ADVANCE AND RETREAT OF CANADIAN GLACIERS 743 



is in some cases advancing. These facts show the glaciers to be 

 vigorous and not in the last stages of decline. 



The great changes in glaciers come as a response to climatic 

 changes. Slight chmatic oscillations take place in periods of about 

 thirty-five years, and now is about the time when a glacial advance 

 is expected. But the advance of these glaciers cannot be due to any 

 such climatic change. Since the winds are deprived of their moisture 

 by the mountains to the west, it is the western glaciers which should 

 first respond to any such change. With the exception of the Asulkan 

 the western glaciers mentioned are all rapidly retreating. 



It would thus appear that the debris covering, and that alone, is 

 responsible for the advance, and indeed for the continued existence, 

 of the glaciers of the eastern Rockies. 



I. H. Ogilvie. 



Columbia University, 

 New York. 



