THE ILLINOIAN ICE INVASION 333 



Vertebrates 

 Mammoth Bison bison 



Mammut americanum Rangijer caribou 



These beds were apparently laid down in a shallowing lake where the 

 waves formed sand flats and bars, and where an interglacial river Humber 

 from the west brot down sand and gravel. The shells occur in the upper 

 layers. 



Following the period of the cold temperate climate the lake fell and the 

 beds were eroded by three interglacial streams, situated near Rough Creek, 

 Highland Creek, and in the Dutch Church Valley. At a later period the entire 

 region was successively covered by three till sheets, representing, probably, the 

 early and late Wisconsin invasions. 



The Sangamon interval appears to be represented near Hamilton, at the 

 west end of Lake Ontario. Excavations made in Hunter Street, of that city, 

 revealed the bones of an elephant and pieces of wood at the base of a blue till 

 referred to the Iowan stage, but more probably representing the earlier Wiscon- 

 sin till. About a mile to the west of this section mammoth tusks and bones 

 were found at a depth of 45 feet beneath hardpan. 



In certain sand pits in western Toronto, 189 near Christie and Shaw streets, 

 there are interglacial deposits of cross-bedded sand and gravel laid down by 

 powerful currents. In these beds the bones of Bison, Cervalces, Mastodon and 

 Elephas, as well as ivory and a few shells, have been found. The relations of 

 these sands to the other beds are uncertain, but they are doubtless interglacial 

 and are probably correlative with the upper Scarboro beds. The Cervalces 

 has been described as C. borealis. 



b. Other Canadian Deposits 



Interglacial deposits occur in various places along the Canadian shore 

 of lakes Erie and Ontario. Strata of this age have been studied at Port Rowan, 

 Norfolk County; Brosiville, Leeds County; Prescott, Greenville County; and 

 Cornwall, Stormont County. A generalized section is shown below. 190 (This 

 section applies especially to the Ontario peninsula). 



Possible correlation Formation 



Postglacial 1 . Clay and sand with gravel near the summit; contains 



Macoma. 

 Wisconsin till. 2. Boulder clay. 



'3. Arenaceous and silty beds. 



4. Gray, paf tially oxidized, brownish clay, thinly stra- 

 Sangamon interval. tified, sandy in spots. The Sangean clay. 



5. Stratified, bluish-gray clay. The Erie clay, with 

 fossils. 



189 Faull, The Natural History of the Toronto Region, Ontario, Canada, p. 72. 

 ]9 ° Chalmers, Can. Geol. Surv., Rep., 1901, pp. 167-168 A, 1905. 



