IO6 ALASKA GLACIERS 



of Alaska, nourishes many glaciers. Of these the Johns 

 Hopkins, descending northeastward, has shared the great 

 retreat of Glacier Bay; but the Brady, flowing south, and 

 the La Perouse and Crillon and their neighbors, flowing 

 southwest, have advanced during the same period. 



Close to Disenchantment Bay lies the Malaspina, a pied- 

 mont glacier fed by alpine glaciers of the St. Elias Range. 

 From other slopes of the same range come the principal 

 feeders of the Hubbard, the main glacier of Disenchant- 

 ment Bay. In a century or two the Hubbard has retreated 

 five miles up Disenchantment Bay, but the Malaspina is 

 bordered in places by a mature forest from which it has 

 retired only a short distance, and at one point it has even 

 advanced against the forest within a few years. 1 



The general fact appears to be that mere proximity 

 does not ensure parallelism of glacial history; on opposite 

 sides of a mountain range the sequences of change may 

 be not only different but antithetic. 



THEORIES 



In the discussion of the causes of the advance and 

 retreat of European glaciers the phenomenon occasioning 

 greatest difficulty is the lack of parallelism between the 

 variations of different glaciers and different groups of gla- 

 ciers. The histories of glaciers of the Alps exhibit dis- 

 parities similar to those of Alaska, with the apparent 

 difference that the Alaskan disparities are of larger scale, 

 just as the Alaskan glaciation has a larger pattern; and 

 the arctic and boreal glaciers of Europe probably exhibit 

 equal irregularity, although Rabot, who has recently 

 assembled the evidence, finds a number of partial corre- 

 spondences. 2 



1 I. C. Russell. Amer. Geol., vol. ix, p. 329, 1892. 



2 Les variations de longueur des glaciers dans les regions artiques et bore'ales. 

 Arch, des Sci. Phys. et Nat., 4me periode, vols. 3, 7, 8, 9, Geneva, 1897-1900. 



