Pacific Coast Ranges

The Pacific 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.

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.

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.

Pacific Coast Ranges
Canadian Coast Range
Canadian Coast Range, Whistler, British Columbia
Highest point
PeakMount Logan
Elevation5,959 m (19,551 ft)
Dimensions
Length3,800 mi (6,100 km)
Geography
CountriesUnited States, Canada and Mexico
Parent rangeNorth American Cordillera
Santa monica mountains canyon
Malibu Canyon, Santa Monica Mountains

Other uses

The term Coast Range is not used by the United States Geological Survey to refer only to the ranges east from the Strait of Juan de Fuca in Washington to the California-Mexico border; and only the ranges west of Puget Sound, the Willamette Valley, the Sacramento and San Joaquin valleys or '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 to refer to the Coast Mountains and adjoining inland ranges such as the Hazelton Mountains, and sometimes also the Saint Elias Mountains.

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).

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:

Turnagain Arm and Kenai Mountains
Kenai Mountains
Juneau Icefield
Juneau Icefield
Rainbow Range Slopes
Rainbow Ridge
Mt Constance Dosewallips River
Mt. Constance, Olympic Mountains
Trinity Alps near Granite Lake
Klamath Mountains
San rafael mountains
San Rafael Mountains
SanGabrielMountains
Puente Hills

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.

Harding Icefield 2
Harding 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

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. ^ a b c d Townsend, Catherine; Figge, John (2002). "Northwest Origins". The Burke Museum.
  7. ^ 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.
  8. ^ a b Humphreys, Eugene (2009). "Relation of flat subduction to magmatism and deformation in the Western United States". GSA.
California Coast Ranges

The Coast Ranges of California span 400 miles (640 km) from Del Norte or Humboldt County, California, south to Santa Barbara County. The other three coastal California mountain ranges are the Transverse Ranges, Peninsular Ranges and the Klamath Mountains.Physiographically, they are a section of the larger Pacific Border province, which in turn are part of the larger Pacific Mountain System physiographic division. UNESCO has included the "California Coast Ranges Biosphere Reserve" in its Man and the Biosphere Programme of World Network of Biosphere Reserves since 1983.

Cascade Range

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).

The Cascades are part of the Pacific Ocean's Ring of Fire, the ring of volcanoes and associated mountains around the Pacific Ocean. All of the eruptions in the contiguous United States over the last 200 years have been from Cascade volcanoes. The two most recent were Lassen Peak from 1914 to 1921 and a major eruption of Mount St. Helens in 1980. Minor eruptions of Mount St. Helens have also occurred since, most recently from 2004 to 2008. The Cascade Range is a part of the American Cordillera, a nearly continuous chain of mountain ranges (cordillera) that form the western "backbone" of North America, Central America, and South America.

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 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.

The Coast Mountains are approximately 1,600 kilometres (1,000 mi) long and average 300 kilometres (190 mi) in width. The range's southern and southeastern boundaries are surrounded by the Fraser River and the Interior Plateau while its far northwestern edge is delimited by the Kelsall and Tatshenshini Rivers at the north end of the Alaska Panhandle, beyond which are the Saint Elias Mountains, and by Champagne Pass in the Yukon Territory. Covered in dense temperate rainforest on its western exposures, the range rises to heavily glaciated peaks, including the largest temperate-latitude ice fields in the world. On its eastern flanks, the range tapers to the dry Interior Plateau and the subarctic boreal forests of the Skeena Mountains and Stikine Plateau.

The Coast Mountains are part of the Pacific Ring of Fire—the ring of volcanoes and associated mountains around the Pacific Ocean—and contain some of British Columbia's highest mountains. Mount Waddington is the highest mountain of the Coast Mountains and the highest that lies entirely within British Columbia, located northeast of the head of Knight Inlet with an elevation of 4,019 metres (13,186 ft).

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).

Although the Coast Mountain Range is usually referred to as the westernmost range of the Pacific Cordillera (since it is the westernmost range on the main landmass at that point), the Insular Mountains are the true westernmost range.

Klamath Mountains

The Klamath Mountains are a rugged and lightly populated mountain range in northwestern California and southwestern Oregon in the western United States. They have a varied geology, with substantial areas of serpentinite and marble, and a climate characterized by moderately cold winters with very heavy snowfall and warm, very dry summers with limited rainfall, especially in the south. As a consequence of the geology and soil types, the mountains harbor several endemic or near-endemic trees, forming one of the largest collections of conifers in the world. The mountains are also home to a diverse array of fish and animal species, including black bears, large cats, owls, eagles, and several species of Pacific salmon. Millions of acres in the mountains are managed by the United States Forest Service. The northernmost and largest sub-range of the Klamath Mountains are the Siskiyou Mountains.

List of glaciers in the United States

This is a list of glaciers existing in the United States, currently or in recent centuries. These glaciers are located in nine states, all in the Rocky Mountains or farther west. The southernmost named glacier among them is the Lilliput Glacier in Tulare County, east of the Central Valley of California.

Northern Oregon Coast Range

The Northern Oregon Coast Range is the northern section of the Oregon Coast Range, in the Pacific Coast Ranges physiographic region, located in the northwest portion of the state of Oregon, United States. This section of the mountain range, part of the Pacific Coast Ranges, contains peaks as high as 3,710 feet (1,131 m) for Rogers Peak. Forests in these mountains are considered to be some of the most productive timber land in the world. The Central Oregon Coast Range is directly south of this section with the Southern Oregon Coast Range beyond the central range.

O'Neill Dam

O'Neill Dam is an earthfill dam on San Luis Creek, 12 miles (19 km) west of Los Banos, California, United States, on the eastern slopes of the Pacific Coast Ranges of Merced County. Forming the O'Neill Forebay, a forebay to the San Luis Reservoir, it is roughly 2.5 miles (4.0 km) downstream from the San Luis Dam.

O'Neill Forebay

O'Neill Forebay is a forebay to the San Luis Reservoir created by the construction of O'Neill Dam across San Luis Creek approximately 12 miles (19 km) west of Los Banos, California, United States, on the eastern slopes of the Pacific Coast Ranges of Merced County.

Olympic Mountains

The Olympic Mountains are a mountain range on the Olympic Peninsula of western Washington in the United States. The mountains, part of the Pacific Coast Ranges, are not especially high – Mount Olympus is the highest at 7,965 ft (2,428 m); however, the eastern slopes rise out of Puget Sound from sea level and the western slopes are separated from the Pacific Ocean by the low-lying 20 to 35 km (12 to 22 mi) wide Pacific Ocean coastal plain. The western slopes are the wettest place in the 48 contiguous states. Most of the mountains are protected within the bounds of Olympic National Park and adjoining segments of the Olympic National Forest.

The mountains are spread out across four counties: Clallam, Grays Harbor, Jefferson and Mason. Physiographically, they are a section of the larger Pacific Border province, which is in turn a part of the larger Pacific Mountain System.

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. This north-south running range extends over 200 miles (320 km) from the Columbia River in the north on the border of Oregon and Washington, south to the middle fork of the Coquille River. It is 30 to 60 miles (48 to 97 km) wide and averages around 1,500 feet (460 m) in elevation above sea level. The coast range has three main sections, a Northern, Central, and Southern.

The oldest portions of the range are over 60 million years old, with volcanics and a forearc basin as the primary mountain building processes responsible for the range. It is part of the larger grouping known as the Pacific Coast Ranges that extends over much of the western edge of North America from California to Alaska. The range creates a rain shadow effect for the Willamette Valley that lies to the east of the mountains, creating a more stable climate and significantly less rain than the coastal region of the state. To the west where the range over-shadows the Oregon Coast, the range causes more precipitation to fall on that side of the mountains, contributing to the numerous rivers that flow to the Pacific Ocean.

Marys Peak in the Central Coast Range is the highest peak at 4,097 feet (1,248 m). Logging is a major industry in the range in both private and government owned forests. Both the state and federal government manage forests in the Oregon Coast Range. The mountains are home to a variety of wildlife including black bear, elk, deer, beaver, many species of birds, and bats among others. Fish, including salmon and trout, and other aquatic life inhabit the streams and rivers flowing through the range.

Pacific Border province

The Pacific Border province is a physiographic province of the Physiographic regions of the world physical geography system.

Pelly Mountains

The Pelly Mountains are a mountain range in the Yukon, Canada. It has an area of 44014 km2 and is a subrange of the Yukon Ranges which in turn form part of the Pacific Coast Ranges.

Peninsular Ranges

The Peninsular Ranges (also called the Lower California province) 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 (152 to 3,302 m).

Rocky Mountain Floristic Region

The Rocky Mountain Floristic Region, also known as the Rocky Mountain Floristic Province, is a floristic region within the Holarctic Kingdom in western North America (Canada and the United States) delineated by Armen Takhtajan and Robert F. Thorne. The region extends from Kodiak Island in Alaska to the San Francisco Bay Area and Sierra Nevada in California. The Vancouverian Province comprises the coastal part of the region for its entire length, including the Pacific Coast Ranges, and the Rocky Mountain Province includes the Rocky Mountains and associated ranges. There are no endemic plant families in the region but many endemic genera and species.

Saint Elias Mountains

The Saint Elias Mountains (French: Chaîne Saint-Élie) 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.This mountain range was named after Mount Saint Elias which had been named in 1741 by the Danish explorer Vitus Bering.

Sierra Madre Mountains (California)

The Sierra Madre Mountains are a mountain range primarily in northern Santa Barbara County and extending into northwestern Ventura County in Southern California, western United States. It is a range of the Inner South Coast Ranges group, and is the southernmost reach of the California Coast Ranges, which are themselves part of the Pacific Coast Ranges of western North America.

Temescal Creek (Northern California)

Temescal Creek is one of the principal watercourses in the city of Oakland, California, United States.

The word "temescal" derives from the word temescalli, which means "sweat house" in the Nahuatl language of the Mexica ("Aztec") people of Mexico. The name was given to the creek when it became part of the Peralta's Rancho San Antonio. It is surmised that the Peraltas or perhaps one of their ranch hands (vaqueros) had seen local indigenous (Ohlone) structures along the creek similar to those in other parts of New Spain which were called temescalli.

Two forks begin in the Berkeley Hills in the northeastern section of Oakland (also referred to as the Oakland Hills), part of the Pacific Coast Ranges, coming together in the Temescal district of Oakland, then flowing westerly across Oakland and Emeryville to San Francisco Bay.

The north fork of Temescal Creek was renamed "Harwood's Creek" in the mid 19th century after an early claimant to grazing lands in the canyon above the Claremont neighborhood, retired sea captain and Oakland wharfinger William Harwood. It was renamed yet again "Claremont Creek" in the early 20th century after a residential development in the same vicinity, today's Claremont district.

The south fork begins in the northern section of Oakland's Montclair district, flowing southwest out of a canyon in the hills, then turning abruptly northwestward in the linear valley formed by the Hayward Fault. It then flows into Lake Temescal, a natural sag pond which was dammed in the 19th century to increase its capacity for use as a reservoir. Lake Temescal is now a public park.

The creek continues out of Lake Temescal, curving westerly around the end of the shutter ridge in the Rockridge district of Oakland, then flowing almost in a line toward the Bay.

Transverse Ranges

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 and Riverside 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.The ranges extend from west of Point Conception eastward approximately 500 kilometers into the Mojave and Colorado Desert. The geology and topography of the ranges express three distinct segments that have contrasting elevations, rock types, and vegetation. The western segment extends to the San Gabriel Mountains and San Gabriel fault. The central segment includes that range eastward to the San Andreas fault. The eastern segment extends from the San Andreas fault eastward to the Colorado Desert. The central and eastern segments (near the San Andreas fault) have the highest elevations.

Most of the ranges lie in the California chaparral and woodlands ecoregion. Lower elevations are dominated by chaparral and scrubland, while higher elevations support large conifer forests. Most of the ranges in the system are fault blocks, and were uplifted by tectonic movements late in the Cenozoic Era. West of Tejon Pass, the primary rock types are varied, with a mix of sedimentary, volcanic, and metamorphic rocks, while regions east of the pass are dominated by plutonic granitic and metasedimentary rocks.

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