244 



LIFE OF THE PLEISTOCENE 



Buena Vista Guthrie 



Monona 



Union 



Chickasaw Harrison 



Mitchell 



Washington 



Cherokee Hancock 



Mills 



Wayne 



Clay Henry 



Marshall 



Woodbury 



Cedar Howard 



Normal 



Winnebago 



Decatur Iowa 



Obrien 



Worth 



Dubuque Johnson 



Plymouth 



Wapello 



Delaware Kossuth 



Powershiek 





In the adjoining states it is 



known from the folio 



Nebraska 



wing counties: 



Cedar 



Knox 

 Linn 



Douglas 





South Dakota 





Union 



Minnehaha 



Minnesota 



Lincoln 



Cottonwood 



McLeod 



Rock 



Jackson 



Murray 

 Nobles 



Missouri 



Wilkin 



Atchison 



Cass 



Harrison 



Bates 



Daviess 



Macon 



Benton 



Kansas 



Vernon 



Leavenw 



srth Douj 

 Illinois 



;las 



McLean 



Rock Island 





Wisconsin 







St. Croix 







The Aftonian was a time of luxuriant forests, the climate was moist, and 

 the winters were not too severe for such animals as the elephant, horse, and 

 peccary. The types of mollusks indicate a climate not essentially different 

 from that of today. The fresh water mollusks also indicate the presence of 

 large streams, while the land snails attest the presence of a rich flora. A study 

 of the entire biota reveals two types of life: (1) a warm temperate, in which the 

 naiads and other mollusks and the larger part of the mammals lived, and (2) 

 a cold temperate climate in which a boreal flora flourished. Shimek remarks 

 that the molluscan fauna of the Aftonian suggests aquatic and low ground 

 conditions, but the mammal fauna suggests also upland or prairie conditions. 

 It is probable that both types of topography prevailed. 



i 



