94 YEARBOOK, PUBLIC MUSEUM, MILWAUKEE [Vol. II. 



guish the Grand Canyon from all other canyons of the world. It is 

 as if one were looking down from the clouds upon a range of moun- 

 tains beneath. 



The hard rocks stand in vertical cliffs which are almost impassable, 

 and form a great barrier to those who wish to climb up or down the 

 canyon walls. The weaker rocks, such as the shales, are usually in 

 long and gentler slopes, and one far down in the canyon forms a level 

 platform which stretches up and down the river as far as one can see. 

 This is the so-called Tonto Platform, along which a trail has been built 

 that allows a visitor to travel for miles in the canyon itself and to gain 

 some closer impressions of the vastness of that work of erosion. 



To many people the varied colors of the rocks are of the greatest 

 interest. The upper part of the canyon is a pure and glistening white, 

 formed of limestone and sandstone, strongly marked off from the thou- 

 sand feet of rock which lie below them. The red bands are again suc- 

 ceeded by a green shale and these farther down give way to a dark and 

 purplish mass which marks the beginning of the granite into which the 

 river has cut. The form of the rock, the course of the river and the 

 shadows of the temples change from every viewpoint, but the bands of 

 color run from one end of the canyon to the other without alteration, 

 except those changes caused by the shift of the sun hour by hour, and 

 by the coming and going of the clouds. These color changes are, how- 

 ever, almost kaleidoscopic. 



Through this great canyon flows the drainage from a large part of 

 the western slope of the Rocky Mountains. The Colorado river, rising 

 far northward in Wyoming near Yellowstone National Park and later 

 joined by the Grand river in Colorado, descends to the sea through 

 this enormous gap which it has cut through the high table-lands that 

 interrupted its path. The length of the canyons through which the 

 Colorado flows, totals some hundreds of miles, and the river is not 

 bridged for over seven hundred miles above Needles, a distance ap- 

 proximately equal to that, in a straight line, between Chicago and New 

 York. Of this long line of canyons stretching from Wyoming to 

 California, the section two hundred and twenty miles in length be- 

 tween the mouth of the Little Colorado river on the east and Shivwits 

 Plateau on the west forms the Grand Canyon. This is separable into at 

 least four divisions, of which the easternmost, the Kaibab, is the one 

 ordinarily visited by tourists. It is the only part in which the buttes, 

 temples and mesas are to be found, and here is the most sublime ex- 

 ample of the work of river erosion in the world. 



