The+Lowlands

THE LOWLANDS
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 There are three lowland regions surrounding the Shield: the Interior Plains, the Great Lakes-St. Lawrence Lowlands, and the Hudson Bay-Arctic Lowlands.The bedrock under these lowlands is formed mainly of sediments eroded from the Shield. The sediments were laid down in the seas that existed at various times millions of years ago. As the rock particles collected, the weight of the upper layers compressed the lower layers into sedimentary rocks.

1. How was the bedrock of the lowlands formed?

 Interior Plains
 The Interior Plains of Canada are part of the Great Plains of North America that stretch from the Arctic Ocean to the Gulf of Mexico. The Interior Plains of Canada extend from the 49th parallel north to the Arctic Ocean, a distance of 2700 km. They are about 1300 km wide in the south but only about 275 km wide in the north.

 The Interior Plains were often covered by shallow inland seas. Sediments from the Shield and the Rocky Mountains were deposited in these seas over millions of years. Eventually the sediments were compressed by the weight of the layers above into sedimentary rock. Part of the sedimentary rock deposited in these areas consists of coral reefs that formed close to the surface of seas during the Paleozoic era. The rock layers are several thousand metres thick and took millions of years to form. Today, the reefs are thousands of metres below the surface of the land. They contain much of the oil and gas found in Alberta and Saskatchewan.

2. a) How thick is the bedrock in the Interior Plains and why is it so thick?  b) Why are the ancient coral reefs of the Interior Plains important today?

 Mineral deposits also lie below the surface. At various times during the Mesozoic era, shallow seas covered the region that is now Saskatchewan. When they evaporated, thick layers of mineral deposits were left in the dried-out sea beds. These layers are now deep in the earth, covered by newer rocks and glacial deposits. Potash is mined from these layers and used as fertilizer in Canada and overseas. The swamps on the edges of these ancient seas produced plants that were changed eventually into coal which is mined today.

Forces of erosion have also shaped the surface of the landscape. Some sedimentary rocks are hard and resistant; others are quite soft. The softer rock erodes more quickly than the harder rock - a process called differential erosion. Different rates of erosion have caused three different levels of elevation on the prairies. Each level is separated by a sharp rise called an escarpment. Escarpments form when a harder rock layer that overlays a softer layer resists erosion. Although many people think of the Interior Plains as flat, there are relatively few areas where this is true. The landscape is, for the most part, composed of rolling hills, and deep, wide, river valleys. Overall, the land slopes gently downward from west to east.

 Glaciation has also marked the landscape in visible ways and affected land use. The Interior Plains, like the rest of Canada, were subjected to glaciation. The glaciers left deposits that produced a rounded, gently rolling landscape in many areas. When the glaciers melted, the meltwater formed a large lake over much of what is now southern Manitoba and Saskatchewan. Later, the land rose, causing most of the water to drain into the ocean. Small portions of the ancient lake remain today as Lake Winnipeg, Lake Manitoba, Lake Winnipegosis and Cedar Lake. The floor of this lake was covered by sediments which made it very flat. The former lake bottom was left as flat land in what is now southern Manitoba and Saskatchewan.

 3. a) Describe the topography of the Interior Plains in your own words.  b) Explain the major processes responsible for what you see.

 The soil that developed on these sediments is deep and fertile. Grain is grown in many locations in the southern part of the Interior Plains. The area is known as Canada's "breadbasket" because so much wheat is grown here. Cattle are raised in places where the climate is too dry for crops. Agricultural products from this region are used both in Canada and overseas.

<span style="background-color: #e1e0e0; font-family: 'Arial Black',Gadget,sans-serif; font-size: 150%;"> 4. Parts of the southern portion of the Interior Plains are often called Canada's "breadbasket." Why?

<span style="font-family: 'Arial Black',Gadget,sans-serif; font-size: 150%;"> Great Lakes-St. Lawrence Lowlands
<span style="font-family: 'Arial Black',Gadget,sans-serif; font-size: 150%;"> South of the Canadian Shield is a smaller landform region, the Great Lakes-St. Lawrence Lowlands. As you might suspect from the name, the region consists of two parts. The parts are separated by a thin wedge of the Canadian Shield that juts across the St. Lawrence River and extends into the United States near Kingston, Ontario. Like the Interior Plains, these lowlands have bedrock formed of sedimentary rock from the Paleozoic era. The Paleozoic bedrock can be seen in several escarpments in the Great Lakes Lowland. The best known is the Niagara Escarpment which extends from Niagara Falls to Manitoulin Island. The Niagara Escarpment was formed by differential erosion.

<span style="font-family: 'Arial Black',Gadget,sans-serif; font-size: 150%;"> In the Great Lakes portion of the lowlands, glaciation has created a rolling landscape. The glaciers carried huge amounts of material (soil sand, and gravel) from the Canadian Shield and dumped them throughout the region. The landscape is characterized by flat plains with glacial hills and deep river valleys. The Great Lakes are located in basins that were gouged out by glaciers. The lakes were even larger than they are now.

<span style="font-family: 'Arial Black',Gadget,sans-serif; font-size: 150%;"> The lakes are smaller today because of the enormous volume of water from the melting glaciers. They eventually shrank to their present size as the meltwater drained into the ocean. The old shorelines of these glacial lakes surround the present-day Great Lakes

<span style="font-family: 'Arial Black',Gadget,sans-serif; font-size: 150%;"> The St. Lawrence Lowland was formed in a different way from the Great Lakes Lowland. A rift valley was formed by faulting. This rift valley was flooded toward the end of the last ice age by a part of the Atlantic Ocean called the Champlain Sea.

<span style="font-family: 'Arial Black',Gadget,sans-serif; font-size: 150%;"> The Great Lakes-St. Lawrence Lowlands Region is the most southerly region in Canada. It is well-suited to agriculture because of its excellent soils and warm climate. The flat land is also ideal for transportation routes and the development of cities. Because of these factors, it is the more densely populated region in Canada. About 50% of Canada's population lives in the area.

<span style="font-family: 'Arial Black',Gadget,sans-serif; font-size: 150%;"> Lakes-St. Lawrence Lowlands which comprise only 14% of Canada's area. Canada's two largest cities, Toronto and Montreal, are located here along with 70% of the country's manufacturing industries. Wouldn't you agree that the Great Lakes-St. Lawrence Lowlands could be called "Canada's industrial and urban heartland?"

<span style="background-color: #e1e0e0; font-family: 'Arial Black',Gadget,sans-serif; font-size: 150%;">5. In what way was the St. Lawrence Lowland formed. How is that different from how the Great Lakes Lowland formed?

<span style="font-family: 'Arial Black',Gadget,sans-serif; font-size: 150%;"> Hudson Bay-Arctic Lowlands
<span style="font-family: 'Arial Black',Gadget,sans-serif; font-size: 150%;"> Around the southwestern shore of Hudson Bay and James Bay is a very flat, low area covered by swampy forest. The waters of Hudson Bay covered much of this lowland at the end of the last Ice Age. Known as the Hudson Bay Lowlands, this region has a layer of sedimentary rock which rests on top of the ancient rock of the Shield. <span style="font-family: 'Arial Black',Gadget,sans-serif; font-size: 150%;">

<span style="font-family: 'Arial Black',Gadget,sans-serif; font-size: 150%;"> The Arctic Lowlands are made up of a series of islands located in Canada's far north, and have a gently rolling landscape. The harsh climate does not permit farming; the ground remains frozen most of the year. However, the Paleozoic sedimentary rock, from which the Lowlands are formed, contains lignite (a form of coal), oil, and natural gas deposits.

<span style="background-color: #e1e0e0; font-family: 'Arial Black',Gadget,sans-serif; font-size: 150%;"> 6. Write 3 descriptive sentences that would describe the Hudson Bay lowlands. Use both the text here and your own personal knowledge to think of what it might be like.