Canada Landform Regions

fly around Canada in a helicopter, you would see beneath you major differs from place and broad valleys, low rocky lake country, plains that stretch to the horizon, jagged peaks and ice fil valleys. To understand these differences and where we should expect to find them, we must have some idea of the rock structure of North America. Geologists see a broad pattern in it. A great core of very old, very hard rock which they call the Canadian shield. This is bordered by areas of younger flat-lying sedimentary rock which in turn are bordered by areas in which the rock has been wrinkled and folded to form mountain ranges. We shall begin in the Canadian shield. This region, like all of Canada, was once covered by vast ice sheets that slowly moved over the land, scraping off soil and as they retreated, creating innumerable lakes. This is what you see flying northwest from Lake Superior. Lakes and forest cover much of this part of the shield. There are probably more lakes in the Canadian Shield than in all the rest of the world. The old hard rock that distinguishes this region is never very far beneath the surface. Spruce forests can grow in very shallow soil. Only occasionally does one see signs of human activity, such as this open pit mine at Steep Rock Lake, Ontario. Scattered throughout the rocks of the shield are rich deposits of minerals. Hundreds of miles to the north. As you fly beyond the treeine, the rock becomes clearly visible, covered in the short summer by a thin layer of mosses and lychans. And so it looks all the way north to where the shield dips beneath the Arctic Sea. The Canadian shield makes up about half of Canada and a small part of the United States. The regions of flat-lying rock, the Great Interior Plains, cover most of the United States and extend north into Canada, forming two regions. The Great Plains to the west, the Great Lakes, St. Lawrence lands to the east. The Hudson Bay and Arctic lands may be considered as outlying portions of the Great Interior Plains. The ice sheets that scraped bare large areas of the shield laid down rich deposits of soil in the plains regions around it. This is what you see flying south from Montreal. Not all the lands are as flat as this. They are generally more rolling. Here you would have to dig down 30 feet to reach bedrock. In other places, as much as 200. Everywhere you look, signs of human activity, especially along the waterway for which the region is named. The Great Lakes St. Lawrence lands is a comparatively small region. The Great Plains region, 1500 miles to the west, is enormous. This is the Regina plane, just north of the American border. This flat, fertile, treeless plane was once the bottom of a glacial lake. On this farm, they had to plant the trees to break the force of prairie winds, and they built a dugout to catch the spring runoff, for this is a generally dry region. Water is precious. But it would be a mistake to think that all the land is as flat as this. There are many areas of rolling plane like this, especially in the west. 300 m north, the land looks different for climate and vegetation change. If a man wants to farm here, he is faced with the job of clearing the land. But although the landscape changes, beneath the forests, beneath the soil they grow in, there is still flat lying sedimentary rock. And a sure sign of sedimentary rock as far north as Norman Wells on the McKenzie oil. There are two other plains regions in Canada. this low swampy plane called the Hudson Bay lands. And on the Arctic Islands, land so far north that it is already frozen over when the leaves are turning color in the south. The interior plains all underlay with flat lying rock around them. The rock has been crumpled by gigantic forces thrusting up the mountain ranges that rim the continent. To the west, the Cordillera. To the north, the remote Inuition or Arctic Mountains, and to the east, the Appalachian. The Rocky Mountain system forms part of the Cordillera in the west. These are young mountains as mountains go. Their peaks have not yet been rounded and smoothed by time. To the west, the valley of the Thompson River, part of the interior plateau between the Rocky Mountains system and the coastal ranges. Orchards flourish only where there is irrigation. There is little rainfall here. The rivers of this mountain region are generally swift flowing and turbulent. Over millions of years, the Fraser River has carried down to its mouth the rich soil that forms the delta. Along the coast, the climate is mild and rainfall very heavy. Great forests thrive in this damp climate on the slopes leading down to the sea. The mountains continue even here. Their peaks emerging as countless islands in the sea. More than 2,000 mi north, another mountain region, the Inuition or Arctic Mountains. This far north, we still find remnants of the ice sheets that once covered all of Canada. Here, the somewhat blunted appearance of the peaks tells us that these mountains are probably older than the high thrusting Rockies, but younger than the Appalachian Mountains in the east. Millions of years of erosion have worn what were once towering mountains into a gentler landscape. In mountain regions as old as this, we find great areas of land and plain like the St. John River Valley. This pattern of land and worn down mountain continues right down to the sea. And here we end our journey. We have seen something of the basic structure of our continent. The Canadian shield bordered by interior plains, bordered by outer mountain regions. There are great variations within each region, but the map stands as a guide to where we are likely to find the varying features that make up the face of our land. Heat. Heat. 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