Hoodoo Mountain
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Hoodoo Mountain, sometimes referred to as Hoodoo Volcano, is a potentially active
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 ...
in the
Northern Interior , settlement_type = Region of British Columbia , image_skyline = , nickname = "The Interior" , subdivision_type = Country , subdivision_name = , subdivision_type1 = Province , subdivi ...
of
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, ...
, Canada. It is located northeast of the
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., ...
–British Columbia border on the north side of 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 ...
opposite of the mouth of the Craig River. With a summit elevation of and 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 , Hoodoo Mountain is one of many prominent peaks within the
Boundary Ranges The Boundary Ranges, also known in the singular and as the Alaska Boundary Range, are the largest and most northerly subrange of the Coast Mountains. They begin at the Nass River, near the southern end of the Alaska Panhandle in the Canadian p ...
of the
Coast Mountains The Coast Mountains (french: La chaîne Côtière) are a major mountain range in the Pacific Coast Ranges of western North America, extending from southwestern Yukon through the Alaska Panhandle and virtually all of the Coast of British Columbia ...
. Its flat-topped summit is covered by an
ice cap In glaciology, an ice cap is a mass of ice that covers less than of land area (usually covering a highland area). Larger ice masses covering more than are termed ice sheets. Description Ice caps are not constrained by topographical features ...
more than thick and at least in diameter. Two
valley glacier A valley is an elongated low area often running between hills or mountains, which will typically contain a river or stream running from one end to the other. Most valleys are formed by erosion of the land surface by rivers or streams ove ...
s surrounding the northwestern and northeastern sides of the mountain have retreated significantly over the last hundred years. They both originate from a large
icefield An ice field (also spelled icefield) is a mass of interconnected valley glaciers (also called mountain glaciers or alpine glaciers) on a mountain mass with protruding rock ridges or summits. They are often found in the colder climates and highe ...
to the north and are the sources of two
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 ...
streams. These streams flow along the western and eastern sides of the
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 ...
before draining into the Iskut River. Much of Hoodoo Mountain was formed beneath glacial ice and it has been overlain by glaciers or an ice cap throughout much of its history. The main rock types composing the volcano are
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 ...
and
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 ...
, which were deposited during six periods of eruptive activity beginning about 85,000 years ago. Most of these eruptive periods were characterized by steady flows of
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 ...
but at least one period of explosive activity occurred as indicated by the presence of
pyroclastic rock Pyroclastic rocks (derived from the el, πῦρ, links=no, meaning fire; and , meaning broken) are clastic rocks composed of rock fragments produced and ejected by explosive volcanic eruptions. The individual rock fragments are known as pyrocl ...
s. The latest eruptive period began about 10,000 years ago with the eruption of extensive lava flows that cover the north–central, northwestern and southeastern mountain slopes. A lava flow covering the southwestern slope may have been produced by a more recent eruption within the last couple of hundred years. Although no historical eruptions are known at Hoodoo Mountain, there have been periods of
seismic activity 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, fr ...
since at least the mid-1980s, indicating possible future eruptions and
volcanic hazards A volcanic hazard is the probability a volcano, volcanic eruption or related geophysical event will occur in a given geographic area and within a specified window of time. The risk that can be associated with a volcanic hazard depends on the proxi ...
. Hoodoo Mountain lies in a remote area of
Cassiar Land District The Cassiar Land District is a cadastral survey subdivision of the province of British Columbia, Canada, created with rest of those on Mainland British Columbia via the Lands Act of the Colony of British Columbia (1858–1866), Colony of British Col ...
that has undergone
mineral exploration Mining in the engineering discipline is the extraction of minerals from underneath, open pit, above or on the ground. Mining engineering is associated with many other disciplines, such as mineral processing, exploration, excavation, geology, and ...
since at least the early 1900s. This exploration led to the discovery of
copper Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkis ...
,
silver Silver is a chemical element with the Symbol (chemistry), symbol Ag (from the Latin ', derived from the Proto-Indo-European wikt:Reconstruction:Proto-Indo-European/h₂erǵ-, ''h₂erǵ'': "shiny" or "white") and atomic number 47. A soft, whi ...
and
gold Gold is a chemical element with the symbol Au (from la, aurum) and atomic number 79. This makes it one of the higher atomic number elements that occur naturally. It is a bright, slightly orange-yellow, dense, soft, malleable, and ductile met ...
within the Iskut River
floodplain A floodplain or flood plain or bottomlands is an area of land adjacent to a river which stretches from the banks of its channel to the base of the enclosing valley walls, and which experiences flooding during periods of high discharge.Goudi ...
where two underground mines operated between 1988 and 1999. Geological studies have been conducted at Hoodoo Mountain since at least the 1940s; the most detailed studies occurred in the 1990s and 2000s. The area has a mostly cool and wet climate with heavy precipitation. As a result, a limited number of mammals live around Hoodoo Mountain. Trees of the
pine A pine is any conifer tree or shrub in the genus ''Pinus'' () of the family Pinaceae. ''Pinus'' is the sole genus in the subfamily Pinoideae. The World Flora Online created by the Royal Botanic Gardens, Kew and Missouri Botanical Garden accep ...
and
willow Willows, also called sallows and osiers, from the genus ''Salix'', comprise around 400 speciesMabberley, D.J. 1997. The Plant Book, Cambridge University Press #2: Cambridge. of typically deciduous trees and shrubs, found primarily on moist s ...
families form forests in the regional river valleys and on the lower slopes of the volcano. They compose one of many
ecoregion An ecoregion (ecological region) or ecozone (ecological zone) is an ecologically and geographically defined area that is smaller than a bioregion, which in turn is smaller than a biogeographic realm. Ecoregions cover relatively large areas of l ...
s that occur throughout British Columbia. Due to its remoteness, Hoodoo Mountain can only be accessed by air, by water or by trekking great distances on foot. The closest communities are more than away from the mountain.


Geography


Background

Hoodoo Mountain lies within the Boundary Ranges Ecoregion, a mountainous region of the Coast Mountains in southeastern Alaska and northwestern British Columbia characterized by rugged, largely ice-capped mountains of
granitic A granitoid is a generic term for a diverse category of coarse-grained igneous rocks that consist predominantly of quartz, plagioclase, and alkali feldspar. Granitoids range from plagioclase-rich tonalites to alkali-rich syenites and from quart ...
and
metamorphic rock 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 ...
s.
Mountain hemlock ''Tsuga mertensiana'', known as mountain hemlock, is a species of hemlock native to the west coast of North America, found between Southcentral Alaska and south-central California. Description ''Tsuga mertensiana'' is a large evergreen conifer ...
,
western hemlock ''Tsuga heterophylla'', the western hemlock or western hemlock-spruce, is a species of hemlock native to the west coast of North America, with its northwestern limit on the Kenai Peninsula, Alaska, and its southeastern limit in northern Sonoma ...
and
Sitka spruce ''Picea sitchensis'', the Sitka spruce, is a large, coniferous, evergreen tree growing to almost tall, with a trunk diameter at breast height that can exceed 5 m (16 ft). It is by far the largest species of spruce and the fifth-larg ...
form forests on valley bottoms and lower valley slopes. They are overlooked by an extensive
alpine tundra Alpine tundra is a type of natural region or biome that does not contain trees because it is at high elevation, with an associated alpine climate, harsh climate. As the latitude of a location approaches the poles, the threshold elevation for alp ...
zone consisting primarily of large icefields, glaciers and barren rock. Several large river valleys with wide
braided channel A braided river, or braided channel, consists of a network of river channel (geography), channels separated by small, often temporary, islands called braid bars or, in English usage, ''aits'' or ''eyots''. Braided streams tend to occur in rivers ...
s penetrate the Boundary Ranges Ecoregion;
black cottonwood ''Populus trichocarpa'', the black cottonwood, western balsam-poplar or California poplar, is a deciduous broadleaf tree species native to western North America. It is used for timber, and is notable as a model organism in plant biology. ...
occur on their floodplains. A limited number of mammal species thrive in this ecoregion, such as
hoary marmot The hoary marmot (''Marmota caligata'') is a species of marmot that inhabits the mountains of northwest North America. Hoary marmots live near the tree line on slopes with grasses and forbs to eat and rocky areas for cover. It is the largest Nor ...
s and
mountain goat The mountain goat (''Oreamnos americanus''), also known as the Rocky Mountain goat, is a hoofed mammal endemic to mountainous areas of western North America. A subalpine to alpine species, it is a sure-footed climber commonly seen on cliffs and ...
s, which inhabit the alpine tundra zone. The Boundary Ranges Ecoregion is part of the Coast and Mountains Ecoprovince which forms part of the Humid Maritime and Highlands Ecodivision. The Boundary Ranges Ecoregion is subdivided into three
ecosection An ecosection is a biogeographic unit smaller than an ecoregion that contains minor physiographic, macroclimatic or oceanographic variations. They are a virtual ecological zone in the Canadian province of British Columbia, which contains 139 ecosec ...
s, the Southern Boundary Ranges Ecosection being the main ecosection at Hoodoo Mountain. This ecosection is cut by several streams, including the
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 ...
, Bear and Unuk rivers, which drain directly into marine
channels Channel, channels, channeling, etc., may refer to: Geography * Channel (geography), in physical geography, a landform consisting of the outline (banks) of the path of a narrow body of water. Australia * Channel Country, region of outback Austral ...
or
sounds In physics, sound is a vibration that propagates as an acoustic wave, through a transmission medium such as a gas, liquid or solid. In human physiology and psychology, sound is the ''reception'' of such waves and their ''perception'' by the ...
. The only settlements in the Southern Boundary Ranges Ecosection are Kincolith, Stewart and Hyder, the latter two of which are connected by the Stewart Highway. There is no human population within of Hoodoo Mountain but 2,330 people live within . Forests of this ecosection grow on the lower slopes of Hoodoo Mountain except for its northeastern flank where rock and ice are dominant. Much of this forest cover lies at elevations below .


Climate

Hoodoo Mountain has a
maritime Maritime may refer to: Geography * Maritime Alps, a mountain range in the southwestern part of the Alps * Maritime Region, a region in Togo * Maritime Southeast Asia * The Maritimes, the Canadian provinces of Nova Scotia, New Brunswick, and Princ ...
glacial climate that is intermediate between fully coastal maritime and
continental Continental may refer to: Places * Continent, the major landmasses of Earth * Continental, Arizona, a small community in Pima County, Arizona, US * Continental, Ohio, a small town in Putnam County, US Arts and entertainment * ''Continental'' ( ...
climates. Moist air from the Pacific Ocean brings intense precipitation over the region while simultaneously allowing cold
Arctic The Arctic ( or ) is a polar regions of Earth, polar region located at the northernmost part of Earth. The Arctic consists of the Arctic Ocean, adjacent seas, and parts of Canada (Yukon, Northwest Territories, Nunavut), Danish Realm (Greenla ...
air to pass down through the
Portland Canal , image = Hyder Alaska IMG 0276 (22495379342).jpg , alt = , caption = Portland Canal from Hyder, Alaska , image_bathymetry = , alt_bathymetry = , caption_bathymetry = , location = Alaska and British Columbia , group = , coordinates ...
into the
Dixon Entrance The Dixon Entrance (french: Entrée Dixon) is a strait about long and wide in the Pacific Ocean at the Canada–United States border, between the U.S. state of Alaska and the province of British Columbia in Canada. The Dixon Entrance is part o ...
where it flows into British Columbia's
North Coast North Coast or Northcoast may refer to : Antigua and Barbuda * Major Division of North Coast, a census division in Saint John Parish Australia *New South Wales North Coast, a region Canada *The British Columbia Coast, primarily the communiti ...
. Therefore, the regional climate is mostly cool and wet with
snowpack Snowpack forms from layers of snow that accumulate in geographic regions and high elevations where the climate includes cold weather for extended periods during the year. Snowpacks are an important water resource that feed streams and rivers as th ...
s and heavy precipitation. About of precipitation falls during the summer months of June, July and August while up to of precipitation can be expected during the winter months of December, January and February. In summer the average temperature is whereas the average winter temperature sits at . The annual average temperature is .


Glaciers

Two valley glaciers wrap partially around the base of Hoodoo Mountain, both of which are actively retreating.
Hoodoo Glacier Hoodoo Glacier is a glacier in northwestern British Columbia, Canada, located on the western flank of Hoodoo Mountain. It lies at the headwaters of the Hoodoo River. The glacier originates from the Andrei Icefield. See also *List of glaciers in ...
surrounding its northwestern base is the source of the
Hoodoo River The Hoodoo River is a tributary of the Iskut River in the northwest part of the province of British Columbia, Canada, located west of Hoodoo Mountain and the Twin River in Cassiar Land District. From its source in Hoodoo Glacier the Hoodoo River f ...
which flows south into the Iskut River. It has lost about of its total thickness over the last 700 years and its terminus has retreated since the 1920s. At the terminus of Hoodoo Glacier is a roughly and lake which may occupy a previously drained depression. The western side of the glacier contains a small possibly drained ice-marginal lake.
Twin Glacier Twin Glacier is a glacier in northwestern British Columbia, Canada, located on the northern and eastern flanks of Hoodoo Mountain. It lies at the headwaters of the Twin River. The glacier originates from the Andrei Icefield. See also *List of g ...
surrounds the northwestern base of Hoodoo Mountain and is the largest of the two valley glaciers. It is the source of the
Twin River The Twin River is a tributary of the Iskut River in the northwest part of the province of British Columbia, Canada. From its source in Twin Glacier the Twin River flows south for about ,Length measured using BCGNIS coordinates, topographic maps, a ...
which also flows south into the Iskut River. Several changes have taken place at this double-lobed glacier since the 1920s. Its terminus has retreated about , having formerly flowed around both sides of a north–south trending ridge. A small
moraine-dammed lake A moraine-dammed lake occurs when the terminal moraine has prevented some meltwater from leaving the valley. Its most common shape is that of a long ribbon (ribbon lake). Example of moraine dammed lakes include: *Argentina/Chile: General Carre ...
lies along the southwestern margin of Twin Glacier. Hoodoo Glacier and Twin Glacier are separated by a
ridgeline A ridge or a mountain ridge is a geographical feature consisting of a chain of mountains or hills that form a continuous elevated crest for an extended distance. The sides of the ridge slope away from the narrow top on either side. The line ...
extending north of Hoodoo Mountain. They have cut deep valleys into the older regional
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 ...
and have interacted with Hoodoo Mountain intermittently since 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 ...
. Both glaciers originate from the
Andrei Icefield The Andrei Icefield is a large icefield in the Boundary Ranges of the Coast Mountains in northwestern British Columbia, Canada. It is located northwest of the community of Stewart in Cassiar Land District. The icefield is the source of many v ...
centered northeast of Hoodoo Mountain. This large glacial field is informally named after the son of Olav Mokievsky-Zubok, a
glaciologist Glaciology (; ) is the scientific study of glaciers, or more generally ice and natural phenomena that involve ice. Glaciology is an interdisciplinary Earth science that integrates geophysics, geology, physical geography, geomorphology, climato ...
who carried out significant glaciological work in the Coast Mountains from the 1960s to the 1970s. The summit of Hoodoo Mountain contains an ice cap that persists at elevations greater than . It varies from thick and has a diameter of , attaining a minimum volume of . Its circular shape and higher elevation have made it relatively stable to
climate change In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to E ...
, having undergone minor retreat and thinning only at its very edges. It therefore maintains at least partial snow cover during all months of the year. At the north–central end of the ice cap lies a prominent
nunatak A nunatak (from Inuit ''nunataq'') is the summit or ridge of a mountain that protrudes from an ice field or glacier that otherwise covers most of the mountain or ridge. They are also called glacial islands. Examples are natural pyramidal peaks. ...
called The Horn or Horn Nunatak. It consists of pyroclastic rock surrounding a core of lava.


Geology


Background

Hoodoo Mountain is part of 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 ...
(NCVP), a broad area of volcanoes extending from northwestern British Columbia northwards through
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 ...
into easternmost Alaska.
Volcanism Volcanism, vulcanism or volcanicity is the phenomenon of eruption of molten rock (magma) onto the surface of the Earth or a solid-surface planet or moon, where lava, pyroclastics, and volcanic gases erupt through a break in the surface called ...
in this
geologic province A geologic province is a spatial entity with common geologic attributes. A province may include a single dominant structural element such as a basin or a fold belt, or a number of contiguous related elements. Adjoining provinces may be simila ...
can be traced as far back as 20 million years ago with the emplacement of
alkali basalt Alkali basalt or alkali olivine basalt is a dark-colored, porphyritic volcanic rock usually found in oceanic and continental areas associated with volcanic activity, such as oceanic islands, continental rifts and volcanic fields. Alkali basalt ...
in western Yukon. Several
types of volcanic eruptions Several types of volcanic eruptions—during which lava, tephra (ash, lapilli, volcanic bombs and volcanic blocks), and assorted gases are expelled from a volcanic vent or fissure—have been distinguished by volcanologists. These are oft ...
have since created different landforms across the NCVP, including
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, stratovolcanoes and
cinder cone A cinder cone (or scoria cone) is a steep conical hill of loose pyroclastic fragments, such as volcanic clinkers, volcanic ash, or scoria that has been built around a volcanic vent. The pyroclastic fragments are formed by explosive eruptions o ...
s. Other volcanic landforms, notably subglacial volcanoes, take their shape from the environment they formed in regardless of the type of
magma Magma () is the molten or semi-molten natural material from which all igneous rocks are formed. Magma is found beneath the surface of the Earth, and evidence of magmatism has also been discovered on other terrestrial planets and some natural sa ...
they produced. The NCVP contains more than 100 volcanoes and is the most volcanically active area in Canada, eruptions are expected to occur there roughly every 100 years. Hoodoo Mountain is part of the Stikine Subprovince of the NCVP. This subprovince, confined to the Stikine region of northwestern British Columbia, includes three other volcanic centres:
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 ...
,
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
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 gla ...
. All four volcanic centres differ petrologically and/or volumetrically from the rest of the NCVP. Heart Peaks, Level Mountain and Mount Edziza are the largest NCVP centres by volume, the latter two of which have experienced volcanism for a much longer timespan than any other NCVP centre. Hoodoo Mountain, Level Mountain and Mount Edziza are the only NCVP centres that contain
volcanic rock Volcanic rock (often shortened to volcanics in scientific contexts) is a rock formed from lava erupted from a volcano. In other words, it differs from other igneous rock by being of volcanic origin. Like all rock types, the concept of volcanic r ...
s of both
mafic A mafic mineral or rock is a silicate mineral or igneous rock rich in magnesium and iron. Most mafic minerals are dark in color, and common rock-forming mafic minerals include olivine, pyroxene, amphibole, and biotite. Common mafic rocks include ...
and intermediate to
felsic In geology, felsic is a modifier describing igneous rocks that are relatively rich in elements that form feldspar and quartz.Marshak, Stephen, 2009, ''Essentials of Geology,'' W. W. Norton & Company, 3rd ed. It is contrasted with mafic rocks, whi ...
composition. The highest of the four complexes is Mount Edziza at , followed by Level Mountain at , Heart Peaks at and Hoodoo Mountain at . Hoodoo Mountain is one of ten volcanoes composing the
Iskut volcanic field 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 al ...
. This is a group of NCVP volcanoes scattered along the Iskut River and its main
tributaries A tributary, or affluent, is a stream or river that flows into a larger stream or main stem (or parent) river or a lake. A tributary does not flow directly into a sea or ocean. Tributaries and the main stem river drain the surrounding drainage b ...
. They consist of both subaerial and glaciovolcanic deposits, the latter of which are in the form of
pillow lava Pillow lavas are lavas that contain characteristic pillow-shaped structures that are attributed to the extrusion of the lava underwater, or ''subaqueous extrusion''. Pillow lavas in volcanic rock are characterized by thick sequences of disconti ...
s,
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 ...
breccia Breccia () is a rock composed of large angular broken fragments of minerals or rocks cemented together by a fine-grained matrix. The word has its origins in the Italian language, in which it means "rubble". A breccia may have a variety of di ...
s and
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 ...
. All of these volcanoes were active in the last 150,000 years; the latest eruption occurred from The Volcano about 150 years ago. The remaining Iskut volcanoes are
Cinder Mountain Cinder Mountain is a partly eroded cinder cone at the head of Snippaker Creek, British Columbia, Canada. It is one of the Iskut-Unuk River Cones and is the source of a basaltic lava flow that extends north into Copper King Creek. An isola ...
,
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 ...
and the Cone Glacier, Iskut Canyon, Second Canyon, Snippaker Creek, King Creek and Tom MacKay Creek cones. Like other volcanoes in the NCVP, Hoodoo Mountain has its origins in
rift In geology, a rift is a linear zone where the lithosphere is being pulled apart and is an example of extensional tectonics. Typical rift features are a central linear downfaulted depression, called a graben, or more commonly a half-grabe ...
ing of the
North American Plate The North American Plate is a tectonic plate covering most of North America, Cuba, the Bahamas, extreme northeastern Asia, and parts of Iceland and the Azores. With an area of , it is the Earth's second largest tectonic plate, behind the Pacific ...
caused by crustal extension. This has resulted from the
Pacific Plate The Pacific Plate is an oceanic tectonic plate that lies beneath the Pacific Ocean. At , it is the largest tectonic plate. The plate first came into existence 190 million years ago, at the triple junction between the Farallon, Phoenix, and Iza ...
sliding northward along the
Queen Charlotte Fault The Queen Charlotte Fault is an active transform fault that marks the boundary of the North American plate and the Pacific plate. It is Canada's right-lateral strike-slip equivalent to the San Andreas Fault to the south in California. The Queen Ch ...
, on its way to the Aleutian subduction zone in Alaska. As the
continental crust Continental crust is the layer of igneous, sedimentary, and metamorphic rocks that forms the geological continents and the areas of shallow seabed close to their shores, known as continental shelves. This layer is sometimes called ''sial'' be ...
stretches, the near surface rocks fracture along steeply dipping faults parallel to the rift. Several dormant volcanoes in the NCVP are potentially active, Hoodoo Mountain being one of many having erupted in the last 10,000 years.
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 ...
, which last erupted about 240 years ago, is the southernmost NCVP volcano while
Prindle Volcano Prindle Volcano is an isolated basaltic cinder cone located in eastern Alaska, United States, in the headwaters of the East Fork of the Fortymile River, approximately 80 kilometers northeast of Tok, Alaska. The cone is fresh-looking and has a base ...
in easternmost-central Alaska, which last erupted in the Pleistocene, is generally considered the northernmost.


Structure

Hoodoo Mountain is one of the largest
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 indicati ...
volcanoes in the NCVP. It is a stratovolcano composed primarily of peralkaline phonolite and trachyte lava flows and hyaloclastites, although some pyroclastic rocks are also present. Its peralkalinity is unique among other volcanoes in the Iskut volcanic field, which range in composition from alkali basalt to
hawaiite Hawaiite is an olivine basalt with a composition between alkali basalt and mugearite. It was first used as a name for some lavas found on the island of Hawaii. It occurs during the later stages of volcanic activity on oceanic islands such as Haw ...
. Hoodoo has also been designated as a subglacial volcano due to much of the mountain having formed subglacially in the last 85,000 years. Its involvement with
glaciation A glacial period (alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age that is marked by colder temperatures and glacier advances. Interglacials, on the other hand, are periods of warmer climate betw ...
has resulted in several interactions with glacial ice as much as thick, affording multiple examples of glaciovolcanic processes. This includes the formation of ice-marginal lava flows and the interlayering of glacial
till image:Geschiebemergel.JPG, Closeup of glacial till. Note that the larger grains (pebbles and gravel) in the till are completely surrounded by the matrix of finer material (silt and sand), and this characteristic, known as ''matrix support'', is d ...
with volcanic deposits. Hoodoo Mountain's constant struggle with surrounding and overlying ice is attested by its nearly flat summit, which attains an elevation of . Lava flows from Hoodoo Mountain partially bury Little Bear Mountain, a much smaller and older
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 ...
ic volcano immediately to the north. Both volcanoes are underlain by
plutonic rock Intrusive rock is formed when magma penetrates existing rock, crystallizes, and solidifies underground to form '' intrusions'', such as batholiths, dikes, sills, laccoliths, and volcanic necks.Intrusive RocksIntrusive rocks accessdate: March ...
s and metamorphosed volcanic and
sedimentary Sedimentary rocks are types of rock (geology), rock that are formed by the accumulation or deposition of mineral or organic matter, organic particles at Earth#Surface, Earth's surface, followed by cementation (geology), cementation. Sedimentati ...
rocks of
Stikinia Stikinia, or the Stikine terrane, is a terrane in British Columbia, Canada; the largest of the Canadian Cordillera. It formed as an independent, intraoceanic volcanic arc during the Paleozoic and Mesozoic. Stikinia forms the bedrock of numerous v ...
. These
basement A basement or cellar is one or more floors of a building that are completely or partly below the ground floor. It generally is used as a utility space for a building, where such items as the furnace, water heater, breaker panel or fuse box, ...
rocks are of
Paleozoic The Paleozoic (or Palaeozoic) Era is the earliest of three geologic eras of the Phanerozoic Eon. The name ''Paleozoic'' ( ;) was coined by the British geologist Adam Sedgwick in 1838 by combining the Greek words ''palaiós'' (, "old") and ' ...
Mesozoic The Mesozoic Era ( ), also called the Age of Reptiles, the Age of Conifers, and colloquially as the Age of the Dinosaurs is the second-to-last era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Cretaceo ...
age;
pyroxene The pyroxenes (commonly abbreviated to ''Px'') are a group of important rock-forming inosilicate minerals found in many igneous and metamorphic rocks. Pyroxenes have the general formula , where X represents calcium (Ca), sodium (Na), iron (Fe II) ...
syenite Syenite is a coarse-grained intrusive igneous rock with a general composition similar to that of granite, but deficient in quartz, which, if present at all, occurs in relatively small concentrations (< 5%). Some syenites contain larger proport ...
composes a significant portion of the Mesozoic basement. Intruding the basement rocks are 1.8-million-year-old
trachyandesite Trachyandesite is an extrusive igneous Rock (geology), rock with a composition between trachyte and andesite. It has little or no free quartz, but is dominated by Sodium, sodic plagioclase and alkali feldspar. It is formed from the cooling of ...
dikes Dyke (UK) or dike (US) may refer to: General uses * Dyke (slang), a slang word meaning "lesbian" * Dike (geology), a subvertical sheet-like intrusion of magma or sediment * Dike (mythology), ''Dikē'', the Greek goddess of moral justice * Dikes ...
, which represent the earliest known manifestations of
Quaternary The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS). It follows the Neogene Period and spans from 2.58 million years ...
magmatism in the Iskut region. Hoodoo Mountain has been described as "one of the most magnificent and interesting mountains in northern British Columbia". This is because it has a different
lithological The lithology of a Rock (geology), rock unit is a description of its physical characteristics visible at outcrop, in hand or core sample, core samples, or with low magnification microscopy. Physical characteristics include colour, texture, grain ...
and
topographical Topography is the study of the forms and features of land surfaces. The topography of an area may refer to the land forms and features themselves, or a description or depiction in maps. Topography is a field of geoscience and planetary sci ...
structure than most glaciated mountains in the
Canadian Cordillera The Pacific Cordillera, also known as the Western Cordillera or simply The Cordillera, is a top-level physiographic region of Canada, referring mainly to the extensive cordillera system in Western and Northwestern Canada that constitutes the north ...
. In contrast to its rugged counterparts, Hoodoo is symmetrical and circular in form. It has a basal diameter of around , a volume of and a topographic prominence of , making it the smallest of the four volcanoes composing the Stikine Subprovince.
Hoodoos A hoodoo (also called a tent rock, fairy chimney, or earth pyramid) is a tall, thin spire of rock formed by erosion. Hoodoos typically consist of relatively soft rock topped by harder, less easily eroded stone that protects each column from the ...
, pillar-like rock formations after which the volcano is named, are as much as in height and give the mountain a unique appearance. In 1919, a
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 ...
removed lava rock from a section on the western side of Hoodoo Mountain. Two sets of prominent cliffs partially circumscribe Hoodoo Mountain, which give the volcano a discontinuous, step-like topographic profile. The lower set of cliffs delimit the base of the volcano except for its southeastern margin where they have been partially overrun by younger lava flows. These cliffs form a broad bench at an elevation of approximately and are high. The upper set of cliffs surround the summit and are between high. Both sets of cliffs formed as a result of lava erupting in a glaciated environment. As lava travelled down slope, the lava came into contact with glacial ice that completely surrounded Hoodoo Mountain and cooled very quickly, forming a barrier around the entire volcano. This is demonstrated by the glassy texture of the lava and
columnar jointing Columnar jointing is a geological structure where sets of intersecting closely spaced fractures, referred to as Joint (geology), joints, result in the formation of a regular array of polygonal Prism (geometry), prisms, or columns. Columnar joint ...
, which indicate fairly quick cooling of an erupted lava flow. The lava cooled, pooled and as the glacial ice receded, it left behind massive lava cliffs.


Subfeatures

The south–central side of Hoodoo Mountain contains a large depression called Long Valley. This feature, having formed by glacial erosion, contains a series of domes with adjacent lava spines. Pointer Ridge on the north–central side of Hoodoo Mountain consists of pyroclastic rocks that form a
stratigraphic unit A stratigraphic unit is a volume of rock of identifiable origin and relative age range that is defined by the distinctive and dominant, easily mapped and recognizable petrographic, lithologic or paleontologic features (facies) that characterize it ...
. The Wall, a more than cliff at the western base of Hoodoo Mountain, forms the front of an ice-marginal lava flow that displays columnar jointing.
The Monument The Monument to the Great Fire of London, more commonly known simply as the Monument, is a fluted Doric column in London, England, situated near the northern end of London Bridge. Commemorating the Great Fire of London, it stands at the j ...
on the southwestern side of Hoodoo Mountain is a vertical rock column that reaches more than in height. It is the eroded remains of a volcanic vent that was fed by a west-trending dike. Horn Ridge, a ridge on the north side of Hoodoo Mountain, consists of highly vesicular lava flows that are locally heavily jointed. The northeastern side of Hoodoo Mountain contains a J-shaped cliff called The Hook. Like The Wall to the southwest, The Hook is the front of an ice-marginal lava flow. Slide Canyon consists of a large chasm that cuts deeply into the southwestern side of Hoodoo Mountain. It is intruded by several dikes, including the one that fed The Monument. Pumice Point on the northwestern side of Hoodoo Mountain contains highly vesicular,
lapilli Lapilli is a size classification of tephra, which is material that falls out of the air during a volcanic eruption or during some meteorite impacts. ''Lapilli'' (singular: ''lapillus'') is Latin for "little stones". By definition lapilli range f ...
to
block Block or blocked may refer to: Arts, entertainment and media Broadcasting * Block programming, the result of a programming strategy in broadcasting * W242BX, a radio station licensed to Greenville, South Carolina, United States known as ''96.3 ...
-sized fragments of "woody
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 ...
" up to long. Extending from the northwestern side of Hoodoo Mountain is the Northwest Flow, a lava flow with well-preserved levees.
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 up to wide occur throughout the flow. The Southwest Flow is a large lava flow on the southwestern side of Hoodoo Mountain that appears to have issued from a poorly formed cinder cone.


Volcanic history

Hoodoo Mountain has experienced at least six eruptive periods over the last 85,000 years. This includes three periods involving volcano-ice interaction and three periods with no apparent ice involvement. They were marked by pyroclastic eruptions, lava flows and subglacial eruptions of peralkaline magmas. These magmas were phonolitic and trachytic in composition, having possibly evolved from differentiation of alkali basaltic melts in the mid- crust. Several
tephra layer Tephra is fragmental material produced by a volcanic eruption regardless of composition, fragment size, or emplacement mechanism. Volcanologists also refer to airborne fragments as pyroclasts. Once clasts have fallen to the ground, they rem ...
s in the Bob Quinn Lake,
Dease Lake Dease Lake is a small community located in the Cassiar Country of the Northern Interior of British Columbia, Canada. It is located a few hours south of the Yukon border on Stewart–Cassiar Highway (Highway 37) at the south end of the lake o ...
and
Finlay River The Finlay River is a 402 km long river in north-central British Columbia flowing north and thence south from Thutade Lake in the Omineca Mountains to Williston Lake, the impounded waters of the Peace River formed by the completion of the W.A. ...
areas of northern British Columbia may have originated from Hoodoo Mountain.


Eruptive periods

The first eruptive period 85,000 years ago produced massive subglacial lava flows and associated hyaloclastite breccia. These volcanic deposits are mainly exposed on the southwestern and northwestern flanks where they are about thick. The lava flows display small diameter columnar joints and are
aphanitic Aphanites (adj. ''aphanitic''; ) are igneous rocks that are so fine-grained that their component mineral crystals are not visible to the naked eye (in contrast to phanerites, in which the crystals are visible to the unaided eye). This geologic ...
in nature with low vesicularity. It remains unclear whether or not the subglacial eruptions during this period completely melted the overlying ice. Glacial till underlying the southwestern flank indicates that the area had already experienced past glaciations before the onset of volcanic activity. Subaerial eruptions from near the summit took place during the second eruptive period 80,000 years ago. Lava travelled down slope from an elevation of roughly but was then confined by thick glacial ice at an elevation of about . Here, the lava cooled and pooled to create the lower discontinuous set of cliffs around the entire base of Hoodoo Mountain. These ice-marginal lava flows vary from about to more than thick and often contain horizontally oriented columnar joints, indicative of a vertical cooling surface. The Wall at the western base of Hoodoo Mountain formed during this eruptive period. Subsequent glacial movements over these flows created north–south trending
striations Striations means a series of ridges, furrows or linear marks, and is used in several ways: * Glacial striation * Striation (fatigue), in material * Striation (geology), a ''striation'' as a result of a geological fault * Striation Valley, in ...
that are consistent with current movements of the Hoodoo and Twin glaciers. Both of these valley glaciers are now roughly below the striations due to their ongoing glacial retreat. After the regional ice had disappeared from lower elevations, subaerial explosive eruptions of the third eruptive period took place between 80,000–54,000 years ago. This explosivity generated
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 on the northern flank where they deposited a roughly sequence of pyroclastic material. The sequence comprises non-
welded Welding is a fabrication process that joins materials, usually metals or thermoplastics, by using high heat to melt the parts together and allowing them to cool, causing fusion. Welding is distinct from lower temperature techniques such as braz ...
lapilli tuff within a matrix of yellow to light green
ash Ash or ashes are the solid remnants of fires. Specifically, ''ash'' refers to all non-aqueous, non- gaseous residues that remain after something burns. In analytical chemistry, to analyse the mineral and metal content of chemical samples, ash ...
, as well as three highly welded
lenses A lens is a transmissive optical device which focuses or disperses a light beam by means of refraction. A simple lens consists of a single piece of transparent material, while a compound lens consists of several simple lenses (''elements''), ...
up to about thick.
Volcanic glass Volcanic glass is the amorphous (uncrystallized) product of rapidly cooling magma. Like all types of glass, it is a state of matter intermediate between the closely packed, highly ordered array of a crystal and the highly disordered array of liqu ...
of phonolitic or trachytic composition occurs within the sequence. A subaerial lava flow travelled down the north–central and northeast flanks of Hoodoo Mountain during the latter stages of this eruptive period. It directly overlies the pyroclastic sequence and contains abundant fresh and devitrified glass. The fourth eruptive period 54,000 years ago produced a subaerially erupted sequence of up to five stacked lava flows on the north–central and southwestern flanks. Individual flows vary from thick and are separated by of lava breccia, giving the sequence a total thickness of around . The lava flows do not appear to have interacted with glacial ice, suggesting that at least the upper flanks of Hoodoo Mountain were ice-free at the time of their eruption. Columnar joints more than thick characterize these flows. After a period of eruptions showing no apparent evidence for ice interaction, subglacial eruptions resumed between 54,000–30,000 years ago, signalling the build-up of regional ice levels. This fifth eruptive period occurred in two stages. The first stage took place between 54,000–40,000 years ago when the overriding glacial ice was possibly more than thick. Isolated vents produced a wide variety of volcanic deposits extensively distributed around the entire summit region. This includes subglacially erupted lava lobes and domes, as well as ice-chilled breccia and hyaloclastite, which form a volcanic unit. The second stage between 40,000–30,000 years ago was characterized by
fissure A fissure is a long, narrow crack opening along the surface of Earth. The term is derived from the Latin word , which means 'cleft' or 'crack'. Fissures emerge in Earth's crust, on ice sheets and glaciers, and on volcanoes. Ground fissure A ...
-fed eruptions beneath relatively thin ice cover. These eruptions produced a roughly unit of lava flows, lava lobes and breccia on the north–central, northwestern and western flanks of Hoodoo Mountain. The sixth and final eruptive period began 10,000–9,000 years ago with the eruption of phonolitic lava flows from vents near the summit. They travelled down the north–central, northwestern, southeastern and southwestern flanks of Hoodoo Mountain without encountering any glacial ice, suggesting that the flows were erupted subaerially after the regional ice had disappeared from lower elevations. Lava flows on the north–central flank display radially-oriented cooling joints. The Northwest Flow travelled about down slope and partially covers cliffs at the base of Hoodoo Mountain. Lava flows on the southeastern flank drape down cliffs and extend into the Twin Glacier valley where they spread out into a broad terminal lobe. The Southwest Flow travelled about down slope to near the Hoodoo River. These lava flows are considered by the
Smithsonian Institution The Smithsonian Institution ( ), or simply the Smithsonian, is a group of museums and education and research centers, the largest such complex in the world, created by the U.S. government "for the increase and diffusion of knowledge". Founded ...
's
Global Volcanism Program The Smithsonian Institution's Global Volcanism Program (GVP) documents Earth's volcanoes and their eruptive history over the past 10,000 years. The mission of the GVP is to document, understand, and disseminate information about global volcanic a ...
to have been erupted in 7050 BCE. However, the Southwest Flow may be much younger as age estimates of more than 180 years have been obtained from tree-ring dating on living trees. This lava flow has also not undergone erosion and it still attains its original characteristics even though it is very easily broken. These observations have been taken to indicate a very recent origin, possibly not more than a few hundred years old.


Tephra layers

Hoodoo Mountain is a possible source for two tephra layers in the Dease Lake and Finlay River areas. They both range in composition from phonolitic to trachytic and are high in
iron(II) oxide Iron(II) oxide or ferrous oxide is the inorganic compound with the formula FeO. Its mineral form is known as wüstite. One of several iron oxides, it is a black-colored powder that is sometimes confused with rust, the latter of which consists ...
, indicating that the two Finlay tephras were likely extruded from a single volcanic centre.
Radiocarbon dating Radiocarbon dating (also referred to as carbon dating or carbon-14 dating) is a method for determining the age of an object containing organic material by using the properties of radiocarbon, a radioactive isotope of carbon. The method was dev ...
of
terrestrial plant A terrestrial plant is a plant that grows on, in, or from land. Other types of plants are aquatic (living in water), epiphytic (living on trees) and lithophytic (living in or on rocks). The distinction between aquatic and terrestrial plants is ...
macrofossil Macrofossils, also known as megafossils, are preserved organic remains large enough to be visible without a microscope. The term ''macrofossil'' stands in opposition to the term microfossil. Microfossils, by contrast, require substantial magnifica ...
s directly overlying the youngest tephra layer suggest an early
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 ...
age for this volcanic material. The glass composition of the tephras is similar to the average whole-rock chemistry of the phonolitic lava flows produced during the final eruptive period at Hoodoo Mountain. However, this eruptive period is not known to have produced any pyroclastic deposits or tephras. Therefore other possible sources have been considered, including Level Mountain, Heart Peaks and the Mount Edziza volcanic complex. A tephra layer of unknown origin occurs in sediments at Bob Quinn Lake northeast of Hoodoo Mountain. It is phonolitic in composition, differing from the Finlay tephras in having about 2% less
silicon dioxide Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , most commonly found in nature as quartz and in various living organisms. In many parts of the world, silica is the major constituent of sand. Silica is one ...
, 1.5% more aluminum oxide and more
titanium dioxide Titanium dioxide, also known as titanium(IV) oxide or titania , is the inorganic compound with the chemical formula . When used as a pigment, it is called titanium white, Pigment White 6 (PW6), or CI 77891. It is a white solid that is insolubl ...
,
calcium oxide Calcium oxide (CaO), commonly known as quicklime or burnt lime, is a widely used chemical compound. It is a white, Caustic (substance), caustic, alkaline, crystalline solid at room temperature. The broadly used term "''lime (material), lime''" co ...
and
magnesium oxide Magnesium oxide ( Mg O), or magnesia, is a white hygroscopic solid mineral that occurs naturally as periclase and is a source of magnesium (see also oxide). It has an empirical formula of MgO and consists of a lattice of Mg2+ ions and O2− ions ...
. The areal distribution of this tephra is poorly constrained but it may extend further to the east. Hoodoo Mountain is a possible source of this tephra due to its location along the trajectory of any ash plume from this volcano. The exact age of this early Holocene tephra layer is unknown but its stratigraphic position suggests that it is about 7,000–8,000 calendar years old. No volcanic deposits of this age are known at Hoodoo Mountain but there may be younger deposits that are completely covered by the summit ice cap.


Monitoring and volcanic hazards

Like other volcanoes in the NCVP, Hoodoo Mountain is not monitored closely enough by the GSC to ascertain its activity level. The
Canadian National Seismograph Network The Canadian National Seismograph Network is a network of seismographs to detect earthquakes across Canada. It is operated by the Geological Survey of Canada The Geological Survey of Canada (GSC; french: Commission géologique du Canada (CGC)) is ...
has been established to monitor earthquakes throughout Canada, but it is too far away to provide an accurate indication of activity under the mountain. The seismograph network may sense an increase in seismic activity if Hoodoo Mountain becomes highly restless, but this may only provide a warning for a large eruption; the system might detect activity only once the volcano has started erupting. If Hoodoo Mountain were to erupt, mechanisms exist to orchestrate relief efforts. 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 ...
was created to outline the notification procedure of some of the main agencies that would respond to an erupting volcano in Canada, an eruption close to the Canada–United States border or any eruption that would affect Canada. Hoodoo Mountain is a dormant but potentially active volcano, having experienced at least eight seismic events since 1985. Hazards stemming from renewed volcanism are lava flows and flooding, as well as fallout from explosive eruptions. Lava flows generated by
effusive eruption An effusive eruption is a type of volcanic eruption in which lava steadily flows out of a volcano onto the ground. Overview There are two major groupings of eruptions: effusive and explosive. Effusive eruption differs from explosive eruption, ...
s could dam the Iskut River and pose a major hazard to mining operations upstream due to rising waters. A major eruption could also significantly melt the summit ice cap or the adjacent glaciers to produce large-scale flooding of the Iskut River and the lower
Stikine River The Stikine River is a major river in northern British Columbia (BC), Canada and southeastern Alaska in the United States. It drains a large, remote upland area known as the Stikine Country east of the Coast Mountains. Flowing west and south f ...
. Such flooding could significantly disrupt the Stikine River
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 ...
fishery, although it would not be as disruptive to mining operations. A
jökulhlaup A jökulhlaup ( ) (literally "glacial run") is a type of glacial outburst flood. It is an Icelandic term that has been adopted in glaciological terminology in many languages. It originally referred to the well-known subglacial outburst flood ...
is unlikely due to the lack of a
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 fill with meltwater. Explosive eruptions could produce significant
pyroclastic fall A pyroclastic fall is a uniform deposit of material which has been ejected from a volcanic eruption or plume such as an ash fall or tuff. Pyroclastic air fall deposits are a result of: # Ballistic transport of ejecta such as volcanic blocks, volca ...
to disrupt local mining operations, as well as airborne ash which would potentially disrupt air traffic to and from the
mining camp Mining is the extraction of valuable minerals or other geological materials from the Earth, usually from an ore body, lode, vein, seam, reef, or placer deposit. The exploitation of these deposits for raw material is based on the economic via ...
s. Air traffic between Canada, Alaska and Asia would likely be disrupted by high
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 ...
s due to the presence of major airways near the volcano.


Human history


Geological studies

The volcanic deposits at Hoodoo Mountain were briefly described in 1948 by F. A. Kerr of 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 ...
(GSC) while studying the
regional geology Regional geology is the geological study of large-scale regions. Usually, it encompasses multiple geological disciplines to piece together the history of an area. It is the geologic equivalent of regional geography. The size and the borders of ea ...
along the southern part of the Iskut River. According to Kerr, "the volcano erupted in the centre of an old valley that must have drained to the Iskut about 3 miles above the present Hoodoo River ..Successive outflows from the volcano repeatedly disrupted the drainage, so that the flanking streams and glaciers have had a difficult struggle to maintain their channels." An ice-filled crater was speculated by Kerr to underlie the summit ice cap. In 1991, Canadian
volcanologist A volcanologist, or volcano scientist, is a geologist who focuses on understanding the formation and eruptive activity of volcanoes. Volcanologists frequently visit volcanoes, sometimes active ones, to observe and monitor volcanic eruptions, col ...
Jack Souther Jack Gordon Souther (April 25, 1924 – June 1, 2014) was an American-born Canadian geologist, volcanologist, professor and engineer. He contributed significantly to the early understanding of recent volcanic activity in the Canadian Cordillera. ...
provided a short account of the
geomorphology Geomorphology (from Ancient Greek: , ', "earth"; , ', "form"; and , ', "study") is the scientific study of the origin and evolution of topographic and bathymetric features created by physical, chemical or biological processes operating at or n ...
of Hoodoo Mountain as well as some age-constraints from preliminary
K–Ar dating Potassium–argon dating, abbreviated K–Ar dating, is a radiometric dating method used in geochronology and archaeology. It is based on measurement of the product of the radioactive decay of an isotope of potassium (K) into argon (Ar). Potassium ...
. Hoodoo's relatively flat-topped geomorphology led Souther to refer to it as a
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 ...
, even though its summit lacks a capping sequence of subaerial lavas typical of tuyas. It does, however, coincide with Souther's original use of the term ''tuya'' in that its overall geomorphology has been strongly influenced by interaction between ice and lava. The first detailed summary of the Quaternary
stratigraphy Stratigraphy is a branch of geology concerned with the study of rock (geology), rock layers (Stratum, strata) and layering (stratification). It is primarily used in the study of sedimentary rock, sedimentary and layered volcanic rocks. Stratigrap ...
and petrology of Hoodoo Mountain was compiled in 1997 by American
geologist A geologist is a scientist who studies the solid, liquid, and gaseous matter that constitutes Earth and other terrestrial planets, as well as the processes that shape them. Geologists usually study geology, earth science, or geophysics, althou ...
Ben Edwards who produced a detailed
geologic map A geologic map or geological map is a special-purpose map made to show various geological features. Rock units or geologic strata are shown by color or symbols. Bedding planes and structural features such as faults, folds, are shown with st ...
of the volcano. An expedition consisting of university, GSC and industry scientists was financed in 1997 to assess the nature and magnitude of hazards posed by Hoodoo Mountain. This included mapping of the shape of the summit ice cap using
ground-penetrating radar Ground-penetrating radar (GPR) is a geophysical method that uses radar pulses to image the subsurface. It is a non-intrusive method of surveying the sub-surface to investigate underground utilities such as concrete, asphalt, metals, pipes, cables o ...
and ice radar, as well as the production of a preliminary hazard assessment for the Iskut area. Analysis of data indicated the absence of a caldera or large crater beneath the ice cap. Instead, the underlying topography was shown to be characteristic of an inverted and very shallow
saucer A saucer is a type of small dishware. While in the Middle Ages a saucer was used for serving condiments and sauces, currently the term is used to denote a small plate or shallow bowl that supports a cup – usually one used to serve coffee ...
. The use of radars to penetrate the ice cap and to assess the subglacial topography proved to be instrumental for studying other glaciated volcanoes in the
American Cordillera The American Cordillera is a chain of mountain ranges (cordilleras) that consists of an almost continuous sequence of mountain ranges that form the western "backbone" of North America, Central America and South America, with Aconcagua as the h ...
and elsewhere. Personnel involved in the 1997 expedition were Catherine Hickson and Mark Stasiuk of the GSC, Jim Nicholls of the
University of Calgary The University of Calgary (U of C or UCalgary) is a public research university located in Calgary, Alberta, Canada. The University of Calgary started in 1944 as the Calgary branch of the University of Alberta, founded in 1908, prior to being ins ...
, Jeff Schmok and Guy Cross of Golder Associates, Alison Rust, Ben Edwards and Kelly Russell of the
University of British Columbia The University of British Columbia (UBC) is a public university, public research university with campuses near Vancouver and in Kelowna, British Columbia. Established in 1908, it is British Columbia's oldest university. The university ranks a ...
, and Trevor Page of
Lancaster University Lancaster University (legally The University of Lancaster) is a public university, public research university in Lancaster, Lancashire, Lancaster, Lancashire, England. The university was established in 1964 by royal charter, as one of several pla ...
. By 2002, Hoodoo Mountain was no longer the least studied volcano of the Stikine Subprovince.


Mining

The Hoodoo Mountain area contains several large mining camps within the floodplain of the Iskut River.
Prospecting Prospecting is the first stage of the geological analysis (followed by exploration) of a territory. It is the search for minerals, fossils, precious metals, or mineral specimens. It is also known as fossicking. Traditionally prospecting reli ...
in Bronson Creek commenced as early as 1907, during which time several
mining claim Mineral rights are property rights to exploit an area for the minerals it harbors. Mineral rights can be separate from property ownership (see Split estate). Mineral rights can refer to sedentary minerals that do not move below the Earth's surfac ...
s had been staked. This was followed by drifting, trenching and stripping of several gold-bearing
veins Veins are blood vessels in humans and most other animals that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are the pulmonary and umbilical veins, both of which carry oxygenated b ...
between 1910 and 1920. A drilling program conducted by the Hudson Bay Mining and Smelting Company from 1954 to 1960 identified copper prospects. In 1964,
Cominco Teck Resources Limited, known as Teck Cominco until late 2008, is a diversified natural resources company headquartered in Vancouver, British Columbia, that is engaged in mining and mineral development, including coal for the steelmaking indust ...
optioned claims from Jodi Explorations and the Tuksi Mining Company. A drilling program to test copper mineralization on the Red Bluff claim was completed by Cominco in 1965.
Texas Gulf Sulphur The Texas Gulf Sulphur Company was one of the largest sulfur mining companies in the world from 1919 to 1981. By 1925 the company controlled 40% of the U.S. sulfur market. It was formed in 1909 and acquired in 1981, after expanding across the Uni ...
examined the area for its copper and
base metal A base metal is a common and inexpensive metal, as opposed to a precious metal such as gold or silver. In numismatics, coins often derived their value from the precious metal content; however, base metals have also been used in coins in the past ...
content from 1973 to 1974. Exploration of the Pickaxe Vein by Skyline Gold began in 1980 to define its gold potential. This was followed by the discovery of the Discovery Vein in 1981, which led to further drilling and the discovery of a high-grade gold vein in 1982 that became known as the 16 Vein. Surveying, drilling and trenching was carried out by Skyline Gold, Placer Development and Anaconda Canada Exploration between 1982 and 1988. The Johnny Mountain Mine commenced production in November 1988 after having been engaged in pre-production since January of that year. This small underground mine operated until August 1990 when high operating costs and low gold prices forced it to shut down. This was followed by closure of the
ore mill In the field of extractive metallurgy, mineral processing, also known as ore dressing, is the process of separating commercially valuable minerals from their ores. History Before the advent of heavy machinery the raw ore was broken up using ...
in September of that year. The mine remained closed until 1993 when further mining and milling took place. A total of 196,358 tonnes of
ore Ore is natural rock or sediment that contains one or more valuable minerals, typically containing metals, that can be mined, treated and sold at a profit.Encyclopædia Britannica. "Ore". Encyclopædia Britannica Online. Retrieved 7 Apr ...
was mined from 1988 to 1993, from which of copper, of silver and of gold was recovered. Intermittent mineral exploration has taken place at the Johnny Mountain Mine since its closure in 1993. In 1982, Cominco staked two mining claims over their Red Bluff property and adjacent ground near the junction of the Craig and Iskut rivers. A geochemical survey consisting of 26 rock and 36 soil samples was completed by Cominco in 1985. Exploration work from 1986 to 1987 included
geochemical Geochemistry is the science that uses the tools and principles of chemistry to explain the mechanisms behind major geological systems such as the Earth's crust and its oceans. The realm of geochemistry extends beyond the Earth, encompassing the e ...
soil survey Soil, also commonly referred to as earth or dirt, is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Some scientific definitions distinguish ''dirt'' from ''soil'' by restricting the former term ...
s, trenching and of diamond drilling in 86 holes. The Snip Mine began as an underground exploration program in March 1988; three levels were established , and underground. About of underground diamond drilling and of underground work was completed between August 1988 and October 1989. By mid-1990, of surface and underground diamond drilling had been completed. The Snip Mine, owned jointly by Cominco and Prime Resources, began production in January 1991. An
airstrip An aerodrome (Commonwealth English) or airdrome (American English) is a location from which aircraft flight operations take place, regardless of whether they involve air cargo, passengers, or neither, and regardless of whether it is for publ ...
was used continuously to ship
ore concentrate Ore concentrate, dressed ore or simply concentrate is the product generally produced by metal ore mines. The raw ore is usually ground finely in various comminution operations and gangue (waste) is removed, thus concentrating the metal component. ...
from the mine until May 1999 when all mining operations ceased. Production throughout the mine's lifespan amounted to of copper, of gold, and of silver from 1.2 million tonnes of ore mined. Mineral exploration has occurred at the Snip Mine intermittently since its closure in 1999.


Accessibility

Hoodoo Mountain is in a remote location with no established road access. The closest point accessible by road is Bob Quinn Lake about northeast of Hoodoo Mountain along the
Stewart–Cassiar Highway The Stewart–Cassiar Highway, also known as the Dease Lake Highway and the Stikine Highway as well as the Thornhill –Kitimat Highway from Kitimat to Thornhill , is the northwesternmost highway in the Canadian province of British Columbia. A ...
. From there the mountain can be reached by charter helicopter or by trekking across mountainous
terrain Terrain or relief (also topographical relief) involves the vertical and horizontal dimensions of land surface. The term bathymetry is used to describe underwater relief, while hypsometry studies terrain relative to sea level. The Latin word ...
with extreme difficulty. Alternatively, fixed-wing aircraft landings can be made on the Bronson Creek runway immediately south of Hoodoo Mountain. The mountain can also be approached from the Alaskan community of Wrangell by boating up the Stikine and Iskut rivers.


See also

*
List of Northern Cordilleran volcanoes The geography of northwestern British Columbia and Yukon, Canada is dominated by volcanoes of the Northern Cordilleran Volcanic Province formed due to continental rifting of the North American Plate. It is the most active volcanic region in Canad ...
*
List of volcanoes in Canada List of volcanoes in Canada is an incomplete list of volcanoes found in Mainland Canada, in the Canadian islands and in Canadian waters. All but one province, Prince Edward Island, have at least one volcano. Alberta British Columbia Ne ...
*
Volcanism of Western Canada Volcanism of Western Canada has produced lava flows, lava plateaus, lava domes, cinder cones, stratovolcanoes, shield volcanoes, greenstone belts, submarine volcanoes, calderas, diatremes and maars, along with examples of more less common volcanic ...


Notes


References


External links

* * {{Northern Cordilleran volcanoes Boundary Ranges Holocene stratovolcanoes Ice caps of Canada Northern Cordilleran Volcanic Province One-thousanders of British Columbia Pleistocene stratovolcanoes Potentially active volcanoes Stikine Country Stratovolcanoes of Canada Subglacial volcanoes of Canada Volcanoes of British Columbia