CHAPTER 5

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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

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