NATURAL HISTORY, TORONTO REGION 
The region is not one of high relief, the most ele- 
vated points to the south not exceeding 850 feet and 
to the east or north within 100 miles probably not 
going beyond 1,200. The highest point in the penin- 
sula between the Great Lakes rises to something over 
1,700 feet near Dundalk, 76 miles northwest of 
Toronto. Lake Ontario is 246 feet above the sea, 
Lake Erie 572 feet and Lake Huron 581. 
Although the variations in elevation are moderate 
there is great variety of surface features, including 
gently sloping lacustrine plains, rolling uplands, and 
an escarpment which crosses the region from south 
to north with a sudden rise of 300 or 400 feet. It 
has adjoining it some of the greatest lakes in the 
world, as well as many smaller bodies of water, and 
it is well watered with streams of every dimension 
up to Niagara River, some, like the Thames or Grand 
River, with gentle, meandering flow, and others with 
rapids or waterfalls having a sheer leap of 160 feet. 
Except in the Archaean portion to the north the 
rocky structure is uniform and undisturbed, the beds 
of sedimentary rocks dipping very gently to the 
southwest without folds or faults or interruptions by 
eruptive rocks. 
From middle Palaeozoic times to the present, so 
far as known, the region has been dry land except 
where lakes have covered it owing to Pleistocene 
shiftings of level or to the damming of valleys by ice 
masses. The most dramatic episodes in its history 
are the advances and retreats of the continental ice 
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