364 LIFE OF THE PLEISTOCENE 



Black soil (Peorian) 



Post-Iowan loess 



Wisconsin drift 



Wisconsin residual sands and gravels 



Post- Wisconsin loess. 



These several loesses are quite distinct near the drift borders, but the 

 distinction grows less clear as we recede from the drift margins, especially 

 southward, and finally practically disappears, probably in the regions in which 

 plant-life was not wholly destroyed by the advances of the several ice-sheets 

 succeeding the Kansan. 



