NA - Physical Geography, continued Lesson
Physical Geography, continued
The Impact of Mountains
The mountains of the Earth, including those of North America, were all created by the movements of tectonic plates. Although humans cannot live at the higher elevations of the mountains and often find them difficult to cross, mountains are extremely important to humans.
Similar to lakes and rivers, mountains can form natural boundaries and sometimes natural defenses. Often, their greatest importance to man comes from their elevation which causes them to be the locations in which the headwaters of major rivers form. As the snow from high elevations gradually melts, it forms rivers that provide fresh water for the inhabitants below. Flooding from these rivers both irrigates and fertilizes soils that are used to produce food.
As you watch the video, look for ways that mountains impact human lives.
You will want to pay particular attention to these segments:
- 3:04-7:41
- 8:50-9:30
- 12:50-19:49
One of the particularly noticeable ways that mountains influence humans is through what is called the rain shadow effect. In the United States, the western mountain ranges (the Cascades and the Sierra Nevada) cause the air to rise up over them dropping their moisture as rain or snow on the western sides of the mountains. This causes the eastern sides of the mountains to be dry and arid. The Great Plains are a result of the rain shadow effect.
As a result of the rain shadow effect, the climate becomes particularly arid the closer the land is to the Rocky Mountains. Land in this area is used for raising cattle. To the east of this dry area, and much further away from the mountains, the center of the North American continent is often called America's breadbasket. This area includes the most fertile agricultural land and produces mostly wheat and corn.
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