The Columbia Plateau is a geologic and geographic region that lies across parts of the U.S. states of Washington,

Oregon Oregon () is a state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington, while the Snake River delineates much of its eastern boundary with Idah ...

, and

Idaho Idaho ( ) is a state in the Pacific Northwest region of the Western United States. To the north, it shares a small portion of the Canada–United States border with the province of British Columbia. It borders the states of Montana and W ...

. It is a wide

flood basalt A flood basalt (or plateau basalt) is the result of a giant volcanic eruption or series of eruptions that covers large stretches of land or the ocean floor with basalt lava. Many flood basalts have been attributed to the onset of a hotspot reac ...

plateau between the Cascade Range and the

Rocky Mountains The Rocky Mountains, also known as the Rockies, are a major mountain range and the largest mountain system in North America. The Rocky Mountains stretch in straight-line distance from the northernmost part of western Canada, to New Mexico in ...

, cut through by the Columbia River.

Geology

During late

Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recent" ...

and early

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58flood basalt A flood basalt (or plateau basalt) is the result of a giant volcanic eruption or series of eruptions that covers large stretches of land or the ocean floor with basalt lava. Many flood basalts have been attributed to the onset of a hotspot reac ...

engulfed about of the Pacific Northwest, forming a large igneous province. Over a period of perhaps 10 to 15 million years, lava flow after lava flow poured out, ultimately accumulating to a thickness of more than 6,000 feet (1.8 km). As the molten rock came to the surface, the Earth's crust gradually sank into the space left by the rising lava. The Columbia River Basalt Group consists of seven formations: The Steens Basalt, Imnaha Basalt, Grande Ronde Basalt, Picture Gorge Basalt, Prineville Basalt, Wanapum Basalt, and Saddle Mountains Basalt. Many of these formations are subdivided into formal and informal members and flows. The subsidence of the crust produced a large, slightly depressed lava plateau. The ancient Columbia River was forced into its present course by the northwesterly advancing lava. The lava, as it flowed over the area, first filled the stream valleys, forming dams that in turn caused impoundments or lakes. Entities found in these lake beds include

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

leaf impressions,

petrified wood Petrified wood, also known as petrified tree (from Ancient Greek meaning 'rock' or 'stone'; literally 'wood turned into stone'), is the name given to a special type of '' fossilized wood'', the fossilized remains of terrestrial vegetation. ' ...

, fossil insects, and bones of vertebrate animals. Evidence suggests that some concentrated heat source is melting rock beneath the Columbia Plateau Province at the base of the lithosphere (the layer of crust and upper mantle that forms Earth's moving tectonic plates). In an effort to figure out why this area, far from a plate boundary, had such an enormous outpouring of lava, scientists established hardening dates for many of the individual lava flows. They found that the youngest volcanic rocks were clustered near the Yellowstone Plateau, and that the farther west they went, the older the lavas. Although scientists are still gathering evidence, a probable explanation is that a

hot spot Hotspot, Hot Spot or Hot spot may refer to: Places * Hot Spot, Kentucky, a community in the United States Arts, entertainment, and media Fictional entities * Hot Spot (comics), a name for the DC Comics character Isaiah Crockett * Hot Spot (Tra ...

, an extremely hot plume of deep

mantle A mantle is a piece of clothing, a type of cloak. Several other meanings are derived from that. Mantle may refer to: *Mantle (clothing), a cloak-like garment worn mainly by women as fashionable outerwear **Mantle (vesture), an Eastern Orthodox ve ...

material, is rising to the surface beneath the Columbia Plateau Province. Beneath

Hawaii Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is an archipelago, and the only ...

and

Iceland Iceland ( is, Ísland; ) is a Nordic island country in the North Atlantic Ocean and in the Arctic Ocean. Iceland is the most sparsely populated country in Europe. Iceland's capital and largest city is Reykjavík, which (along with its ...

, a temperature instability develops (for reasons not yet well understood) at the boundary between the core and mantle. The concentrated heat triggers a plume hundreds of kilometers in diameter that ascends directly through to the surface of the Earth. The track of this hot spot starts in the west and sweeps up to

Yellowstone National Park Yellowstone National Park is an American national park located in the western United States, largely in the northwest corner of Wyoming Wyoming () is a state in the Mountain West subregion of the Western United States. It is border ...

. The steaming fumaroles and explosive geysers are ample evidence of a concentration of heat beneath the surface. The hotspot is stationary, but the North American plate is moving over it, creating a superb record of the rate and direction of plate motion.

Flora

Part of the Columbia Plateau is associated with the Columbia Plateau ecoregion, part of the "Nearctic temperate and subtropical grasslands, savannas, and shrublands"

ecoregion An ecoregion (ecological region) or ecozone (ecological zone) is an ecologically and geographically defined area that is smaller than a bioregion, which in turn is smaller than a biogeographic realm. Ecoregions cover relatively large areas o ...

of the temperate grasslands, savannas, and shrublands

biome A biome () is a biogeographical unit consisting of a biological community that has formed in response to the physical environment in which they are found and a shared regional climate. Biomes may span more than one continent. Biome is a broader ...

Geography

Washington cities in the Columbia Plateau include: * Colfax *

Davenport Davenport may refer to: Places Australia *Davenport, Northern Territory, a locality * Hundred of Davenport, cadastral unit in South Australia **Davenport, South Australia, suburb of Port Augusta **District Council of Davenport, former local govern ...

* Ellensburg * Reardan * Kennewick * Moses Lake * Pasco * Pullman * Richland *

Spokane Spokane ( ) is the largest city and county seat of Spokane County, Washington, United States. It is in eastern Washington, along the Spokane River, adjacent to the Selkirk Mountains, and west of the Rocky Mountain foothills, south of the Canada ...

* Walla Walla * Yakima *

Goldendale Goldendale is a city and county seat of Klickitat County, Washington, United States, near the Columbia River Gorge. The population within city limits was 3,760 at the 2000 census and 3,407 at the 2010 census, a 9.4% decrease. It is situated i ...

* Deer Park *

Othello ''Othello'' (full title: ''The Tragedy of Othello, the Moor of Venice'') is a tragedy written by William Shakespeare, probably in 1603, set in the contemporary Ottoman–Venetian War (1570–1573) fought for the control of the Island of Cyp ...

Warden A warden is a custodian, defender, or guardian. Warden is often used in the sense of a watchman or guardian, as in a prison warden. It can also refer to a chief or head official, as in the Warden of the Mint. ''Warden'' is etymologically ident ...

* Lind Oregon cities in the Columbia Plateau include: * Hermiston * Hood River *

Pendleton Pendleton may refer to: Places ;United Kingdom *Pendleton, Lancashire, England *Pendleton, Greater Manchester, England ;United States *Pendleton, Indiana * Pendleton, Missouri *Pendleton, New York *Pendleton, Oregon *Pendleton, South Carolina *Pe ...

* The Dalles *

Milton-Freewater Milton-Freewater is a city in Umatilla County, Oregon, United States. The city received its current name in 1951 when the neighboring rival cities of Milton and Freewater voted to merge. The population was 7,151 at the 2020 census. It is part of ...

Idaho cities in the Columbia Plateau include: * Coeur d'Alene * Lewiston *

Moscow Moscow ( , US chiefly ; rus, links=no, Москва, r=Moskva, p=mɐskˈva, a=Москва.ogg) is the capital and largest city of Russia. The city stands on the Moskva River in Central Russia, with a population estimated at 13.0 million ...

References

External links

USGS Page on Columbia Plateau

* ttps://web.archive.org/web/20080907133026/http://harvester.lib.utah.edu/wwdl/index.php/browse/guide/columbia Guide to digital documents and photographs about the Columbia River area.
Columbia River Basin Ethnic History Archive
{{Authority control Columbia River Physiographic provinces Large igneous provinces Volcanism of Washington (state) Miocene volcanism Pliocene volcanism Plateaus of the United States Landforms of Idaho Regions of Oregon Regions of Washington (state) Landforms of Umatilla County, Oregon Landforms of Hood River County, Oregon Landforms of Wasco County, Oregon

Geology

Flora

Geography

See also

References

External links