THE GEOGRAPHIC SOCIETY'S ALASKAN EXPEDITION 



47 



THE SURFACE OE MARVINE GLACIER IN I906, SHOWING THE DEEP CREVASSES WEIICH 



MADE ITS CROSSING IMPOSSIBLE 



The National Geographic Society's Expedition three years later, 1909, found these crevasses 

 healed and the surface comparatively smooth and easy of traverse (see pp. 17 and 28-29) 



Alaska ; but enough has already been seen 

 to make it possible to compare two 

 widely separated regions, and to show 

 that their glacial history has been differ- 

 ent. While in both cases ice formerly 

 extended beyond the present limits, the 

 Prince William Sound and Copper River 

 regions have not shared in an important 

 episode of recent great ice advance, of 

 which the evidence is so clear and con- 

 vincing in Yakutat Bay and Glacier Bay. 

 Why one part of the Alaskan coast 

 should have been favorable to an ad- 

 vance of glaciers to a distance of many 

 miles, and then to recession of these gla- 

 ciers, while another part gives evidence 

 of no such oscillation, is an interesting 

 question. Other notable differences in 



glacier condition are also found, such, 

 for example, as the dift'erence between 

 Columbia glacier, which is now farther 

 out than it has been for at least a century 

 and is still advancing, and the \'aldez, 

 Nunatak, Muir, and other glaciers, which 

 are now greatly shrunken as compared 

 with their condition a few years ago. 

 Some of these problems cannot be ade- 

 quately discussed until a wider area has 

 been studied and a greater body of fact 

 accumulated. 



In conclusion, the authors wish to ex- 

 press their opinion that the problems of 

 Alaskan glaciers and glaciation present a 

 field for geographical research of the 

 very highest scientific importance. In so 

 lar^e a field not all the glaciers, and in 



