Pacific Coast Ranges

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Pacific Coast Ranges
Canadian Coast Range.jpg
Canadian Coast Range, Whistler, British Columbia
Highest point
PeakMount Logan
Elevation 5,959 m (19,551 ft)
Dimensions
Length3,800 mi (6,100 km)
Geography
CountriesUnited States, Canada and Mexico
Parent range North American Cordillera
Malibu Canyon, Santa Monica Mountains Santa monica mountains canyon.jpg
Malibu Canyon, Santa Monica Mountains

ThePacific Coast Ranges (officially gazetted as the Pacific Mountain System [1] in the United States but referred to as the Pacific Coast Ranges), [2] are the series of mountain ranges that stretch along the West Coast of North America from Alaska south to Northern and Central Mexico.

United States Federal republic in North America

The United States of America (USA), commonly known as the United States or America, is a country comprising 50 states, a federal district, five major self-governing territories, and various possessions. At 3.8 million square miles, the United States is the world's third or fourth largest country by total area and is slightly smaller than the entire continent of Europe's 3.9 million square miles. With a population of over 327 million people, the U.S. is the third most populous country. The capital is Washington, D.C., and the most populous city is New York City. Most of the country is located contiguously in North America between Canada and Mexico.

Mountain range A geographic area containing several geologically related mountains

A mountain range or hill range is a series of mountains or hills ranged in a line and connected by high ground. A mountain system or mountain belt is a group of mountain ranges with similarity in form, structure, and alignment that have arisen from the same cause, usually an orogeny. Mountain ranges are formed by a variety of geological processes, but most of the significant ones on Earth are the result of plate tectonics. Mountain ranges are also found on many planetary mass objects in the Solar System and are likely a feature of most terrestrial planets.

North America Continent entirely within the Northern Hemisphere and almost all within the Western Hemisphere

North America is a continent entirely within the Northern Hemisphere and almost all within the Western Hemisphere. It is also considered by some to be a northern subcontinent of the Americas. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the west and south by the Pacific Ocean, and to the southeast by South America and the Caribbean Sea.

Contents

The Pacific Coast Ranges are part of the North American Cordillera (sometimes known as the Western Cordillera, or in Canada, as the Pacific Cordillera and/or the Canadian Cordillera), which includes the Rocky Mountains, Columbia Mountains, Interior Mountains, the Interior Plateau, Sierra Nevada Mountains, the Great Basin mountain ranges, and other ranges and various plateaus and basins.

North American Cordillera mountain chain along the western side of North America

The North American Cordillera is the North American portion of the American Cordillera which is a mountain chain (cordillera) along the western side of the Americas. The North American Cordillera covers an extensive area of mountain ranges, intermontane basins, and plateaus in western North America, including much of the territory west of the Great Plains. It is also sometimes called the Western Cordillera, the Western Cordillera of North America, or the Pacific Cordillera.

Canada Country in North America

Canada is a country in the northern part of North America. Its ten provinces and three territories extend from the Atlantic to the Pacific and northward into the Arctic Ocean, covering 9.98 million square kilometres, making it the world's second-largest country by total area. Its southern border with the United States, stretching some 8,891 kilometres (5,525 mi), is the world's longest bi-national land border. Canada's capital is Ottawa, and its three largest metropolitan areas are Toronto, Montreal, and Vancouver.

Rocky Mountains Major mountain range in western North America

The Rocky Mountains, also known as the Rockies, are a major mountain range in western North America. The Rocky Mountains stretch 3,000 km (1,900 mi) in straight-line distance from the northernmost part of British Columbia, in western Canada, to New Mexico in the Southwestern United States. Located within the North American Cordillera, the Rockies are distinct from the Pacific Coast Ranges, Cascade Range, and the Sierra Nevada, which all lie farther to the west.

The Pacific Coast Ranges designation, however, only applies to the Western System of the Western Cordillera, [3] which comprises the Saint Elias Mountains, Coast Mountains, Insular Mountains, Olympic Mountains, Cascade Range, Oregon Coast Range, California Coast Ranges, Transverse Ranges, Peninsular Ranges, and the Sierra Madre Occidental.

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 United States and Kluane National Park and Reserve in Canada and includes all of Glacier Bay National Park in Alaska. In Alaska, the range includes parts of the city/borough of Yakutat and the Hoonah-Angoon and Valdez-Cordova census areas.

Coast Mountains major mountain range in western North America

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 south to the Fraser River. The mountain range's name derives from its proximity to the sea coast, and it is often referred to as the Coast Range. The range includes volcanic and non-volcanic mountains and the extensive ice fields of the Pacific and Boundary Ranges, and the northern end of the volcanic system known as the Cascade Volcanoes. The Coast Mountains are part of a larger mountain system called the Pacific Coast Ranges or the Pacific Mountain System, which includes the Cascade Range, the Insular Mountains, the Olympic Mountains, the Oregon Coast Range, the California Coast Ranges, the Saint Elias Mountains and the Chugach Mountains. The Coast Mountains are also part of the American Cordillera—a Spanish term for an extensive chain of mountain ranges—that consists of an almost continuous sequence of mountain ranges that form the western backbone of North America, Central America, South America and Antarctica.

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 rise to elevations of more than 2000m (6,600 ft). The highest of these mountains is Golden Hinde on Vancouver Island, which rises to 2,196.818 m (7,207 ft).

Other uses

The term Coast Range is used by the United States Geological Survey to refer only to the ranges south of the Strait of Juan de Fuca in Washington to the California-Mexico border, and to those west of Puget Sound, the Willamette Valley, and the Sacramento and San Joaquin valleys (the California Central Valley).

United States Geological Survey Scientific agency of the United States government

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, geography, geology, and hydrology. The USGS is a fact-finding research organization with no regulatory responsibility.

Strait of Juan de Fuca strait

The Strait of Juan de Fuca is a large body of water about 154 kilometres (96 mi) long that is the Salish Sea's outlet to the Pacific Ocean. The international boundary between Canada and the United States runs down the center of the Strait.

Puget Sound sound along the northwestern coast of the U.S. state of Washington

Puget Sound is a sound along the northwestern coast of the U.S. state of Washington, an inlet of the Pacific Ocean, and part of the Salish Sea. It is a complex estuarine system of interconnected marine waterways and basins, with one major and two minor connections to the open Pacific Ocean via the Strait of Juan de Fuca—Admiralty Inlet being the major connection and Deception Pass and Swinomish Channel being the minor.

That definition excludes the Sierra Nevada and Cascade Ranges, the Mojave (High), and Sonoran (Low) Deserts. [4] i.e. the Pacific Border province. The same term is used informally in Canada to refer to the Coast Mountains and adjoining inland ranges such as the Hazelton Mountains, and sometimes also the Saint Elias Mountains.

Sierra Nevada (U.S.) mountain range

The Sierra Nevada is a mountain range in the Western United States, between the Central Valley of California and the Great Basin. The vast majority of the range lies in the state of California, although the Carson Range spur lies primarily in Nevada. The Sierra Nevada is part of the American Cordillera, a chain of mountain ranges that consists of an almost continuous sequence of such ranges that form the western "backbone" of North America, Central America, South America and Antarctica.

Cascade Range mountain range in western North America

The Cascade Range or Cascades 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. The small part of the range in British Columbia is referred to as the Canadian Cascades or, locally, as the Cascade Mountains. The latter term is also sometimes used by Washington residents to refer to the Washington section of the Cascades in addition to North Cascades, the more usual U.S. term, as in North Cascades National Park. The highest peak in the range is Mount Rainier in Washington at 14,411 feet (4,392 m).

Mojave Desert desert in southwestern United States

The Mojave Desert is an arid rain-shadow desert and the driest desert in North America. It is in the Southwestern United States, primarily within southeastern California and southern Nevada, and it occupies 47,877 sq mi (124,000 km2). Very small areas also extend into Utah and Arizona. Its boundaries are generally noted by the presence of Joshua trees, which are native only to the Mojave Desert and are considered an indicator species, and it is believed to support an additional 1,750 to 2,000 species of plants. The central part of the desert is sparsely populated, while its peripheries support large communities such as Las Vegas, Barstow, Lancaster, Palmdale, Victorville, and St. George.

Geography

The character of the ranges varies considerably, from the record-setting tidewater glaciers in the ranges of Alaska, to the rugged Central and Southern California ranges, the Transverse Ranges and Peninsular Ranges, in the chaparral and woodlands ecoregion with Oak Woodland, Chaparral shrub forest or Coastal sage scrub-covering them. The coastline is often dropping steeply into the sea with photogenic views. Along the British Columbia and Alaska coast, the mountains intermix with the sea in a complex maze of fjords, with thousands of islands. Off the Southern California coast the Channel Islands archipelago of the Santa Monica Mountains extends for 160 miles (260 km).

Southern California Place in California, United States

Southern California is a geographic and cultural region that generally comprises California's southernmost counties, and is the second most populous urban agglomeration in the United States. The region contains ten counties: Imperial, Los Angeles, Orange, Riverside, San Bernardino, San Diego, Santa Barbara, San Luis Obispo, Ventura, and Kern counties.

Transverse Ranges mountain range in California

The Transverse Ranges are a group of mountain ranges of southern California, in the Pacific Coast Ranges physiographic region in North America. The Transverse Ranges begin at the southern end of the California Coast Ranges and lie within Santa Barbara, Ventura, Los Angeles, San Bernardino, Riverside and Kern counties. The Peninsular Ranges lie to the south. The name Transverse Ranges is due to their east–west orientation, making them transverse to the general northwest–southeast orientation of most of California's coastal mountains.

Peninsular Ranges

The Peninsular Ranges are a group of mountain ranges that stretch 1,500 km (930 mi) from Southern California to the southern tip of the Baja California Peninsula; they are part of the North American Coast Ranges, which run along the Pacific Coast from Alaska to Mexico. Elevations range from 500 to 10,834 feet.

There are coastal plains at the mouths of rivers that have punched through the mountains spreading sediments, most notably at the Copper River in Alaska, the Fraser River in British Columbia, and the Columbia River between Washington and Oregon. In California: the Sacramento and San Joaquin Rivers' San Francisco Bay, the Santa Clara River's Oxnard Plain (home to some of the most fertile soil in the world), the Los Angeles, San Gabriel, and Santa Ana Rivers' Los Angeles Basin - a coastal sediment-filled plain between the peninsular and transverse ranges with sediment in the basin up to 6 miles (10 km) deep, and the San Diego River's Mission Bay.

From the vicinity of San Francisco Bay north, it is common in winter for cool unstable air masses from the Gulf of Alaska to make landfall in one of the Coast Ranges, resulting in heavy precipitation, both as rain and snow, especially on their western slopes. The same Winter weather occurs with less frequency and precipitation in Southern California, with the mountains' western faces and peaks causing an eastward rainshadow that produces the arid desert regions.

Omitted from the list below, but often included is the Sierra Nevada, a major mountain range of eastern California that is separated by the Central Valley over much of its length from the California Coast Ranges and the Transverse Ranges. [5]

Geology

On the West coast of North America, the coast ranges and the coastal plain form the margin. Most of the land is made of terranes that have been accreted onto the margin. In the north, the insular belt is an accreted terrane, forming the margin. This belt extends from the Wrangellia Terrane in Alaska to the Chilliwack group of Canada. [6]

A rupture in Rodinia 750 million years ago formed a passive margin in the eastern Pacific Northwest. The breakup of Pangea 200 million years ago began the westward movement of the North American plate, creating an active margin on the western continent. As the continent drifted West, terranes were accreted onto the west coast. [6] The timing of the accretion of the insular belt is uncertain, although the closure did not occur until at least 115 million years ago. [6] Other Mesozoic terranes that accreted onto the continent include the Klamath Mountains, the Sierra Nevada, and the Guerrero super-terrane of western Mexico. [7] 80 to 90 million years ago the subducting Farallon plate split and formed the Kula Plate to the North. This formed an area in what is now Northern California, where the plates converged forming a Mélange. North of this was the Columbia Embayment, where the continental margin was east of the surrounding areas. [6] Many of the major batholiths date from the late Cretaceous. [7] As the Laramide Orogeny ended around 48 million years ago, the accretion of the Siletzia terrane began in the Pacific Northwest. This began the volcanic activity in the Cascadia subduction zone, forming the modern Cascade Range, and lasted into the Miocene. Events here may relate to the ignimbrite flare-up of the southern Basin and Range. [8] As extension in the Basin and Range Province slowed by a change in North American Plate movement circa 7 to 8 Million years ago, rifting began on the Gulf of California. [8]

Although many of the ranges do share a common geologic history, the Pacific Coast Ranges province is not defined by geology, but rather by geography. Many of the various ranges are composed of distinct forms of rock from many different periods of geological time from the Precambrian in parts of the Little San Bernardino Mountains to 10,000-year-old rock in the Cascade Range. For one example, the Peninsular Ranges, composed of Mesozoic batholitic rock, are geologically extremely different from the San Bernardino Mountains, composed of a mix of Precambrian metamorphic rock and Cenozoic sedimentary rock. However, both are considered part of the Pacific Coast Ranges due to their proximity and similar economic and social impact on surrounding communities.

Major ranges

These are the members of the Pacific Coast Ranges, from north to south:

Kenai Mountains Turnagain Arm and Kenai Mountains.jpg
Kenai Mountains

Major icefields

These are not named as ranges, but amount to the same thing. The Pacific Coast Ranges are home to the largest temperate-latitude icefields in the world.

Only the largest icefields are listed above; smaller icefields may be listed on the various range pages. Formally unnamed icefields are not listed

See also

Related Research Articles

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California Coast Ranges mountain range

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References

  1. Physiographic regions of the United States, USGS
  2. Merriam-Webster's collegiate encyclopedia , page 361 (Merriam-Webster, 2000).
  3. S. Holland, Landforms of British Columbia , BC Govt. 1976.
  4. "Coast Ranges". Geographic Names Information System . United States Geological Survey . Retrieved 2007-07-30.
  5. "Pacific mountain system". Britannica Online Encyclopedia. Encyclopædia Britannica. Retrieved 2007-09-29.
  6. 1 2 3 4 Townsend, Catherine; Figge, John (2002). "Northwest Origins". The Burke Museum.
  7. 1 2 Dickinson, William (2004). "Evolution of the North American Cordillera" (PDF). Annual Review of Earth and Planetary Sciences. 32: 13–45. doi:10.1146/annurev.earth.32.101802.120257. Archived from the original (PDF) on 4 January 2014. Retrieved 9 April 2013.
  8. 1 2 Humphreys, Eugene (2009). "Relation of flat subduction to magmatism and deformation in the Western United States". GSA.