QUATERNARY 



649 



even warmer than at present in the same regions, are conclusive. 

 The drift of the earlier glacial stages, where it has not been covered 

 by more recent drift, differs from the latter in a number of particulars : 

 (1) the drainage of the surface is mature, being in this respect in 

 marked contrast to the immature drainage of the most recent drift, 

 with its lakes and marshes ; (2) the bowlders of the older drift sheets 

 are found to be different from those of later drifts, showing that they 

 were brought by ice sheets that moved in a somewhat different direc- 

 tion; (3) the bowlders of the older drift are, moreover, much weath- 

 ered, so that even granite bowlders can sometimes be crumbled in 

 the hand, and the clay is deeply oxidized and the lime largely leached 

 out. (4) Deeply eroded surfaces, covered with peat or ancient 

 soils (Fig. 567) occur, underlying more recent drift. The most satisfy- 

 ing proof is found in two sections, one in Iowa and the other near 

 Toronto, in which stratified deposits containing fossils rest upon old, 

 weathered till and are, in turn, overlain by younger drift. 

 The recognized glacial stages in America and Europe are : 



North America 



Germany 



Postglacial 



Iron 



Bronze 



Neolithic 



Later 

 Wisconsin Fourth Interglacial 

 Earlier 



Wurm 



( ?) Interglacial (Peorian) 

 (There is some doubt as to 

 ( ?) Iowa tne interpretation of the 

 Iowan.) 

 Third Interglacial 

 (Sangamon) 



Third Interglacial 

 Paleolithic man in Europe 



Illinoian 



Riss 



Second Interglacial 

 (Yarmouth) 



Second Interglacial 

 Earliest remains of Pale- 

 olithic man in Europe 



Kansan 



Mindel 



Heidelberg man (Europe) 



First Interglacial 



(Aftonian) 



First Interglacial 



Subaftonian (Jerseyan) 



Giinz 



