Columbia Plateau

from Wikipedia, the free encyclopedia
Map of the Columbia Plateau
The Columbia Plateau covers large parts of the Columbia Plateau basalt (green on the map). In Washington are the cities of Spokane, Yakima and Pasco and in Oregon the city of Pendleton on the area of ​​the Columbia Plateau.

The Columbia Plateau, or Columbia Basin, is a geographic region that lies almost entirely within east Washington and northern and central Oregon - with an east corner extending into northern Idaho . The area is characterized by its mainly semi-arid climate ( abbreviated to "Bsk" after the Köppen and Geiger climate classification ) - with some areas in the area of desert climate ("BWk") and Mediterranean climate ("Csa" and "Csb") - which is a Shrub steppe vegetation can grow.

geology

During the late Miocene and early Pliocene swallowed a Trapp from flood basalt about 160,000 square kilometers of the Pacific Northwest and created a Magmatic United Province . Over a period of maybe 10 ... 15 million years, lava flow poured onto lava flow and finally formed a layer 1.8 kilometers thick. As the molten rock rose to the surface, the earth's crust gradually sank into the cavity left by the rising lava. The Columbia plateau basalt is made up of seven formations: the Steens Basalt, the Imnaha Basalt, the Grande Ronde Basalt, the Picture Gorge Basalt, the Prineville Basalt, the Wanapum Basalt, and the Saddle Mountains Basalt. Many of these formations are further divided into formal and informal parts and rivers.

The subsidence of the earth's crust created the Great Plateau - a large, slightly sunken lava plain, sometimes referred to as the Columbia River Basin. The prehistoric Columbia River was forced into its current course by the northwest advancing lava. The lava, as it flowed over the area, first filled the river valleys and formed dams that in turn formed reservoirs and lakes. Objects that can be found in these lakes are e.g. B. fossil leaf prints, petrified wood , fossil insects and vertebrate bones.

Findings suggest that concentrated heat sources melted the rocks near the Columbia Plateau at the base of the lithosphere (the earth's crust and upper mantle that make up the moving tectonic plates). In an attempt to find out why this area, far from a plate boundary, produced such enormous lava flows, the scientists collected the data for each of the individual lava flows they hardened into. They found that the youngest volcanic rocks are found near the Yellowstone Plateau and older and older lava can be found on the way west.

Although scientists are still collecting evidence, hotspots offer a possible explanation: extremely hot vents of material from the Earth's mantle rising to the surface near the Columbia Plateau. Geologists know that near Hawaii and Iceland, core-mantle temperature instability is developing (for reasons that are not yet well understood). The concentrated heat creates a chimney hundreds of kilometers in diameter that rises directly to the surface of the earth.

The trail of this hotspot begins in the west and extends all the way to Yellowstone National Park . The steaming fumaroles and explosive geysers are sufficient evidence of the concentration of heat on the surface. The hotspot is stationary, but the North American plate moves over it, making an excellent record of the direction and speed of its movement.

flora

Part of the Columbia Plateau is the ecoregion Columbia Plateau associated that are part of the eco-region Nearctic temperate and sutropische grasslands, savannas and shrub landscapes of the biome temperate grasslands, savannas and shrub landscapes are.

geography

Cities in Washington on the Columbia Plateau include:

In Oregon, the following cities are on the Columbia Plateau:

See also

swell

Individual evidence

  1. ^ Columbia River Basalt Group Stretches from Oregon to Idaho . United States Geological Service. Retrieved March 28, 2018.
  2. ↑ Columbia Basin . Washington State Department of Natural Resources. Retrieved March 28, 2018.
  3. ↑ Floyd, Ben, et al. Glossary ( Memento of the original from March 22, 2005 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. . (1998) Hanford Reach Protection and Management Program Interim Action Plan ( Memento of the original from September 27, 2007 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. . Prosser, Washington: Benton County Planning Department. @1@ 2Template: Webachiv / IABot / www.co.benton.wa.us @1@ 2Template: Webachiv / IABot / www.co.benton.wa.us
  4. ^ Columbia Plateau in the Geographic Names Information System of the United States Geological Survey
  5. ↑ a b c d e f Description: Columbia Plateau Columbia River Basalt . United States Geological Survey. Retrieved October 9, 2007.
  6. ^ Columbia River Basalt Group Stretches from Oregon to Idaho . United States Geological Survey. Retrieved December 28, 2017.
  7. ↑ a b c Geologic Provinces of the United States: Columbia Plateau Province . USGS . Archived from the original on February 18, 2013. Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. Retrieved May 28, 2018. @1@ 2Template: Webachiv / IABot / geomaps.wr.usgs.gov

Web links

Wikivoyage: Columbia River Plateau  Travel Guide

Coordinates: 46 ° 0 ′  N , 119 ° 0 ′  W