The volcanic history of the Northern Cordilleran Volcanic Province presents a record of volcanic activity in northwestern
British Columbia
British Columbia (commonly abbreviated as BC) is the westernmost province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include rocky coastlines, sandy beaches, ...
, central
Yukon
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 ...
and the
U.S. state
In the United States, a state is a constituent political entity, of which there are 50. Bound together in a political union, each state holds governmental jurisdiction over a separate and defined geographic territory where it shares its sover ...
of easternmost
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.S., ...
. The volcanic activity lies in the northern part of the Western Cordillera of the
Pacific Northwest
The Pacific Northwest (sometimes Cascadia, or simply abbreviated as PNW) is a geographic region in western North America bounded by its coastal waters of the Pacific Ocean to the west and, loosely, by the Rocky Mountains to the east. Though ...
region of
North America
North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...
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 Pacific ...
in this part of North America has existed for millions of years. Continuation of this continental rifting has fed scores of
volcano
A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface.
On Earth, volcanoes are most often found where tectonic plates are ...
es throughout the
Northern Cordilleran Volcanic Province
The Northern Cordilleran Volcanic Province (NCVP), formerly known as the Stikine Volcanic Belt, is a geologic province defined by the occurrence of Miocene to Holocene volcanoes in the Pacific Northwest of North America. This belt of volcanoes ex ...
over at least the past 20 million years (see
Geology of the Pacific Northwest
The geology of the Pacific Northwest includes the composition (including rock, minerals, and soils), structure, physical properties and the processes that shape the Pacific Northwest region of North America. The region is part of the Ring of Fir ...
) and occasionally continued into geologically recent times.
Eruptive activity in the Northern Cordilleran Volcanic Province throughout its 20 million year history has been mainly the production of
alkaline
In chemistry, an alkali (; from ar, القلوي, al-qaly, lit=ashes of the saltwort) is a base (chemistry), basic, ionic compound, ionic salt (chemistry), salt of an alkali metal or an alkaline earth metal. An alkali can also be defined as ...
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 un ...
s, including alkaline
basalt
Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial ...
s. A range of alkaline rock types not commonly found in the Western Cordillera are regionally widespread in the Northern Cordilleran Volcanic Province. These include
nephelinite
Nephelinite is a fine-grained or aphanitic igneous rock made up almost entirely of nepheline and clinopyroxene (variety augite). If olivine is present, the rock may be classified as an olivine nephelinite. Nephelinite is dark in color and may rese ...
,
basanite
Basanite () is an igneous, volcanic (extrusive) rock with aphanitic to porphyritic texture. It is composed mostly of feldspathoids, pyroxenes, olivine, and plagioclase and forms from magma low in silica and enriched in alkali metal oxides that s ...
and
peralkaline
Peralkaline rocks include those igneous rocks which have a deficiency of aluminium such that sodium and potassium are in excess of that needed for feldspar. The presence of aegerine (sodium pyroxene) and riebeckite (sodium amphibole) are indicative ...
phonolite
Phonolite is an uncommon extrusive rock, of intermediate chemical composition between felsic and mafic, with texture ranging from aphanitic (fine-grained) to porphyritic (mixed fine- and coarse-grained). Phonolite is a variation of the igneous ...
,
trachyte
Trachyte () is an extrusive igneous rock composed mostly of alkali feldspar. It is usually light-colored and aphanitic (fine-grained), with minor amounts of mafic minerals, and is formed by the rapid cooling of lava enriched with silica and al ...
and
comendite
Comendite is a hard, peralkaline igneous rock, a type of light blue grey rhyolite. Phenocrysts are sodic sanidine with minor albite and bipyramidal quartz. Iddings, Joseph Paxson, 1913, ''Igneous rocks: composition, texture and classification'', v ...
lavas. The trachyte and comendite lavas are understood to have been created by fractionation of mainly alkali basalt magma in crustal reservoirs. An area of continental rifting, such as the Northern Cordilleran Volcanic Province, would aid the formation of high-level reservoirs of capable size and thermal activity to maintain long-lived fractionation.
In the past 15 million years, at least four large volcanoes have formed their way through dense
igneous
Igneous rock (derived from the Latin word ''ignis'' meaning fire), or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rock is formed through the cooling and solidification of magma or ...
and
metamorphic
Metamorphic rocks arise from the transformation of existing rock to new types of rock in a process called metamorphism. The original rock (protolith) is subjected to temperatures greater than and, often, elevated pressure of or more, causin ...
composed
bedrock
In geology, bedrock is solid Rock (geology), rock that lies under loose material (regolith) within the crust (geology), crust of Earth or another terrestrial planet.
Definition
Bedrock is the solid rock that underlies looser surface mater ...
of this part of North America. This includes
Hoodoo Mountain
Hoodoo Mountain, sometimes referred to as Hoodoo Volcano, is a potentially active stratovolcano in the Northern Interior of British Columbia, Canada. It is located northeast of the Alaska–British Columbia border on the north side of the Isk ...
, the
Mount Edziza volcanic complex
The Mount Edziza volcanic complex is a large and potentially active north-south trending complex volcano in Stikine Country, northwestern British Columbia, Canada, located southeast of the small community of Telegraph Creek. It occupies the sout ...
,
Level Mountain
Level Mountain is a large volcanic complex in the Northern Interior of British Columbia, Canada. It is located north-northwest of Telegraph Creek and west of Dease Lake on the Nahlin Plateau. With a maximum elevation of , it is the second-hig ...
and
Heart Peaks
Heart Peaks, originally known as the Heart Mountains, is a mountain massif in the Northern Interior of British Columbia, Canada. It is northwest of the small community of Telegraph Creek and just southwest of Callison Ranch. With a maximum elev ...
, which are primarily located in northwestern British Columbia. Most notable of these is the 7.5 million year old Mount Edziza volcanic complex, which has had more than 20 eruptions in the past 10,000 years. The only activity present in the Northern Cordilleran Volcanic Province has been occasional
earthquake
An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth's lithosphere that creates seismic waves. Earthquakes can range in intensity, from ...
s and constant boiling of
hot spring
A hot spring, hydrothermal spring, or geothermal spring is a spring produced by the emergence of geothermally heated groundwater onto the surface of the Earth. The groundwater is heated either by shallow bodies of magma (molten rock) or by circ ...
s. However, a high potential exists for renewed eruptive activity that could threaten life and property in the volcanic zone.
Production and rates in volcanism
More than 100 eruptions have occurred in the past 20 million years with a broad range of eruptive styles. These volcanic processes have created a range of different volcanic landforms, including
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 per ...
es,
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 v ...
es,
lava dome
In volcanology, a lava dome is a circular mound-shaped protrusion resulting from the slow extrusion of viscous lava from a volcano. Dome-building eruptions are common, particularly in convergent plate boundary settings. Around 6% of eruptions on ...
s and cinder cones, along with a few isolated examples of rarer volcanic forms such as
tuya
A tuya is a flat-topped, steep-sided volcano formed when lava erupts through a thick glacier or ice sheet. They are rare worldwide, being confined to regions which were covered by glaciers and had active volcanism during the same period.
As lava ...
s. Large persistent volcanoes of the Northern Cordilleran Volcanic Province can remain dormant for hundreds or thousands of years between eruptions and therefore the greatest risk caused by volcanic activity is not always readily apparent. Volcanics older than 14 million years are mainly found in the northern portion of the volcanic province while volcanics ranging from nine to four million years old exist only in the middle of the volcanic province. At least three types of volcanic zones are present in the Northern Cordilleran Volcanic Province, including large persistent
lava plateau
A volcanic plateau is a plateau produced by volcanism, volcanic activity. There are two main types: lava plateaus and pyroclastic plateaus.
Lava plateau
Lava plateaus are formed by highly fluid basaltic lava during numerous successive erup ...
s like those found at the Mount Edziza volcanic complex,
polygenetic volcanoes
Polygenesis can refer to:
* Polygenesis (linguistics), a theory of language origin
* Polygenism, a theory of human origin
* Gene duplication
Gene duplication (or chromosomal duplication or gene amplification) is a major mechanism through whi ...
such as Hoodoo Mountain and
monogenetic volcanoes
Monogenetic may refer to:
* Monogenetic in biology, of or pertaining to monogenesis (Mendelian inheritance)
* Monogenetic volcanic field in geology, a cluster of volcanoes that only erupted once
* Monogenetic theory of pidgins in linguistics, a th ...
like the basaltic cinder cones found throughout the volcanic province. When Northern Cordilleran volcanoes do erupt,
pyroclastic flow
A pyroclastic flow (also known as a pyroclastic density current or a pyroclastic cloud) is a fast-moving current of hot gas and volcanic matter (collectively known as tephra) that flows along the ground away from a volcano at average speeds of bu ...
s, lava flows and
landslide
Landslides, also known as landslips, are several forms of mass wasting that may include a wide range of ground movements, such as rockfalls, deep-seated grade (slope), slope failures, mudflows, and debris flows. Landslides occur in a variety of ...
s can devastate areas away and
mudflow
A mudflow or mud flow is a form of mass wasting involving fast-moving flow of debris that has become liquified by the addition of water. Such flows can move at speeds ranging from 3 meters/minute to 5 meters/second. Mudflows contain a significa ...
s of
volcanic ash
Volcanic ash consists of fragments of rock, mineral crystals, and volcanic glass, created during volcano, volcanic eruptions and measuring less than 2 mm (0.079 inches) in diameter. The term volcanic ash is also often loosely used t ...
and
debris
Debris (, ) is rubble, wreckage, ruins, litter and discarded garbage/refuse/trash, scattered remains of something destroyed, or, as in geology, large rock fragments left by a melting glacier, etc. Depending on context, ''debris'' can refer to ...
can inundate valleys downstream. Falling ash from
explosive eruption
In volcanology, an explosive eruption is a volcanic eruption of the most violent type. A notable example is the 1980 eruption of Mount St. Helens. Such eruptions result when sufficient gas has dissolved under pressure within a viscous magma such ...
s can disrupt human activities hundreds of kilometres downwind, and drifting clouds of fine volcanic ash can cause severe damage to
jet aircraft
A jet aircraft (or simply jet) is an aircraft (nearly always a fixed-wing aircraft) propelled by jet engines.
Whereas the engines in propeller-powered aircraft generally achieve their maximum efficiency at much lower speeds and altitudes, je ...
even hundreds of kilometres away. Volcanic deposits in the Northern Cordilleran Volcanic Province include lava flows, welded and unwelded pyroclastic deposits, hydroclastic deposits and other ice-contact volcanic deposits. The variety of different volcanic deposits is partly due to changes in eruption characteristics from mainly
subaerial eruption A subaerial eruption is any sort of volcanic eruption that occurs on the Earth's surface, or in the open air subaerial, 'under the air', and not underwater or underground. They generally produce pyroclastic flows, lava fountains, and lava flows, whi ...
s to broadly
subglacial eruption
Subglacial eruptions, those of ice-covered volcanoes, result in the interaction of magma with ice and snow, leading to meltwater formation, jökulhlaups, and lahars. Flooding associated with meltwater is a significant hazard in some volcan ...
s throughout the history of the Northern Cordilleran Volcanic Province.
There is evidence of a decline in volcanic activity over the past few million years. This decline in volcanic activity can be grouped into two phases. From eight to four million years ago, volcanism rates were higher than they are at present. Magma production during this volcanic phase was most active from seven to five million years ago and was related to a period of rifting along the Pacific and North American Plate boundary. Between four and three million years ago in the Pliocene epoch, a pause in volcanic activity began to happen. The most recent magmatic phase ranging from two million years ago to present resulted from nearby areas of rifting during a period of compression between the Pacific and North American plates. Volcanism rates during this volcanic phase was most active from two to one million years ago with the construction of 25 volcanic zones then decreased one million years ago with the construction of 11 volcanic zones. To date, the most recent volcanic phase has produced of volcanic material whereas the first phase produced of volcanic material. Even though the rate in volcanism throughout the Northern Cordilleran Volcanic Province has changed considerably, there is no correlation between the rate in magma production and the number of active volcanoes during any interval of time. The present day volcanism rate for the Northern Cordilleran Volcanic Province is considerably lower than the
Cascade Volcanic Arc
The Cascade Volcanoes (also known as the Cascade Volcanic Arc or the Cascade Arc) are a number of volcanoes in a volcanic arc in western North America, extending from southwestern British Columbia through Washington and Oregon to Northern Califo ...
and Hawaiian volcanism rates. However, geologists are aware the temporal volcanic patterns known for the Northern Cordilleran Volcanic Province should be looked at carefully because volcanics that pre-date the last glacial period have been eroded by glacial ice and many of the volcanics have not been directly dated or have not been dated in significant detail to identify more individual temporal patterns.
Lava fountain
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 und ...
s can occur in the Northern Cordilleran Volcanic Province roughly every 100 years.
Large basaltic shield volcanoes throughout the central Northern Cordilleran Volcanic Province form large lava plateaus and are the largest volcanoes of the volcanic zone. These extensive volcanoes are generally larger and more long-lived than volcanoes of adjacent volcanic zones, including the stratovolcanoes of the Cascade and Aleutian arcs.
Mount Shasta
Mount Shasta ( Shasta: ''Waka-nunee-Tuki-wuki''; Karuk: ''Úytaahkoo'') is a potentially active volcano at the southern end of the Cascade Range in Siskiyou County, California. At an elevation of , it is the second-highest peak in the Cascades ...
, the largest stratovolcano in the Cascade Arc and
Mount Veniaminof
Mount Veniaminof (russian: Вулкан Вениаминова) is an active stratovolcano on the Alaska Peninsula. The mountain was named after Ioann (Ivan Popov) Veniaminov (1797–1879), a Russian Orthodox missionary priest (and later a pro ...
, one of the largest and most active volcanoes in the Aleutian Arc, have volumes of at least , less than half of that of the Level Mountain and Edziza shield complexes. The massive Level Mountain shield, occupying an area of and a volume of more than , is the most voluminous and most long-lived volcano of the Northern Cordilleran Volcanic Province. Further south, the Mount Edziza volcanic complex resides as the seconed most voluminous volcano with an area of and a volume of . Just west of Level Mountain lies Heart Peaks, the third most voluminous volcano of the Northern Cordilleran Volcanic Province with an area of . However, remains of a shield volcano that once covered an area of more than are present in the western
Cassiar Mountains
, photo = Cassiar Highway.jpg
, photo_size = 280px
, photo_caption = Cassiar Mountains along Stewart-Cassiar Highway near Good Hope Lake
, country = Canada
, subdivision1_type = Provinces
, subdivision1 ...
as Maitland Volcano.
All of the known most recent eruptions have occurred in British Columbia, although there is evidence for volcanic activity in Yukon in the past thousand years. The two most recent were lava flow eruptions at
Tseax Cone
The Tseax Cone ( ), also called the Tseax River Cone or the Aiyansh Volcano, is a young and active cinder cone and adjacent lava flows associated with the Nass Ranges and the Northern Cordilleran Volcanic Province. It is located east of Crater C ...
in the 18th century and at The Volcano in 1904. Reports of an eruption south of
Gladys Lake
Gladys may refer to:
* Gladys (given name), people with the given name Gladys
* ''Gladys'' (album), a 2013 album by Leslie Clio
* ''Gladys'' (film), 1999 film written and directed by Vojtěch Jasný
Vojtěch Jasný (30 November 1925 – 15 N ...
in northern British Columbia were made by placer miners at the end of the 19th century, but no evidence for this eruption has been found, leading researchers to speculate the eruption as uncertain.
Volcanic activity begins
The first volcanic activity in the Northern Cordilleran Volcanic Province 20 million years ago was infrequent, creating small amounts of volcanic material. This infrequent volcanic activity was interrupted when considerable volcanism began to form the large Level Mountain shield volcano 15 million years ago. The shield volcano forms a broad cliff-bounded lava plateau long and wide, with an average thickness of . Ropy
pāhoehoe
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 und ...
lava flows predominate over blocky
ʻaʻā
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 und ...
lava flows, breccias and tuffs, attesting to a fluid and effusive character for the volcanism.
When the Mount Edziza volcanic complex began to form 7.5 million years ago, volcanism rates in the Northern Cordilleran Volcanic Province increased again. Early volcanic activity of the Mount Edziza volcanic complex seven million years ago constructed Armadillo Peak, the oldest and most central of the four central volcanoes comprising the complex. Its summit is capped by thick fine-grained silica-rich trachyte lava flows that ponded inside the
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 ...
to produce a
lava lake
Lava lakes are large volumes of molten lava, usually basaltic, contained in a volcanic vent, crater, or broad depression. The term is used to describe both lava lakes that are wholly or partly molten and those that are solidified (sometim ...
six million years ago during its final stage of activity. A massive stratovolcano was also formed on top of the Level Mountain shield volcano 7.1 to 5.3 million years ago during this increased period of volcanism when viscous peralkaline trachyte and comendite lavas were erupted. The stratovolcano has a volume of and comprises several volcanic vents, some of which were formally more than in elevation. Glacial ice and streams have since dissected the stratovolcano into a series of valleys with intervening ridges, forming the so-named Level Mountain Range on the central summit of Level Mountain.
More Miocene age volcanics of and years are present at the
Anderson
Anderson or Andersson may refer to:
Companies
* Anderson (Carriage), a company that manufactured automobiles from 1907 to 1910
* Anderson Electric, an early 20th-century electric car
* Anderson Greenwood, an industrial manufacturer
* Anderson Ra ...
and
Moose
The moose (in North America) or elk (in Eurasia) (''Alces alces'') is a member of the New World deer subfamily and is the only species in the genus ''Alces''. It is the largest and heaviest extant species in the deer family. Most adult mal ...
bays of
Atlin Lake
Atlin Lake (Lingít: ''Áa Tlein'') is the largest natural lake in the Canadian province of British Columbia. The northern tip of the lake is in Yukon, as is Little Atlin Lake. However, most of the lake lies within the Atlin District of British Co ...
in northern British Columbia that represent remnants of columnar-jointed basalt lava flows. This indicates these volcanics are older than the Edziza and Level Mountain shields and they might represent the oldest volcanic events in the Northern Cordilleran Volcanic Province. However, their distinctive chemical characteristics and apparent large age differences compared to other volcanics in the Atlin area could also indicate that these columnar-jointed basalt lava flows are not part of the Northern Cordilleran Volcanic Province assemblage. In northern Yukon, similar aged volcanics can be found, including million year old volcanics at Forty Mile and million year old volcanics at Sixty Mile. However, the type of volcanic landforms these volcanics represent are unknown.
Volcanism 5.3 to 1.6 million years ago
In northern British Columbia, remnants of a shield volcano are found throughout the western Cassiar Mountains. This prehistoric shield volcano, known as Maitland Volcano, was erupted from five to four million years ago on a mature eroded surface as thin hawaiite and basaltic lava flows engulfed the surrounding landscape. Remnants of this prehistoric shield volcano include a cluster of 14 volcanic plugs and scattered cliff-bounded basaltic lava flows.
At the southern end of the Mount Edziza volcanic complex, volcanism constructed the
Spectrum Range
The Spectrum Range, formerly called the Spectrum Mountains and the Rainbow Mountains, is a subrange of the Tahltan Highland in the Stikine Country of northwestern British Columbia, 20 km west of the Stewart-Cassiar Highway, south of Mount ...
three to 2.5 million years ago. Named for its extensive colouration, this nearly circular lava dome is up to thick and more than wide with a basaltic shield volcano forming its broad base. Since its formation, the Spectrum Range lava dome has been deeply cut by erosion, forming an extensive valley system. This valley system exposes large comendite and trachyte lava flows of the dome, including faults of a hidden wide caldera.
A series of lava domes were constructed in the Level Mountain Range alpine valley system 4.5 to 2.5 million years ago. These domes intrude the glacially eroded core of the stratovolcano and headward erosion has further modified the Level Mountain shield by incising youthful V-shaped stream canyons into the lava plateau margin.
Volcanism 1.6 million to 10,000 years ago
Throughout the
Pleistocene
The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fina ...
epoch 1.6 million to 10,000 years ago, volcanism in the Northern Cordilleran Volcanic Province was broadly associated with glacial ice and ice sheets during glacial periods, including the large Cordilleran Ice Sheet. This volcano-ice association can be recognized in three different physiographic settings, each displaying unique relationships between topography, volcanism and glacial ice. The first volcano-ice interaction is displayed as tuyas, including
Tuya Butte
Tuya Butte is a tuya in the Tuya Range of north-central British Columbia, Canada. It is a bit less isolated from other ranges than neighbouring Mount Josephine. Some of the other volcanoes in the area include South Tuya, Ash Mountain, and Math ...
, on the
Tanzilla Plateau
The Tanzilla Plateau is a plateau in the Stikine Country of the Northern Interior of British Columbia, Canada. It is a sub-plateau of the Stikine Plateau and is located east of the Tuya River, north of the Stikine River and surrounding Dease Lak ...
in the
Northern Interior of British Columbia
Northern may refer to the following:
Geography
* North, a point in direction
* Northern Europe, the northern part or region of Europe
* Northern Highland, a region of Wisconsin, United States
* Northern Province, Sri Lanka
* Northern Range, a ra ...
. This sub-section of the
Stikine Plateau
The Stikine Plateau is a plateau in northern British Columbia, Canada. It lies between the Boundary Ranges of the Coast Mountains on the west and southwest and the Cassiar Mountains along its northeast, and between the Skeena Mountains on its sout ...
consists of large flatlands with hills of low relief, and might have been one of the areas of ice accumulation for the Cordilleran Ice Sheet. Tanzilla Plateau volcanism throughout the Pleistocene epoch was basaltic
subglacial eruption
Subglacial eruptions, those of ice-covered volcanoes, result in the interaction of magma with ice and snow, leading to meltwater formation, jökulhlaups, and lahars. Flooding associated with meltwater is a significant hazard in some volcan ...
s. The most generally known
subglacial volcano
A subglacial volcano, also known as a glaciovolcano, is a volcanic form produced by subglacial eruptions or eruptions beneath the surface of a glacier or ice sheet which is then melted into a lake by the rising lava. Today they are most ...
es are distinctive tuyas, which commonly reach more than in elevation. Other volcanic forms also exist, some of which are basic and others that are probably the products of weathering. The subdued relief on the Tanzilla Plateau strongly influenced edifice morphologies, favoring broad-based tuyas. The hydrological conditions in these areas likely were controlled by relatively uniform ice thickness and gentle topography.
The seconed type of volcano-ice interaction is located only to the east, south and southwest of the Tanzilla Plateau, in the Cassiar Mountains,
Skeena Mountains
The Skeena Mountains, also known as the Skeenas, are a subrange of the Interior Mountains of northern British Columbia, Canada, essentially flanking the upper basin of the Skeena River. They lie just inland from the southern end of the Boundary ...
and in the Boundary Ranges. Volcanic activity in these locations is also largely mafic in composition, but the extensive elevations of these areas had a much more impressive influence on glaciation and subglacial volcanism. High altitude glaciation took over when the Cordilleran Ice Sheet was not present and even when buried by the Cordilleran Ice Sheet, basal ice movement was strongly influenced by the deep, pre-glacial drainages. Accordingly, the erosional remnants of subglacial volcanoes are minor and intermittent. In the Skeena Mountains, separated outcrops of pillow lava and volcanic breccia are generally found side by side on the summits of sharp rugged mountain ridges, with presumably temporally-associated pyroclastic rocks having collected downslope.
The third type of volcano-ice interaction is geographically restricted to three volcanoes, including Level Mountain, the Mount Edziza volcanic complex and Hoodoo Mountain. All three volcanoes are broad enough to hold ice caps that likely altered regional ice flow while still being altered by the Cordilleran Ice Sheet at individual periods. The Mount Edziza and Level Mountain complexes have shelves of older lava with elevations more than and have been zones of volcanic activity long enough that their geothermal activities might have had effects on movements of the Cordilleran Ice Sheet much like the
Grímsvötn
Grímsvötn (; ''vötn'' = "waters", singular: ) is a volcano with a (partially subglacial) fissure system located in Vatnajökull National Park, Iceland. The volcano itself is completely subglacial and located under the northwestern side of the Va ...
caldera in Iceland, which has been a significant heat source beneath the vast
Vatnajökull
Vatnajökull ( Icelandic pronunciation: , literally "Glacier of Lakes"; sometimes translated as Vatna Glacier in English) is the largest and most voluminous ice cap in Iceland, and the second largest in area in Europe after the Severny Island ice ...
icecap. At the Edziza complex, most of the subglacial products were formed on top of the main lava plateau, which now rises at least in elevation above adjacent stream valleys. The Edziza complex consists of a collection of mafic subglacial products, but more unusually, including Hoodoo Mountain and Level Mountain, comprises some of the largest deposits of peralkaline felsic subglacial volcanics known. At the Edziza and Level Mountain complexes, glacier hydrology of the Cordilleran Ice Sheet was possibly dominated by a complicated interaction between drainage on the flat plateaus under relatively thinner ice and drainage within nearby steep valleys filled with much thicker ice.
Just northwest of Level Mountain, the
Heart Peaks
Heart Peaks, originally known as the Heart Mountains, is a mountain massif in the Northern Interior of British Columbia, Canada. It is northwest of the small community of Telegraph Creek and just southwest of Callison Ranch. With a maximum elev ...
shield volcano rises with a
topographic prominence
In topography, prominence (also referred to as autonomous height, relative height, and shoulder drop in US English, and drop or relative height in British English) measures the height of a mountain or hill's summit relative to the lowest contou ...
of above the
Nahlin Plateau
The Nahlin Plateau is a plateau in northwestern British Columbia, Canada, located between the Sheslay River and Tuya River on the west and east and the Nahlin River and the Stikine River to the north and south. It is a subplateau of the Stikine Pl ...
with rhyolitic lava domes capping its summit. Heart Peaks is made of flat-lying basaltic and trachybasaltic lava flows and pyroclastic rocks. The most recent eruption at the shield is of dominantly Pleistocene age and late-stage Holocene activity is uncertain.
On the divide between the head of the Omineca and
Bear
Bears are carnivoran mammals of the family Ursidae. They are classified as caniforms, or doglike carnivorans. Although only eight species of bears are extant, they are widespread, appearing in a wide variety of habitats throughout the Nor ...
rivers,
The Thumb
The Thumb is a region and a peninsula of the U.S. state of Michigan, so named because the Lower Peninsula is shaped like a mitten. The Thumb area is generally considered to be in the Central Michigan region, east of the Tri-Cities and north of M ...
rises with a
topographic prominence
In topography, prominence (also referred to as autonomous height, relative height, and shoulder drop in US English, and drop or relative height in British English) measures the height of a mountain or hill's summit relative to the lowest contou ...
of above gently sloping benchland near the crest of the
Connelly Range
The Connelly Range is a subrange of the Hogem Ranges of the Omineca Mountains, located between Bear Lake and the headwaters of the Omineca River in northern British Columbia, Canada. As the Omineca is in the Arctic Ocean drainage and Bear Lake t ...
. It is the largest among a cluster of seven steep-sided volcanic plugs associated with dikes, lava flows and remnants of cinder cones.
Ne Ch'e Ddhawa
Ne Ch'e Ddhäwa is the Northern Tutchone name for an eroded tuya approximately 7 km up the Yukon River from Fort Selkirk (UTM zone 8V 383955 E, 69600091 N) (it has been informally called Wootten's Cone) in the Fort Selkirk Volcanic Field of centr ...
, an extinct volcano in the Fort Selkirk Volcanic Field of central Yukon, reaches a height of near the junction of the Pelly and
Yukon
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 ...
rivers. It was erupted subglacially under the Cordilleran Ice Sheet between 0.8 and one million years ago, depositing
hyaloclastite
Hyaloclastite is a volcanoclastic accumulation or breccia consisting of glass (from the Greek ''hyalus'') fragments (clasts) formed by quench fragmentation of lava flow surfaces during submarine or subglacial extrusion. It occurs as thin margin ...
tuff
Tuff is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption. Following ejection and deposition, the ash is lithified into a solid rock. Rock that contains greater than 75% ash is considered tuff, while rock cont ...
s, breccias and pillow breccias that now form the volcano.
In the Boundary Ranges of northwestern British Columbia, Hoodoo Mountain began its formation at least 100,000 years ago mostly under glacial ice of the Cordilleran Ice Sheet. More than 90% of Hoodoo Mountain was formed during this eruptive period and interlayed peralkaline phonolitic and trachytic lava flows and hyaloclastites are the main volcanics comprising the volcano. On the northern flank of Hoodoo Mountain lies the smaller
Little Bear Mountain
Little Bear Mountain is a basaltic Pleistocene age tuya in the Boundary Ranges of the Coast Mountains that adjoins Hoodoo Mountain to the north. Little Bear Mountain is part of the Northern Cordilleran Volcanic Province.
See also
* List of vol ...
, a tuya which also formed in the Pleistocene epoch.Ice Peak, which overlaps the northern flank of Armadillo Peak, began to form when the regional Cordilleran Ice Sheet began retreating from the Mount Edziza volcanic complex 1,600,000 years ago. It is a stratovolcano that was constructed when large areas of the Edziza lava plateau were free from glacial ice, but additional parts of the Mount Edziza volcanic complex were likely still covered by glacial ice. Volcanic activity at Ice Peak during this period produced lava flows and pyroclastic rocks, which mixed with
meltwater
Meltwater is water released by the melting of snow or ice, including glacial ice, tabular icebergs and ice shelves over oceans. Meltwater is often found in the ablation zone of glaciers, where the rate of snow cover is reducing. Meltwater can be ...
to produce
debris flow
Debris flows are geological phenomena in which water-laden masses of soil and fragmented rock rush down mountainsides, funnel into stream channels, entrain objects in their paths, and form thick, muddy deposits on valley floors. They generally ...
s. As Ice Peak began to form, basic lava spread to the flanks of Ice Peak where it formed meltwater lakes and combines with and forms part of the adjacent shield volcano.
Mount Edziza
Mount Edziza is a stratovolcano in the Stikine Country of northwestern British Columbia, Canada. The volcano and the surrounding area are protected within Mount Edziza Provincial Park. It consists of multiple peaks and ridges, with several glaci ...
, a steep-sided stratovolcano overlapping the northern flank of Ice Peak and the most northerly of the four central volcanoes comprising the Mount Edziza volcanic complex, began to form a million years ago when the Cordilleran Ice Sheet retreated from the upper flanks of the Edziza lava plateau. Its smooth northern and western flanks are only slightly channeled by erosion and they curve up to a circular summit ridge which surrounds a central ice-filled caldera in diameter. Active
cirque
A (; from the Latin word ') is an amphitheatre-like valley formed by glacial erosion. Alternative names for this landform are corrie (from Scottish Gaelic , meaning a pot or cauldron) and (; ). A cirque may also be a similarly shaped landform ...
s on Edziza's eastern flank have breached the caldera rim, exposing the remnants of several lava lakes that ponded in the caldera 900,000 years ago. As well, subglacial eruptions around the flanks of Mount Edziza and Ice Peak constructed piles of pillow lava and hyaloclastite.
Prindle Volcano, the northernmost volcano of the Northern Cordilleran Volcanic Province and one of the most isolated volcanoes in Alaska, was formed on the Yukon-Tanana upland during the Pleistocene epoch. It is a small cinder cone made of basanite with a deep breached volcanic crater at its summit. Extending from Prindle's breached volcanic crater is a long basanite lava flow that flowed southeast of the cone then flowed southwest into a river valley.
The Cassiar Mountains and Tanzilla Plateau in northern British Columbia are dominated by tuyas of the broad Tuya Volcanic Field. These flat-topped, steep-sided subglacial volcanoes were formed when magma intruded into and melted a vertical pipe in the overlying Cordilleran Ice Sheet. At least six volcanoes formed beneath glacial ice close to
Tuya Lake
Tuya Lake, located in northwestern British Columbia, Canada, presumably derives its name from the presence of nearby steep-sided, flat-topped volcanoes, known as tuyas. The lake is situated just south of Tuya Butte at a latitude of about 59 degree ...
South Tuya
South Tuya, also called Southern Tuya, is a tuya clustered around Tuya Lake in the Northern Cordilleran Volcanic Province in British Columbia, Canada. The base of South Tuya comprises hyaloclastite and pillow lava indicating that the volcano forme ...
,
Tuya Butte
Tuya Butte is a tuya in the Tuya Range of north-central British Columbia, Canada. It is a bit less isolated from other ranges than neighbouring Mount Josephine. Some of the other volcanoes in the area include South Tuya, Ash Mountain, and Math ...
,
Mathews Tuya
Mathews Tuya is a tuya in northcentral British Columbia. It is one of the six tuyas close to Tuya Lake. It has been partly glaciated and Ar-Ar geochronology shows that is it about 730,000 years old. It mainly comprises palagonitized tephra (tuff, ...
. Ash Mountain at the head of Parallel Creek consists of pillow lava and hyaloclastite, South Tuya consists of loose volcanic debris with basaltic dikes intruding into the volcano and Tuya Butte and Mathews Tuya consist of pillow lava and hyaloclastite on its lower flanks with subaerially erupted lava flows at their flat-topped summits.
Volcanism in the past 10,000 years
Numerous eruptions have occurred since the beginning of the
Holocene
The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene togethe ...
epoch 10,000 years ago, when the vast Cordilleran Ice Sheet retreated rapidly at the end of the last glacial period. The majority of volcanic eruptions throughout the Holocene have occurred in British Columbia while fewer Holocene eruptions have occurred in Yukon.
In the early Holocene epoch, volcanism at Hoodoo Mountain produced lava flows with well-preserved
lava channel A lava channel is a stream of fluid lava contained within zones of static (i.e., solid and stationary) lava or lava levees. The initial channel may not contain levees per se, until the parental flow solidifies over what develops into the channel and ...
s on its northwestern and southwestern flanks and are largely unglaciated, suggesting the last eruptive activity at Hoodoo Mountain occurred in an ice-free environment. These lava flows originated from the mountain's flat-topped summit and volcanic vents on its flanks. Geologists do not always agree on the dates of these more recent eruptions, some dating them to nice thousand years ago, others to as recently as seven thousand years ago.
At the southern end of the Northern Cordilleran Volcanic Province near the border between British Columbia and the
Alaska Panhandle
Southeast Alaska, colloquially referred to as the Alaska(n) Panhandle, is the southeastern portion of the U.S. state of Alaska, bordered to the east and north by the northern half of the Canadian province of British Columbia (and a small part ...
, lava flows and eight small volcanoes form a volcanic field known as the
Iskut-Unuk River Cones
The Iskut volcanic field is a group of volcanoes and lava flows on and adjacent to the Alaska–British Columbia border in the Boundary Ranges of the Coast Mountains. All the volcanoes in this volcanic field are situated in British Columbia alo ...
. Lava flows date back 70,000 years ago during the Pleistocene epoch, but the eight volcanoes were likely formed between nine thousand and a few hundred years ago. At least five volcanoes sent lava down the Iskut and Unuk River valleys and their tributaries. The other three volcanoes were formed when glacial ice existed adjacent to the associated volcanic vents, creating scoria, pillow lava and hyaloclastite breccia. Volcanism in the Iskut River area has created at least ten lava flows and Lava Fork at least three. The most recent eruption of the Iskut-Unuk River Cones at The Volcano (also called Lava Fork volcano) in 1904 is also the most recent volcanic eruption in Canada.
Immediately north of the junction of the Pelly and Yukon rivers,
Volcano Mountain
Volcano Mountain is a cinder cone in central Yukon, Yukon Territory, Canada, located a short distance north of Fort Selkirk, near the confluence of the Pelly River, Pelly and Yukon Rivers. Volcano Mountain is called Nelrúna in the Northern Tutc ...
in central Yukon consists of a cinder cone and a series of lava flows. It is the youngest volcano in the Fort Selkirk Volcanic Field and lava flows originated from fractures in the volcano's flank. These lava flows extend northeast and southwest of the volcano. The northeastern lava flow extends from Volcano Mountain whereas the southwestern lava flow extends from the volcano. These lava flows are composed of olivine nephelinite, a type of lava not commonly found on Earth. Nephelinite lavas are usually interpreted to have originated much deeper in the Earth's mantle unlike the typical basaltic lava found throughout the Northern Cordilleran Volcanic Province. The nephelinite lava flows at Volcano Mountain remain clear from vegetation and seem to be only a few hundred years old. However, dating of sediments in a lake dammed by the nephelinite lavas suggest the lava flows could not be younger than mid-Holocene and could be early Holocene or older. Therefore, the exact age for the most recent eruptions at Volcano Mountain are unknown.
At the southernmost end of the Northern Cordilleran Volcanic Province, Tseax Cone lies in a valley above and east of the
Tseax River
The Ksi Sii Aks (formerly Tseax River) is a tributary of the Nass River in northwestern British Columbia, Canada. It is most notable as the namesake of Tseax Cone, a volcano within its basin that was responsible for an eruption in the 17th century ...
. It is a young Holocene age cinder cone that was the source for a major basalt lava flow eruption around the years 1750 and 1775 that travelled into the Tseax River, damming it and forming
Lava Lake
Lava lakes are large volumes of molten lava, usually basaltic, contained in a volcanic vent, crater, or broad depression. The term is used to describe both lava lakes that are wholly or partly molten and those that are solidified (sometim ...
. The lava flow subsequently travelled north to the
Nass River
The Nass River is a river in northern British Columbia, Canada. It flows from 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 Inl ...
, where it filled the flat valley floor for an additional , making the entire lava flow long. Native legends from
Nisga'a
The Nisga’a , often formerly spelled Nishga and spelled in the Nisga'a language as (pronounced ), are an Indigenous people of Canada in British Columbia. They reside in the Nass River valley of northwestern British Columbia. The name is a r ...
people in the area tell of a prolonged period of disruption by the volcano, including the destruction of two Nisga'a villages known as Lax Ksiluux and Wii Lax K'abit. Nisga'a people dug pits for shelter but at least 2,000 Nisga'a people were killed due to
volcanic gas
Volcanic gases are gases given off by active (or, at times, by dormant) volcanoes. These include gases trapped in cavities (vesicles) in volcanic rocks, dissolved or dissociated gases in magma and lava, or gases emanating from lava, from volcanic ...
es and poisonous smoke (most likely
carbon dioxide
Carbon dioxide (chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is transpar ...
). This is Canada's worst known geophysical disaster and is the only eruption in Canada for which legends of
First Nations
First Nations or first peoples may refer to:
* Indigenous peoples, for ethnic groups who are the earliest known inhabitants of an area.
Indigenous groups
*First Nations is commonly used to describe some Indigenous groups including:
**First Natio ...
people have been proven true. As of 1993, the Tseax Cone quietly rests in Nisga'a Memorial Lava Beds Provincial Park.
More than 20 eruptions have occurred at the Mount Edziza volcanic complex in the past 10,000 years, including Mess Lake Cone,
Kana Cone Kana Cone is a red nested cinder cone in northern British Columbia, Canada, located northeast of Eve Cone in Mount Edziza Provincial Park.
Adopted 2 January 1980 on 104G/12, as submitted by Geological Survey of Canada.https://apps.gov.bc.ca/pub/bc ...
Icefall Cone
Icefall Cone is a cinder cone in northern British Columbia, Canada. It is thought to have last erupted during the Holocene period and forms part of the Mount Edziza volcanic complex.Ridge Cone,
Williams Cone
Williams Cone is a satellite cone of Mount Edziza, located east of Telegraph Creek. It lies just off the northern edge of the Tencho Icefield and is one of the many postglacial cinder cones that lie on the Mount Edziza volcanic complex. Williams ...
,
Walkout Creek Cone
Walkout Creek is a tributary of Raspberry Creek (British Columbia), Raspberry Creek, which in turn is a tributary of Mess Creek, part of the Stikine River drainage basin, watershed in northwest part of the Provinces and territories of Canada, prov ...
,
Moraine Cone Moraine Cone is a cinder cone in northern British Columbia, Canada. It is thought to have last erupted in the Holocene period and is part of the Mount Edziza volcanic complex.Sidas Cone,Sleet Cone,Storm Cone,
Triplex Cone
Triplex Cone is a cinder cone in northern British Columbia, Canada. It is thought to have last erupted in the Holocene period.
,
Twin Cone Twin Cone is a cinder cone in northern British Columbia, Canada. It is thought to have last erupted in the Holocene period.
Coffee Crater
Coffee Crater is a well-preserved cinder cone south of Mount Edziza, British Columbia, Canada. It was formed during the Holocene period. It is within the Snowshoe lava field, part of the Mount Edziza volcanic complex.
See also
* List of volcano ...
The Saucer The Saucer is a cinder cone in northern British Columbia, Canada. It is thought to have last erupted in the Holocene epoch. and the well-preserved
Eve Cone
Eve Cone is a well-preserved black cinder cone on the Big Raven Plateau, British Columbia, Canada. It is one of the 30 cinder cones on the flanks of the massive shield volcano of Mount Edziza that formed in the year 700, making it one of the mos ...
. These cinder cones were formed no more than the year 700 based on the age of burnt plant stems still rooted in former soil under of loose basaltic fragments. The cones were built on the basaltic fragments and blocky lava fields surrounding the cones. The Snowshoe Lava Field on the southern end of the
Big Raven Plateau
The Big Raven Plateau is a volcanic plateau, lava plateau in northern British Columbia, Canada, located west of Mount Edziza in Mount Edziza Provincial Park. It is part of the Tahltan Highland, which is the southwestern sub-region of the Stikine P ...
is one of the areas of young lava flows in the region while the
Desolation Lava Field
The Desolation Lava Field is a volcanic field associated with the Mount Edziza volcanic complex in British Columbia, Canada. It covers on the northern end of the Mount Edziza volcanic complex and is the largest area of the youngest lava flows. The ...
on the northern end of the Big Raven Plateau is the largest area of young lava flows, covering an area of . The longest lava flow is . This volcanic activity was followed by at least two younger, but still undated eruptions.
Two well-preserved reddish-brown basaltic cinder cones cap a small shield volcano of the Alligator Lake volcanic complex in southcentral Yukon. These cinder cones are likely younger than the adjacent Holocene glaciation and both cones were erupting at the same time. These cinder cones produced alkaline olivine basalt to basanitic lava flows that extend to the north. Lava flows from the northeast cone are the largest, extending from the cone and expanding to a width of at the end. Sections of the lava flows comprise spinel lherzolite,
xenolith
A xenolith ("foreign rock") is a rock fragment (country rock) that becomes enveloped in a larger rock during the latter's development and solidification. In geology, the term ''xenolith'' is almost exclusively used to describe inclusions in igne ...
s composed of granite and megacrysts of olivine, pyroxene and spinel.
An eruption was reported in the
Atlin Volcanic Field
The Atlin Volcanic Field, also called the Llangorse Volcanic Field and the Surprise Lake Volcanic Field, is a group of late-Pleistocene to Holocene cinder cones that lies on the Teslin Plateau east of Atlin Lake, Canada. The largest volcanic fea ...
by placer miners on November 8, 1898. Miners working in the area reportedly were able to work during the dark nights due to the glow of the eruption. A news report published on December 1, 1898 by the American newspaper publisher
The New York Times
''The New York Times'' (''the Times'', ''NYT'', or the Gray Lady) is a daily newspaper based in New York City with a worldwide readership reported in 2020 to comprise a declining 840,000 paid print subscribers, and a growing 6 million paid ...
stated:
In 1898 the Atlin area was in dispute with the Alaska-British Columbia boundary, leading American news broadcasters stating the Atlin area was in Alaska rather than in northwestern British Columbia. This Alaska-British Columbia boundary dispute was eventually resolved by arbitration in 1903 and no evidence for the 1898 eruption has been found, leading researchers to speculate the eruption and report as uncertain. However, given the location of the placer operations from which the eruption was supposedly visible (Pine, Birch, Discovery, and McKee creeks) and the reported location of the volcano south of Gladys Lake, the vent might possibly be in the very rugged and inaccessible Coast Mountains south or southwest of Atlin Lake.
On the south side of the
Khutzeymateen Inlet
Khutzeymateen Inlet (also spelled K’tzim-a-Deen in the Tsimshian language of the Gits'iis people) is one of the lesser principal inlets of the British Columbia Coast. It is important in being part of the first area in Canada protected to prese ...
north of
Prince Rupert
Prince Rupert of the Rhine, Duke of Cumberland, (17 December 1619 (O.S.) / 27 December (N.S.) – 29 November 1682 (O.S.)) was an English army officer, admiral, scientist and colonial governor. He first came to prominence as a Royalist cavalr ...
, thick basaltic Plinian eruption tephra deposits are recognized at Crow Lagoon. These volcanics originated from a volcanic vent that remains unidentified. However, existence of
volcanic bomb
A volcanic bomb or lava bomb is a mass of partially molten rock (tephra) larger than 64 mm (2.5 inches) in diameter, formed when a volcano ejects viscous fragments of lava during an eruption. Because volcanic bombs cool after they l ...
s at the Plinian tephra deposits indicates the volcanic vent of its origin is located nearby. The age of these volcanics is unknown but they were deposited throughout the Holocene epoch.
In the Pleistocene Tuya Volcanic Field, small subaerial shield volcanoes and postglacial cinder cones and lava flows can be recognized. At least one of these volcanoes is of Holocene age.Gabrielse Cone near the headwaters of
Iverson Creek Iverson Creek is a small river in San Mateo County, California and is a tributary of Pescadero Creek.
It flows about from its source on Butano Ridge in Pescadero Creek County Park
Pescadero Creek Park, located near Loma Mar, California, Loma Mar ...
in the
Stikine Ranges
The Stikine Ranges are a group of mountain ranges and mountainous plateaus in northwestern British Columbia, Canada. They are the northernmost subdivision of the Cassiar Mountains and among the least explored and most undeveloped parts of the pro ...
rises with an elevation of and a diameter of . It is mostly made of loose basaltic
scoria
Scoria is a pyroclastic, highly vesicular, dark-colored volcanic rock that was ejected from a volcano as a molten blob and cooled in the air to form discrete grains or clasts.Neuendorf, K.K.E., J.P. Mehl, Jr., and J.A. Jackson, eds. (2005) ''G ...
with a
volcanic crater
A volcanic crater is an approximately circular depression in the ground caused by Volcano, volcanic activity. It is typically a bowl-shaped feature containing one or more vents. During Types of volcanic eruptions, volcanic eruptions, molten magm ...
deep at its summit. The northeastern flank of Gabrielse Cone is ruptured where remnants of a basaltic lava flow exists. This basalt lava flow extends more than from the volcano and there is no proof Gabrielse Cone was formed during or before the Cordilleran Ice Sheet. As a result, Gabrielse Cone is unmistakably younger than 11,000 years and it was formed in the Holocene epoch.
Recent activity and hazards
At least five volcanoes have had seismic activity since 1985, including the Mount Edziza volcanic complex (eight events), Castle Rock (two events), Hoodoo Mountain (eight events), Crow Lagoon (four events) and The Volcano (five events). Seismic data suggests that these volcanoes still contain living
magma chamber
A magma chamber is a large pool of liquid rock beneath the surface of the Earth. The molten rock, or magma, in such a chamber is less dense than the surrounding country rock, which produces buoyant forces on the magma that tend to drive it upw ...
s, indicating possible future eruptive activity. Although the available data does not allow a clear conclusion, these observations are further indications that some Northern Cordilleran volcanoes are potentially active and that their associated hazards may be significant. The seismic activity correlates both with some of Canada's most youthful volcanoes and with long-lived volcanoes with a history of significant explosive activity, such as Hoodoo Mountain and the Mount Edziza volcanic complex. To date, Edziza and Hoodoo pose the greatest threats in the Northern Cordilleran Volcanic Province. A large
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 vol ...
deposit scattered throughout the Edziza complex highlights one of the significant volcanic hazards associated with the complex, including the possibility of a large explosive eruption. This large pumice deposit indicates that the Mount Edziza volcanic complex has a history of producing not only fluid and passive basaltic lava flows, but also more silica-rich trachytic and rhyolitic lava flows and explosive eruptions. The silica-rich compositions are similar to those associated with the most catastrophic eruptions on Earth. A large explosive eruption at the Edziza complex could produce an
eruption column
An eruption column or eruption plume is a cloud of super-heated ash and tephra suspended in gases emitted during an explosive volcanic eruption. The volcanic materials form a vertical column or plume that may rise many kilometers into the air a ...
that would affect parts of the
Pacific Northwest
The Pacific Northwest (sometimes Cascadia, or simply abbreviated as PNW) is a geographic region in western North America bounded by its coastal waters of the Pacific Ocean to the west and, loosely, by the Rocky Mountains to the east. Though ...
. Similarly, high eruption columns from Hoodoo Mountain would disrupt air traffic between Canada, Alaska and Asia. The flat summit of Hoodoo Mountain is also covered by an ice cap more than thick. An eruption from Hoodoo's summit would cause considerable melting of the ice cap to create large
flood
A flood is an overflow of water ( or rarely other fluids) that submerges land that is usually dry. In the sense of "flowing water", the word may also be applied to the inflow of the tide. Floods are an area of study of the discipline hydrol ...
s and
lahar
A lahar (, from jv, ꦮ꧀ꦭꦲꦂ) is a violent type of mudflow or debris flow composed of a slurry of pyroclastic material, rocky debris and water. The material flows down from a volcano, typically along a river valley.
Lahars are extreme ...
s, which would have significant effects on adjacent river valleys. This includes the
Iskut River
The Iskut River, located in the northwest part of the province of British Columbia is the largest tributary of the Stikine River, entering it about above its entry into Alaska.
From its source at Kluachon Lake the Iskut River flows south and wes ...
just on the southern flank of Hoodoo Mountain, which is the host for a large amount of
salmon
Salmon () is the common name for several list of commercially important fish species, commercially important species of euryhaline ray-finned fish from the family (biology), family Salmonidae, which are native to tributary, tributaries of the ...
, logging operations and a large mining and mineral exploration camp. Edziza and Hoodoo Mountain are two of the three most hazardous volcanoes in Western Canada that have been active in the past 10,000 years, the other being the
Mount Meager massif
The Mount Meager massif is a group of volcanic peaks in the of the Coast Mountains in southwestern British Columbia, Canada. Part of the Cascade Volcanic Arc of western North America, it is located north of Vancouver at the northern end of the ...
in the
Garibaldi Volcanic Belt
The Garibaldi Volcanic Belt is a northwest–southeast trending volcanic chain in the Pacific Ranges of the Coast Mountains that extends from Watts Point in the south to the Ha-Iltzuk Icefield in the north. This chain of volcanoes is located in ...
of southwestern British Columbia which produced a large-scale eruption 2,350 years ago that sent ash as far as central
Alberta
Alberta ( ) is one of the thirteen provinces and territories of Canada. It is part of Western Canada and is one of the three prairie provinces. Alberta is bordered by British Columbia to the west, Saskatchewan to the east, the Northwest Ter ...
.
Lava flows in the Northern Cordilleran Volcanic Province are among the least hazardous, even though they can be enormously destructive to property in their path. This is because lava generally moves slowly enough for people to get out of their way, though this is dependent on the viscosity of the lava. Lava flows typically have secondary hazards, including the destruction of buildings and ejection of
volcanic gas
Volcanic gases are gases given off by active (or, at times, by dormant) volcanoes. These include gases trapped in cavities (vesicles) in volcanic rocks, dissolved or dissociated gases in magma and lava, or gases emanating from lava, from volcanic ...
es. Forest fires started by lava flows are also a possibility in this part of Canada. The typical lava fountains in the Northern Cordilleran Volcanic Province are commonly associated with lava flows, but these do not normally reach heights more than a few hundred metres. Therefore, the dangers caused by lava fountains are only adjacent to the erupting volcano.
Currently, no volcanoes in the Northern Cordilleran Volcanic Province are monitored closely enough by the
Geological Survey of Canada
The Geological Survey of Canada (GSC; french: Commission géologique du Canada (CGC)) is a Canadian federal government agency responsible for performing geological surveys of the country, developing Canada's natural resources and protecting the en ...
to ascertain how active their magma chambers are. An existing network of
seismographs
A seismometer is an instrument that responds to ground noises and shaking such as caused by earthquakes, volcanic eruptions, and explosions. They are usually combined with a timing device and a recording device to form a seismograph. The output ...
has been established to monitor tectonic earthquakes and is too far away to provide a good indication of what is happening beneath them. It may sense an increase in activity if a volcano becomes very restless, but this may only provide a warning for a large eruption. It might detect activity only once a volcano has started erupting. The
Interagency Volcanic Event Notification Plan
The Interagency Volcanic Event Notification Plan (IVENP) is a program in Canada established to outline the notification procedure of some of the main agencies that would be involved in response to a volcanic eruption in Canada, an eruption close to ...
, Canada's volcanic emergency notification program, was established to outline the notification procedure of some of the main agencies that would be involved in response to a volcanic eruption in Canada, an eruption close to Canada's borders, or an eruption significant enough to have an effect on Canada and its people. It focuses primarily on aviation safety because jet aircraft can quickly enter areas of volcanic ash. The program notifies all impacted agencies that have to deal with volcanic events. Aircraft are rerouted away from hazardous ash and people on the ground are notified of potential ash fall.
See also
*
Volcanology of Canada
Volcanic activity is a major part of the geology of Canada and is characterized by many types of volcanic landform, including lava flows, volcanic plateaus, lava domes, cinder cones, stratovolcanoes, shield volcanoes, submarine volcanoes, calder ...
*
Volcanology of Northern Canada
Volcanism of Northern Canada has produced hundreds of volcanic areas and extensive lava formations across Northern Canada. The region's different volcano and lava types originate from different tectonic settings and types of volcanic eruptions, ra ...
*
Volcanology of Western Canada
Volcanism of Western Canada has produced lava flows, lava plateaus
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 eru ...