The Coast Mountains ( French : La chaîne Côtière ) 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 .
33-655: The Elaho River is a c.70 km long river beginning in the Coast Mountains northwest of the towns of Whistler and Pemberton, British Columbia . It is a tributary of the Squamish River and is known for its whitewater rafting and kayaking as well as for the intense alpine scenery lining its route. The Elaho is much larger than the Squamish River when it meets with it. The Elaho is often subject to flash flooding. The Elaho River originates at
66-516: A Tlingit word for "food depot". Former spellings are Naas and Nasse. The Nisga'a name for the river is K'alii Aksim Lisims "Lisims (river name) Valley". The Gitxsan name is Git-Txaemsim meaning People of Txeemsim (Raven or Trickster); Xsitxemsem in the dialect of the Gitanyow). Lisims means "murky" in Nisga'a, referring to the river's silt-laden flow. The last 40 km (25 mi) of
99-704: A large mass of igneous rock , creating a new continental margin. This large mass of igneous rock is the largest granite outcropping in North America. The final event began when the Farallon Plate continued to subduct under the new continental margin after the Insular Plate and Insular Islands collided with the old continental margin, supporting a new continental volcanic arc called the Coast Range Arc about 100 million years ago during
132-876: A popular whitewater rafting section. From the Clendinning Creek confluence, the river continues south for another 8.9 km to its confluence with Sims Creek, its second largest tributary. After Sims Creek, the river turns southeast for about 21.4 km until its confluence with the Squamish. While Clendinning and Sims Creeks are the Elaho’s largest tributaries, the Elaho has many other smaller tributaries as well: Coast Mountains 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
165-539: A pre-existing continental margin and coastline of North America. These volcanic islands, known as the Insular Islands by geoscientists, were formed on a pre-existing tectonic plate called the Insular Plate by subduction of the former Farallon Plate to the west during the early Paleozoic era. This subduction zone records another subduction zone to the east under an ancient ocean basin between
198-640: Is from the Tlingit tongue, and when, as was probable, the Tlingits from Tongass, at the entrance to Observatory inlet, met Captain Vancouver they gave him their name for the river, i.e., Nass, which means literally "the stomach," from the fact that their food supplies of salmon, oolachan.. a noted fishery." About 220 years ago, as recorded by the oral history of the Nisga'a people, the Nass River
231-756: The British Columbia Interior from the Pacific weather systems, resulting in dry warm summers and dry cold winters. Beyond the eastern slopes is a 154,635 km (59,705 sq mi) plateau occupying the southern and central portions of British Columbia called the Interior Plateau . Included within the Interior Plateau is a coalescing series of layered flood basalt lava flows. These sequences of fluid volcanic rock cover about 25,000 km (9,700 sq mi) of
264-636: The Coast Mountains southwest to Nass Bay, a sidewater of Portland Inlet , which connects to the North Pacific Ocean via the Dixon Entrance . Nass Bay joins Portland Inlet just south of Observatory Inlet . The English name "Nass" is derived from the Tlingit name Naas which means "intestines" or "guts" in reference to the river's large food capacity in its fish (Naish & Story 1963; Leer, Hitch, & Ritter 2001). Can also be
297-756: 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
330-682: The Late Cretaceous period. Magma rising from the Farallon Plate under the new continental margin ascended through the newly accreted Insular Belt, injecting huge quantities of granite into older igneous rocks of the Insular Belt. At the surface, new volcanoes were built along the continental margin. Named after the Coast Mountains, the basement of this arc was likely Early Cretaceous and Late Jurassic intrusions from
363-727: The Stikine Icecap , which lies between the lower Stikine River and the Whiting River . Because the Coast Mountains are just east of the Pacific Ocean , they have a profound effect on British Columbia's climate by forcing moisture-laden air off the Pacific Ocean to rise, dropping heavy rainfalls on the western slopes where lush forests exist. This precipitation is among the heaviest in North America. The eastern slopes are relatively dry and less steep and protect
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#1732787162569396-711: The Bridge River Ocean, the Insular Islands drew closer to the former continental margin and coastline of western North America, supporting a pre-existing volcanic arc on the former continental margin of North America called the Omineca Arc . As the North American Plate drifted west and the Insular Plate drifted east to the old continental margin of western North America, the Bridge River Ocean eventually closed by ongoing subduction under
429-544: The Bridge River Ocean. This subduction zone eventually jammed and shut down completely 115 million years ago, ending the Omineca Arc and the Insular Islands collided, forming the Insular Belt . Compression resulting from this collision crushed, fractured and folded rocks along the old continental margin. The Insular Belt then welded onto the pre-existing continental margin by magma that eventually cooled to create
462-661: 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). The Coast Mountains consists of three subdivisions known as the Pacific Ranges , the Kitimat Ranges , and the Boundary Ranges . The Pacific Ranges are the southernmost subdivision of the Coast Mountains, extending from
495-513: The Coast Range Arc were then deformed under the heat and pressure of later intrusions, turning them into layered metamorphic rock known as gneiss . In some places, mixtures of older intrusive rocks and the original oceanic rocks have been distorted and warped under intense heat, weight and stress to create unusual swirled patterns known as migmatite , appearing to have been nearly melted in the procedure. Volcanism began to decline along
528-577: The Insular Islands and the former continental margin of North America called the Bridge River Ocean . This arrangement of two parallel subduction zones is unusual in that very few twin subduction zones exist on Earth; the Philippine Mobile Belt off the southeastern coast of Asia is an example of a modern twin subduction zone. As the Insular Plate drew closer to the pre-existing continental margin by ongoing subduction under
561-646: The Insular Islands. One of the major aspects that changed early during the Coast Range Arc was the status of the northern end of the Farallon Plate, a portion now known as the Kula Plate . About 85 million years ago, the Kula Plate broke off from the Farallon Plate to form a mid-ocean ridge known to geoscientists as the Kula-Farallon Ridge . This change apparently had some important ramifications for regional geologic evolution. When this change
594-612: The Interior Plateau and have a volume of about 1,800 km (430 cu mi), forming a large volcanic plateau constructed atop of the Interior Plateau. North of the Interior Plateau on the range's northeastern slopes lies a huge mountainous area known by geographers as the Interior Mountains , which includes the neighbouring Skeena , Cassiar and Hazelton Mountains . The Coast Mountains consist of deformed igneous and metamorphosed structurally complex pre- Tertiary rocks. These originated in diverse locations around
627-841: The Nass River in the south to the Kelsall River in the north. It is also the largest subdivision of the Coast Mountains, spanning the British Columbia-Alaska border and northwards into Yukon flanking the west side of the Yukon River drainage as far as Champagne Pass , north of which being the Yukon Ranges . The Boundary Ranges include several large icefields, including the Juneau Icefield between Juneau, Alaska and Atlin Lake in British Columbia, and
660-420: The early Eocene period. Volcanism along the entire length of the Coast Range Arc shut down about 50 million years ago and many of the volcanoes have disappeared from erosion. What remains of the Coast Range Arc to this day are outcrops of granite when magma intruded and cooled at depth beneath the volcanoes, forming the present Coast Mountains. During construction of intrusions 70 and 57 million years ago,
693-513: The gases emitted by the volcanoes and the institution of a warning system to alert people living down slope from the volcanoes . If the Tseax Cone were to erupt again, there could be a repeat of the poisonous gas disaster that happened to the Nisga'a people 220 years ago. The eruption could also cause forest fires and could potentially dam local rivers such as the Nass River and the Tseax if
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#1732787162569726-549: The globe: the area is built of several different terranes of different ages with a broad range of tectonic origins. In addition, oceanic crust under the Pacific Ocean is being subducted at the southern portion of the range to form a north–south line of volcanoes called the Garibaldi Volcanic Belt , a northern extension of the Cascade Volcanoes in the northwestern United States , and contains
759-736: The highest mountain of the Coast Mountains, lies in the Waddington Range of the Pacific Ranges. Just north of the Pacific Ranges lies the central subdivision known as the Kitimat Ranges. This subdivision extends from the Bella Coola River and Burke Channel in the south to the Nass River in the north. The third and northernmost subdivision of the Coast Mountains is the Boundary Ranges , extending from
792-655: The length of the arc about 60 million years ago during the Albian and Aptian faunal stages of the Cretaceous period. This resulted from the changing geometry of the Kula Plate, which progressively developed a more northerly movement along the Pacific Northwest . Instead of subducting beneath the Pacific Northwest, the Kula Plate began subducting underneath southwestern Yukon and Alaska and during
825-417: The lower stretches of the Fraser River to Bella Coola . Included in this subdivision is four of the five major coastal icecaps in the southern Coast Mountains. These are the largest temperate-latitude icecaps in the world and fuel a number of major rivers . Other than logging and a large ski resort at the resort town of Whistler , most of the land in the range is completely undeveloped. Mount Waddington ,
858-575: The most explosive young volcanoes in Canada. Further north the northwesterly structural trend of the Coast Mountains lies partly in a large continental rift responsible for the creation of several volcanoes. These volcanoes form part of the Northern Cordilleran Volcanic Province , the most volcanically active area in Canada. The first event began 130 million years ago when a group of active volcanic islands approached
891-404: The northern motion of the Kula Plate might have been between 140 mm (6 in) and 110 mm (4 in) per year. However, other geologic studies determined the Kula Plate moved at a rate as fast as 200 mm (8 in) per year. Download coordinates as: Nass River The Nass River is a river in northern British Columbia , Canada. It flows 380 km (240 mi) from
924-562: The outlet of an unnamed lake fed directly by the Elaho Glacier . The river starts off by flowing southeast for about 10.2 miles until its confluence with Marlow Creek, which flows from the Pemberton Icefield . The river turns south here and flows south here about 12.6 to its confluence with its largest tributary, Clendinning Creek . Between Marlow Creek and Clendinning Creek, the river flows through spectacular Elaho Canyon,
957-669: The river are navigable. The river is a commercially valuable salmon fishery. The basin of the Nass is the location of the first modern-day treaty settlement in British Columbia, between the government of that province and the Nisga'a Nation. The name Nisga'a is a reduced form of [naːsqaʔ] , which is a loan from Tongass Tlingit , where it means "people of the Nass River". On the term: Archdeacon W. H. Collison, an authority on this subject, and who has resided at Kincolith, Nass bay, since 1883, states as follows: - "The term Nass
990-527: 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
1023-431: The zone of Cretaceous dextral thrust faulting appears to have been widespread. It was also during this period when massive amounts of molten granite intruded highly deformed ocean rocks and assorted fragments from pre-existing island arcs, largely remnants of the Bridge River Ocean. This molten granite burned the old oceanic sediments into a glittering medium-grade metamorphic rock called schist . The older intrusions of
Elaho River - Misplaced Pages Continue
1056-434: Was dammed by a 22.5 km (14.0 mi) long lava flow which came from the Tseax Cone and destroyed the Nisga'a villages and caused the death of at least 2000 Nisga'a people by volcanic gas and poisonous smoke. The volcano has been active on at least two occasions (220 and 650 years ago) in the last millennium. Because of our knowledge of this previous disaster, modern monitoring techniques should include studies of
1089-530: Was completed, Coast Range Arc volcanism returned and sections of the arc were uplifted considerably in latest Cretaceous time. This started a period of mountain building that affected much of western North America called the Laramide orogeny . In particular a large area of dextral transpression and southwest-directed thrust faulting was active from 75 to 66 million years ago. Much of the record of this deformation has been overridden by Tertiary age structures and
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