14 



THE ICE AGE IN NORTH AMERICA. 



Pacific Railroad that they can be easily visited by tourists. 

 The snow-fields of all these are from 9,000 to 10,000 feet above 

 sea-level, but none of the glaciers descend much below 6,000 

 feet, except the Illecillewaet which reaches the level of 4,800 

 feet. 



Fig. 12.— West end of Samovar Glacier. Alaska. 



A wide arid space, of which few who have not traversed 

 the region can have any conception, separates the Rocky 

 Mountains from the Sierra Nevada nearer the Pacific coast. 

 This latter range of mountains is, in some respects, favorably 

 situated for the production of glaciers, since the peaks are 

 lofty, rising in many places upward of 14,000 feet, and there 

 is abundance of snowfall. Ordinarily, however, there is not 

 breadth enough to the summit of the range to furnish ade- 

 quate snow -fields for the production of first-class glaciers. 



The most southern collection of glaciers in the Sierra 

 Nevada is found near the thirty-seventh parallel, a little 

 east of the Yosemite Valley, in Tuolumne and Mono coun- 

 ties, California. Here is a remarkable cluster of mount- 



