THE TIME OF GLACIAL LOESS ACCUMULATION 479 



the ice. This argument is not convincing for two special reasons: 

 First, on the corresponding (Wisconsin) drift sheet in America 

 loess is present — in small quantities to be sure, but unmistakably 

 present. Second, there is no reason to assume that conditions 

 were identical at each advance and retreat of the ice. Indeed, 

 the fact that in Europe, as in the United States, nearly all the loess 

 was formed at one time, and only a Httle is associated with the 

 other ice advances, points clearly against Penck's fundamental 

 assumption that the accumulation of loess was due to the approach 

 of a cold cHmate. The relative abundance of loess associated with 

 the lowan ice sheet would be explained by the present hypothesis 

 if ice retreated more rapidly for a time than did any of the later ice 

 sheets. 



Thus the hypothesis that the loess accumulated chiefly during 

 the retreat of the ice sheets appears to have enough support to 

 merit consideration by students of loess. 



