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Columbia Plateau
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Learn how basaltic rock composing the Columbia Plateau was once lava from a series of volcanic fissure eruptions
Map of the United States highlighting the Columbia Plateau region in orange, spanning parts of Washington, Oregon, and Idaho in the Pacific Northwest. The rest of the country is shown in light gray, with a small inset map indicating the region's location within North America. Aerial view of the Columbia Plateau showing a wide expanse of flat land with steep, dark basalt cliffs and sparse vegetation in Idaho, Washington, and Oregon.
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Also called:
Columbia Intermontane
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Columbia Plateau

region, United States
Also known as: Columbia Intermontane
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History
Learn how basaltic rock composing the Columbia Plateau was once lava from a series of volcanic fissure eruptions
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Learn how basaltic rock composing the Columbia Plateau was once lava from a series of volcanic fissure eruptionsThe Columbia Plateau was formed by volcanic eruptions and subsequently reshaped by erosion.
See all videos for this article
Map of the United States highlighting the Columbia Plateau region in orange, spanning parts of Washington, Oregon, and Idaho in the Pacific Northwest. The rest of the country is shown in light gray, with a small inset map indicating the region's location within North America.
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Columbia Plateau

Columbia Plateau, geographic region, northwestern United States. It forms part of the intermontane plateaus and is bordered east by the Northern Rocky Mountains and west by the Sierra Nevada–Cascade region. The plateau covers an area of about 100,000 square miles (260,000 square km) in Washington, Oregon, and Idaho and is noted for its diverse landforms (see video). It is uniformly covered with basaltic lava flows, but significant warping and faulting have caused elevations to range from 200 to 5,000 feet (60 to 1,500 meters) above sea level. The climate is semiarid, and vegetation is limited mostly to shrubs and grasses. The Columbia and Snake rivers drain the region.

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