258 K. S. TARE RECENT ADVANCE OE GLACIERS IN ALASKA 



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Otlier tributaries to Malaspina glacier 277 



Summary of observations 277 



Consideration of hypotbeses 278 



The problem to be solved 278 



Hypothesis of climatic causes 279 



Hypothesis of possible uplift 279 



Hypothesis of change of grade 279 



Hypothesis of breaking by earthquake shocks 280 



Hj'pothesis of snovs^ supply resulting from earthquake shaking 280 



Glaciers that are not advancing 282 



Consideration of the f utvire condition 284 



Geologic effects 284 



Possible economic effects 285 



Conclusion ; 285 



Introductory Statement 



Since its discovery, the Malaspina glacier has been in a nearly stagnant 

 condition around most of its periphery. As a result of ablation, in this 

 outer portion of the glacier, there has developed a fringe of moraine- 

 veneered ice, parts of which support forest growth. Back of this morainic 

 fringe the ice plateau has been so smooth as to permit easy sledging in all 

 directions by the several parties (the last in 1897) which have crossed it 

 on their way to mount Saint Elias. Such was apparently its condition 

 even as late as the summer of 1905 ; but in 1906 that part of the Malas- 

 pina glacier which borders Yakutat bay was transformed to a sea of 

 crevasses, across which travel was utterly impossible. This crevassing 

 has been caused by a great forward thrust, which has not only broken the 

 ice surface, but has also pushed forward the glacier margin, and in tlie 

 summer of 1906 was still pushing it forward. 



The evidence is clear that the many smaller glaciers of the Yakutat 

 Bay region were in a condition of general recession up till 1905; but be- 

 tween August, 1905, and June, 1906, three of them have undergone a 

 remarkable advance, accompanied by profound crevassing. It is the pur- 

 pose of this paper to describe these changes and to offer an interpretation 

 of them. 



Location and TopoGRArHY of the Area studied 



Yakutat bay is an indentation in an otherwise straight coastline about 

 midway between Cross sound and ControHer bay. Malaspina glacier bor- 



