THE PEORIAN SOIL AND WEATHERED ZONE 

 (TORONTO FORMATION ?)« 



The interval between the Iowan and Wisconsin stage of gla- 

 ciation has been provisionally named Toronto by Professor 

 Chamberlin, because of excellent exposures of interglacial fos- 

 siliferous beds along the Don Valley in Toronto, Ontario, which 

 may prove to have this age. 2 Professor Chamberlin remarks in 

 connection with the introduction of this name that the grounds 

 for this correlation are not very strong, and further investiga- 

 tion may show them to be erroneous, but that it is not likely that 

 the beds upon the Don can be referred to any earlier period. 

 He further remarks, that, "Whether the beds on the Don 

 belong to the horizon suggested or not, it is certain that vege- 

 tal 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 advisable to employ for the present a substitutional name 

 which is known to be applicable to the interval between the 

 Iowan and the early Wisconsin. In case the correlation sug- 

 gested by Professor Chamberlin is demonstrated to be correct 

 the name Toronto has precedence. 



Extensive deposits of muck and peat occur at the base of 

 the Wisconsin drift in northern Illinois, notably in McHenry, 

 Kane, De Kalb, La Salle, and Bureau counties, which are in all 

 probability immediately underlain, in some cases at least, by 



1 This paper forms part of an unpublished report by the writer on the Illinois 

 glacial lobe. It is published in connection with the two papers read before the Iowa 

 Academy because of the close relation of the subject-matter. 



3 Classification of American Glacial Deposits, by T. C. Chamberlin, Jour. 

 Geol., Vol. Ill, 1895, pp. 270-277. 



244 



