North American Cordillera

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North American Cordillera
Denali National Park
Highest point
PeakDenali
Elevation6,168 m (20,236 ft)
Dimensions
Length6,400 km (4,000 mi)
Geography
CountriesUnited States, Canada and Mexico

The North American Cordillera, sometimes also called the Western Cordillera of North America, the Western Cordillera, or the Pacific Cordillera,[1][2] is the North American portion of the American Cordillera, the mountain chain system (cordillera) along the western coast (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.[3][4]

Major features

Pacific Border Province
(24).
Physiographic divisions of Mexico include three mountain systems: the Sierra Madre Oriental, the Sierra Madre Occidental and the Sierra Madre del Sur (which is an extension of the Peninsular Ranges).

The North American Cordillera extends from the

Sierra Nevada), and the Laramide belt in the east (including the Rocky Mountains).[6][7][8]

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.[9] 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.[10][11][12][13]
Generally speaking, it will be convenient here to consider these three belts going west to east, and north to south.

In

Alaska panhandle, the mainland mountain ranges and offshore islands (the Alexander Archipelago) are extensions of respective ranges further south.[15]

In Canada, the North American Cordillera is usually divided into three physiographic regions: the western system, the interior system, and the eastern system.[16] The western system includes the Coast Mountains, the interior system includes the Columbia Mountains, and the eastern system includes the Canadian Rockies.[3]

At its midsection between San Francisco, California and Denver, Colorado, the North American Cordillera is about 1,000 miles (1,600 km) 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.[5] 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[17] – and the Rocky Mountains.

In Mexico, the Sierra Madre Occidental, and the Sierra Madre Oriental further east, surround the Mexican Plateau.[17][18] 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.[19] 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

Main article: Pacific Coast Ranges

The Pacific Coast Ranges, comprising the Pacific Coast Belt, parallel the North American Pacific Coast, and comprise several mountain systems. Along the

Channel Islands archipelago of the Santa Monica Mountains
extends for 160 miles (260 km).

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.[20][21]

Western System of Canada

Mount Robson in British Columbia

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 364,710 km2 (140,820 sq mi).[22]

The

Champagne Pass and Chilkat Pass northwest of Haines, Alaska.[23] 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.[23]

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.[24] 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.[25]

Pacific Border Province in contiguous U.S.

Olympic Mountains in Washington

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 7,962 ft (2,427 m) – but the western slopes of the Olympics rise directly out of the Pacific Ocean and are the wettest place in the 48 contiguous states.[26][27] Most of the mountains are protected within the bounds of the Olympic National Park.

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 200 miles (320 km) long. The highest peak is Marys Peak, at 4,101 ft (1,250 m).

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 the Klamath Mountains are not included).[28]

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.[19] 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.[29] They include the Hazelton Mountains, Cassiar Mountains, Omineca Mountains, and Skeena Mountains
.

Location map of Columbia Mountains
Monashee Mountains

The Columbia Mountains are a designation in British Columbia for a group of four ranges lying between the Rocky Mountain Trench (to the east) and the Interior Plateau (to the west). These ranges are the Cariboo Mountains, which are the northernmost and sometimes considered to be part of the Interior Plateau, the Selkirk Mountains, the Purcell Mountains, and the Monashee Mountains.

The Columbia Mountains are classified as being in Canada's interior system, rather than its eastern system.[30] However, the Columbia Mountains are an extension of mountains in the United States that are considered part of the Rocky Mountains, and therefore the Columbia Mountains are often treated as being part of the Rockies.[31]

The Selkirks and Purcells lie entirely within the basin of the Columbia River, while the Monashees lie to the river's west on its southward course from its

Kootenai River
are essentially part of the same landform, but are officially designated part of the Rocky Mountains in the United States.

To the west of the Monashees and Cariboos, there are three intermediary upland areas which are transitional between the mountain ranges and the plateaus flanking the Fraser and Thompson Rivers. These – the Quesnel, Shuswap and Okanagan Highlands, are sometimes considered as being part of the neighbouring ranges rather than the plateaus and are often spoken of that way locally but are formally designated as being part of the Interior Plateau. The southernmost extends into the Washington, where it is named by the American spelling Okanogan Highland (and was the first-named of these groupings).[30]

Cascade–Sierra Mountains in contiguous U.S.

The

Lassen Peak, and are more severely alpine and steeply rugged, particularly the Skagit Range. Inland portions of the range are dryland and plateau-like in character, e.g. the Okanagan Range, which lies along the Cascades' northeastern margin, separated by the Similkameen River
.

The

Central Valley of California to the Transverse Ranges, forming a mountain region of complex terrain and varied geology which separates the Central Valley from the Great Basin to the east. The mean height of the mountain summits in the Sierra Nevada gradually increases from north to south, culminating at Mount Whitney (14,505 feet (4,421 m)), the highest point in the contiguous United States. From east to west, the Sierra is wedge-shaped: the west slope gradually rises and the east slope forms a steep escarpment
, particularly so in the southern portion.

The northern Sierra surface rocks are predominantly volcanic, while the southern Sierra granitic batholith has been sculpted by glaciers into dramatic U-shaped valleys and thin ridges called arêtes.

Sierra Madre Occidental in Mexico

The Sierra Madre Occidental mountain range is a southern extension of the Sierra Nevada.[32] The range extends from near the Arizona border down to the Sierra Madre del Sur, along the western mainland of Mexico. The high plateau that is formed by the range is cut by deep river valleys.

Laramide Belt

The Laramide belt is on the side of the North American Cordillera most distant from the Pacific Coast Ranges. It is named for the Laramie Mountains of eastern Wyoming (in turn named for Jacques La Ramee, a trapper who disappeared in the Laramie Mountains in 1820 and was never heard from again).[33]

Alaska and Eastern System of Canada

The Brooks Range in Alaska

The

British Mountains and Richardson Mountains, towards their eastern end, and at their farthest west is the small subrange that De Long Mountains. The Brooks Range forms the northern flank of the lower Yukon River basin, separating it from Alaska's North Slope region, facing the Beaufort Sea. The Brooks Range is considered part of (or an extension of) the Rockies.[34][35][36] South of the Brooks Range are the Mackenzie Mountains, and the Canadian Rockies
.

Rocky Mountain System in contiguous U.S.

In the

Kootenai River, the Columbia Mountains, are sometimes considered a separate system lying to the west of the huge Rocky Mountain Trench which runs the length of British Columbia.[31]

Sierra Madre Oriental in Mexico

The Sierra Madre Oriental mountains in eastern Mexico are a southern extension of the Rocky Mountains.[36][37] The Sierra Madre Oriental spans about 1,000 km (600 miles). Mexico's Gulf Coastal Plain lies to the east of the range, between the mountains and the Gulf of Mexico coast. The Mexican Plateau lies to the west of the range.

Intermontane areas seaward from the Nevadan belt

The Nevadan belt runs down the middle of the North American Cordillera. Therefore, the intermontane areas can be divided up into the areas east of the Nevadan belt, and those west of the Nevadan belt.

Canadian portion

Interior Plateau
Shuswap Highland

The

Canadian Cascades are to the southwest, and the Hazelton Mountains and Coast Range to the west and northwest.[38]

Within the Interior plateau, the Shuswap Highland consists of a portion of the foothills between the Thompson Plateau and Bonaparte Plateau on the west, and the Monashee Mountains and Cariboo Mountains on the east and northeast.[39]

Thompson Plateau
Okanagan Highland

Also within the Interior plateau, the

Canadian Cascades and on the north by the Thompson River.[40]

The Okanagan Highland is the part of the Interior Plateau to the east of the Thompson Plateau, and is bounded by the

Kettle River on the east side. The Okanagan Highland is described as being a hilly plateau, and is located in southern British Columbia and northern Washington.[41] The Interior Plateau also includes the Quesnel Highland, Fraser Plateau, Nechako Plateau, and McGregor Plateau
.

Portion in contiguous U.S.

California's

Coast Ranges
to the west.

In northwestern Oregon, the fertile

Puget Trough
.

Mexican portion

The Gulf of California is a body of water that separates the Peninsular Ranges from the Sierra Madre Occidental on the Mexican mainland. The Gulf of California is 1,126 km (700 miles) long and 48 to 241 km (30 to 150 miles) wide, with an area of 177,000 km2 (68,000 sq mi), a mean depth of 818.08 m (2,684.0 ft), and a volume of 145,000 km3 (35,000 cu mi).[42]

Intermontane areas inland from the Nevadan belt

Canadian portion

The

faulting. The Trench separates the Rocky Mountains on its east from the Columbia Mountains and the Cassiar Mountains
on its west. It is up to 25 km (16 miles) wide, if measured peak-to-peak.

For convenience the Rocky Mountain Trench may be divided into northern and southern sections. The dividing point reflects the separation of north and easterly flows to the Arctic Ocean versus south and westerly flows to the Pacific Ocean. A break in the valley system at around 54°N near Prince George, British Columbia may be used for this purpose. There are three main mountain ranges in the Canadian area named the Rocky Mountains, the Columbia Mountains, and the Coast Mountains.

Portion in contiguous U.S.

Colorado Plateau
Basin & Range Province (indicated in blue)

The

Columbia Basin" refers to more or less the same area as the Columbia Plateau.[44]

The

basin and range topography.[45]

The

Green River which flows south from the northernmost part of the plateau. The Green is a tributary of the Colorado, the confluence being west of Moab, Utah in Canyonlands National Park.[46]

Mexican portion

The

United States border in the north to the Trans-Mexican Volcanic Belt in the south and is bounded by the Sierra Madre Occidental and Sierra Madre Oriental
to the west and east, respectively.

A low east–west mountain range in the state of

Zacatecas
divides the plateau into northern and southern sections. These two sections, called the Northern Plateau (Spanish: Mesa del Norte) and Central Plateau (Spanish: Mesa Central), are now generally regarded by geographers as sections of one plateau.

See also

References

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    , pp. 6, 12, and 20: "The Cordillera is one of the seven geographic regions in Canada".
  4. ISBN 0717201333
    , p. 687: "[N]ame from the Spanish....It is used particularly in physical geography, although in geology also it is sometimes applied...."
  5. ^ a b Frank Press and Raymond Siever Earth, pp. 534–535, Macmillan, 1986.
  6. doi:10.1306/5d25c1b1-16c1-11d7-8645000102c1865d
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  12. ^ D. Alt and D. Hyndman. (1995). Northwest Exposures: A Geological Story of the North West. Mountain Press Publishing Company, Missoula, Montana
  13. ^ 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.
  14. ^ 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".
  15. ^ 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."
  16. ^ William Bailey et al. The surface climates of Canada, McGill–Queen's Press – MQUP, 1997, p. 226.
  17. ^
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  19. ^ a b 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).
  20. ^ Hultén, Eric. Flora of Alaska and Neighboring Territories: A Manual of the Vascular Plants, p. xiv (Stanford University Press, 1968).
  21. ^ Stefoff, Rebecca. Alaska, p. 14 (Marshall Cavendish, 2006).
  22. ^ Yukon Ranges in the Canadian Mountain Encyclopedia
  23. ^ a b c Wilson, Robert J. Geology and Economic Minerals of Canada, p. 26 (Geological Survey of Canada, Department of Energy, Mines and Resources, 1976).
  24. ^ Rogers, John. A History of the Earth, p. 281 (CUP Archive, November 18, 1993).
  25. ^ Solski, Ruth. Canadian Provinces & Territories Gr. 4-6, p. 91 (S&S Learning Materials 2003).
  26. ^ "Visiting the Hoh Rainforest". U.S. National Park Service. Retrieved January 27, 2011.
  27. ^ "SEQUIM 2 E, WASHINGTON Climate Summary". Western Regional Climate Center. Retrieved January 27, 2011.
  28. ISBN 9780520061866
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  29. ^ Parsons, M. and Quinn, O. "Insular and Coastal Mountains, Interior Mountains Archived October 10, 2012, at the Wayback Machine", 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."
  30. ^ a b S. Holland, Landforms of British Columbia Archived March 4, 2016, at the Wayback Machine, BC Govt, 1976
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  32. ^ Merrill, Tim et al. Mexico: A Country Study, p. 80 (Library of Congress, Federal Research Division, Claitors Pub Div. 2005): "The Sierra Madre Occidental on the west is a continuation of California's Sierra Nevada (with a break in southeastern California and extreme northern Mexico)…."
  33. ^ Thiem, Jon. Rabbit Creek Country: Three Ranching Lives in the Heart of the Mountain West, p. 143 (UNM Press, 2008).
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  37. ^ "Sierra Madre Oriental", Encyclopædia Britannica Online (2011).
  38. ^ Interior Plateau[permanent dead link] in the BCGNIS (British Columbia Geographic Names Information System)
  39. ^ Shuswap Highland[permanent dead link] in the BCGNIS (British Columbia Geographic Names Information System)
  40. ^ Thompson Plateau[permanent dead link] in the BCGNIS (British Columbia Geographic Names Information System)
  41. ^ Okanagan Highland[permanent dead link] in the BCGNIS (British Columbia Geographic Names Information System)
  42. ^ Rebekah K. Nix. "The Gulf of California: A Physical, Geological, and Biological Study" (PDF). University of Texas at Dallas. Retrieved April 10, 2010.
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  44. ^ Ben Floyd, et al. "Glossary Archived March 22, 2005, at the Wayback Machine". (1998) Hanford Reach Protection and Management Program Interim Action Plan Archived September 27, 2007, at the Wayback Machine. Prosser, Washington: Benton County Planning Department.
  45. ^ "Boundary Descriptions and Names of Regions, Subregions, Accounting Units and Cataloging Units". U.S. Geological Survey. Retrieved October 23, 2010.
  46. ^ "Colorado Plateau". Geographic Names Information System. United States Geological Survey.

External links

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