At night the view from above of these intricate passages was appalling. The black material of which the rocks are composed did not permit a single ray of light to penetrate the depths below, and the ebony-like darkness seemed dense enough to cut.
Long ridges, terminating in perpendicular cliffs, whose bases impinge upon the river a thousand feet below, extend back into the country for miles. Often they are cut by lateral ravines into peaks and pinnacles, obelisks and towers, and other fantastic forms. These ridges are so narrow that we could hardly walk along them, and their sides drop at an angle of forty-five degrees. It was only the disintegrated shale on the surface, into which our feet sank at every step, that gave us a foothold and kept us from shooting with frightful velocity into the gorges below.
One day the Professor asked me to climb to a point near the summit of a lofty ridge, crowned by two massive ledges of sandstone, four feet thick, which projected over the steep slope like the window sills of some Titanic building. These ledges, one above the other and separated by sixty feet of shale, had been swept clean for about three feet, so that I found an easy pathway for my feet, when after laborious climbing I reached the lower ledge. From my lofty perch I had a bird’s-eye view of mile upon mile of the wonderful Bad Lands, a scene of desolation such as no pen can picture.
It was my duty to search every square inch of the dust-covered slope between the ledges for fossil bones. After much unsuccessful effort, I came to a place at the head of a gorge, where a perpendicular escarpment dropped downward for a thousand feet. The upper ledge of sandstone had broken loose for a space of thirty feet, and this huge mass of rock, four feet thick, carrying with it the loose dirt and polishing the underlying surface as it thundered down the slope, had struck the lower ledge with such force that it too had broken loose and plunged downward into the abyss. A grove of pine trees at the base of the cliff had been crushed to the earth by this avalanche. To my view the remaining trees, which I knew to be about fifty feet high, appeared like seedlings, and the vast mass of rock like a cobblestone.