CHAPTER VIII. 



THE PEORIAN SOIL AND WEATHERED ZONE (TORONTO 



FORMATION?). 



GENERAL STATEMENT. 



The interval between the Iowan and Wisconsin stage of glaciation has 

 been provisionally named Toronto by Chamberlin because of excellent 

 exposures of interglacial fossiliferous beds along the Don Valley in Toronto, 

 Ontario, which may prove to have this age. 1 Chamberlin remarks in con- 

 nection with the introduction of this name that the grounds for this corre- 

 lation are not very strong and that further investigation may show them to 

 be erroneous. He further remarks that "whether the beds on the Don 

 belong to the horizon suggested or not, it is certain that vegetal beds were 

 formed in the interval of the retreat between the formation of the Iowan 

 till and the formation of the Wisconsin till, and some of these less well 

 developed and less known deposits must be looked to as a type of this 

 interglacial horizon if the Toronto beds prove unavailable." 



In view of the uncertainty attached to this correlation it seems advis- 

 able to employ for the present a substitutional name (Peorian) which is 

 known to be applicable to the interval between the Iowan and the early 

 Wisconsin. In case the correlation suggested by Chamberlin is demon- 

 strated to be correct, the name Toronto has precedence. 



SOIL AND PEAT BETWEEN THE IOWAN AND WISCONSIN DRIFT SHEETS. 



Extensive deposits of muck and peat occur at the base of the Wis- 

 consin drift in northern Illinois, notably in McHenry, Kane, Dekalb, 

 Lasalle, and Bureau counties, which are in all probability immediately 



■Classification of American glacial deposits, by T. C. Chamberlin: Jour. Geology, Vol. Ill, 1895, 

 pp. 270-277. 



185 



