AN OUTLINE OF THE PHYSIOGRAPHIC HISTORY 

 OF NORTHEASTERN ONTARIO^ 



W. H. COLLINS 



Canada Geological Survey, Ottawa 



The region here referred to as northeastern Ontario is one about 

 250 miles square, lying between Lake Superior and the Quebec 

 boundary and reaching from Lake Huron north to the Trans- 

 continental Railway. Its topography has been described so many 

 times in reports of the Geological Survey and of the Ontario Bureau 

 of Mines that no extended account of it is needed in this place. 

 The region is referred to by geologists and topographers as a glaci- 

 ated peneplain. As a matter of fact it is a hilly country and only 

 conveys an impression of flatness when a large area is seen at one 

 time. Viewed from the top of one of the more commanding hills 

 the horizon appears as an even line and the intervening hills 

 can be seen to stand at about the same elevation. The rivers have 

 slopes of only 5 to 10 feet a mile, and the highest and lowest points 

 on the railways which cross the region are 1,350 and 600 feet 

 above sea. 



This condition holds true for most of northeastern Ontario. 

 There are a few places, however, where the relief is greater, and 

 where significant traces remain of a former topography of more 

 rugged character. There is, for example, one hilltop, about 40 

 miles west of Sudbury, from which one can see, on a fine day, a 

 hne of white hills on the southern horizon that certainly remind 

 one of mountains. These are the Lacloche Mountains, to which 

 further reference will be made. It also requires considerable 

 scientific faith to acknowledge the wild country bordering Lake 

 Superior as plainlike or nearly plainhke. 



In the case of a true plain, like the Mississippi basin, or the 

 western plains of Canada, the impression of tranquillity conveyed 

 by the landscape is borne out by the rocky structure underneath. 



^ Read before Section E, American Association for the Advancement of Science, 

 December 27, 1921. 



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