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The Idaho Batholith ecoregion is a Level III ecoregion designated by the United States Environmental Protection Agency (EPA) in the U.S. states of Idaho and Montana. It is contained within the following biomes (or major habitat types) designated by the World Wild Fund for Nature (WWF): Temperate coniferous forests; Temperate grasslands, savannas, and shrublands; and Deserts and xeric shrublands.〔Olson, D. M., Dinerstein, E., Wikramanayake, E. D., Burgess, N. D., Powell, G. V. N., Underwood, E. C., D'Amico, J. A., Itoua, I., Strand, H. E., Morrison, J. C., Loucks, C. J., Allnutt, T. F., Ricketts, T. H., Kura, Y., Lamoreux, J. F., Wettengel, W. W., Hedao, P., Kassem, K. R. 2001. Terrestrial ecoregions of the world: a new map of life on Earth. Bioscience 51(11):933-938.〕 ==Setting== The Idaho batholith ecoregion is bordered on the north by the Northern Rockies, on the east by the Middle Rockies, on the south by the Snake River Plain, on the west by the Blue Mountains, and partially on the northwest by the Columbia Plateau. It has been subdivided into eleven Level IV ecoregions in Idaho and Montana.〔Glenn E. Griffith, James M. Omernik (Lead Author);Mark McGinley (Topic Editor) "Ecoregions of Idaho (EPA)". In: Encyclopedia of Earth. Eds. Cutler J. Cleveland (Washington, D.C.: Environmental Information Coalition, National Council for Science and the Environment). [First published in the Encyclopedia of Earth December 11, 2008; Last revised Date December 11, 2008; Retrieved February 15, 2013 The ecoregion is found within the Nearctic ecozone as designated by WWF, which covers most of North America.〔Bittner, Thomas. "On the Integration of Regional Classification and Delineation Systems into The National Map." Cartographica: The International Journal for Geographic Information and Geovisualization 45.2 (2010): 127-139.〕 Ecozones are the broadest way of breaking up the Earth's land surface biogeographically. Ecozones characterize large amounts of habitat that contain organisms that have been evolving together in relative isolation for long time periods. The most prevalent geological feature in this ecoregion is its namesake, the Idaho batholith. A batholith is a body of intrusive igneous rock formed by the cooling of magma under the Earth's surface. Igneous rocks are those formed by magma cooling and solidifying, while intrusive rocks are igneous rocks that form beneath the Earth's surface.〔(【引用サイトリンク】url=http://vulcan.wr.usgs.gov/LivingWith/VolcanicPast/Notes/igneous_rocks.html )〕 The Idaho batholith is fundamentally different from other batholiths of the North American Cordillera in that it is mostly made up of peraluminous granites and positioned completely within the Precambrian continental crust. Peraluminous granites are those that contain more aluminum oxide than sodium oxide, potassium oxide, and calcium oxide combined. The batholith is composed of the Bitterroot lobe in the north and the larger Atlanta lobe in the south. The major mountain ranges in the region are part of the Rocky Mountains; they include the Bitterroot Range, Clearwater Mountains, Salmon River Mountains, and the Sawtooth Range.〔(【引用サイトリンク】url=http://www.freeworldmaps.net/united-states/idaho/map.html )〕 Major mountain peaks include 10,201 ft (3,085 m) tall Trapper Peak in the Bitterroot Mountains in Montana and 12,009 ft (3,660 m) tall Hyndman Peak in the Pioneer Mountains in Idaho. Soils derived from the granite that characteristically underlays the ecoregion tend to retain water poorly and be limited in fertility. The removal of vegetation causes these soils to be highly erodible.〔http://www.blm.gov/.../Chapter_2_Area_Profile_Final_508.pdf〕 The rivers that flow through the ecoregion include the Payette, Selway, Salmon, Lochsa, Clearwater, Boise in Idaho, and the Bitterroot in Montana.〔(【引用サイトリンク】url=http://geology.com/lakes-rivers-water/idaho.shtml )〕 The region lies within the Columbia and Missouri Watersheds for named rivers as designated by the United States Geological Survey (USGS). The Idaho Batholith ecoregion lies within the following WWF freshwater ecoregions: the Upper Snake, the Upper Missouri, and the Columbia Unglaciated. Lake Cascade, the fourth largest lake or reservoir in the state of Idaho is situated on the North Fork of the Payette River. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Idaho Batholith ecoregion」の詳細全文を読む スポンサード リンク
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