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The Basin and Range Province is a vast physiographic region defined by a unique topographic expression. Basin and range topography is characterized by abrupt changes in elevation, alternating between narrow faulted mountain chains and flat arid valleys or basins. The region covers much of the western United States, extends into northwestern Mexico and is mostly desert, with numerous ecoregions. The physiography of the province is the result of tectonic extension that began around 17 Ma (million years ago) in Early Miocene time. The numerous ranges within the Province in the United States are collectively referred to as the Great Basin Ranges, although many are not actually in the Great Basin. Major ranges include the Snake Range, the Panamint Range, the White Mountains, the Sandia Mountains, and the Tetons . Depending on the various geographical definitions of the Province, the highest point of the Province is either Mount Whitney or Pico de Orizaba, both of which are located at the boundary of the Province and belong to other geologic regions as well. The highest point fully within the Province is White Mountain Peak in California, while the lowest point is the Badwater Basin in Death Valley at . Clarence Dutton famously compared the many narrow parallel mountain ranges that distinguish the unique topography of the Basin and Range to an "army of caterpillars marching toward Mexico", which is a helpful way to visualize the overall appearance of the region.〔Reynolds, D., & Christensen, J. (2001). Nevada. Portland, Or: Graphic Arts Center Pub.〕 The Basin and Range province should not be confused with The Great Basin, which is a sub-section of the greater Basin and Range physiographic region defined by its unique hydrological characteristics (internal drainage). ==Geography== The Basin and Range Province includes much of western North America. In the United States, it is bordered on the west by the eastern fault scarp of the Sierra Nevada and spans over to its eastern border marked by the Wasatch Fault, the Colorado Plateau and the Rio Grande Rift. The Basin and Range Province extends north to the Columbia Plateau and south as far as the Trans-Mexican Volcanic Belt in Mexico, though the southern boundaries of the Basin and Range are debated.〔Henry, C., & Aranda-Gomez, J. (1992). The real southern Basin and Range: Mid- to late Cenozoic extension in Mexico. Geology, 20701-704. Retrieved from General Science Abstracts (H.W. Wilson) database.〕 In Mexico, the Basin and Range Province is dominated by and largely synonymous with the Mexican Plateau. Evidence suggests that the less-recognized southern portion of the Basin and Range Province is bounded on the east by the Laramide Thrust Front of the Sierra Madre Oriental and on the west by the Gulf of California and Baja Peninsula with notably less faulting apparent in the Sierra Madre Occidental in the center of the southernmost Basin and Range Province.〔Dickinson, William R. "The Basin and Range Province as a Composite Extensional Domain". International Geology Review, Vol. 22, 2002, p. 1-38.〕 Common geographic features include numerous endorheic basins, ephemeral lakes, plateaus, and valleys alternating with mountains (as described below). The area is mostly arid and sparsely populated, although there are several major metropolitan areas, including Mexico City, the largest city in the western hemisphere.〔(CPD; Mexico regional overview )〕 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「Basin and Range Province」の詳細全文を読む スポンサード リンク
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