112 GRAND CANON DISTRICT. 



comparison with its limiting dill's might be regarded aa smooth, but 

 which in reality is diversified by rocky hammocks and basins, and by 

 hillocks where patches of soil give life to scattered cedars and pihons. 

 Of the inner chasm nothing as yet is to be seen. Moving outward into 

 this platform we find its surface to be mostly bare rock, with broad shal- 

 low basins etched in them, which hold water after the showers. There 

 are thousands of these pools, and when the showers have passed they 

 gleam and glitter in the sun like innumerable mirrors. As we move 

 outward towards the center of the grand avenue the immensity and 

 beautiful proportions of the walls develop. The vista, towards the east 

 lengthens out and vanishes against the blue ramp of the Kaibab, which 

 lies as a cloud upon the horizon. To the west the view is less symmet- 

 ric and regular, and the eye wanders vaguely among cliffs and buttes 

 of stupendous magnitude, displaying everywhere the profile with which 

 we have become of late familiar. Much of the distance towards the 

 west is obstructed by the crater, but the portions in view bewilder us by 

 the great number of objects presented, and oppress us by their magni- 

 tudes. At a distance of about two miles irom the base of the northern 

 wall we come suddenly upon the inner chasm. We are not conscious of 

 its proximity until we are within a few yards of it. In less than a min- 

 ute after we have recognized the crest of the farther wall of this abyss 

 we crane over its terrible brink and gaze upon the waters of the river 

 full 3,000 feet below. 



The scene before us is a type of the Grand Canon throughout those por- 

 tions which extend through the Kanab, Uinkaret, and Sheavwits Plateaus. 

 The plan and section here presented are quite simple. They consist of 

 a broad upper chasm from five to six miles in width with walls varying 

 in altitude but little from 2,000 feet. Between these escarpments is a 

 rocky plain, rough indeed, but in the overpowering presence of such 

 walls seeming relatively smooth and uniform. In this floor is cut the 

 inner chasm 3,000 feet deep and from 3,500 to 4,000 feet wide from crest 

 to crest. The true profile will be best understood by consulting the dia- 

 gram, Fig. 10, which is drawn to scale. The strata in which the chasm is 

 excavated are all of Carboniferous age excepting three or four hundred 

 feet at the bottom of the gorge. The strata beneath the Carboniferous 

 are at present believed to be Lower Silurian, and their contact with the 

 Carboniferous is unconformable, both by dip and by erosion. In the up- 

 per part of the palisades which form the wall of the upper chasm we 

 find at the summit two series of limestones. The upper contains an 

 abundance of siliceous matter, one portion of which is intimately dis- 

 seminated through the mass while another portion is aggregated into 

 myriads of cherty nodules varying from two to ten inches in diameter. 

 The lower one is a purer limestone with few nodules. The cherty mem- 

 bers form a nearly vertical band at the summit of the wall; the purer 

 members form a Mansard slope beneath, covered with talus. The total 

 thickness of the limestones is about 700 to 750 feet. Beneath them come 



