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North American Cordillera

North American Cordillera

Overview
The North American Cordillera is the North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

n portion of the American Cordillera
American cordillera
The American Cordillera is a cordillera that consists of an essentially continuous sequence of mountain ranges that form the western "backbone" of North America, Central America, South America and Antarctica. From north to south, this sequence of overlapping and parallel ranges begins with the...

 which is a cordillera
Cordillera
A cordillera is an extensive chain of mountains or mountain ranges, that runs along a coastline . It comes from the Spanish word cordilla, which is a diminutive of cuerda, or "cord"...

 extending up and down the western side of the Americas
Americas
The Americas, or America , are lands in the Western hemisphere, also known as the New World. In English, the plural form the Americas is often used to refer to the landmasses of North America and South America with their associated islands and regions, while the singular form America is primarily...

. The North American Cordillera covers an extensive area of mountain range
Mountain range
A mountain range is a single, large mass consisting of a succession of mountains or narrowly spaced mountain ridges, with or without peaks, closely related in position, direction, formation, and age; a component part of a mountain system or of a mountain chain...

s, intermontane
Intermontane
Intermontane is a physiographic adjective formed from the prefix "inter-" and the adjective "montane" Usage includes intermontane basin such as New Zealand's Mackenzie Basin and intermontane...

 basins, and plateau
Plateau
In geology and earth science, a plateau , also called a high plain or tableland, is an area of highland, usually consisting of relatively flat terrain. A highly eroded plateau is called a dissected plateau...

s in western North America, including much of the territory west of the Great Plains
Great Plains
The Great Plains are a broad expanse of flat land, much of it covered in prairie, steppe and grassland, which lies west of the Mississippi River and east of the Rocky Mountains in the United States and Canada. This area covers parts of the U.S...

. 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
Physical geography
Physical geography is one of the two major subfields of geography. Physical geography is that branch of natural science which deals with the study of processes and patterns in the natural environment like the atmosphere, biosphere and geosphere, as opposed to the cultural or built environment, the...

.
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Encyclopedia
The North American Cordillera is the North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

n portion of the American Cordillera
American cordillera
The American Cordillera is a cordillera that consists of an essentially continuous sequence of mountain ranges that form the western "backbone" of North America, Central America, South America and Antarctica. From north to south, this sequence of overlapping and parallel ranges begins with the...

 which is a cordillera
Cordillera
A cordillera is an extensive chain of mountains or mountain ranges, that runs along a coastline . It comes from the Spanish word cordilla, which is a diminutive of cuerda, or "cord"...

 extending up and down the western side of the Americas
Americas
The Americas, or America , are lands in the Western hemisphere, also known as the New World. In English, the plural form the Americas is often used to refer to the landmasses of North America and South America with their associated islands and regions, while the singular form America is primarily...

. The North American Cordillera covers an extensive area of mountain range
Mountain range
A mountain range is a single, large mass consisting of a succession of mountains or narrowly spaced mountain ridges, with or without peaks, closely related in position, direction, formation, and age; a component part of a mountain system or of a mountain chain...

s, intermontane
Intermontane
Intermontane is a physiographic adjective formed from the prefix "inter-" and the adjective "montane" Usage includes intermontane basin such as New Zealand's Mackenzie Basin and intermontane...

 basins, and plateau
Plateau
In geology and earth science, a plateau , also called a high plain or tableland, is an area of highland, usually consisting of relatively flat terrain. A highly eroded plateau is called a dissected plateau...

s in western North America, including much of the territory west of the Great Plains
Great Plains
The Great Plains are a broad expanse of flat land, much of it covered in prairie, steppe and grassland, which lies west of the Mississippi River and east of the Rocky Mountains in the United States and Canada. This area covers parts of the U.S...

. 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
Physical geography
Physical geography is one of the two major subfields of geography. Physical geography is that branch of natural science which deals with the study of processes and patterns in the natural environment like the atmosphere, biosphere and geosphere, as opposed to the cultural or built environment, the...

. Of all the physiographic features in North America, the North American Cordillera is among the most impressive, and the most diverse.

Major features


This cordillera extends from the U.S. state
U.S. state
A U.S. state is any one of the 50 federated states of the United States of America that share sovereignty with the federal government. Because of this shared sovereignty, an American is a citizen both of the federal entity and of his or her state of domicile. Four states use the official title of...

 of Alaska
Alaska
Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...

 to the southern border of Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

. Its mountain ranges generally run north to south along three main belts: the Pacific Coast Ranges
Pacific Coast Ranges
The Pacific Coast Ranges and the Pacific Mountain System are the series of mountain ranges that stretch along the West Coast of North America from Alaska south to Northern and Central Mexico...

 to the west, the central Nevadan belt (including the Sierra Nevada), and the Laramide belt to the east (including the Rocky Mountains
Rocky Mountains
The Rocky Mountains are a major mountain range in western North America. The Rocky Mountains stretch more than from the northernmost part of British Columbia, in western Canada, to New Mexico, in the southwestern United States...

). The North American Cordillera includes some of the highest peaks on the continent.

At its midsection between San Francisco, California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

 and Denver, Colorado
Colorado
Colorado is a U.S. state that encompasses much of the Rocky Mountains as well as the northeastern portion of the Colorado Plateau and the western edge of the Great Plains...

, this cordillera is about 1000 miles (1,609.3 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
Basin and Range
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...

 province (forming many narrow ranges and valleys), the Colorado Plateau
Colorado Plateau
The Colorado Plateau, also called the Colorado Plateau Province, is a physiographic region of the Intermontane Plateaus, roughly centered on the Four Corners region of the southwestern United States. The province covers an area of 337,000 km2 within western Colorado, northwestern New Mexico,...

, and the Rocky Mountains. In the United States, another major feature of the Cordillera is the Columbia Plateau
Columbia Plateau
The Columbia Plateau is a geologic and geographic region that lies across parts of the U.S. states of Washington, Oregon, and Idaho. It is a wide flood basalt plateau between the Cascade Range and the Rocky Mountains, cut through by the Columbia River...

, located north of California between the Cascade Range
Cascade Range
The Cascade Range is a major mountain range of western North America, extending from southern British Columbia through Washington and Oregon to Northern California. It includes both non-volcanic mountains, such as the North Cascades, and the notable volcanoes known as the High Cascades...

 — which is a northern extension of the Sierra Nevada — and the Rocky Mountains.

The Canadian portion of the cordillera likewise includes three primary mountain ranges. They are the Coast Mountains
Coast Mountains
The Coast Mountains are a major mountain range, in the Pacific Coast Ranges, of western North America, extending from southwestern Yukon through the Alaska Panhandle and virtually all of the Coast of British Columbia. They are so-named because of their proximity to the sea coast, and are often...

 in the west, the Columbia Mountains
Columbia Mountains
The Columbia Mountains are a group of mountain ranges located in southeastern British Columbia, and partially in Montana, Idaho and Washington. The mountain range covers 135,952 km² . The range is bounded by the Rocky Mountain Trench on the east, and the Kootenay River on the south; their...

 in the middle, and the Canadian Rockies
Canadian Rockies
The Canadian Rockies comprise the Canadian segment of the North American Rocky Mountains range. They are the eastern part of the Canadian Cordillera, extending from the Interior Plains of Alberta to the Rocky Mountain Trench of British Columbia. The southern end borders Idaho and Montana of the USA...

 in the east.

In Mexico, the Sierra Madre Occidental
Sierra Madre Occidental
The Sierra Madre Occidental is a mountain range in western Mexico.-Setting:The range runs north to south, from just south of the Sonora–Arizona border southeast through eastern Sonora, western Chihuahua, Sinaloa, Durango, Zacatecas, Nayarit, Jalisco, Aguascalientes to Guanajuato, where it joins...

, and the Sierra Madre Oriental
Sierra Madre Oriental
The Sierra Madre Oriental is a mountain range in northeastern Mexico.-Setting:Spanning the Sierra Madre Oriental runs from Coahuila south through Nuevo León, southwest Tamaulipas, San Luis Potosí, Querétaro, and Hidalgo to northern Puebla, where it joins with the east-west running Eje Volcánico...

 to the east, surround the Mexican Plateau
Mexican Plateau
The Central Mexican Plateau, also known as the Mexican Altiplano or Altiplanicie Mexicana, is a large arid-to-semiarid plateau that occupies much of northern and central Mexico...

. To the west, the Peninsular Ranges
Peninsular Ranges
The Peninsular Ranges are a group of mountain ranges, in the Pacific Coast Ranges, which stretch from southern California in the United States to the southern tip of Mexico's Baja California peninsula; they are part of the North American Coast Ranges that run along the Pacific coast from Alaska...

 border the Pacific Ocean, and the Sierra Madre del Sur
Sierra Madre del Sur
The Sierra Madre del Sur is a mountain range in southern Mexico, extending from southern Michoacán east through Guerrero, to the Istmo de Tehuantepec in eastern Oaxaca.-Geography:...

 is the southern extension of the Peninsular Ranges.

Geologic origin


The historical geomorphology
Geomorphology
Geomorphology is the scientific study of landforms and the processes that shape them...

 and orogenic
Orogeny
Orogeny refers to forces and events leading to a severe structural deformation of the Earth's crust due to the engagement of tectonic plates. Response to such engagement results in the formation of long tracts of highly deformed rock called orogens or orogenic belts...

 development of the North American Cordillera is dynamic and controversial, but the paleoenvironmental details provide context on the geography (physical geography
Physical geography
Physical geography is one of the two major subfields of geography. Physical geography is that branch of natural science which deals with the study of processes and patterns in the natural environment like the atmosphere, biosphere and geosphere, as opposed to the cultural or built environment, the...

, human geography
Human geography
Human geography is one of the two major sub-fields of the discipline of geography. Human geography is the study of the world, its people, communities, and cultures. Human geography differs from physical geography mainly in that it has a greater focus on studying human activities and is more...

, and biogeography
Biogeography
Biogeography is the study of the distribution of species , organisms, and ecosystems in space and through geological time. Organisms and biological communities vary in a highly regular fashion along geographic gradients of latitude, elevation, isolation and habitat area...

) and how it evolved to its modern state. For example, the Laramide orogeny
Laramide orogeny
The Laramide orogeny was a period of mountain building in western North America, which started in the Late Cretaceous, 70 to 80 million years ago, and ended 35 to 55 million years ago. The exact duration and ages of beginning and end of the orogeny are in dispute, as is the cause. The Laramide...

 changed the topography
Topography
Topography is the study of Earth's surface shape and features or those ofplanets, moons, and asteroids...

 of the central Rocky Mountains and adjoining Laramide regions (from central Montana to central New Mexico) during the Late Cretaceous
Late Cretaceous
The Late Cretaceous is the younger of two epochs into which the Cretaceous period is divided in the geologic timescale. Rock strata from this epoch form the Upper Cretaceous series...

 80 million years ago. Prior to this time the Rocky Mountain region was occupied by a broad foreland basin. Topographic relief continued to evolve with much activity occurring in the middle Eocene
Eocene
The Eocene Epoch, lasting from about 56 to 34 million years ago , is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era. The Eocene spans the time from the end of the Palaeocene Epoch to the beginning of the Oligocene Epoch. The start of the...

 (50-55 million years ago), but since this time the deformation of the region has been relatively stable. High altitude formations were common during the Eocene and Oligocene
Oligocene
The Oligocene is a geologic epoch of the Paleogene Period and extends from about 34 million to 23 million years before the present . As with other older geologic periods, the rock beds that define the period are well identified but the exact dates of the start and end of the period are slightly...

. Orogenic activity is recorded in the Pacific Coastal Mountains (Cascade and Sierra) during the Oligocene, but major uplift did not occur in this area until after the Miocene
Miocene
The Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...

. The coastal and interior mountains were higher during the Eocene than at present.

Pacific Coast Ranges


The Pacific Coast Ranges from southeastern Alaska and southern Yukon parallel the coast 150 to 200 mi (241.4 to 321.9 km) inland and comprise several mountain systems, from north to south the Saint Elias Mountains
Saint Elias Mountains
The Saint Elias Mountains are a subgroup of the Pacific Coast Ranges, located in southeastern Alaska in the United States, southwestern Yukon and the very far northwestern part of British Columbia in Canada. The range spans Wrangell-St. Elias National Park and Preserve in the USA and Kluane...

, Coast Mountains
Coast Mountains
The Coast Mountains are a major mountain range, in the Pacific Coast Ranges, of western North America, extending from southwestern Yukon through the Alaska Panhandle and virtually all of the Coast of British Columbia. They are so-named because of their proximity to the sea coast, and are often...

, the Insular Mountains
Insular Mountains
The Insular Mountains are a range of mountains in the Pacific Coast Ranges on the coast of British Columbia, Canada, comprising the Vancouver Island Ranges and Queen Charlotte Mountains. The Insular Mountains are rugged, particularly on Vancouver Island where peaks in Strathcona Provincial Park...

, the Olympic Mountains
Olympic Mountains
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...

, the Oregon
Oregon Coast Range
The Oregon Coast Range, often called simply the Coast Range and sometimes the Pacific Coast Range, is a mountain range, in the Pacific Coast Ranges physiographic region, in the U.S. state of Oregon along the Pacific Ocean...

 and California Coast Ranges, and the Sierra Nevada. The Cascade Range
Cascade Range
The Cascade Range is a major mountain range of western North America, extending from southern British Columbia through Washington and Oregon to Northern California. It includes both non-volcanic mountains, such as the North Cascades, and the notable volcanoes known as the High Cascades...

 (called the Cascade Mountains in Canada) is a northern extension of the Sierra Nevada, and the United States Geological Survey
United States Geological Survey
The United States Geological Survey is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, and the natural hazards that threaten it. The organization has four major science disciplines, concerning biology,...

 excludes both the Sierra Nevada and Cascade Ranges from the Coast Ranges.

Southern Alaska ranges



Coast Mountains



The Coast Mountains run from the lower Fraser River
Fraser River
The Fraser River is the longest river within British Columbia, Canada, rising at Fraser Pass near Mount Robson in the Rocky Mountains and flowing for , into the Strait of Georgia at the city of Vancouver. It is the tenth longest river in Canada...

 and the Fraser Canyon
Fraser Canyon
The Fraser Canyon is an 84 km landform of the Fraser River where it descends rapidly through narrow rock gorges in the Coast Mountains en route from the Interior Plateau of British Columbia to the Fraser Valley...

 northwestward, separating the Interior Plateau
Interior Plateau
The Interior Plateau comprises a large region of central British Columbia, and lies between the Cariboo and Monashee Mountains on the east, and the Hazelton Mountains, Coast Mountains and Cascade Range on the west. The continuation of the plateau into the United States is known there as the...

 from the Pacific Ocean. Their coastal flank is characterized by an intense network of fjords and associated islands, very similar to the Norwegian coastline
Norway
Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...

, while their inland side against the plateau they transition 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
Pacific Ranges
The Pacific Ranges are the southernmost subdivision of the Coast Mountains portion of the Pacific Cordillera. Located entirely within British Columbia, Canada, they run northwest from the lower stretches of the Fraser River to Bella Coola, north of which are the Kitimat Ranges.The Pacific Ranges...

 between the Fraser and Bella Coola
Bella Coola, British Columbia
Bella Coola is a community of approximately 600 at the western extremity of the Bella Coola Valley. Bella Coola usually refers to the entire valley, encompassing the settlements of Bella Coola proper , Lower Bella Coola, Hagensborg, Saloompt, Nusatsum, Firvale and Stuie...

, the Kitimat Ranges
Kitimat Ranges
The Kitimat Ranges are one of the three main subdivisions of the Coast Mountains in British Columbia, Canada, the other being the Pacific Ranges to the south and the Boundary Ranges to the north...

 from there northwards to the Nass River
Nass River
The Nass River is a river in northern British Columbia, Canada. It flows from the Coast Mountains southwest to Nass Bay, a sidewater of Portland Inlet, which connects to the North Pacific Ocean via the Dixon Entrance...

 and the Boundary Ranges
Boundary Ranges
The Boundary Ranges, also known in the singular and as the Alaska Boundary Range, are the largest and most northerly subrange of the Coast Mountains...

 from there to their terminus in the Yukon
Yukon
Yukon is the westernmost and smallest of Canada's three federal territories. It was named after the Yukon River. The word Yukon means "Great River" in Gwich’in....

 Territory at Champagne Pass
Champagne, Yukon
Champagne Landing is a small Indian settlement on the Alaska Highway in Canada's Yukon. The few residents are citizens of the Champagne and Aishihik First Nations. The resident population was 24 in the Canada 2006 Census.Champagne is on the Dezadeash River, one of the tributaries of the Alsek...

 and Chilkat Pass
Chilkat Pass
The Chilkat Pass is a mountain pass on the border of Alaska, United States, and the province of British Columbia, Canada, at the divide between the Klehini and Kelsall Rivers just northwest of Haines, Alaska. It is used by the Haines Highway and was the route used by the Dalton Trail during the...

 northwest of Haines, Alaska
Haines, Alaska
Haines is a census-designated place in Haines Borough, Alaska, United States. As of the 2000 census, the population of the area was 1,811. Haines was formerly a city but no longer has a municipal government...

. The Saint Elias Mountains
Saint Elias Mountains
The Saint Elias Mountains are a subgroup of the Pacific Coast Ranges, located in southeastern Alaska in the United States, southwestern Yukon and the very far northwestern part of British Columbia in Canada. The range spans Wrangell-St. Elias National Park and Preserve in the USA and Kluane...

 lie to their west and northwest, while the Yukon Ranges
Yukon Ranges
The Yukon Ranges are a mountain range comprising the mountains in the southeastern part of the U.S. state of Alaska and most of the Yukon, Canada...

 and Yukon Basin lie to their north. On the inland side of the Boundary Ranges are the Tahltan
Tahltan Highland
The Tahltan Highland is an upland area of plateau and relatively lower mountain ranges in British Columbia, Canada, lying east of the Boundary Ranges and south of the Inklin River...

 and Tagish Highland
Tagish Highland
The Tagish Highland is an upland area on the inland side of the northernmost Boundary Ranges of the Coast Mountains, spanning far northwestern British Columbia from Atlin Lake to the area of the pass at Champagne, Yukon between the Alsek and Yukon Rivers...

s and also the Skeena Mountains
Skeena Mountains
The Skeena Mountains, also known as the Skeenas, are a subrange of the Interior Mountains of northern British Columbia, Canada, essentially flanking the upper basin of the Skeena River. They lie just inland from the southern end of the Boundary Ranges of the Coast Mountains, and also of the...

, part of the Interior Mountains
Interior Mountains
The Interior Mountains, also called the Northern Interior Mountains and Interior Ranges, are the semi-official names for a huge area that comprises much of the northern two thirds of the Canadian province of British Columbia and a large area of southern Yukon...

 system, which also extend southwards on the inland side of the Kitimat Ranges
Kitimat Ranges
The Kitimat Ranges are one of the three main subdivisions of the Coast Mountains in British Columbia, Canada, the other being the Pacific Ranges to the south and the Boundary Ranges to the north...

.

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
Mount Waddington
Mount Waddington, once known as Mystery Mountain, is the highest peak in the Coast Mountains of British Columbia, Canada. Although Mount Fairweather and Mount Quincy Adams, which straddle the US border between Alaska and British Columbia are taller, Mount Waddington is the highest peak that lies...

, while the Boundary Ranges contain the largest icefields, the Juneau Icefield
Juneau Icefield
The Juneau Icefield is an ice field located just north of Juneau, Alaska and continues north through the border with British Columbia and is the fifth-largest ice field in the Western Hemisphere, extending through an area of in the Coast Range ranging north to south and east to west. The...

 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
Igneous rock
Igneous rock is one of the three main rock types, the others being sedimentary and metamorphic rock. Igneous rock is formed through the cooling and solidification of magma or lava...

 and metamorphic rock
Metamorphic rock
Metamorphic rock is the transformation of an existing rock type, the protolith, in a process called metamorphism, which means "change in form". The protolith is subjected to heat and pressure causing profound physical and/or chemical change...

 from an episode of arc volcanism
Volcanic arc
A volcanic arc is a chain of volcanoes positioned in an arc shape as seen from above. Offshore volcanoes form islands, resulting in a volcanic island arc. Generally they result from the subduction of an oceanic tectonic plate under another tectonic plate, and often parallel an oceanic trench...

 related to subduction
Subduction
In geology, subduction is the process that takes place at convergent boundaries by which one tectonic plate moves under another tectonic plate, sinking into the Earth's mantle, as the plates converge. These 3D regions of mantle downwellings are known as "Subduction Zones"...

 of the Kula
Kula Plate
The Kula Plate is an oceanic tectonic plate under the northern Pacific Ocean south of the Near Islands segment of the Aleutian Islands. It is subducting under the North American Plate at the Aleutian Trench and is surrounded by the Pacific Plate...

 and Farallon Plate
Farallon Plate
The Farallon Plate was an ancient oceanic plate, which began subducting under the west coast of the North American Plate— then located in modern Utah— as Pangaea broke apart during the Jurassic Period...

s during the Laramide orogeny
Laramide orogeny
The Laramide orogeny was a period of mountain building in western North America, which started in the Late Cretaceous, 70 to 80 million years ago, and ended 35 to 55 million years ago. The exact duration and ages of beginning and end of the orogeny are in dispute, as is the cause. The Laramide...

 about 100 million years ago. The widespread granite
Granite
Granite is a common and widely occurring type of intrusive, felsic, igneous rock. Granite usually has a medium- to coarse-grained texture. Occasionally some individual crystals are larger than the groundmass, in which case the texture is known as porphyritic. A granitic rock with a porphyritic...

 forming the Coast Mountains formed when magma intruded and cooled at depth beneath volcanoes of the Coast Range Arc
Coast Range Arc
The Coast Range Arc was a large volcanic arc system, extending from northern Washington through British Columbia and the Alaska Panhandle to southwestern Yukon. The Coast Range Arc lies along the western margin of the North American Plate in the Pacific Northwest of western North America...

 whereas the metamorphic formed when intruding magma heated the surrounding rock to produce schist
Schist
The schists constitute a group of medium-grade metamorphic rocks, chiefly notable for the preponderance of lamellar minerals such as micas, chlorite, talc, hornblende, graphite, and others. Quartz often occurs in drawn-out grains to such an extent that a particular form called quartz schist is...

.

Insular Mountains



The Insular Mountains extend from Vancouver Island
Vancouver Island
Vancouver Island is a large island in British Columbia, Canada. It is one of several North American locations named after George Vancouver, the British Royal Navy officer who explored the Pacific Northwest coast of North America between 1791 and 1794...

 in the south to the Queen Charlotte Islands
Queen Charlotte Islands
Haida Gwaii , formerly the Queen Charlotte Islands, is an archipelago on the North Coast of British Columbia, Canada. Haida Gwaii consists of two main islands: Graham Island in the north, and Moresby Island in the south, along with approximately 150 smaller islands with a total landmass of...

 in the north on the British Columbia Coast
British Columbia Coast
The British Columbia Coast or BC Coast is Canada's western continental coastline on the Pacific Ocean. The usage is synonymous with the term West Coast of Canada....

. It contains two main mountain ranges, the Vancouver Island Ranges
Vancouver Island Ranges
The Vancouver Island Ranges, formerly called the Vancouver Island Mountains, is a mountain range extending along the length of Vancouver Island which has an area of 31,788 km² . The Vancouver Island Ranges comprise the central and largest part of the island...

 on Vancouver Island and the Queen Charlotte Mountains
Queen Charlotte Mountains
The Queen Charlotte Mountains are a mountain range comprising all mountains and small mountain ranges of Haida Gwaii , British Columbia, Canada. It is the northernmost subrange of the Insular Mountains...

 on the Queen Charlotte Islands.

Oregon Coast Range



The Oregon Coast Range is the part of the Coast Range system that is denoted as between the mouth of the Columbia River
Columbia River
The Columbia River is the largest river in the Pacific Northwest region of North America. The river rises in the Rocky Mountains of British Columbia, Canada, flows northwest and then south into the U.S. state of Washington, then turns west to form most of the border between Washington and the state...

 and the Middle Fork Coquille River
Coquille River
The Coquille River is a stream long, in southwestern Oregon in the United States. It drains a mountainous area of of the Southern Oregon Coast Range into the Pacific Ocean. Its watershed is located between that of the Coos River to the north and the Rogue River to the south.-Geography:The river,...

. It is about 200 miles (321.9 km) long. The highest peak is Marys Peak
Marys Peak
Marys Peak is a mountain in Benton County, Oregon, United States, just southwest of Philomath. It is the highest peak in the Oregon Coast Range...

, at 4,101 ft/1,249m.

Sierra Madre del Sur



These mountains in southwestern Mexico form a southern extension of the Peninsular Ranges of Baja, California.

Northern Interior Mountains


The Northern Interior Mountains in Canada are a northern extension of the Columbia Mountains.

Columbia Mountains



The Columbia Mountains are a designation in British Columbia for a group of four ranges lying between the Rocky Mountain Trench
Rocky Mountain Trench
The Rocky Mountain Trench, or the Trench or The Valley of a Thousand Peaks, is a large valley in the northern part of the Rocky Mountains. It is both visually and cartographically a striking physiographic feature extending approximately from Flathead Lake, Montana, to the Liard River, just south...

 and the Interior Plateau
Interior Plateau
The Interior Plateau comprises a large region of central British Columbia, and lies between the Cariboo and Monashee Mountains on the east, and the Hazelton Mountains, Coast Mountains and Cascade Range on the west. The continuation of the plateau into the United States is known there as the...

. These are the Cariboo Mountains
Cariboo Mountains
The Cariboo Mountains are the northernmost subrange of the Columbia Mountains, which run down into the Spokane, Washington area of the United States and include the Selkirks, Monashees and Purcells. The Cariboo Mountains are entirely within the province of British Columbia, Canada. The range is...

, which are the northernmost and sometimes considered to be part of the Interior Plateau, the Selkirk Mountains
Selkirk Mountains
The Selkirk Mountains are a mountain range spanning the northern portion of the Idaho Panhandle, eastern Washington, and southeastern British Columbia. They begin at Mica Peak near Coeur d'Alene, Idaho and extend approximately 320 km north from the border. The range is bounded on its west,...

, the Purcell Mountains
Purcell Mountains
The Purcell Mountains are a mountain range in southeastern British Columbia, Canada. They are a subrange of the Columbia Mountains, which includes the Selkirk, Monashee, and Cariboo Mountains. They are located on the west side of the Rocky Mountain Trench in the area of the Columbia Valley, and on...

, and the Monashee Mountains
Monashee Mountains
The Monashee Mountains are a mountain range mostly in British Columbia, Canada, extending into the U.S. state of Washington. They stretch from north to south and from east to west. They are a subrange of the Columbia Mountains...

.

The Columbia Mountains are classified as being in Canada's interior system, rather than its eastern system. 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.

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 Big Bend
Big Bend Country
Big Bend Country is a term used in the Canadian province of British Columbia to refer to the region around the northernmost bend of the Columbia River, where the river leaves its initial northwestward course along the Rocky Mountain Trench to curve around the northern end of the Selkirk Mountains...

 and are flanked on the west by the basin of the Thompson
Thompson River
The Thompson River is the largest tributary of the Fraser River, flowing through the south-central portion of British Columbia, Canada. The Thompson River has two main branches called the South Thompson and the North Thompson...

 and Okanagan Rivers. There are many named subranges of all four subgroupings, particularly in the Selkirks and Monashees. The southward extension of the Selkirks, Purcells and Monashees into the United States are reckoned to be part of the Rocky Mountains
Rocky Mountains
The Rocky Mountains are a major mountain range in western North America. The Rocky Mountains stretch more than from the northernmost part of British Columbia, in western Canada, to New Mexico, in the southwestern United States...

 and the designation Columbia Mountains is not used there (the Purcells, also, go by the name "Percell Mountains" in the United States). The Salish
Salish Mountains
The Salish Mountains are located in the northwest corner of the U.S. State of Montana....

 and Cabinet Mountains
Cabinet Mountains
The Cabinet Mountains are part of the Rocky Mountains, located in northwest Montana and the Idaho panhandle, in the United States. The mountains cover an area of 2,134 square miles...

 south of the 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
Fraser River
The Fraser River is the longest river within British Columbia, Canada, rising at Fraser Pass near Mount Robson in the Rocky Mountains and flowing for , into the Strait of Georgia at the city of Vancouver. It is the tenth longest river in Canada...

 and Thompson River
Thompson River
The Thompson River is the largest tributary of the Fraser River, flowing through the south-central portion of British Columbia, Canada. The Thompson River has two main branches called the South Thompson and the North Thompson...

s. These - the Quesnel
Quesnel Highland
The Quesnel Highland is a geographic area in the Central Interior of the Canadian province of British Columbia. As defined by BC government geographer in Landforms of British Columbia, an account and analysis of British Columbia geography that is often cited as authoritative...

, Shuswap
Shuswap Highland
The Shuswap Highland is a plateau-like hilly area of in British Columbia, Canada. It spans the upland area between the Bonaparte and Thompson Plateaus from the area of Mahood Lake, at the southeast corner of the Cariboo Plateau, southeast towards the lower Shuswap River east of Vernon in the...

 and Okanagan Highland
Okanagan Highland
The Okanagan Highland is a plateau-like hilly area in British Columbia, Canada, and the U.S. state of Washington . It lies between the Okanagan Valley on its west and the Kettle River on its east, and geologically is more or less an extension of the Thompson Plateau, which lies west of the Okanagan...

s, 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
Interior Plateau
The Interior Plateau comprises a large region of central British Columbia, and lies between the Cariboo and Monashee Mountains on the east, and the Hazelton Mountains, Coast Mountains and Cascade Range on the west. The continuation of the plateau into the United States is known there as the...

. The southernmost extends into the Washington, where it is named by the American spelling Okanogan Highland (and was the first-named of these groupings).

Cascade Range



The Cascade Range
Cascade Range
The Cascade Range is a major mountain range of western North America, extending from southern British Columbia through Washington and Oregon to Northern California. It includes both non-volcanic mountains, such as the North Cascades, and the notable volcanoes known as the High Cascades...

 (called the Cascade Mountains in Canada) is distinct from the Coast Ranges. The Cascade Range extends from Northern California
Northern California
Northern California is the northern portion of the U.S. state of California. The San Francisco Bay Area , and Sacramento as well as its metropolitan area are the main population centers...

, United States to southern British Columbia
British Columbia
British Columbia is the westernmost of Canada's provinces and is known for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . Its name was chosen by Queen Victoria in 1858...

, Canada. It consists of non-volcanic and volcanic
Volcano
2. Bedrock3. Conduit 4. Base5. Sill6. Dike7. Layers of ash emitted by the volcano8. Flank| 9. Layers of lava emitted by the volcano10. Throat11. Parasitic cone12. Lava flow13. Vent14. Crater15...

  mountains: all of the known historic eruptions in the contiguous United States have been from the volcanoes of the Cascade Volcanic Arc
Cascade Volcanoes
The Cascade Volcanoes are a number of volcanoes in a volcanic arc in western North America, extending from southwestern British Columbia through Washington and Oregon to Northern California, a distance of well over 700 mi ...

. The highest peak in the Cascade Range is Mount Rainier
Mount Rainier
Mount Rainier is a massive stratovolcano located southeast of Seattle in the state of Washington, United States. It is the most topographically prominent mountain in the contiguous United States and the Cascade Volcanic Arc, with a summit elevation of . Mt. Rainier is considered one of the most...

 (4392 metres (14,409 ft), a stratovolcano
Stratovolcano
A stratovolcano, also known as a composite volcano, is a tall, conical volcano built up by many layers of hardened lava, tephra, pumice, and volcanic ash. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile and periodic, explosive eruptions...

. The small portion of the Cascade Range in Canada is called the Cascade Mountains or Canadian Cascades, and in its southwestern area is similar in terrain to the area north of Glacier Peak
Glacier Peak
Glacier Peak is the most isolated of the five major stratovolcanoes of the Cascade Volcanic Arc in Washington...

, known as the North Cascades
North Cascades
The North Cascades are a section of the Cascade Range of western North America. They span the border between the Canadian province of British Columbia and the U.S. state of Washington and are officially named in Canada as the Cascade Mountains...

, and its northern and eastern extremities verge on the Thompson Plateau
Thompson Plateau
The Thompson Plateau, also known as the Okanagan-Thompson Plateau, forms the southern portion of the Interior Plateau of British Columbia, Canada, lying to the west of Okanagan Lake, south of the Thompson River and to the east of the Fraser River...

 in a less rugged fashion than in most other parts of the range. The North Cascades are very different in character from the series of high volcanic stratovolcanoes from Rainier southwards to Mounts Shasta
Mount Shasta
Mount Shasta is located at the southern end of the Cascade Range in Siskiyou County, California and at is the second highest peak in the Cascades and the fifth highest in California...

 and Lassen, and is more severely alpine and steeply rugged, particularly the Hozomeen Range. Inland portions of the range are dryland and plateau-like in character, e.g. the Okanagan Range
Okanagan Range
The Okanagan Range or Okanogan Range is a small subrange of the Cascade Range straddling the border between British Columbia and Washington south of the Similkameen River on the inland side of the range...

, which lies along the Cascades' northeastern margin, separated by the Similkameen River
Similkameen River
The Similkameen River runs through southern British Columbia, eventually discharging into the Okanogan River near Oroville, Washington in the United States. The river is approximately long, and its drainage basin is in area...

.

Sierra Nevada



The Sierra Nevada form an inland mountain spine of California running south from the area of the terminus of the Cascade Range
Cascade Range
The Cascade Range is a major mountain range of western North America, extending from southern British Columbia through Washington and Oregon to Northern California. It includes both non-volcanic mountains, such as the North Cascades, and the notable volcanoes known as the High Cascades...

 near Mount Lassen along the east flank of the Central Valley of California to the Mojave Desert
Mojave Desert
The Mojave Desert occupies a significant portion of southeastern California and smaller parts of central California, southern Nevada, southwestern Utah and northwestern Arizona, in the United States...

, forming a mountain region of complex terrain and varied geology which separates the Central Valley from the Great Basin
Great Basin
The Great Basin is the largest area of contiguous endorheic watersheds in North America and is noted for its arid conditions and Basin and Range topography that varies from the North American low point at Badwater Basin to the highest point of the contiguous United States, less than away at the...

 which lies inland to the east. The height of the mountains in the Sierra Nevada gradually increases from north to south, culminating at Mount Whitney
Mount Whitney
Mount Whitney is the highest summit in the contiguous United States with an elevation of . It is on the boundary between California's Inyo and Tulare counties, west-northwest of the lowest point in North America at Badwater in Death Valley National Park...

 (4421 metres (14,505 ft)), the highest point in the Continental United States. From east to west, the Sierra are shaped like a trapdoor: the west slope gradually rises, and the east slope forms a steep escarpment
Escarpment
An escarpment is a steep slope or long cliff that occurs from erosion or faulting and separates two relatively level areas of differing elevations.-Description and variants:...

.

The northern Sierra are predominately volcanic rock, while the southern Sierra are granite (formed deep underground in the Jurassic
Jurassic
The Jurassic is a geologic period and system that extends from about Mya to  Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the age of reptiles. The start of the period is marked by...

 period), and then subsequently sculpted by glaciers into dramatic U-shaped valleys and aretes.

Sierra Madre Occidental



These mountains may be considered a southern extension of the Sierra Nevada.

Laramide belt


The Laramide belt is at the opposite side of the North American Cordillera from the Pacific Coast Ranges.

Brooks Range




The Brooks Range are the northernmost of the major mountain systems of the North American Cordillera, and extend along an east-west axis across northern Alaska
Alaska
Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...

 from near the northern opening of the Bering Strait
Bering Strait
The Bering Strait , known to natives as Imakpik, is a sea strait between Cape Dezhnev, Chukotka Autonomous Okrug, Russia, the easternmost point of the Asian continent and Cape Prince of Wales, Alaska, USA, the westernmost point of the North American continent, with latitude of about 65°40'N,...

 to the northern Yukon
Yukon
Yukon is the westernmost and smallest of Canada's three federal territories. It was named after the Yukon River. The word Yukon means "Great River" in Gwich’in....

 Territory. Major subranges include the British Mountains and Richardson Mountains
Richardson Mountains
The Richardson Mountains are a mountain range located west of the mouth of the Mackenzie River in northern Yukon, Canada. They parallel the northernmost part of the boundary of the Yukon and Northwest Territories....

, 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
Yukon River
The Yukon River is a major watercourse of northwestern North America. The source of the river is located in British Columbia, Canada. The next portion lies in, and gives its name to Yukon Territory. The lower half of the river lies in the U.S. state of Alaska. The river is long and empties into...

 basin, separating it from Alaska's North Slope
Alaska North Slope
The Alaska North Slope is the region of the U.S. state of Alaska located on the northern slope of the Brooks Range along the coast of two marginal seas of the Arctic Ocean, the Chukchi Sea being on the western side of Point Barrow, and the Beaufort Sea on the eastern.The region contains the...

 region, facing the beaufort Sea
Beaufort Sea
The Beaufort Sea is a marginal sea of the Arctic Ocean, located north of the Northwest Territories, the Yukon, and Alaska, west of Canada's Arctic islands. The sea is named after hydrographer Sir Francis Beaufort...

. The Brooks Range is considered part of (or an extension of) the Rockies
Rocky Mountains
The Rocky Mountains are a major mountain range in western North America. The Rocky Mountains stretch more than from the northernmost part of British Columbia, in western Canada, to New Mexico, in the southwestern United States...

.

Rocky Mountains in United States mainland



The range's highest peak is Mount Elbert
Mount Elbert
Mount Elbert is the highest peak in the Rocky Mountains of North America, at , the highest of the fourteeners in Colorado, and the high point of the Sawatch Range. It is located in Lake County, approximately southwest of Leadville...

 in Colorado
Colorado
Colorado is a U.S. state that encompasses much of the Rocky Mountains as well as the northeastern portion of the Colorado Plateau and the western edge of the Great Plains...

 at 4401 metres (14,439 ft) above sea level. The American Rockies rise steeply over the Interior Plains
Interior Plains
The Interior Plains is a vast physiographic region that spreads across the Laurentian craton of central North America.-Geography:The Interior Plains are an extensive physiographic division encompassing 8 distinct physiographic provinces, the Interior Low Plateaus, Great Plains, Central Lowland,...

 to the east, and over the Great Basin
Great Basin
The Great Basin is the largest area of contiguous endorheic watersheds in North America and is noted for its arid conditions and Basin and Range topography that varies from the North American low point at Badwater Basin to the highest point of the contiguous United States, less than away at the...

 to the west, and extend south to the Rio Grande
Rio Grande
The Rio Grande is a river that flows from southwestern Colorado in the United States to the Gulf of Mexico. Along the way it forms part of the Mexico – United States border. Its length varies as its course changes...

 in New Mexico. Other mountain ranges continue as far north as the Selwyn Range
Selwyn Range (Canada)
The Selwyn Range is a mountain range in the Canadian Rockies in British Columbia. A subrange of the Park Ranges of the Continental Ranges, it is located west of Jasper National Park, east of Valemount and south of Mount Robson Provincial Park....

 in Yukon
Yukon
Yukon is the westernmost and smallest of Canada's three federal territories. It was named after the Yukon River. The word Yukon means "Great River" in Gwich’in....

 and the Brooks Range
Brooks Range
The Brooks Range is a mountain range in far northern North America. It stretches from west to east across northern Alaska and into Canada's Yukon Territory, a total distance of about 1100 km . The mountains top out at over 2,700 m . The range is believed to be approximately 126 million years old...

 in Alaska
Alaska
Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...

, and likewise the Sierra Madre
Sierra Madre Occidental
The Sierra Madre Occidental is a mountain range in western Mexico.-Setting:The range runs north to south, from just south of the Sonora–Arizona border southeast through eastern Sonora, western Chihuahua, Sinaloa, Durango, Zacatecas, Nayarit, Jalisco, Aguascalientes to Guanajuato, where it joins...

 in Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

 extends south, but none of those mountains are considered part of the American Rockies. The United States definition of the Rockies includes the Cabinet
Cabinet Mountains
The Cabinet Mountains are part of the Rocky Mountains, located in northwest Montana and the Idaho panhandle, in the United States. The mountains cover an area of 2,134 square miles...

 and Salish Mountains
Salish Mountains
The Salish Mountains are located in the northwest corner of the U.S. State of Montana....

 of Idaho and Montana, whereas their counterparts north of the Kootenai River, the Columbia Mountains
Columbia Mountains
The Columbia Mountains are a group of mountain ranges located in southeastern British Columbia, and partially in Montana, Idaho and Washington. The mountain range covers 135,952 km² . The range is bounded by the Rocky Mountain Trench on the east, and the Kootenay River on the south; their...

, are sometimes considered a separate system lying to the west of the huge Rocky Mountain Trench
Rocky Mountain Trench
The Rocky Mountain Trench, or the Trench or The Valley of a Thousand Peaks, is a large valley in the northern part of the Rocky Mountains. It is both visually and cartographically a striking physiographic feature extending approximately from Flathead Lake, Montana, to the Liard River, just south...

 which runs the length of British Columbia.

Sierra Madre Oriental



These mountains in eastern Mexico are often considered a southern extension of the Rocky Mountains
Rocky Mountains
The Rocky Mountains are a major mountain range in western North America. The Rocky Mountains stretch more than from the northernmost part of British Columbia, in western Canada, to New Mexico, in the southwestern United States...

.

Intermontane areas


Interior Plateau


The Interior Plateau is the northern continuation of the Columbia Plateau
Columbia Plateau
The Columbia Plateau is a geologic and geographic region that lies across parts of the U.S. states of Washington, Oregon, and Idaho. It is a wide flood basalt plateau between the Cascade Range and the Rocky Mountains, cut through by the Columbia River...

, covering much of inland British Columbia
British Columbia
British Columbia is the westernmost of Canada's provinces and is known for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . Its name was chosen by Queen Victoria in 1858...

. The Cariboo Mountains
Cariboo Mountains
The Cariboo Mountains are the northernmost subrange of the Columbia Mountains, which run down into the Spokane, Washington area of the United States and include the Selkirks, Monashees and Purcells. The Cariboo Mountains are entirely within the province of British Columbia, Canada. The range is...

 and Monashee Mountains
Monashee Mountains
The Monashee Mountains are a mountain range mostly in British Columbia, Canada, extending into the U.S. state of Washington. They stretch from north to south and from east to west. They are a subrange of the Columbia Mountains...

 lie to the east, the Canadian Cascades are to the southwest, and the Hazelton Mountains
Hazelton Mountains
The Hazelton Mountains are a grouping of mountain ranges on the inland lee of the Kitimat Ranges of the Coast Mountains in northwestern British Columbia, Canada, spanning the area of Hazelton, British Columbia south to the Nechako Reservoir...

 and Coast Range
Coast Mountains
The Coast Mountains are a major mountain range, in the Pacific Coast Ranges, of western North America, extending from southwestern Yukon through the Alaska Panhandle and virtually all of the Coast of British Columbia. They are so-named because of their proximity to the sea coast, and are often...

 to the west and northwest.

Shuswap Highland


The Shuswap Highland consists of a portion of the foothills between the Thompson Plateau
Thompson Plateau
The Thompson Plateau, also known as the Okanagan-Thompson Plateau, forms the southern portion of the Interior Plateau of British Columbia, Canada, lying to the west of Okanagan Lake, south of the Thompson River and to the east of the Fraser River...

 and Bonaparte Plateau
Bonaparte Plateau
The Bonaparte Plateau, in British Columbia, Canada, is a subarea of the larger Cariboo Plateau which extends to the Quesnel River and lies between the Cariboo Mountains on the east and the Fraser River on the west. The Cariboo Plateau is a subarea of the Interior Plateau, aka the Fraser Plateau...

 on the west, and the Monashee Mountains
Monashee Mountains
The Monashee Mountains are a mountain range mostly in British Columbia, Canada, extending into the U.S. state of Washington. They stretch from north to south and from east to west. They are a subrange of the Columbia Mountains...

 and Cariboo Mountains
Cariboo Mountains
The Cariboo Mountains are the northernmost subrange of the Columbia Mountains, which run down into the Spokane, Washington area of the United States and include the Selkirks, Monashees and Purcells. The Cariboo Mountains are entirely within the province of British Columbia, Canada. The range is...

 on the east and northeast.

Thompson Plateau


The Thompson Plateau forms the southern portion of the Interior Plateau. It is bordered on the south by the Canadian Cascades and on the north by the Thompson River
Thompson River
The Thompson River is the largest tributary of the Fraser River, flowing through the south-central portion of British Columbia, Canada. The Thompson River has two main branches called the South Thompson and the North Thompson...

.

Okanagan Highland


The Okanagan Highland is to the east of the Thompson Plateau, and is bounded by the Okanagan River on the west, the Shuswap River
Shuswap River
The basin of the Shuswap River lies northeast of the Okanagan Valley in British Columbia. It is the upper part of the drainage better known to British Columbians as belonging to Shuswap Lake and the South Thompson River...

 on the north, and the Kettle River
Kettle River (Columbia River)
The Kettle River is a tributary of the Columbia River in northeastern Washington in the United States and southeastern British Columbia in Canada. Its drainage basin is large, of which are in Canada and in the United States.-Course:...

 on the east side. The Okanagan Highland is described as being a hilly plateau, and is located in southern British Columbia
British Columbia
British Columbia is the westernmost of Canada's provinces and is known for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . Its name was chosen by Queen Victoria in 1858...

 and northern Washington.

Basin and Range province


The Basin and Range province covers most of the state of Nevada
Nevada
Nevada is a state in the western, mountain west, and southwestern regions of the United States. With an area of and a population of about 2.7 million, it is the 7th-largest and 35th-most populous state. Over two-thirds of Nevada's people live in the Las Vegas metropolitan area, which contains its...

 and parts of the states of Arizona
Arizona
Arizona ; is a state located in the southwestern region of the United States. It is also part of the western United States and the mountain west. The capital and largest city is Phoenix...

, California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

, Idaho
Idaho
Idaho is a state in the Rocky Mountain area of the United States. The state's largest city and capital is Boise. Residents are called "Idahoans". Idaho was admitted to the Union on July 3, 1890, as the 43rd state....

, New Mexico
New Mexico
New Mexico is a state located in the southwest and western regions of the United States. New Mexico is also usually considered one of the Mountain States. With a population density of 16 per square mile, New Mexico is the sixth-most sparsely inhabited U.S...

, Oregon
Oregon
Oregon is a state in the Pacific Northwest region of the United States. It is located on the Pacific coast, with Washington to the north, California to the south, Nevada on the southeast and Idaho to the east. The Columbia and Snake rivers delineate much of Oregon's northern and eastern...

, Texas
Texas
Texas is the second largest U.S. state by both area and population, and the largest state by area in the contiguous United States.The name, based on the Caddo word "Tejas" meaning "friends" or "allies", was applied by the Spanish to the Caddo themselves and to the region of their settlement in...

, Utah
Utah
Utah is a state in the Western United States. It was the 45th state to join the Union, on January 4, 1896. Approximately 80% of Utah's 2,763,885 people live along the Wasatch Front, centering on Salt Lake City. This leaves vast expanses of the state nearly uninhabited, making the population the...

, and Wyoming
Wyoming
Wyoming is a state in the mountain region of the Western United States. The western two thirds of the state is covered mostly with the mountain ranges and rangelands in the foothills of the Eastern Rocky Mountains, while the eastern third of the state is high elevation prairie known as the High...

, as well as much of northern Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

. It is an extremely arid region characterized by basin and range
Basin and Range
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...

 topography.

Colorado Plateau




The Colorado Plateau is an area of high desert located in Arizona
Arizona
Arizona ; is a state located in the southwestern region of the United States. It is also part of the western United States and the mountain west. The capital and largest city is Phoenix...

, New Mexico
New Mexico
New Mexico is a state located in the southwest and western regions of the United States. New Mexico is also usually considered one of the Mountain States. With a population density of 16 per square mile, New Mexico is the sixth-most sparsely inhabited U.S...

, Colorado
Colorado
Colorado is a U.S. state that encompasses much of the Rocky Mountains as well as the northeastern portion of the Colorado Plateau and the western edge of the Great Plains...

, and Utah
Utah
Utah is a state in the Western United States. It was the 45th state to join the Union, on January 4, 1896. Approximately 80% of Utah's 2,763,885 people live along the Wasatch Front, centering on Salt Lake City. This leaves vast expanses of the state nearly uninhabited, making the population the...

, bisected by the Colorado River
Colorado River
The Colorado River , is a river in the Southwestern United States and northwestern Mexico, approximately long, draining a part of the arid regions on the western slope of the Rocky Mountains. The watershed of the Colorado River covers in parts of seven U.S. states and two Mexican states...

 which flows westward through the southern part, and the Green River
Green River (Utah)
The Green River, located in the western United States, is the chief tributary of the Colorado River. The watershed of the river, known as the Green River Basin, covers parts of Wyoming, Utah, and Colorado. The Green River is long, beginning in the Wind River Mountains of Wyoming and flowing...

 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.

Alaskan portion


Generally speaking, Alaska has four physiographic regions. In the north part of the state, there is the Interior Plains area, and the three areas to the south of that are part of the North American Cordillera. Those three areas are the Rocky Mountain System, the Intermontane Basins and Ranges, and in the southern part of the state are the Pacific Mountains and Valleys. In the Alaska panhandle, the mainland mountain ranges and offshore islands (the Alexander Archipelago
Alexander Archipelago
The Alexander Archipelago is a long archipelago, or group of islands, of North America off the southeastern coast of Alaska. It contains about 1,100 islands, which are the tops of the submerged coastal mountains that rise steeply from the Pacific Ocean. Deep channels and fjords separate the...

) are extensions of respective ranges further south.

Canadian portion


In Canada, the North American Cordillera is usually divided into three physiographic regions: the western system, the interior system, and the eastern system. The Canadian portion of the cordillera begins in the north at the Brooks Range
Brooks Range
The Brooks Range is a mountain range in far northern North America. It stretches from west to east across northern Alaska and into Canada's Yukon Territory, a total distance of about 1100 km . The mountains top out at over 2,700 m . The range is believed to be approximately 126 million years old...

 and De Long Mountains of Northern Alaska. The area extends south through the diverse topography of the Yukon Territory and British Columbia
British Columbia
British Columbia is the westernmost of Canada's provinces and is known for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . Its name was chosen by Queen Victoria in 1858...

 - the Saint Elias Mountains
Saint Elias Mountains
The Saint Elias Mountains are a subgroup of the Pacific Coast Ranges, located in southeastern Alaska in the United States, southwestern Yukon and the very far northwestern part of British Columbia in Canada. The range spans Wrangell-St. Elias National Park and Preserve in the USA and Kluane...

 and Coast Mountains
Coast Mountains
The Coast Mountains are a major mountain range, in the Pacific Coast Ranges, of western North America, extending from southwestern Yukon through the Alaska Panhandle and virtually all of the Coast of British Columbia. They are so-named because of their proximity to the sea coast, and are often...

 along the Pacific coast. In the Yukon the Yukon Ranges
Yukon Ranges
The Yukon Ranges are a mountain range comprising the mountains in the southeastern part of the U.S. state of Alaska and most of the Yukon, Canada...

 and Yukon Plateau
Yukon Plateau
The Yukon Plateau is a plateau comprising much of the central and southern Yukon Territory and the far northern part of British Columbia, Canada between Tagish Lake and the Cassiar Mountains and north of the Nakina River....

 lie to the northeast of the Saint Elias Mountains and to the north and east of the Coast Mountains, beyond which the eastern part of the cordillera comprises the Selwyn Mountains
Selwyn Mountains
The Selwyn Mountains are a mountain range in northern Canada, forming part of the border between the Yukon Territory and the Northwest Territories, and which are part of the Eastern System of the Canadian Cordillera . They are neighboured on the east by the Mackenzie Mountains and on their...

, forming the spine of the border between the Yukon and the Northwest Territories
Northwest Territories
The Northwest Territories is a federal territory of Canada.Located in northern Canada, the territory borders Canada's two other territories, Yukon to the west and Nunavut to the east, and three provinces: British Columbia to the southwest, and Alberta and Saskatchewan to the south...

, and the Mackenzie Mountains
Mackenzie Mountains
The Mackenzie Mountains are a mountain range forming part of the Yukon-Northwest Territories boundary between the Liard and Peel rivers. The range is named in honour of Canada's second Prime Minister Alexander Mackenzie. Nahanni National Park Reserve is in the Mackenzie Mountains.The Mackenzie...

. In British Columbia, inland from the Coast Mountains lie the Interior Mountains
Interior Mountains
The Interior Mountains, also called the Northern Interior Mountains and Interior Ranges, are the semi-official names for a huge area that comprises much of the northern two thirds of the Canadian province of British Columbia and a large area of southern Yukon...

, Interior Plateau
Interior Plateau
The Interior Plateau comprises a large region of central British Columbia, and lies between the Cariboo and Monashee Mountains on the east, and the Hazelton Mountains, Coast Mountains and Cascade Range on the west. The continuation of the plateau into the United States is known there as the...

 and Columbia Mountains
Columbia Mountains
The Columbia Mountains are a group of mountain ranges located in southeastern British Columbia, and partially in Montana, Idaho and Washington. The mountain range covers 135,952 km² . The range is bounded by the Rocky Mountain Trench on the east, and the Kootenay River on the south; their...

, comprising what is known in Canada as the Interior System, to the Canadian Rockies
Canadian Rockies
The Canadian Rockies comprise the Canadian segment of the North American Rocky Mountains range. They are the eastern part of the Canadian Cordillera, extending from the Interior Plains of Alberta to the Rocky Mountain Trench of British Columbia. The southern end borders Idaho and Montana of the USA...

, which form the southern half of the boundary between British Columbia and Alberta and are the British Columbia component of the eastern part of the cordillera.