segment of the Pacific mountain system of western North America, consisting of a series of ranges in the United States running parallel to the Pacific coast for more than 1,000 miles (1,600 km) from west-central Washington in the north to the Transverse Ranges of California in the south. The Coast Ranges are separated from the higher mountains of the Cascade Range and the Sierra Nevada to the east by broad depressions known as the Puget Sound Lowland in Washington, the Willamette Valley in Oregon, and the Central Valley in California; the Klamath Mountains of northern California and the Transverse Ranges of southern California, however, serve as links to the eastern ranges. On the west the coastal plain is very narrow, and deep water occurs within 25 miles (40 km) of the coast. The average elevation of the ranges is about 3,300 feet (1,000 m) above sea level, but some peaks and ridges rise to more than 6,600 feet (2,000 m). The region, especially in the south, is subject to occasional earthquakes and landslides.
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