<P> Along the Pacific Ocean coast lie the Coast Ranges, which, while not approaching the scale of the Rocky Mountains, are formidable nevertheless . They collect a large part of the airborne moisture moving in from the ocean . East of the Coast Ranges lie several cultivated fertile valleys, notably the San Joaquin and Sacramento valleys of California and the Willamette Valley of Oregon . </P> <P> Beyond the valleys lie the Sierra Nevada in the south and the Cascade Range in the north . Mount Whitney, at 14,505 feet (4,421 m) the tallest peak in the contiguous 48 states, is in the Sierra Nevada . The Cascades are also volcanic . Mount Rainier, a volcano in Washington, is also over 14,000 feet (4,300 m). Mount St. Helens, a volcano in the Cascades erupted explosively in 1980 . A major volcanic eruption at Mount Mazama around 4860 BC formed Crater Lake . These mountain ranges see heavy precipitation, capturing most of the moisture that remains after the Coast Ranges, and creating a rain shadow to the east forming vast stretches of arid land . These dry areas encompass much of Nevada, Utah, and Arizona . The Mojave Desert and Sonoran Desert along with other deserts are found here . </P> <P> Beyond the deserts lie the Rocky Mountains . In the north, they run almost immediately east of the Cascade Range, so that the desert region is only a few miles wide by the time one reaches the Canada--US border . The Rockies are hundreds of miles (kilometers) wide, and run uninterrupted from New Mexico to Alaska . The Rocky Mountain Region is the highest overall area of the United States, with an average elevation of above 4,000 feet (1,200 m). The tallest peaks of the Rockies, 54 of which are over 14,000 feet (4,300 m), are found in central and western Colorado . </P> <P> The West has several long rivers that empty into the Pacific Ocean, while the eastern rivers run into the Gulf of Mexico . The Mississippi River forms the easternmost possible boundary for the West today . The Missouri River, a tributary of the Mississippi, flows from its headwaters in the Rocky Mountains eastward across the Great Plains, a vast grassy plateau, before sloping gradually down to the forests and hence to the Mississippi . The Colorado River snakes through the Mountain states, at one point forming the Grand Canyon . </P>

What is the west region of the us known for