08B0RN, REVIEW OF THE PLEISTOCE'SE 269 



Missouri, Iowa, Kansas and Nebraska beyond the limits both of the First 

 and the Fourth glaciation. 



Thus the Saxonian drift of North Germany, the Mindel drift of the 

 Swiss Alps and the Kansas drift of America are correlated (Penck, Lev- 

 erett) both by their great antiquity and by their very wide extent. The 

 eminent geologist Wahnschaffe, however, correlates the "Old Drift''' of 

 the north German lowland with the Third or Riss glaciation instead of 

 with the Second. 



Second Inteeglacial Stage — Mixdel-Riss 



Penck regards the Second Interglacial or Mindel-Riss Stage as by far 

 the longest of the interglacial intervals in the Alpine region, estimating 

 the period between the maximum Second glaciation (Mindel) and maxi- 

 mum Third (Riss) as high as 360,000 years. In America also by com- 

 paring the erosion of the Second Glacial (Kansan) drifts with those of 

 the Third Glacial (lUinoian) drifts it would appear that the Second 

 Interglacial Yarmouth Stage was of greater duration than the entire 

 interval between the Third Glacial and present time. In the north Ger- 

 man lowlands it is shown' to be a long interval from the amount of sedi- 

 mentation effected by the interglacial rivers and streams, but whether in 

 this region it is longer than the First Interglacial Stage is doubtful (Lev- 

 erett, 1910, p. 273). 



MOISTURE FOLLOWED BY AKIDITY 



In course of this long warm Second Interglacial Stage the climate 

 again moderated, becoming slightly warmer than the climate of to-day. 

 The climate immediately following the retreat of the ice was cool and 

 moist, then followed a long warm stage, but this stage was finally suc- 

 ceeded by a period of aridity both in Europe and America in which the 

 first loess deposits occurred. In Russia also the Second Interglacial seems 

 to begin with a cool and moist phase followed by a more arid or steppe- 

 like climate favorable to the deposition of loess. It would appear that 

 the height of the interglacial aridity was reached during the deposition 

 of the loess. The "Older Loess'' deposition certainly began both in Europe 

 and America during the Second Interglacial Stage although in neither 

 country is the "Older Loess" so continuous or so thick a deposit as the 

 "Newer Loess." In Europe the "Old Loess" lies betvs^een the "Old Drift" 

 of the First and Second Glacial advances and the "Middle Drift" of the 

 Third Glacial advance. At Mauer near Heidelberg the loess lies imme- 

 diately above the Upper Mauer sand layer which contains an arctic- 

 tundra fauna (Forster, 1913). The various layers of loess are of the 



