Volcanism in Canada

Canada has examples of almost every type of volcano found on earth, including stratovolcanoes, calderas, cinder cones, shield volcanoes, maars, submarine volcanoes and tuyas. Most of Canada's volcanoes are located in British Columbia. Several mountains that many British Columbians look at every day are dormant volcanoes. Most of them have erupted during the Pleistocene or Holocene epochs, and others have the potential to erupt in the near future.

Western Canada is commonly thought to occupy a gap in the Pacific Ring of Fire between the Cascade volcanoes of the western United States and the Aleutian volcanoes of Alaska, yet the Cordillera of British Columbia and Yukon includes more than 100 separate volcanic centers that have been active during the Quaternary.

Volcanism in British Columbia and Yukon

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The Mount Meager volcanic complex as seen from the east near Pemberton, BC. Summits left to right are Capricorn Mountain, Mount Meager, and Plinth Peak.
Western Canada lies in an area of active tectonics and volcanism, but the scattered population has witnessed few eruptions due to the remoteness of the volcanoes and their low level of activity. There are over 200 potentially-active volcanic centers that stretch northward from the Cascade Range, 49 of which have erupted in the past 10,000 years[1] and many of which have been active in the past two million years.

Ten to fifteen million years ago, floods of basaltic lava erupted on a gently undulating topography with relief of about 7000 m (2,000 ft) and built up flat-lying plateaus in central British Columbia and Yukon Territory covering more than 39,000 km (1500 sq mi).

Numerous shield volcanoes developed during the Tertiary period in north-central British Columbia and some were active intermittently to recent times. Mount Edziza and Level Mountain are most spectacular examples. Mount Edziza is a stratovolcano consisting of a basal shield of basaltic flows surmounted by a central vent and flanked by numerous satellite cones, ash beds and blocky lavas. The complex has a long history of volcanic eruption that began about 10 million years ago and ended about 1300 years ago. The volcanoes are grouped into several volcanic fields and volcanic belts:

The Garibaldi Volcanic Belt is a north-south range of volcanoes in southwestern British Columbia. It is the northern extension of the Cascade Volcanic Arc in the northwestern United States (including Mount Rainier and Mount St. Helens), and contains the most explosive young volcanoes in Canada. It was formed by subduction of the Juan de Fuca Plate at the Cascadia subduction zone. Eruption styles within the belt range from effusive to explosive, with compositions from basalt to rhyolite. A major catastrophic eruption occurred in the Garibaldi Volcanic Belt about 2,350 years ago at a volcanic complex called Mount Meager. The eruption sent an ash column at least 20 km high into the stratosphere and dammed the Lillooet River with breccia. The Garibaldi Volcanic Belt contains two extra volcanic fields, the Franklin Glacier Volcano and Mount Silverthrone, which lie 140 and 190 kilometres northwest of the main volcanic belt. These volcanoes are originally part of the eroded Miocene Pemberton Volcanic Belt.

The Anahim Volcanic Belt is an east-west line of volcanoes stretching from just north of Vancouver Island to near Quesnel, British Columbia. These volcanoes probably formed when the North American Plate moved over a hotspot, similar to the one feeding the Hawaiian Islands called the Anahim hotspot. It contains three major shield volcanoes called the Rainbow Range, Ilgachuz Range and Itcha Range. The last volcanic eruption within the belt was about 7000 years ago at a small tree-covered cinder cone called Nazko Cone. The volcano's oldest eruption is approximately 340,000 years old.

The Stikine Volcanic Belt (also called the Northern Cordilleran Volcanic Province) is the most active volcanic region in Canada, contaning more than 100 potentially active volcanoes. Several eruptions are known to have occurred within this region in the past 400 years and contains Canada's largest volcanoes. It formed as a result of faulting, cracking, rifting and the interaction between the Pacific Plate and the North American Plate. The Fort Selkirk Volcanic Field is Canada's northernmost Holocene volcanic field. The youngest cone, Volcano Mountain, produced young nephelinitic lava flows that remain unvegetated and appear to be only a few hundred years old. However, dating of sediments in a lake impounded by the lava flows indicated that the youngest flows could not be younger than mid-Holocene and could be early Holocene or older.

The Chilcotin Plateau Basalts in southern British Columbia is an area of small lava flows about 150 kilometers ofrom the Pacific Ocean. It is thought to have formed as a result of back-arc extension behind the Cascadia subduction zone. Most of the volcanoes erupted while the Garibaldi Volcanic Belt was just forming. However, there have been smaller eruptions during the Pleistocene period.

Enlarge picture
Mount Cayley as seen from its southeast slopes
The Wells Gray-Clearwater Volcanic Field in southeastern British Columbia consists of numerous small, basaltic volcanoes and extensive lava flows. The origin of the volcanism is yet unknown but is probably related to crust thinning. Many indivdual volcanoes have been active for the last 3 million years. Some of the lava flows are similar to those that erupted at Volcano Mountain in the Yukon, which is called olivine nephelinite. The only maar-like volcano known in Canada is found in this field.

The Wrangell Volcanic Field lies mostly in Alaska, but extends into southeastern Yukon. It was formed by subduction of the Pacific Plate beneath the North American Plate at the easternmost end of the Aleutian Trench. The Canadian portion is dominated by Tertiary lavas with minor alkaline and calc-alkaline lavas that overlie a leaky transform fault.

Eruptions of basaltic to rhyolitic volcanoes and hypabyssal rocks of the Alert Bay Volcanic Belt in northern Vancouver Island are probably linked with the subducted margin flanked by the Explorer and Juan de Fuca plates at the Cascadia subduction zone. It appears to have been active during the Pliocene and Pleistocene time. However, no Holocene eruptions are known, and volcanic activity in the belt has likely ceased.

Monitoring Canadian volcanoes

Volcano monitoring in Canada is a lower priority than other hazards, such as earthquakes, tsunamis and landslides. Most of Canada's volcanoes are located in remote locations, even though some volcanoes pose a significant threat to local population. However, as for earthquake monitoring, future eruptions in Canada are expected and could have a large effect on people that live in the region. Over the past 50 years, the Geological Survey of Canada has known past activity at Canada's volcanoes. However, there is still not enough knowledge about the occurrence of their eruptions to expect which volcanoes will possibly erupt next and what their effects will be. Volcano monitoring in Canada is continuing, but none of the volcanoes are being satisfactorily monitored to let scientists verify how active their magma chambers and systems are. If a Canadian volcano turns highly tense, the seismic monitoring system will possibly sense the growing of movement at the volcanoes.

A scenario of an eruption at Mount Cayley shows how western Canada is vulnerable to an eruption. The scenario is based on past activity in the Garibaldi Volcanic Belt and involves both effusive and explosive eruptions. The scenario impact is largely a result of the concentration of vulnerable infrastructure in valleys.

Recent volcanic activity

Many Canadian volcanoes continue to be geologically active. The most geologically recent volcanic eruptions include: Western Canada is also seismically active. 10 volcanoes in Canada appear related to seismic activity since 1975, including: Mount Silverthrone, Mount Meager, Wells Gray-Clearwater Volcanic Field, Mount Garibaldi, Mount Cayley, Castle Rock, Lava Fork Valley, Mount Edziza, Hoodoo Mountain and Crow Lagoon.[2]

The last eruption of the Tseax River Cone is Canada's worst known geophysical disaster. The eruption produced a 22.5 km long lava flow, destroying two Nisga'a villages and resulted in the death of approximately 2000 Nisga'a people by poisonous smoke and gases. The lava flows traveled south 5 km where they crossed the border into Alaska and dammed the Blue River. The Nass River valley was inundated by the lava flows and contain abundant tree molds and lava tubes. The event happened at the same time with the arrival of the first European explorers to penetrate the uncharted coastal waters of northern British Columbia. Today, the basaltic lava deposits are a draw to tourists and are part of the Nisga'a Memorial Lava Beds Provincial Park.

Volcanism outside British Columbia and Yukon

Canadian Shield

Volcanism has occurred in other regions, apart from British Columbia and the Yukon. The Canadian Shield contains some of the most ancient volcanoes in Canada and on earth. It has over 150 volcanic belts (now deformed and eroded down to nearly flat plains) that range from 600 to 2800 million years old. Each belt probably grew by the coalescence of accumulations erupted from numerous vents, making the tally of volcanoes in the hundreds. Many of Canada's major ore deposits are associated with Precambrian volcanoes. The Sturgeon Lake Caldera in Kenora District, Ontario is one of the world's best preserved mineralized Neoarchean caldera complexes, which is some 2.7 billion years old.[3] Pillow lavas in the Northwest Territories are about 2600 million years old and are preserved in the Cameron River Volcanic Belt. The pillow lavas in rocks over 2 billion years old in the Canadian Shield signify that great oceanic volcanoes existed during the early stages of the formation of the Earth's crust. Ancient volcanoes play an important role in estimating Canada's mineral potential. Many volcanic belts bear ore deposits that are related to the volcanism. Consequently geologists study volcanic belts to understand the volcanoes and the environment in which they erupted, and to provide a working model for mineral exploration.

Some of the most ancient geological remnants of basaltic plains lie in Canada's Precambrian Shield. Eruption of plateau lavas near the Coppermine River southwest of Coronation Gulf in the Arctic, built an extensive volcanic plateau about 1200 million years ago with an area of about 170,000 km² (65,000 sq mi) representing a volume of lavas of at least 500,000 cu km (120,000 cu mi).



About 200 million years ago, just as the Atlantic Ocean was beginning to form, the area northwest of Hudson Bay was over the New England hotspot. Kimberlite volcanoes were formed, carrying diamonds to the Earth's surface. About 50 million years later, as the Atlantic Ocean opened slightly, the hotspot was under present-day Ontario. As the North American Plate slid westward over the hotspot, it created the magma intrusions of the Monteregian Hills about 125 million years ago in southern Quebec, Canada. In some cases, magma erupted at the surface, feeding volcanoes that have now completely disappeared. Since that time, erosion has removed several kilometres of rock. The hills that are visible today represent the magma chambers and part of the conduits through which the molten rock rose toward the surface. Of all these features, Mont Saint-Hilaire is the best known as a source of rare specimens. Location of numerous kimberlite fields and clusters in Ontario and Quebec lie along the continental extension of the New England hotspot track and represents one of the best examples in the world of kimberlite magmatism activated by mantle plumes.

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Geological map of North America showing (in white) the Midcontinent Rift, here labeled Keweenawan Rift.


The Slave craton located in the Northwest Territories contains the Back River volcanic complex, located 480 km northwest of Yellowknife. It is an Archean stratovolcano, constituting the Back Group of the Yellowknife Supergroup and is somewhat anomalous in the Slave craton because it has undergone only a low degree of deformation and is subhorizontal. The southern half of the complex is exposed at the crest of a small dome. This is the eroded portion of the stratovolcano that has been preserved in an upright position. The complex comprises four volcanic sedimentary sequences (Innerring, Thlewyco, Boucher-Regan, Kelsh) that correspond to the phases of growth and destruction of this stratovolcano.

Lava flows created by the Midcontinent Rift System in the Lake Superior area were formed from basaltic magma. The upwelling of this magma may have been the result of a hotspot which produced a triple junction in the vicinity of Lake Superior. The hotspot made a dome that covered the Lake Superior area. Voluminous basaltic lava flows erupted from the central axis of the rift, similar to the rifting of the Afar Depression of the East African Rift system. The southwest and southeast extensions represent two arms of the triple junction while a third failed arm extends north into Ontario.[4][5] This failed arm now forms Lake Nipigon. It is also possible that the rift is the result of extensional forces behind the continental collision of the Grenville orogeny to the east which in part overlaps the timing of the rift development.[5]

It is likely that later compressive forces from the Grenville orogeny also played a major role in the rift's eventual failure and closure.[5][4] Had the rifting process continued, the eventual result would have been sundering of the North American craton and creation of a sea. The Midcontinent Rift appears to have progressed almost to the point where the ocean intruded.[6] But after about 10-20 million years the rift failed.[5] The Midcontinent Rift is the deepest closed or healed rift yet discovered; no deeper rift ever failed to become an ocean.[6]

Eastern Canada

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Basal contact of a lava flow section of Fundy basin
The North Mountain volcanic range on the mainland portion of southwestern Nova Scotia, is a 201 million year old sequence of tholeiitic basalts, which contains columnar jointing and forms the northern edge of Annapolis Valley along the shore of the Bay of Fundy. The basalts also extend under the Bay of Fundy and parts of it are exposed on the shore at Five Islands, east of Parrsboro on the north side of the bay.[8] Numerous sediment-filled fissures are present near the upper surface of the range. North Mountain is believed to have formed during the opening of the Atlantic Ocean.[9] It is a portion of the Central Atlantic Magmatic Province, which is an gigantic flood basalt and intrusive complex along east coast of the United States, Europe, northwest Africa and South America with a diameter of 4,000 km3. A viscous (<175 m) North Mountain flow at McKay Head shows ~25-cm-thick distinguished layers separated by ~130 centimeter of basalt in its upper 34 meters. Upper layers (5 meters below the lava top) are extremely vesicular while lower ones are pegmatitic and includes a narrow (~2 cm) rhyolite band. The layering of the flow closely resemble that of some Hawaiian lava lakes.[10]

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A volcanic rock formation seen from Cape Dorset, Nunavut.
In southwestern New Brunswick lies the large 17 x 12 kilometer eroded Late Devonian Mount Pleasant Caldera. It is one of few noticeable pre-Cenozoic calderas. Its formation is associated to a period of crustal thinning that followed the Acadian orogeny in the northern Appalachian Mountains.

Mountains of volcanic rock in the northern Arctic Cordillera range from 1.2 billion to 65 million years old,[11] which are part of the High Arctic Large Igneous Province. Even though these volcanics are about 90 million years old, the volcanoes and cinder are still able to be seen.[12] The Late Cretaceous volcanics of northern Ellesmere Island has been uncertainly associated to both the early volcanic activity of the Iceland hotspot and the Alpha Ridge. The Late Cretaceous Strand Fiord Formation is interpreted to represent the cratonward extension of the Alpha Ridge, a volcanic ridge that was active during the formation of the Amerasian Basin.[13]

Major volcanoes

See also

Major eruptions

Eruption date Volcano Cessation date VEI Characteristics Flood Tephra volume
1730 ± 150 yearsTseax River ConeUnknown-lf, exnoN/A
950Mount EdzizaUnknown3lf, exno6 x 107 m3
2350 BPMount MeagerUnknown5pf, lf, lm, ex, ldyesN/A
~10000 BPMount GaribaldiUnknown3lf, exno8.3 x 107 m3
50 million BPBennett Lake Volcanic ComplexUnknown7pf, cc, exno850 km3
Notes: pf=pyroclastic flows, lf=lava flows, lm=lahar mudflows, ex=explosive eruption ld=lava dome collapse, cc=caldera collapse, fl=Flood.

References

1. ^ The Vulnerability of Canada to Volcanic Hazards Retrieved on 2007-07-27
2. ^ Volcanoes of Canada Retrieved on 2007-09-19
3. ^ Caldera Volcanoes Retrieved on 2007-07-27
4. ^ Van Schmus, W. R.; Hinze, W. J. (May 1985). "[https://kuscholarworks.ku.edu/dspace/bitstream/1808/104/1/fac6cit13.pdf The Midcontinent Rift System]". Annual Review of Earth and Planetary Sciences 13: 345-83. DOI:10.1146/annurev.ea.13.050185.002021. Retrieved on 2007-06-10. 
5. ^ Kean, William F. (2000-11-24). Keweenawan Rift System. Field Trips, Northern Wisconsin and Upper Michigan. University of Wisconsin-Milwaukee. Retrieved on 2007-06-08.
6. ^ Reeves, T.K.; Carroll, Herbert B. (April 1999). Geologic Analysis of Priority Basins for Exploration and Drilling. U.S. Department of Energy, Office of Scientific and Technical Information. Retrieved on 2007-06-10.
7. ^ Soofi, Muhammad A.; King, Scott D. (2002-12-06). "Post-rift deformation of the Midcontinent Rift under Grenville tectonism". Tectonophysics 359 (3): 209-23. DOI:10.1016/S0040-1951(02)00512-7. Retrieved on 2007-06-10. 
8. ^ Hot Spots and Rifts in Continental Crust Retrieved on 2007-10-15
9. ^ North Mountain Basalt Retrieved on 2007-10-15
10. ^ Cooling history and differentiation of a thick North Mountain Basalt flow (Nova Scotia, Canada) Retrieved on 2007-10-15
11. ^ Landforms and Climate of the Arctic Cordillera Ecozone Retrieved on 2007-09-26
12. ^ Chris's journal entries Retrieved on 2007-08-05
13. ^ Volcanic style in the Strand Fiord Formation (Upper Cretaceous), Axel Heiberg Island, Canadian Arctic Archipelago Retrieved on 2007-08-15

External links

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Volcano:
1. Large magma chamber
2. Bedrock
3. Conduit (pipe)
4. Base
5. Sill
6. Branch pipe
7. Layers of ash emitted by the volcano
8. Flank 9. Layers of lava emitted by the volcano
10. Throat
11. Parasitic cone
12. Lava flow
13. Vent
14.
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EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001. Their greatest hit, their debut single "time after time", peaked at #13 in the Oricon singles chart.
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stratovolcano, also called a composite volcano, is a tall, conical volcano composed of many layers of hardened lava, tephra, and volcanic ash. These volcanoes are characterized by a steep profile and periodic, explosive eruptions.
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caldera is a volcanic feature formed by the collapse of land following a volcanic eruption. They are often confused with volcanic craters. The word 'caldera' comes from the Spanish language, meaning "cauldron".
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cinder cone or scoria cone is a steep, conical hill of volcanic fragments that accumulate around and downwind from a volcanic vent.[1] The rock fragments, often called cinders or scoria, are glassy and contain numerous gas bubbles "frozen" into place as magma
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A shield volcano is a large volcano with shallow-sloping sides. The name derives from a translation of "Skjaldbreiður", an Icelandic shield volcano whose name means "broad shield," from its resemblance to a warrior's shield.
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maar is a broad, low relief crater that is caused by a phreatic eruption or explosion caused by groundwater contact with hot lava or magma. The maar typically fills with water to form a relatively shallow crater lake.
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Submarine volcanoes are underwater fissures in the earth's surface from which magma can erupt. They estimated to account for 75% of annual magma output. The vast majority are located near areas of tectonic plate movement, known as mid-ocean ridges.
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tuya is a type of distinctive, flat-topped, steep-sided volcano formed when lava erupts through a thick glacier or ice sheet. They are somewhat rare worldwide, being confined to regions which were formerly covered by continental ice sheets and also had active volcanism during the
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British Columbia
Colombie-Britannique


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Largest city Vancouver
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dormant volcano is a volcano which is not currently active (that is, not erupting nor showing signs of unrest), but is believed to be still capable of erupting. This contrasts with an extinct volcano, where it is believed that no eruptions will occur for the foreseeable future.
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Pleistocene epoch (IPA: /'plaɪstəsi:n/) on the geologic timescale is the period from 1,808,000 to 11,550 years BP. The Pleistocene epoch had been intended to cover the world's recent period of repeated glaciations.
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The Holocene epoch is a geological period, which began approximately 11,550 calendar years BP (about 9600 BC) and continues to the present. The Holocene is part of the Neogene and Quaternary periods.
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Western Canada, commonly referred to as the West, is a region of Canada normally including all parts of Canada west of the province of Ontario. From west to east, this comprises four provinces:
  • British Columbia (20 July 1871)
  • Alberta (1 September 1905)

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Pacific Ring of Fire is an area of frequent earthquakes and volcanic eruptions encircling the basin of the Pacific Ocean. In a 40,000 km horseshoe shape, it is associated with a nearly continuous series of oceanic trenches, volcanic arcs, and volcanic belts and/or plate
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Alaska

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Official language(s) None[1]
Spoken language(s) English 85.7%,
Native North American 5.
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A cordillera is an extensive chain of mountains or mountain ranges, especially the principal mountain system of a continent or large island. It comes from the Spanish word cordilla, which is a diminutive of cuerda, or "cord".
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Yukon


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Capital Whitehorse
Largest city Whitehorse
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Government
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Quaternary Period is the geologic time period from the end of the Pliocene Epoch roughly 1.806 million years ago to the present. The Quaternary includes 2 geologic subdivisions — the Pleistocene, including Gelasian that used to belong to Pliocene, and the Holocene
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Western Canada, commonly referred to as the West, is a region of Canada normally including all parts of Canada west of the province of Ontario. From west to east, this comprises four provinces:
  • British Columbia (20 July 1871)
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Cascade Range
The Cascades

Mount Rainier in Washington state


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flood basalt or trapp basalt is the result of a giant volcanic eruption or series of eruptions that coats large stretches of land or the ocean floor with basalt lava. Flood basalts have occurred on continental scales (large igneous provinces) in prehistory, creating great plateaus
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plateau, also called a high plateau or tableland, is an area of highland, usually consisting of relatively flat rural area.

Genesis

A plateau is a large and highland area of fairly level land separated from surrounding land by steep slopes (as in the Tibet),
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A shield volcano is a large volcano with shallow-sloping sides. The name derives from a translation of "Skjaldbreiður", an Icelandic shield volcano whose name means "broad shield," from its resemblance to a warrior's shield.
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Tertiary geological time interval covers roughly the time span between the demise of the non-avian dinosaurs and beginning of the most recent Ice Age, approximately 65 million to 1.8 million years ago.
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Mount Edziza is a potentally active volcanic complex in Regional District of Kitimat-Stikine, British Columbia, Canada. The volcano and the surrounding area are protected within Mount Edziza Provincial Park.
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Level Mountain (officially gazetted as Meszah Peak) is a volcanic cone located 66 kilometers north of Telegraph Creek and 136 kilometers southwest of Zus Mountain. It is one of the highest peaks of the range.
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stratovolcano, also called a composite volcano, is a tall, conical volcano composed of many layers of hardened lava, tephra, and volcanic ash. These volcanoes are characterized by a steep profile and periodic, explosive eruptions.
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