628 ALFRED W. G. WILSON 



tances in the central parts the surface is practically the same as 

 on the western half. Toward the margins it is more rugged or 

 uneven, while toward the extreme northeast, close to the 

 Atlantic coast, there is a narrow range of mountains rising 

 prominently above the peneplain surface. 



When the character of the surface is considered more in detail, 

 it is found that, except for some very small areas, and in places 

 where the peneplain surface is buried beneath the much younger 

 glacial and alluvial deposits, the surface is nowhere quite flat, 

 but is covered with low, rounded domes and ridges, which are 

 roughly parallel to themselves and whose longer axes conform 

 in general to the strike of the rocks. 



The remarkably even character of the sky-line together with 

 the universal distribution of many large and small lakes at levels 

 little below that of the even sky-line, justifies the assumption 

 that differences of elevation between different water bodies in 

 the depressions upon the surface of the plain represent closely 

 the differences in elevation between portions of the peneplain 

 adjacent to each of these water bodies respectively. On this 

 basis it will be found that the average gradient varies in differ- 

 ent parts from one to about four feet per mile. For example, 

 between Selwyn Lake (1,340') and Doobaunt Lake (500'), 

 along the line of the Doobaunt River, west of Hudson Bay, the 

 average gradient is 2.8 feet per mile for a distance of approxi- 

 mately 300 miles. A section eastward from Cree Lake (1,530') 

 to the junction of the Churchill and Little Churchill Rivers 

 shows an average gradient of 1.8 feet per mile for 450 miles. 

 A study of the profiles of the Canadian Pacific Railway between 

 Montreal and Winnipeg, where the line runs over the upland, 

 shows between Buda (1,472') and Brule (1,355') ^ ^^^^ of 117 

 feet in a distance of 146 miles; between Cartier (1,398') and 

 Lac Poulin (1,504') the rising gradient is 106 feet in a distance 

 of 129 miles. In central Labrador a section between Lake 

 Ni-chikun (1,760') and Lake Kaniapiskau (1,850'), and thence 

 to Lobstick Lake (1,630') above the Grand Falls on the Hamil- 

 ton River, shows an ascending gradient of 90 feet in the first 

 100 miles, and then a descent of 220 feet in 200 miles, or a mean 



