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The Changing Face of Earth - Canada's Geology - Lowlands - Great Lakes-St. Lawrence



Plate Tectonics

Geologic Time


Canada's Geology
...Canadian Sheild
........Interior Plains
........Great Lakes-St. Lawr.



Located to the south of the Canadian Shield, the Great Lakes-St. Lawrence Lowlands, are comprised of two major parts. The two areas, suggested by the name, are divided a little wedge of the Canadian Shield near Kingston, Ontario. The bedrock of these lowlands are made of the similar material as that of the interior plains - sedimentary rock. These too were formed in the Palaeozoic Era.
The Great Lakes Lowlands were formed by the effects of glaciation. This is fundamental cause of their rolling landscape where flat plains are interrupted with glacial hills and deep river valleys. After the glacial period, when a large volume of water melted out from the melting glaciers, the lakes were large, even larger than they are today. However the lakes shrank to their present size, and flat plains of sediments remained. These sediments formed excellent soil for farming.

Unlike the Great Lakes Lowlands were formed by faulting. This faulting took place and a rift valley was formed. During the last ice age, this rift valley was flooded by a area of the Atlantic Ocean called the Champlian Sea. The deposits laid down under this sea have made this flat lowland very suitable for farming.

Pictures: Top- Farming in the Great Lakes Lowlands; Bottom- Formation of the St. Lawrence river valley