The North American Cordillera, sometimes also called the Western Cordillera of North America, the Western Cordillera, or the Pacific Cordillera, is the North American portion of the American Cordillera, the mountain chain system along the Pacific coast of the Americas. The North American Cordillera covers an extensive area of mountain ranges, intermontane basins, and plateaus in Western and Northwestern Canada, Western United States, and Mexico, including much of the territory west of the Great Plains.
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 Limited, , 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, , p. 687: "[N]ame from the Spanish....It is used particularly in physical geography, although in geology also it is sometimes applied...."
Major features
The North American Cordillera extends from the U.S. state of Alaska to the southern border of Mexico, and 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 and the Black Hills).
These three orogenic belts (also called "orogens") 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 (55–50 million years ago) and Oligocene (34–23 million years ago), but since that time, 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, MontanaS. 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, 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, Shatrughna Sinha and Faguni Ram (1993) Instant Encyclopaedia of Geography, Mittal Publications, p. 140, 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.
Pacific Coast Belt
The Pacific Coast Ranges, comprising the Pacific Coast Belt, parallel the North American Pacific Coast, and comprise several mountain systems. Along the British Columbia and Alaska coasts, the mountains intermix with the sea in a complex maze of fjords, with thousands of islands. Off the Southern California coast, the Channel Islands archipelago of the Santa Monica Mountains extends for .
Southern Alaska ranges In southern Alaska, the primary mountain ranges are the Alaska Range, Wrangell Mountains, Saint Elias Mountains, Kenai Mountains, Chugach Mountains, and Talkeetna Mountains.Hultén, Eric. Flora of Alaska and Neighboring Territories: A Manual of the Vascular Plants, p. xiv (Stanford University Press, 1968).Stefoff, Rebecca. Alaska, p. 14 (Marshall Cavendish, 2006).
Western System of Canada
The Yukon Ranges comprise the mountains in the southeastern part of the U.S. state of Alaska and most of the Yukon, Canada. This range has an area of .Yukon Ranges in the Canadian Mountain Encyclopedia
The Coast Mountains run from the lower Fraser River and the Fraser Canyon northwestward, separating the Interior Plateau from the Pacific Ocean.Wilson, Robert J. Geology and Economic Minerals of Canada, p. 26 (Geological Survey of Canada, Department of Energy, Mines and Resources, 1976). Their coastal flank is characterized by an intense network of fjords and associated islands, very similar to the Norwegian coastline, while their inland side against the plateau transitions to the high plateau in dryland valleys notable for a series of large lakes similar to the alpine lakes of southern Switzerland, beginning in deep mountains and ending in flatland. They are subdivided in three main groupings, the Pacific Ranges between the Fraser and Bella Coola, the Kitimat Ranges from there northwards to the Nass River, and the Boundary Ranges from there to their terminus in the Yukon Territory at Champagne Pass and Chilkat Pass northwest of Haines, Alaska. The Saint Elias Mountains lie to their west and northwest, while the Yukon Ranges and Yukon Basin lie to their north. On the inland side of the Boundary Ranges are the Tahltan and Tagish Highlands and also the Skeena Mountains, part of the Interior Mountains system, which also extend southwards on the inland side of the Kitimat Ranges.
The terrain of the main spine of the Coast Mountains is typified by heavy glaciation, including several very large icefields of varying elevation. Of the three subdivisions, the Pacific Ranges are the highest and are crowned by Mount Waddington, while the Boundary Ranges contain the largest icefields, the Juneau Icefield being the largest. The Kitimat Ranges are lower and less glacier-covered than either of the other two groupings, but are extremely rugged and dense.
The Coast Mountains are made of igneous and metamorphic rock from an episode of arc volcanism related to subduction of the Kula and Farallon Plates during the Laramide orogeny about 100 million years ago.Rogers, John. A History of the Earth, p. 281 (CUP Archive, November 18, 1993). The widespread granite forming the Coast Mountains formed when magma intruded and cooled at depth beneath volcanoes of the Coast Range Arc, whereas the metamorphic formed when intruding magma heated the surrounding rock to produce schist.
The Insular Mountains extend from Vancouver Island in the south to Haida Gwaii in the north on the British Columbia Coast. It contains two main mountain ranges, the Vancouver Island Ranges on Vancouver Island and the Queen Charlotte Mountains on Haida Gwaii.Solski, Ruth. Canadian Provinces & Territories Gr. 4-6, p. 91 (S&S Learning Materials 2003).
Pacific Border Province in contiguous U.S.
The Olympic Mountains is a mountain range on the Olympic Peninsula of western Washington in the United States. The mountains, part of the Pacific Coast Ranges, are not especially high – Mount Olympus is the highest at – but the western slopes of the Olympics rise directly out of the Pacific Ocean and are the wettest place in the contiguous 48 states. Most of the mountains are protected within the bounds of the Olympic National Park.
South of the Olympics lies the Chehalis River valley representing a break in elevation and drainages, followed by the Willapa Hills. The highest peak in the Willapa Hills is Boistfort Peak with an elevation of .name="ngs"> This region represents the lowest of the upland areas in the Pacific Coast Ranges.
The Oregon Coast Range is the part of the Coast Range system that is denoted as between the mouth of the Columbia River and the Middle Fork Coquille River. It is about long. The highest peak is Marys Peak, at .
The California Coast Ranges are one of the eleven traditional geomorphic provinces of California. This province includes several – but not all – mountain ranges along the California coast (the Transverse Ranges, Peninsular Ranges, and Klamath Mountains are not included).
Western mountain ranges of Mexico The Sierra Madre del Sur mountains in southwestern Mexico form a southern extension of the Peninsular Ranges of Baja California. The Peninsular Ranges are separated from the Sierra Madre del Sur by an expanse of ocean.
Nevadan belt The Nevadan belt is located between the Pacific coast belt and the Laramide belt. Nevada means "snow-covered" in Spanish.
Interior System of Canada In Canada, the Northern Interior Mountains are a northern extension of the Columbia Mountains.Parsons, M. and Quinn, O. "Insular and Coastal Mountains, Interior Mountains ", Canadian Ministry of Environment: "Interior Mountains comprising the Columbia Mountains of the southern interior and the Omineca, Cassiar, Skeena and Hazelton Mountains of the northern interior." They include the Hazelton Mountains, Cassiar Mountains, Omineca Mountains, and Skeena Mountains.