DISTRIBUTION OF GLACIERS 9 



Along the western coast of Alaska the conditions are 

 different. Bering Sea lies practically outside the influence 

 of the Pacific circulation and the temperature of its water 

 is approximately normal. Its power to charge air cur- 

 rents with moisture is small, especially in winter; and 

 though the winter temperature over the adjacent land is 

 low, the snowfall is not heavy. There are no great moun- 

 tain ranges to concentrate the precipitation, and the snow 

 of winter, being broadly spread over plains or caught by 

 ranges of moderate height, is dissipated by the melting 

 and evaporation of summer. 



The glacier-bearing belt includes about three-tenths 

 of the vast territory of Alaska. Its exploration has but 

 begun, yet enough is known to give it rank as the third 

 great glacier district of the world, only the Antarctic con- 

 tinent and Greenland surpassing it. Its ice may be 

 roughly estimated to occupy a tenth of the surface, or an 

 absolute area of between 15,000 and 20,000 square miles, 

 and this expanse is so divided and scattered as to offer to 

 the student the utmost variety of local condition and de- 

 tail. Of alpine glaciers, such as would receive individual 

 names if near the homes of men, there are many hundreds, 

 possibly more than a thousand; of broad, composite fields, 

 like the Muir and Malaspina, there are about a half dozen; 

 and more than thirty are known to reach the coast and 

 cast bergs into the sea. 



Skirting the land in a ship and making only brief ex- 

 cursions away from it, we saw only glaciers of the coastal 

 mountains and lowlands, and close inspection was limited 

 to the lower ends of ice streams. The phenomena which 

 arrested our attention were those of wasting, of the depo- 

 sition of detritus, and of the advance and retreat of the ice 

 fronts. It soon became evident that our chief opportunity 

 to advance glacial science was through contributions to 

 the history of local changes in the frontal boundaries of 



