcove sandstone.
Over the alcove sandstone there are 1,600 feet of limestone, in many places a beautiful marble, as in Marble Canyon. As it appears along the Grand Canyon it is always stained a brilliant red, for immediately over it there are thin seams of iron, and the storms have painted these limestones with pigments from above. Altogether this is the red-wall group. It is chiefly limestone. Let it be called the red wall limestone.
Above the red wall there are 800 feet of gray and bright red sandstone, alternating in beds that look like vast ribbons of landscape. Let it be called the banded sandstone.
And over all, at the top of the wall, is the Aubrey limestone, 1,000 feet in thickness. This Aubrey has much gypsum in it, great beds of alabaster that are pure white in comparison with the great body of limestone below. In the same limestone there are enormous beds of chert, agates, and carnelians. This limestone is especially remarkable for its pinnacles and towers. Let it be called the tower limestone.
Now recapitulate: The black gneiss below, 800 feet in thickness; the variegated quartzite, 800 feet in thickness; the cliff sandstone, 500 feet in thickness; the alcove sandstone, 700 feet in thickness; the red wall limestone, 1,600 feet in thickness; the banded sandstone, 800 feet in thickness; the tower limestone, 1,000 feet in thickness.
These are the elements with which the walls are constructed, from black buttress below to alabaster tower above. All of these elements weather in different forms and are painted in different colors, so that the wall presents a highly complex facade. A wall of homogeneous granite, like that in the Yosemite, is but a naked wall, whether it be 1,000 or 5,000 feet high. Hundreds and thousands of feet mean nothing to the eye when they stand in a meaningless front. A mountain covered by pure snow 10,000 feet high has but little more effect on the imagination than a mountain of snow 1,000 feet high - it is but more of the same thing; but a facade of seven systems of rock has its sublimity multiplied sevenfold.
Let the effect of this multiplied facade be more clearly realized. Stand by the river side at some point where only the black gneiss is seen. A precipitous wall of mountain rises over the river, with crag and pinnacle and cliff in black and brown, and through it runs an angular pattern of red and gray dikes of granite. It is but a mountain cliff which may be repeated in many parts of the world, except that it is singularly naked of vegetation, and the few plants that find footing are of strange tropical varieties and are conspicuous because of their infrequency.
Now climb 800 feet and a point of view is reached where the variegated quartzites are seen. At the summit of the black gneiss a terrace is found, and, set back of this terrace, walls of elaborate sculpture appear, 800 feet in height. This is due to the fact that though the rocks are exceedingly hard they are in very thin layers or strata, and these strata are not horizontal, but stand sometimes on edge, sometimes highly inclined, and sometimes gently inclined. In these variegated beds there are many deep recesses and sharp salients, everywhere set with crags, and the wall is buttressed by a steep talus in many places. In the sheen of the midday sun, these rocks, which are besprinkled with quartz crystals, gleam like walls of diamonds.
A climb of 800 feet over the variegated beds and the foot of the cliff sandstone is reached. It is usually olive green, with spots of brown and black, and presents 500 feet of vertical wall over the variegated sandstone. The dark green is in fine contrast with the variegated beds below and the red wall above.