Columbia Plateau: Difference between revisions
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[[File:pacificNW volcanics.png|thumb|The Columbia Plateau covers much of the [[Columbia River Basalt Group]], shown in green on this map. The Washington cities of Spokane, Yakima and Pasco, and the Oregon city of Pendleton, lie on the Columbia Plateau.]] |
[[File:pacificNW volcanics.png|thumb|The Columbia Plateau covers much of the [[Columbia River Basalt Group]], shown in green on this map. The Washington cities of Spokane, Yakima and Pasco, and the Oregon city of Pendleton, lie on the Columbia Plateau.]] |
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The '''Columbia Plateau''' is a [[geology|geologic]] and [[geography|geographic]] region that lies across parts of the [[U.S. state]]s of [[Washington (state)|Washington]], [[Oregon]], and [[Idaho]].<ref>{{gnis|1159062}}</ref> It is a wide [[flood basalt]] plateau between the [[Cascade Range]] and the [[Rocky Mountains]], cut through by the [[Columbia River]]. In one of various usages, the term "[[Columbia Basin]]" refers to more or less the same area as the Columbia Plateau.<ref>Floyd, Ben, et al. "[http://www.co.benton.wa.us/pl/iap/html/body_glossary.htm Glossary]". (1998) [http://www.co.benton.wa.us/pl/iap/iapindex.htm Hanford Reach Protection and Management Program Interim Action Plan]. Prosser, Washington: Benton County Planning Department.</ref> |
The '''Columbia Plateau''' is a [[geology|geologic]] and [[geography|geographic]] region that lies across parts of the [[U.S. state]]s of [[Washington (state)|Washington]], [[Oregon]], and [[Idaho]].<ref>{{gnis|1159062}}</ref> It is a wide [[flood basalt]] plateau between the [[Cascade Range]] and the [[Rocky Mountains]], cut through by the [[Columbia River]]. In one of various usages, the term "[[Columbia Basin]]" refers to more or less the same area as the Columbia Plateau.<ref>Floyd, Ben, et al. "[http://www.co.benton.wa.us/pl/iap/html/body_glossary.htm Glossary] {{webarchive|url=https://web.archive.org/web/20050322200416/http://www.co.benton.wa.us/pl/iap/html/body_glossary.htm |date=2005-03-22 }}". (1998) [http://www.co.benton.wa.us/pl/iap/iapindex.htm Hanford Reach Protection and Management Program Interim Action Plan] {{webarchive|url=https://web.archive.org/web/20070927220350/http://www.co.benton.wa.us/pl/iap/iapindex.htm |date=2007-09-27 }}. Prosser, Washington: Benton County Planning Department.</ref> |
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== Geology == |
== Geology == |
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* [http://vulcan.wr.usgs.gov/Volcanoes/ColumbiaPlateau/framework.html USGS Page on Columbia Plateau] |
* [http://vulcan.wr.usgs.gov/Volcanoes/ColumbiaPlateau/framework.html USGS Page on Columbia Plateau] |
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* [http://www.nps.gov/laro/webdirectory/geology.htm Geology of Lake Roosevelt National Recreation Area (source of much of this page)] |
* [http://www.nps.gov/laro/webdirectory/geology.htm Geology of Lake Roosevelt National Recreation Area (source of much of this page)] |
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* [http://harvester.lib.utah.edu/wwdl/index.php/browse/guide/columbia Guide to digital documents and photographs about the Columbia River area.] |
* [https://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.] |
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* [http://www.vancouver.wsu.edu/crbeha/ Columbia River Basin Ethnic History Archive] |
* [http://www.vancouver.wsu.edu/crbeha/ Columbia River Basin Ethnic History Archive] |
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Revision as of 01:36, 11 August 2017
The Columbia Plateau is a geologic and geographic region that lies across parts of the U.S. states of Washington, Oregon, and Idaho.[1] It is a wide flood basalt plateau between the Cascade Range and the Rocky Mountains, cut through by the Columbia River. In one of various usages, the term "Columbia Basin" refers to more or less the same area as the Columbia Plateau.[2]
Geology
During late Miocene and early Pliocene times, one of the largest flood basalts ever to appear on the earth's surface engulfed about 63,000 square miles (160,000 km2) of the Pacific Northwest, forming a large igneous province.[3] 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).[3] 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.[4][3]
The subsidence of the crust produced the large plateau—a large, slightly depressed lava plain sometimes also known as the Columbia Basin.[3] 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.[3] Entities found in these lake beds include fossil leaf impressions, petrified wood, fossil insects, and bones of vertebrate animals.[3]
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 of the temperate grasslands, savannas, and shrublands biome.
Geography
Washington cities in the Columbia Plateau include:
Oregon cities in the Columbia Plateau include:
See also
References
- ^ U.S. Geological Survey Geographic Names Information System: Columbia Plateau
- ^ Floyd, Ben, et al. "Glossary Archived 2005-03-22 at the Wayback Machine". (1998) Hanford Reach Protection and Management Program Interim Action Plan Archived 2007-09-27 at the Wayback Machine. Prosser, Washington: Benton County Planning Department.
- ^ a b c d e f Description: Columbia Plateau Columbia River Basalt. United States Geological Survey, accessed October 9, 2007.
- ^ http://volcanoes.usgs.gov/observatories/cvo/cvo_columbia_river_basalt.html
External links
- Columbia River
- Physiographic provinces
- Large igneous provinces
- Volcanism of Washington (state)
- Miocene volcanism
- Pliocene volcanism
- Plateaus of the United States
- Landforms of Idaho
- Landforms of Oregon
- Landforms of Washington (state)
- Regions of Oregon
- Regions of Washington (state)
- Landforms of Umatilla County, Oregon
- Landforms of Hood River County, Oregon
- Landforms of Wasco County, Oregon