NATURAL HISTORY, TORONTO REGION 
Above this sheet of boulder clay resting on the 
eroded surface of the delta there are three other 
layers of till with stratified sand or clay between, the 
whole reaching a thickness of two hundred feet. 
None of the upper interglacial beds seem of much 
importance compared with the earliest, the Toronto 
Formation. 
At certain sand pits in western Toronto near 
Christie and Shaw Streets, a little north of Bloor 
Street, there are interglacial deposits of a quite dif- 
ferent character, cross-bedded sand and gravel laid 
down by powerful currents. In these beds bones 
of bison, Cervalces borealis, and of mammoth or 
mastodon have been found, as well as ivory and a 
few shells. The relations of these sands to the other 
beds are uncertain, but they are undoubtedly inter- 
glacial. 
Interglacial beds have been found at the Whirl- 
pool, Niagara, near Dundas, at the head of Lake 
Ontario, and at some other points; but few or no 
fossils have been obtained from them, and it is not 
known whether they should be correlated with the 
Toronto Formation or not. There is some reason to 
believe that the Aftonian interglacial beds of Iowa, 
which have yielded Cervalces, as well as a number. 
of other mammals, may be of the same age as the 
Toronto Formation. 
GuacraL Lakes. 
Each advance of the ice must have ponded back 
the water before it in the present lake basins, but 
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