The Wrangell Volcanic Field is a

volcanic field A volcanic field is an area of Earth's crust that is prone to localized volcanic activity. The type and number of volcanoes required to be called a "field" is not well-defined. Volcanic fields usually consist of clusters of up to 100 volcanoes ...

stretching from eastern

Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U ...

in the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...

to the southwestern

Yukon Territory Yukon (; ; formerly called Yukon Territory and also referred to as the Yukon) is the smallest and westernmost of Canada's three territories. It also is the second-least populated province or territory in Canada, with a population of 43,964 as ...

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by to ...

. The field includes the four highest volcanoes in the United States,

Mount Bona Mount Bona is one of the major mountains of the Saint Elias Mountains in eastern Alaska, and is the fifth-highest independent peak in the United States.This counts both the North and South Peaks of Denali (Mount McKinley), which is not a universal ...

Mount Blackburn Mount Blackburn is the highest peak in the Wrangell Mountains of Alaska in the United States. It is the fifth-highest peak in the United States and the twelfth-highest peak in North America. The mountain is an old, eroded shield volcano, the se ...

, Mount Sanford, and

Mount Churchill Mount Churchill is a volcano in the Saint Elias Mountains and the Wrangell Volcanic Field of eastern Alaska. Churchill and its higher neighbor Mount Bona about to the southwest are both large ice-covered stratovolcanoes, with Churchill being ...

, all of which exceed 15,000 ft (4,600 m) in elevation. It formed as a result of

subduction Subduction is a geological process in which the oceanic lithosphere is recycled into the Earth's mantle at convergent boundaries. Where the oceanic lithosphere of a tectonic plate converges with the less dense lithosphere of a second plate, ...

of the

Pacific Plate The Pacific Plate is an oceanic tectonic plate that lies beneath the Pacific Ocean. At , it is the largest tectonic plate. The plate first came into existence 190 million years ago, at the triple junction between the Farallon, Phoenix, and I ...

beneath the

North American Plate The North American Plate is a tectonic plate covering most of North America, Cuba, the Bahamas, extreme northeastern Asia, and parts of Iceland and the Azores. With an area of , it is the Earth's second largest tectonic plate, behind the Paci ...

at the easternmost end of the

Aleutian Trench The Aleutian Trench (or Aleutian Trough) is an oceanic trench along a convergent plate boundary which runs along the southern coastline of Alaska and the Aleutian islands. The trench extends for from a triple junction in the west with the Ulak ...

. The bulk of the Wrangell Volcanic Field lies within the

Wrangell Mountains The Wrangell Mountains are a high mountain range of eastern Alaska in the United States. Much of the range is included in Wrangell-Saint Elias National Park and Preserve. The Wrangell Mountains are almost entirely volcanic in origin, and they i ...

of Alaska, but the field also extends eastwards into the neighboring

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 r ...

and the

. The east-west length of the field is over 200 mile (320 km), while the width reaches up to 80 miles (130 km) in the central Wrangell Mountains. The field includes numerous

shield volcano A shield volcano is a type of volcano named for its low profile, resembling a warrior's shield lying on the ground. It is formed by the eruption of highly fluid (low viscosity) lava, which travels farther and forms thinner flows than the more vi ...

es,

stratovolcano A stratovolcano, also known as a composite volcano, is a conical volcano built up by many layers (strata) of hardened lava and tephra. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile with a summit crater and peri ...

es,

caldera A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcano eruption. When large volumes of magma are erupted over a short time, structural support for the rock above the magma chamber is ...

complexes,

cinder cones A cinder cone (or scoria cone) is a steep conical hill of loose pyroclastic fragments, such as volcanic clinkers, volcanic ash, or scoria that has been built around a volcanic vent. The pyroclastic fragments are formed by explosive eruptions ...

, and extensive

lava flow Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a moon onto its surface. Lava may be erupted at a volcano or through a fracture in the crust, on land or un ...

s, which have erupted throughout the past 26 million years. All of the higher peaks are less than 5 million years old, since the rate of glacial erosion is very high in this region of extreme snowfall and cold temperatures. Higher elevations of the field above 5,000 ft (1,500 m) are almost entirely covered in

glacier A glacier (; ) is a persistent body of dense ice that is constantly moving under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires distinguishing features, such a ...

s and

icefield An ice field (also spelled icefield) is a mass of interconnected valley glaciers (also called mountain glaciers or alpine glaciers) on a mountain mass with protruding rock ridges or summits. They are often found in the colder climates and highe ...

s, especially on the windward southern side of the ranges. The field is named for

Mount Wrangell Mount Wrangell, in Ahtna K’ełt’aeni or K’ełedi when erupting, is a massive shield volcano located in Wrangell-St. Elias National Park and Preserve in southeastern Alaska, United States. The shield rises over above the Copper River to it ...

, a massive

which has been active historically. The

has had the largest recent eruptions, with two large-magnitude explosive eruptions in the last 2,000 years that blanketed most of the Yukon with

volcanic ash Volcanic ash consists of fragments of rock, mineral crystals, and volcanic glass, created during volcanic eruptions and measuring less than 2 mm (0.079 inches) in diameter. The term volcanic ash is also often loosely used to refer ...

(the

White River Ash The White River Ash is a 1,200-year-old ash deposit. It was formed by two large ( VEI 6) explosive eruptions from the stratovolcano of Mount Churchill that occurred around 850 AD and blanketed of Yukon and Northwest Territories, Canada and the U. ...

). The volcanoes of the western Wrangell Mountains are less than 5 million years old with the youngest lava flows are probably as young as 50,000 years ago. The Canadian portion of the field is dominated by scattered remnants of upper

Cenozoic The Cenozoic ( ; ) is Earth's current geological era, representing the last 66million years of Earth's history. It is characterised by the dominance of mammals, birds and flowering plants, a cooling and drying climate, and the current configu ...

subaerial

lava Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a moon onto its surface. Lava may be erupted at a volcano or through a fracture in the crust, on land or ...

s and

pyroclastic rock Pyroclastic rocks (derived from the el, πῦρ, links=no, meaning fire; and , meaning broken) are clastic rocks composed of rock fragments produced and ejected by explosive volcanic eruptions. The individual rock fragments are known as pyrocl ...

s. Over large areas extrusive rocks lie in flat undisturbed piles on a Cenozoic surface of moderate relief. Locally, however,

strata In geology and related fields, a stratum ( : strata) is a layer of rock or sediment characterized by certain lithologic properties or attributes that distinguish it from adjacent layers from which it is separated by visible surfaces known as e ...

of the same age have been affected by a late pulse of tectonism, during which they were faulted, contorted into tight symmetrical folds, or overridden by pre-Cenozoic baserocks along southwesterly dipping thrust faults. Considerable recent uplift, accompanied by rapid erosion, has reduced once vast areas of upper Cenozoic volcanic rocks to small isolated remnants. Although no centers younger than late

Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recen ...

are known in Canada, the eruption of

rhyolite Rhyolite ( ) is the most silica-rich of volcanic rocks. It is generally glassy or fine-grained (aphanitic) in texture, but may be porphyritic, containing larger mineral crystals ( phenocrysts) in an otherwise fine-grained groundmass. The miner ...

pumice Pumice (), called pumicite in its powdered or dust form, is a volcanic rock that consists of highly vesicular rough-textured volcanic glass, which may or may not contain crystals. It is typically light-colored. Scoria is another vesicular v ...

, from

near the head of

Klutlan Glacier Klutlan Glacier is a long glacier in the U.S. state of Alaska. It is located southwest of Mount Nazirean and flows east across the border with Canada, then north to form the headwaters of the Klutlan River. Its native name was reported in 1891 ...

blanketed large areas of northwestern Canada with

tephra Tephra is fragmental material produced by a volcanic eruption regardless of composition, fragment size, or emplacement mechanism. Volcanologists also refer to airborne fragments as pyroclasts. Once clasts have fallen to the ground, they r ...

some 2,000 years ago. Most of volcanoes of the Western Wrangell Mountains are not like the other volcanoes located around the

Pacific Rim The Pacific Rim comprises the lands around the rim of the Pacific Ocean. The '' Pacific Basin'' includes the Pacific Rim and the islands in the Pacific Ocean. The Pacific Rim roughly overlaps with the geologic Pacific Ring of Fire. List of ...

. Rather than erupting explosive lavas forming stratovolcanoes, they have been built by the buildup of hundreds of comparatively fluid lava flows to form shield volcanoes. Only the young Mount Wrangell still shows its shield-like form; the other, commonly older volcanoes have had much of their original form removed by glacial and other erosional processes, such as Rabbit Mountain and

Felsite Peak Felsite Peak is an eroded outcrop, volcanic outcrop in the Wrangell Volcanic Field, Yukon, Yukon Territory, Canada, located 54 km south of Silver City, Yukon, Silver City, 8 km southwest of Snowshoe Peak and 30 km east of Pinnacle ...

, which are now eroded to form an

outcrop An outcrop or rocky outcrop is a visible exposure of bedrock or ancient superficial deposits on the surface of the Earth. Features Outcrops do not cover the majority of the Earth's land surface because in most places the bedrock or superficia ...

. Major volcanoes of the Wrangell Volcanic Field include: *

, , Saint Elias Mountains *

, , Wrangell Mountains * Mount Sanford, , Wrangell Mountains *

, , Saint Elias Mountains *

, , Wrangell Mountains *

Atna Peaks Atna Peaks is an eroded stratovolcano or shield volcano in the Wrangell Mountains of eastern Alaska. It is located in Wrangell–Saint Elias National Park about east of Mount Blackburn, the second-highest volcano in the United States, and just ...

, , Wrangell Mountains * Regal Mountain, , Wrangell Mountains * Mount Jarvis, , Wrangell Mountains *

Mount Drum Mount is often used as part of the name of specific mountains, e.g. Mount Everest. Mount or Mounts may also refer to: Places * Mount, Cornwall, a village in Warleggan parish, England * Mount, Perranzabuloe, a hamlet in Perranzabuloe parish, C ...

, , Wrangell Mountains Volcanoes of the Canadian portion of the Wrangell Volcanic Field include: *

, , Coast Mountains * Rabbit Mountain, , Nutzotin Mountains

References

* * * *

External links

Alaska Volcano Observatory - Wrangell Volcanic FieldNational Resources Canada: Catalogue of Canadian volcanoes
{{Coord missing, Alaska Volcanic fields of Alaska Volcanoes of Yukon Volcanic fields of Canada Landforms of Copper River Census Area, Alaska Potentially active volcanoes Polygenetic volcanic fields Landforms of Unorganized Borough, Alaska he:ראנגל-סנט אליאס#השדה הגעשי

See also

References

External links