Starting from the high plateau of Utah, and going south toward the canon, we descend a grand geologic stairway, every shelf or tread of which consists of different formations fifty or more miles broad, from the Eocene, at an altitude of over ten thousand feet at the start, across the Cretaceous, the Jurassic, the Triassic, the Permian, to the Carboniferous, which is the bottom or landing of the Grand Canon plateau at an altitude of about five thousand feet.  Each step terminates more or less abruptly, the first by a drop of eight hundred feet, ornamented by rows of square obelisks and pilasters of uniform pattern and dimension, “giving the effect,” says Major Dutton, “of a gigantic colonnade from which the entablature has been removed or has fallen in ruins.”

The next step, or platform, the Cretaceous, slopes down gradually or dies out on the step beneath it; then comes the Jurassic, which ends in white sandstone cliffs several hundred feet high; then the Triassic, which ends in the famous vermilion cliffs thousands of feet high, most striking in color and in form; then the Permian tread, which also ends in striking cliffs, with their own style of color and architecture; and, lastly, the great Carboniferous platform in which the canon itself is carved.  Now, all these various strata above the canon, making at one time a thickness of over a mile, were worn away in Pliocene times, before the cutting of the Grand Canon began.  Had they remained, and been cut through, we should have had a chasm two miles deep instead of one mile.

The cutting power of a large, rapid volume of water, like the Colorado, charged with sand and gravel, is very great.  According to Major Dutton, in the hydraulic mines of California, the escaping water has been known to cut a chasm from twelve to twenty feet deep in hard basaltic rock, in a single year.  This is, of course, exceptional, but there have, no doubt, been times when the Colorado cut downward very rapidly.  The enormous weathering of its side walls is to me the more wonderful, probably because the forces that have achieved this task are silent and invisible, and, so far as our experience goes, so infinitely slow in their action.  The river is a tremendous machine for grinding and sawing and transporting, but the rains and the frost and the air and the sunbeams smite the rocks as with weapons of down, and one is naturally incredulous as to their destructive effects.

Some of the smaller rivers in the plateau region flow in very deep but very narrow canons.  The rocks being harder and more homogeneous, the weathering has been slight.  The meteoric forces have not taken a hand in the game.  Thus the Parunuweap Canon is only twenty to thirty feet wide, but from six hundred to fifteen hundred feet deep.