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The Pacific Coast Ranges
Coast Ranges
(officially gazetted as the Pacific Mountain System[1] in the United States
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
North America
from Alaska
Alaska
south to Northern and Central Mexico. The Pacific Coast Ranges
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. The Pacific Coast Ranges
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
Oregon
Coast Range, California
California
Coast Ranges, Transverse Ranges, Peninsular Ranges, and the Sierra Madre Occidental.

Contents

1 Other uses 2 Geography 3 Geology 4 Major ranges 5 Major icefields 6 See also 7 References

Other uses[edit] The term Coast Range is used by the United States
United States
Geological Survey to refer only to the ranges south from the Strait of Juan de Fuca
Strait of Juan de Fuca
in Washington to the California- Mexico
Mexico
border; and only the ranges west of Puget Sound, the Willamette Valley, the Sacramento and San Joaquin valleys or ' California
California
Central Valley' (thereby excluding the Sierra Nevada and Cascade Ranges), and the Mojave (High) and Sonoran (Low) Deserts.[4] i.e. the Pacific Border province. The same term is used informally in Canada
Canada
to refer to the Coast Mountains
Coast Mountains
and adjoining inland ranges such as the Hazelton Mountains, and sometimes also the Saint Elias Mountains. Geography[edit] 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
Southern California
ranges, the Transverse Ranges and Peninsular Ranges, in the chaparral and woodlands ecoregion with Oak Woodland, Chaparral
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
British Columbia
and Alaska
Alaska
coast, the mountains intermix with the sea in a complex maze of fjords, with thousands of islands. Off the Southern California
Southern California
coast the Channel Islands archipelago of the Santa Monica Mountains
Santa Monica Mountains
extends for 160 miles (260 km). 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
Fraser River
in British Columbia, and the Columbia River
Columbia River
between Washington and Oregon. In California: the Sacramento and San Joaquin Rivers' San Francisco Bay, the Santa Clara River's Oxnard Plain
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
San Francisco Bay
north, it is common in winter for cool unstable air masses from the Gulf of Alaska
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
California
that is separated by the Central Valley over much of its length from the California
California
Coast Ranges and the Transverse Ranges.[5] Geology[edit] 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
Alaska
to the Chilliwack group of Canada.[6] A rupture in Rodinia
Rodinia
750 million years ago formed a passive margin in the eastern Pacific Northwest. The breakup of Pangea
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
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
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
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
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
Precambrian
in parts of the Little San Bernardino Mountains
Little San Bernardino Mountains
to 10,000-year-old rock in the Cascade Range. For one example, the Peninsular Ranges, composed of Mesozoic
Mesozoic
batholitic rock, are geologically extremely different from the San Bernardino Mountains, composed of a mix of Precambrian
Precambrian
metamorphic rock and Cenozoic sedimentary rock. However, both are considered part of the Pacific Coast Ranges
Coast Ranges
due to their proximity and similar economic and social impact on surrounding communities. Major ranges[edit] These are the members of the Pacific Coast Ranges, from north to south:

Kenai Mountains, southern Alaska Chugach Mountains, southern Alaska Talkeetna Mountains, southern Alaska

Kenai Mountains

Yukon
Yukon
Ranges, Alaska, Yukon

Wrangell Mountains, southern Alaska

Saint Elias Mountains, southern Alaska, southwestern Yukon, far northwestern British Columbia

Alsek Ranges

Fairweather Range Takshanuk Mountains, Haines, Alaska-area. Between Chilkat and Chilkoot watersheds

Coast Mountains

Boundary Ranges, southeastern Alaska, northwestern British Columbia

Cheja Range (southeast of Taku/Whiting Rivers) Chechidla Range Chutine Icefield Adam Mountains Ashington Range Burniston Range Dezadeash Range Florence Range Halleck Range

Juneau Icefield

Juneau Icefield Kakuhan Range Lincoln Mountains Longview Range Peabody Mountains Rousseau Range Seward Mountains Snowslide Range Spectrum Range Stikine Icecap

Kitimat Ranges
Kitimat Ranges
BC North Coast Pacific Ranges
Pacific Ranges
BC South & Central Coast

Rainbow Range northwest Chilcotin, also classifiable as part of the Interior Plateau

Rainbow Ridge

Pantheon Range Homathko area Niut Range
Niut Range
Homathko area Waddington Range
Waddington Range
Homathko area Whitemantle Range Homathko area Bendor Range Garibaldi Ranges Clendinning Range Tantalus Range Chilcotin Ranges

Dickson Range Shulaps Range Camelsfoot Range

Lillooet Ranges, (Fraser Canyon west bank)

Cantilever Range Cayoosh Range

Douglas Ranges Front Ranges (North Shore Mountains)

Insular Mountains, British Columbia

Vancouver Island Ranges, British Columbia Queen Charlotte Mountains, British Columbia

Mt. Constance, Olympic Mountains

Olympic Mountains, Washington Cascade Range, British Columbia
British Columbia
(Fraser Canyon east bank), Washington, Oregon
Oregon
and California Oregon
Oregon
Coast Range, Oregon

Northern Oregon
Oregon
Coast Range Central Oregon
Oregon
Coast Range Southern Oregon
Oregon
Coast Range

Calapooya Mountains, Oregon Klamath-Siskiyou, Oregon, Northern California

Klamath Mountains, Oregon, Northern California Siskiyou Mountains, Oregon, Northern California Trinity Alps
Trinity Alps
and Salmon Mountains, Northern California Yolla Bolly Mountains, Northern California

Northern Coast Ranges, Northern California

King Range, Northern California Mendocino Range, Northern California

Klamath Mountains

Mayacamas Mountains, Northern California Marin Hills, Northern California, (including Mount Tamalpais)

Central California
California
Coast Ranges, Central California

Santa Cruz Mountains, Central California Diablo Range, Central California Gabilan Range, Central California Santa Lucia Range, Central California Temblor Range, Central California Caliente Range, Central California

Transverse Ranges, Southern California

Sierra Madre Mountains, Southern California Sierra Pelona Mountains, Southern California

San Rafael Mountains

San Emigdio Mountains, Southern California San Rafael Mountains, Southern California Santa Ynez Mountains, Southern California Tehachapi Mountains, Southern California Topatopa Mountains, Southern California Santa Susana Mountains, Southern California Simi Hills, Southern California Santa Monica Mountains, Southern California Chalk Hills, Southern California San Gabriel Mountains, Southern California

Puente Hills

San Rafael Hills, Southern California Puente Hills, Southern California San Bernardino Mountains, Southern California Little San Bernardino Mountains, Southern California

Peninsular Ranges, Southern California
Southern California
and Mexico

Santa Ana Mountains, Southern California Chino Hills, Southern California San Jacinto Mountains, Southern California Palomar Mountain Range, Southern California Laguna Mountains, Southern California Sierra Juarez, Northern Baja California, Mexico Sierra San Pedro Martir, Central Baja California, Mexico Sierra de San Borja, Central Baja California, Mexico Sierra de San Francisco, Central Baja California, Mexico Sierra de Guadalupe cave paintings, Central Baja California, Mexico Sierra de la Giganta, Southern Baja California, Mexico Sierra de la Laguna, Southern Baja California, Mexico

Sierra Madre Occidental, Northwestern Mexico

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

Harding Icefield Sargent Icefield

Harding Icefield

Bagley Icefield Kluane Icefields Juneau Icefield Stikine Icecap Ha-Iltzuk Icefield
Ha-Iltzuk Icefield
(Silverthrone Glacier) Monarch Icefield Waddington Icefield Homathko Icefield Lillooet Icecap (Lillooet Crown) Pemberton Icefield

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[edit]

Wikimedia Commons has media related to Pacific Coast Ranges.

List of Pacific Coast Ranges
Coast Ranges
topics Coast Range (ecoregion) California Coast Ranges
California Coast Ranges
(geomorphic province) Coast Ranges
Coast Ranges
(geomorphic province) United States
United States
physiographic regions

References[edit]

^ Physiographic regions of the United States, USGS ^ Merriam-Webster's collegiate encyclopedia, page 361 (Merriam-Webster, 2000). ^ S. Holland, Landforms of British Columbia, BC Govt. 1976. ^ "Coast Ranges". Geographic Names Information System. United States Geological Survey. Retrieved 2007-07-30.  ^ "Pacific mountain system". Britannica Online Encyclopedia. Encyclopædia Britannica. Retrieved 2007-09-29.  ^ a b c d Townsend, Catherine; Figge, John (2002). "Northwest Origins". The Burke Museum.  ^ a b 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.  ^ a b Humphreys, Eugene (2009). "Relation of flat subduction to magmatism and deformation in the Western United States". GSA.  access-date= req

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