

FRESH-WATER STREAMS. 



645 



all the tributaries flow in similar profound gorges or chasms. (Fig. 

 1079, from one of the excellent photographs by the artist of Pow- 

 ell's expedition, is a view of " Marble Canon " — a part of the Colo- 

 rado gorge, fifty-five miles long, extending from the mouth of the 

 Paria to the mouth of the Little Colorado. The walls, in the dis- 

 tance, have a height of 3,500 feet. The lofty walls of horizontal 

 strata have in places been chiseled down nearly to a true vertical. 

 On page 792, is a bird's-eye view of part of the Colorado basin. 



Fig. 1080 is another view from the same remarkable region, illus- 

 trating the mountain-forms produced by water-carving within the 



Fig. 1079. 



Canon of the Colorado. 



It is 



canon ; some of the peaks rise 5,500 feet above the bottom, 

 from the Report of Captain C. E. Dutton. 



These profound gorges, as explained by Newberry, are due simply 

 to erosion, each stream having made its own channel. The cliffs are 

 so high that in general no undermining can set back the walls far 

 enough to allow of alluvial plains along the bottom, even when the 

 water is not too rapid ; and, when a channel is cut in granite, lateral 

 wear is always small. 



In the distant part of many similar views, there is a higher level of 



