Intermontane Plateaus and Basins

West of the Rocky Mountains lies an area of intermontane plateaus and basins. The intermontane means "between mountains". The region lies between the Rocky

Mountains and mountain ranges along the Pacific coast.

The intermontane area is long and broad, stretching from Washington to the border with Mexico. Most of the area lies in a "rain shadow" of the Pacific mountains. The mountains

block rain, and as a result, the lowland basins are dry.

Vegetation is sparse — scrub glasses and desert plants.

Except for the Colorado and Columbia rivers and their tributaries, the region has interior drainage. This means that water from the highlands flows into lakes or rivers in the area rather than to the ocean. However, the Columbia River flows west into the Pacific

Ocean and the Colorado River flows south into the Gulf of California. Some of the most impressive landscapes in the country are found in the region.

The best known is the Grand Canyon, one of the most beautiful landscapes in the world.

Fore some hundreds of million of years, the Colorado River slowly cut its way downward to the sea. The combined action of the river cutting downward and the gradual rise of the adjacent plateaus created some of the most breathtaking sights in America with rocks shaped by rain and wind into perfect arches, pillars and straggering walls which turn red at sunset.

Early settlers along the Colorado tried to alter the river's impact on the land by diverting for waters for irrigation. But each year the Colorado, fed by melting snows in the spring and early summer, and property low-lying lands along its route, destroying lives, crops, livestock property n a:e summer and early fall, the river often dried to a trickle, too low to

d.e-~ ла:ег crops and livestock withered and died. Eventually, a solution was

found - re construction of a large dam on the Colorado River was begun and it

was c o r: e:e: n "^35 Or ginally called Boulder Dam it was later renamed Hoover Dam

in honour of US F-es cent Herbert Hoover. It is 221 metres high, generating low-cost

hydroelectric power for use n Nevada, Arizona and California. Lake Mead backs up

arc л 176 kilometers behind the Hoover Dam creating America's largest man-made

-eservoir. Its waters irrigate more than a million acres of land in the US, and nearly half a

~ ion acres in Mexico.

The Mojave Desert and the Great Basin of Oregon, Utah, and Nevada lie within the

e: or The Great Salt Lake lies within the Great Basin. Death Valley, in California, is the

: est spot in the United States at 86 meters below sea level.