402 LIFE OF THE PLEISTOCENE 



Lake Erie, is well mapped and described by Fairchild in his paper "Glacial 

 Waters in the Lake Erie Basin." 11 



The Ridge Road north of Rochester, and particularly the old Irondequoit 

 Bay silts, should produce evidences of the life of the Lake Iroquois stage. The 

 region has been mapped and described by Fairchild. 12 The bed of glacial 

 Lake Tonawanda 13 is also worthy of study. The old glacial outlets near Syra- 

 cuse, especially the region of the Montezuma marsh, should contain some evi- 

 dences of postglacial life, as should also parts of the old Mohawk-Hudson outlet. 



LAKE ALGONQUIN AND THE NIPISSING GREAT LAKES 



The silts of the Trent outlet as well as those of the Nipissing-Ottawa (North 

 Bay) outlet should be examined. It is possible that certain marine organisms 

 (as My sis, Pontoporeia etc.) may have migrated into the present Great Lake 

 system at this time, from the Champlain Sea. The postglacial distribution 

 of a number of animals, notably the naiades, might be far better understood 

 if a naiad fauna could be found in these outlets. 



INTERGLACIAL DEPOSITS 



Interglacial deposits may be looked for in many places south of the Wiscon- 

 sin drift sheet. North of this till reliance can only be placed on well drillings 

 or deep stream cuttings. 



Iowa 



In Iowa, deposits referable to the Aftonian, Yarmouth, Sangamon and 

 Peorian intervals are known. The reports of the Iowa Geological Survey 

 serve as admirable guides for the stratigraphical location of these deposits. 

 In not a few places several of these horizons are superimposed and reasonable 

 care will place the biotic remains found in strata of undoubted age. Many 

 rivers, which cut thru the upper drift, expose the earlier tills and interglacial 

 deposits in their banks. 



Illinois 



In Illinois the Yarmouth, Sangamon, and Peorian intervals occur, with 

 possibly the Aftonian. Along the Fox and Illinois rivers many excellent sec- 

 tions may be found, penetrating all the Pleistocene deposits and entering the 

 underlying bed rock strata. In these valleys the Illinoian and Wisconsin drift 

 sheets are separated by the Sangamon soil, which affords excellent material for 

 the study of some phases of the life of this interval. Along the Mississippi 



11 Bull. N. Y. State, Mus., No. 106. 



" The Geology of Irondequoit Bay, Proc. Roch. Acad. Sci., Ill, pp. 236-239, 1906; see 

 also Bull. N. Y. State Mus., No. 114, 1907. 



» Niagara Folio, U. S. Geol. Surv., No. 190. 





