XV 



GLACIAL PHENOMENA IN NEVADA 1 



THE monuments of the Ice Age in the Great 

 Basin have been greatly obscured and broken, 

 many of the more ancient of them having 

 perished altogether, leaving scarce a mark, 

 however faint, of their existence a condi 

 tion of things due not alone to the long-con 

 tinued action of post-glacial agents, but also 

 in great part to the perishable character of 

 the rocks of which they were made. The bot 

 toms of the main valleys, once grooved and 

 planished like the glacier pavements of the 

 Sierra, lie buried beneath sediments and detri 

 tus derived from the adjacent mountains, and 

 now form the arid sage plains; characteristic 

 U-shaped canons have become V-shaped by 

 the deepening of their bottoms and straight 

 ening of their sides, and decaying glacier head 

 lands have been undermined and thrown down 

 in loose taluses, while most of the moraines 

 and striae and scratches have been blurred 

 or weathered away. Nevertheless, enough re 

 mains of the more recent and the more enduring 



1 Written at Eureka, Nevada, in November, 1878. 

 [Editor.] 



184 



