|
The North American Cordillera is the North American portion of the American Cordillera which is a mountain chain (cordillera) along the western side of the Americas. The North American Cordillera covers an extensive area of mountain ranges, intermontane basins, and plateaus in western North America, including much of the territory west of the Great Plains. It is also sometimes called the Western Cordillera, the Western Cordillera of North America, or the Pacific Cordillera. The precise boundaries of this cordillera and its subregions, as well as the names of its various features, may differ depending on the definitions in each country or jurisdiction, and also depending on the scientific field; this cordillera is a particularly prominent subject in the scientific field of physical geography.〔Melanie Ostopowich (2005) ''(The Cordillera )'', Weigl Educational Publishers, ISBN 1553881494, pp. 6, 12, and 20: "The Cordillera is one of the seven geographic regions in Canada".〕〔''(The Encyclopedia Americana: a library of universal knowledge )'', Encyclopedia Americana Corp., 1918, ISBN 0717201333, p. 687: "()ame from the Spanish....It is used particularly in physical geography, although in geology also it is sometimes applied...."〕 ==Major features== This cordillera extends from the U.S. state of Alaska to the southern border of Mexico. The North American Cordillera includes some of the highest peaks on the continent.〔Frank Press and Raymond Siever ''(Earth )'', pp. 534–535, Macmillan, 1986.〕 Its mountain ranges generally run north to south along three main belts: the Pacific Coast Ranges in the west, the Nevadan belt in the middle (including the Sierra Nevada), and the Laramide belt in the east (including the Rocky Mountains). These three orogenic belts arose due to the engagement of tectonic plates which deformed the Earth's lithosphere (crust and uppermost mantle). For example, the Laramide orogeny changed the topography of the central Rocky Mountains and adjoining Laramide regions (from central Montana to central New Mexico) during the Late Cretaceous 80 million years ago. Prior to this time the Rocky Mountain region was occupied by a broad basin. Further topographical evolution occurred during the Eocene (50–55 million years ago) and Oligocene (34-23 million years ago), but since that time the deformation of the region has been relatively stable.〔D. Alt and D. Hyndman. (1995). Northwest Exposures: A Geological Story of the North West. Mountain Press Publishing Company, Missoula, Montana〕〔S. Brunsfeld, J. Sullivan, D. Soltis, and P. Sotis (2001). ("Comparative phylogeography of north-western north america: A synthesis" ). In: Silverton, J., Antonovics, J. (Eds.), ''Integrating Ecology and Evolution in a Spatial Context''. The 14th Special Symposium of the British Ecological Society. British Ecolological Society, Blackwell Science Ltd., Ch. 15, pp. 319–339.〕 Generally speaking, it will be convenient here to consider these three belts going west to east, and north to south. In Alaska, south of the Interior Plains area, is the Rocky Mountain System, then the Intermontane Basins and Ranges, and in the southern part of the state are the Pacific Mountains and Valleys.〔(The Geography of Alaska: Physical Geography ), Alaska Humanities Forum: "At a very general level, Alaska is part of four general physiographic regions, the Interior Plains, Rocky Mountains, Intermontane Basins and Ranges, and the Pacific Mountains and Valleys".〕 In the Alaska panhandle, the mainland mountain ranges and offshore islands (the Alexander Archipelago) are extensions of respective ranges further south.〔Wheeler, J. and Kostbade, J. ''World Regional Geography'' (Saunders College Publishing 1990): "The mainland ranges of the panhandle are a northward extension of the cascade range and the British Columbia Coastal ranges, while the mountainous offshore islands are an extension of the Coast Ranges of the Pacific Northwest and the islands of British Columbia."〕 In Canada, the North American Cordillera is usually divided into three physiographic regions: the western system, the interior system, and the eastern system.〔William Bailey et al. ''(The surface climates of Canada )'', McGill-Queen's Press – MQUP, 1997, p. 226.〕 The western system includes the Coast Mountains, the interior system includes the Columbia Mountains, and the eastern system includes the Canadian Rockies.〔 At its midsection between San Francisco, California and Denver, Colorado, the North American Cordillera is about wide, and its physiographic provinces at this midpoint are as follows, going from west to east: the Pacific Coast Ranges, the Central Valley, the Sierra Nevada, the Basin and Range province (forming many narrow ranges and valleys), the Colorado Plateau, and the Rocky Mountains.〔 In the United States, another major feature of the Cordillera is the Columbia Plateau, located north of California between the Cascade Range — which is a northern extension of the Sierra Nevada〔 — and the Rocky Mountains. In Mexico, the Sierra Madre Occidental, and the Sierra Madre Oriental further east, surround the Mexican Plateau.〔''(Merriam-Webster's Geographical Dictionary )'', Merriam-Webster, 1997, pp. 219 and 1087, ISBN 0877795460〕〔Shatrughna Sinha and Faguni Ram (1993) ''(Instant Encyclopaedia of Geography )'', Mittal Publications, p. 140, ISBN 8170994896〕 To the west of the Sierra Madre Occidental, the Peninsular Ranges border the Pacific Ocean, and the Sierra Madre del Sur is the southern extension of the Peninsular Ranges.〔''Encyclopedia Americana: the International Reference Work'', Volume 18: "Sierra Madre del Sur. — This sierra, which crosses the states of Colima, Michoacan, Guerrero, and Oaxaca, is the continuation of the Sierra de Baja California and the other mountain ranges linked with it." (Americana Corporation 1961).〕 Sierra Madre means "Mother Range" in Spanish. The Nevadan belt runs up and down the middle of the North American Cordillera. Therefore, the intermontane areas of the cordillera can be divided up into the areas east of the Nevadan belt, and those west of the Nevadan belt. 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「North American Cordillera」の詳細全文を読む スポンサード リンク
|