RESEARCHES IN ALASKA 



553 



Photo by Lawrence Martin 

 COLUMBIA GLACIER OVERRIDING A FOREST (SEE PAGE 549) 



able sizes, and the largest, Columbia and 

 Valdez, seem to have begun to advance 

 in 1 907- '08, before the smaller ones of 

 College Fiord, where seven ice tongues — 

 the large Yale and Harvard, and the 

 smaller Wellesley, Vassar, and others — 

 all began to advance together in 1909-' 10. 



This absence of relation between size 

 and period of advance and the lack of 

 spasmodic transformation to activity, 

 with rapid return to stagnation observed 

 in Yakutat Bay, suggests that the ad- 

 vances now in progress may be climatic. 

 An increase in precipitation at Valdez 

 from 56 inches in 1904 to 91 inches in 

 1907, and back to 70 inches in 1909, sup- 

 ports this hypothesis, though we do not 

 feel at all sure that the increase was 

 more than local, for such great varia- 

 tions are common in Alaska and are 

 usually not widespread. 



The only satisfactory course for the 

 present is to ascribe the great awakening 



of certain of these glaciers either to cli- 

 matic variations or to earthquakes, and 

 then wait to see whether the other gla- 

 ciers, now retreating, also advance, and 

 whether those now advancing behave as 

 have the Columbia Glacier and certain 

 advancing glaciers in the Alps, suggest- 

 ing a climatic explanation, or whether 

 they develop the characteristics of the 

 earthquake-stimulated Yakutat Bay gla- 

 ciers, as the Childs Glacier seems possi- 

 bly to be doing. It would be most 

 desirable if some one could revisit these 

 glaciers in a year or two to obtain evi- 

 dence bearing on this question. 



OLDER ADVANCES DUE POSSIBLY TO 

 EARTHQUAKES 



I studied the previous history of a 

 group of glaciers in Harriman Fiord 

 carefully, and it furnishes clear evidence 

 of two previous periods of advance. The 

 best evidence comes from the Barry, 



