Beyond the valleys lie the Sierra Nevada in the south and the Cascade Range in the north. Mount Whitney, at 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 . 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.