The Columbia Plateau is an important

geologic Geology (). is a branch of natural science concerned with the Earth and other astronomical objects, the rocks of which they are composed, and the processes by which they change over time. Modern geology significantly overlaps all other Earth s ...

and

geographic Geography (from Ancient Greek ; combining 'Earth' and 'write', literally 'Earth writing') is the study of the lands, features, inhabitants, and phenomena of Earth. Geography is an all-encompassing discipline that seeks an understanding o ...

region that lies across parts of the

U.S. state In the United States, a state is a constituent political entity, of which there are 50. Bound together in a political union, each state holds governmental jurisdiction over a separate and defined geographic territory where it shares its so ...

s of

Washington Washington most commonly refers to: * George Washington (1732–1799), the first president of the United States * Washington (state), a state in the Pacific Northwest of the United States * Washington, D.C., the capital of the United States ** A ...

Oregon Oregon ( , ) is a U.S. state, state in the Pacific Northwest region of the United States. It is a part of the Western U.S., with the Columbia River delineating much of Oregon's northern boundary with Washington (state), Washington, while t ...

, and

Idaho Idaho ( ) is a landlocked U.S. state, state in the Pacific Northwest and Mountain states, Mountain West subregions of the Western United States. It borders Montana and Wyoming to the east, Nevada and Utah to the south, and Washington (state), ...

. 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 (geolo ...

plateau between the

Cascade Range The Cascade Range or Cascades is a major mountain range of western North America, extending from southern British Columbia through Washington (state), Washington and Oregon to Northern California. It includes both non-volcanic mountains, such as m ...

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 great-circle distance, straight-line distance from the northernmost part of Western Can ...

, cut through by the

Columbia River The Columbia River (Upper Chinook language, Upper Chinook: ' or '; Sahaptin language, Sahaptin: ''Nch’i-Wàna'' or ''Nchi wana''; Sinixt dialect'' '') is the largest river in the Pacific Northwest region of North America. The river headwater ...

Geology

During late

Miocene The Miocene ( ) is the first epoch (geology), 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 mea ...

and early

Pliocene The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 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 (geolo ...

engulfed about of the Pacific Northwest, forming a

large igneous province A large igneous province (LIP) is an extremely large accumulation of igneous rocks, including intrusive ( sills, dikes) and extrusive (lava flows, tephra deposits), arising when magma travels through the crust towards the surface. The format ...

. 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

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 preserve ...

leaf impressions,

petrified wood Petrified wood (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 plant, terrestrial vegetation. ''Petrifaction ...

, 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 The upper mantle of Earth is a very thick layer of rock inside the planet, which begins just beneath the crust (geology), crust (at about under the oceans and about under the continents) and ends at the top of the lower mantle (Earth), lower man ...

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, an extremely hot plume of deep mantle material, is rising to the surface beneath the Columbia Plateau Province. Beneath

Hawaii Hawaii ( ; ) is an island U.S. state, state of the United States, in the Pacific Ocean about southwest of the U.S. mainland. One of the two Non-contiguous United States, non-contiguous U.S. states (along with Alaska), it is the only sta ...

and

Iceland Iceland is a Nordic countries, Nordic island country between the Atlantic Ocean, North Atlantic and Arctic Oceans, on the Mid-Atlantic Ridge between North America and Europe. It is culturally and politically linked with Europe and is the regi ...

, 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 a List of national parks of the United States, national park of the United States located in the northwest corner of Wyoming, with small portions extending into Montana and Idaho. It was established by the 42nd U ...

. The steaming fumaroles and explosive

geyser A geyser (, ) is a spring with an intermittent water discharge ejected turbulently and accompanied by steam. The formation of geysers is fairly rare and is caused by particular hydrogeological conditions that exist only in a few places on Ea ...

s 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) is an ecological and geographic area that exists on multiple different levels, defined by type, quality, and quantity of environmental resources. Ecoregions cover relatively large areas of land or water, and c ...

of the

temperate grasslands, savannas, and shrublands Temperate grasslands, savannas, and shrublands are terrestrial biomes defined by the World Wide Fund for Nature. The predominant vegetation in these biomes consists of grass and/or shrubs. The climate is temperate and ranges from Semi-arid clima ...

biome A biome () is a distinct geographical region with specific climate, vegetation, and animal life. It consists of a biological community that has formed in response to its physical environment and regional climate. In 1935, Tansley added the ...

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 Ellensburg is a city in and the county seat of Kittitas County, Washington, United States. It is located just east of the Cascade Range near the junction of Interstate 90 and Interstate 82. The population was 18,666 at the 2020 census. and was ...

* Reardan *

Kennewick Kennewick () is a city in Benton County, Washington, Benton County in the U.S. state of Washington (state), Washington. It is located along the southwest bank of the Columbia River, just southeast of the confluence of the Columbia and Yakima ...

Moses Lake Moses Lake is a lake and reservoir along the course of Crab Creek, in the U.S. state of Washington. Moses Lake is part of the Columbia River basin, as Crab Creek is a tributary of the Columbia River. Although originally a shallow natural lake ...

* Pasco * Pullman * Richland *

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

* Walla Walla *

Yakima Yakima ( or ) is a city in and the county seat of Yakima County, Washington, United States, and the state's 11th most populous city. As of the 2020 census, the city had a total population of 96,968 and a metropolitan population of 256,728. The ...

* Goldendale * Deer Park *

Othello ''The Tragedy of Othello, the Moor of Venice'', often shortened to ''Othello'' (), is a tragedy written by William Shakespeare around 1603. Set in Venice and Cyprus, the play depicts the Moorish military commander Othello as he is manipulat ...

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 Lind is a surname of both Swedish and Estonian origin. In Swedish, it is the word for the linden tree. In Estonian, it is the word for bird. Geographical distribution As of 2014, 36.1% of all known bearers of the surname ''Lind'' were resid ...

Oregon cities in the Columbia Plateau include: *

Athena Athena or Athene, often given the epithet Pallas, is an ancient Greek religion, ancient Greek goddess associated with wisdom, warfare, and handicraft who was later syncretism, syncretized with the Roman goddess Minerva. Athena was regarde ...

Hermiston Hermiston () is a city in Umatilla County, Oregon, United States. Its population of 20,322 makes it the largest city in Eastern Oregon. Hermiston is the largest and fastest-growing city in the Hermiston-Pendleton Micropolitan Statistical Area, t ...

* Hood River * Pendleton * The Dalles * Milton-Freewater Idaho cities in the Columbia Plateau include: * Coeur d'Alene * Lewiston *

Moscow Moscow is the Capital city, capital and List of cities and towns in Russia by population, largest city of Russia, standing on the Moskva (river), Moskva River in Central Russia. It has a population estimated at over 13 million residents with ...

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