PLEISTOCENE OF EUROPE, NORTH AFRICA, AND NORTH AMERICA 435 



GEOLOGIC DIVISIONS OF THE AMERICAN QUATERNARY 



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II. HOLOCENE OR ReCENT 



I. Pleistocene, or Glacial 

 3. Post-Glacial 



2. Glacial 



1. Pre-Glacial 



A moderate elevation of 

 the laud where de- 

 pressed in the preced- 

 ing period. Mam- 

 mals of existing spe- 

 cies. 



Depression of lands 

 that were glaciated in 

 the Glacial Period; 

 amelioration of cli- 

 mate; final disappear- 

 ance of the ice; great 

 river floods and lakes, 

 and fluviatile and 

 lacustrine deposits. 

 Forests and mammals 

 of the temperate zone 

 spread over parts of 

 the previously glaci- 

 ated regions. 



Increased elevation of 

 the land over wide re- 

 gions in higher lati- 

 tudes; climate in 

 these latitudes of low 

 temperature, abund- 

 ant precipitation, and 

 consequent produc- 

 tion of glaciers. Suc- 

 cessive widespread 

 glaciation of the frigid 

 lands, with the ex- 

 clusion of all life ex- 

 cept that of boreal 

 and arctic regions. A 

 subsidence beginning 

 toward the close. 

 Mammals in the gla- 

 ciated areas preserved 

 in interglacial peat de- 

 posits, bogs in glacial 

 moraines, and drift 

 deposits. South of 

 the glaciated areas in I 1 

 caves and in river 

 sands, loess, wind 

 drift and clay depos- 

 its. 



7. Champlain Sub-Stage (Marine) 



0. GLACio-LAcnsTRiNE Sud-Stagi- 



5a. 



3. 



2. 



Wisconsin Glacial, Later 



5th Interglacial 

 Wisconsin Glacial, Earlier 



4th Interylacial 

 lowAN Glacial 



3d Interylacial 

 Illinoian Glacial 



2d Interylacial 

 Kansan Glacial 



lat Interglacial 

 Sub-.\ftonian Glacial 



'Ozarkian Stage' of the Eastern 

 States = ' Sierran Stage ' of the 

 Pacific coast. 



