Chapter 5 The Physical Geography of the U.S. and Canada
Land Forms • Western Mountain Ranges: The Pacific Ocean forms the western border of both the United States and Canada. • Paralleling the coastline are a series of mountain ranges that were formed by the collision of two tectonic plates millions of years ago. • The mountain system includes: • Alaska Range, Coast Range, Cascade Range, and Sierra Nevada. • Together, these mountains are called the Pacific Ranges.
Land forms • Another western chain called the Rocky Mountains lies east of the Pacific Ranges. • Stretch more than 3,000 miles. • The area that lies between the Pacific Ranges and the Rocky Mountains is known as the inter-montane basins and plateaus. • The northern and southern parts of this dry expanse are plateaus, or high, level surfaces. • The natural activity that plateaus produce unusual landforms, such as the Grand Canyon and various flat-topped natural elevations called mesas.
Land forms • Plains: The area east of the Rockies marks the beginning of the Great Plains. • Great Plains is a broad, flat upland extending for about 400 miles from the Rocky Mountains through the central parts of Canada and the United States.
Land forms • Eastern Mountains and Lowlands: Appalachian Mountains lie to the easts of the plains. • Second longest mountain range. • East and south of the Appalachians in the U.S. lie the coastal lowlands.
Water systems • Water Systems: • A continental divide is a line that separates rivers that flow toward the opposite ends of a continent. • In Canada, the Continental Divide joins another divide known as the Height of Land, which separates the waters flowing into the Arctic Ocean.
Water Systems • Rivers in the U.S. whose headwaters, or water sources, are found in the Rocky Mountains include the Colorado River. • The headwaters of the Rio Grande, Mackenzie River, and Missouri River are also in the Rockies. • Each of these rivers has many tributaries, or brooks, rivers, and streams that feed their waters into one river.
Water systems • Mississippi River is the largest river in the U.S. and Canada. • The U.S. and Canada also include many lakes formed as a result of the Ice Age. • Some of this water blocked by glacial dams became lakes. • In northern Canada two major lakes, Great Bear Lake and Great Slave Lake. • As the glaciers moved over the land, they also gouged out and scoured hollows in the rocks they passed. • As the glaciers receded, these hollows filled with water, the Great Lakes.
Resources • Resources: • The major freshwater fisheries of the United States include the inland waters of the southern states and the Great Lakes. • The Great Lakes are the center of the freshwater fishing industry in Canada. • Mineral resources of the United States and Canada include gold, silver, nickel, iron, copper, uranium, and zinc. • Rocky Mountains contain a great wealth of gold, silver, and copper. • Parts of the Canadian Shield have deposits of iron and nickel. • Canadian officials estimate that the mostly unexplored northern areas of Canada may hold as much as 40 percent of the country’s mineral rich.
Resources • Important energy resources energy resources, such as oil, natural gas, and coal, are found throughout both nations. • Rich coal deposits are found in the Appalachian Mountains and in the central and western parts of the U.S. and Canada. • Timber reserves include the huge forests that cover about one-third of each nation. • Both U.S. and Canada have great parts for agriculture. • The Great Plains and the Central Lowlands in the United States have some of the world’s most fertile soil.
Climate • Climate: • Climate Regions: Winds, oceans currents, and protective mountains along the Pacific coast help create a marine west coast climate from northern California through British Columbia to the southern border of Alaska. • As they blow eastward, the Pacific winds encounter the Pacific Ranges. • As the winds are forced over the mountains, the air-cools and moisture is released. • This means that the west coast enjoys tremendous rainfall, and some parts of the area receive more than 100 inches of ran each year.
Climate • The Pacific Ranges also create a rain shadow, which limits the amount of rainfall east of the mountains. • This place of plateaus and basins, bordered in the east by the Rocky Mountains, is known for its hot, dry air. • The only deserts in the northern part of North America are found here. • Deserts include: Great Salt Lake Desert, Blackrock Desert, and Death Valley.
Climate • Large parts of Canada and Alaska lie in a subarctic climate zone with very cold winters. • Two-thirds of Canada has January temperatures that aver below 0° F. Winter temperatures of -70°F have been recorded in some places. • A persistent high-pressure cell in this area spawns the cold winds that chill much of the central United States during the winter. • Farther north, lands across the Arctic coastlines line in a tundra climate zone. • These areas experience bitter winters and cool summers.
Climate • The Great Plains are far from oceans or other large bodies of water moderate climate. • The Great Palins are not completely dry because moisture travels with winds that blow north along the Rockies from the Gulf of Mexico and south from the Arctic region. • The region is classified as a humid continental climate region with bitter winters and hot summers. • The humid continental climate region continues east to the Atlantic. • Most of the southern states, however, are in a humid subtropical climate region.
Seasonal Weather Conditions • Seasonal Weather Conditions: Canada and U.S. are affected by seasonal weather conditions. • In winter much of northern America experiences blizzards. • Blizzards are snowstorms with winds excess of 35 miles per hour, temperatures below freezing, and visibility of less than 500 feet for 3 hours or more.
Seasonal Weather Conditions • Summers are plagued by tornadoes in Great Plains and the eastern portion of the U.S. • Tornadoes: swirling columns of air whose winds can reach 300 miles per hour. • Hurricanes: ocean storms hundreds of miles wide with winds of 74 miles per hour or more. • Threaten the Atlantic and Gulf of Mexico coastlines. • Typhoons: or Pacific hurricanes, threaten Hawaii and other Pacific islands each year. • Some seasonal weather conditions are improvements over the normal patterns for a climate zone. • For example, a warm wind called the Chinook blows down the slops of the Rockies in winter and early spring.
Vegetation • Vegetation: Before the arrival of settlers, almost half of present-day U.S. and Canada, estimated 3 million square miles, was covered with forests. • Despite human pressures on the land’s resources, a vast forest area still spans subarctic Canada. • Forests also cover the sides of the western mountain ranges until they reach the timberline, or the elevation above which trees cannot grow.
Vegetation • The Great Plains of the United States and Canada were once a prairie region, a treeless expanse of grasses whose tangled roots formed dense layers of vegetation called sod. • Settlers, however, soon populated the plains, broke up the sod, and used it to build homes. • This caused the dust bowl conditions in the 1930. • Since then, scientific farming methods have improved conditions on the Great Plains, and the region now supplies most of North America’s wheat. • Dust Bowl Video: • http://www.history.com/shows/america-the-story-of-us/videos/america-black-blizzard