1865.] GEOGRAPHICAL SKETCH OF CANADA. 361 



including the great area lying between the Lakes Ontario, Erie 

 and Huron, generally known as the south-western peninsula of 

 Canada. The whole of this region, from east to west, is essentially 

 a vast plain, with a sufficient slope to allow of easy drainage. The 

 distance from Quebec to the west end of Lake Superior is about 

 1,200 miles, yet this lake is only 600 feetabove the sea-level, while 

 Lake Erie is 565 feet, and Lake Ontario 232 feet above the sea. 

 The land on the banks of the St. Lawrence and its lakes, either 

 near the margin, or not very far removed, generally rises to a height 

 of from fifty to one hundred and fifty feet, and from this level very 

 gradually ascends to the base of the hills which bound the region. 

 Unlike the two regions already described, these great plains are 

 underlaid by beds of unaltered Silurian and Devonian rocks, con- 

 sisting of sandstones, limestones, and shales. These are but little 

 disturbed, and are generally nearly horizontal ; but over by far the 

 greater part of the region they are covered by beds of clay, occasion- 

 ally interstratified with or overlaid by sand and gravel. These 

 superficial strata, which are in some parts several hundred feet in 

 thickness, are throughout the eastern division, in great part of 

 marine origin, and date from a time when this champaign region 

 was covered by the waters of the ocean; while throughout the 

 western division the clays are more probably of fresh-water origin. 

 It results from the distribution of these superficial post-tertiary 

 strata, that the soil over the greater part of the region consists of 

 strong and heavy clays, which in the newly cleared portions are 

 overlaid by a considerable thickness of vegetable mould. In the 

 eastern division, a line drawn from Quebec to Ottawa, and two 

 others from these points, converging at the outlet of Lake Cham- 

 plain, will enclose a triangular area of about 9000 square miles, 

 which is very nearly that occupied by the marine clays. These 

 are overlaid, chiefly around the borders of this space, by more sandy 

 deposits, which are well seen near Three Rivers, and about Sorel. 

 They form a warm but light soil, which yields good crops when 

 well manured, but is not of lasting fertility. The greater part of 

 this area however is covered by a tenacious blue clay, often more 

 or less calcareous, and of great depth, which constitutes a strong 

 and rich soil, bearing in abundance crops of all kinds, but parti- 

 cularly adapted for wheat, and was in former times noted for its 

 great fertility. These clay lands of Lower Canada, have been for 

 a long time under cultivation, and by repeated cropping with wheat 



