THE TIME OF GLACIAL LOESS ACCUMULATION IN ITS 

 RELATION TO THE CLIMATIC IMPLICATIONS OF 

 THE GREAT LOESS DEPOSITS: DID THEY CHIEFLY 

 ACCUMULATE DURING GLACIAL RETREAT? 



STEPHEN SARGENT VISHER 

 Indiana University, Bloomington, Indiana 



Although deposits similar in several respects to glacial loess 

 are forming today near the borders of certain deserts and along 

 the bluffs of some great rivers, the widespread, thick loess deposits 

 which are associated with some drift sheets imply pecuHar cH- 

 matic conditions, for no deserts are now close to these ancient 

 deposits, and parts of them are far from great rivers. There have 

 been many discussions of the probable origin of loess, and thus, 

 indirectly, of its climatic implications. Much has been learned, 

 among other things that different deposits accumulated under differ- 

 ent conditions. But one question appears not to have been satis- 

 factorily settled, that is. At what time, in respect to glaciation, did 

 the greater part of the accumulation take place ? Several American 

 and European students have thought that the great loess deposits 

 date from interglacial times. On the other hand, Penck has 

 concluded that the loess was formed shortly before the commence- 

 ment of the glacial epochs; while many American geologists have 

 held that most of the loess accumulated while the ice sheets were 

 at approximately their maximum size. Chamberlin and Salisbury,^ 

 McGee, and others lean toward this view. 



There is evidence in support of each of these hypotheses, but it 

 seems well to reconsider the possibilities that a large share of the 

 great deposits associated with glaciation were formed at the one other 

 possible glacial time, namely immediately following the retreat of 

 the ice. Recent evidence affords light not available to the workers 



'Chamberlin and Salisbury, Geology, Vol. Ill (1906), pp. 405-12, a comprehensive 

 discussion of the characteristics and distribution of the American loess, with references 

 to McGee, Shimek, and others. 



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