Mount Edziza volcanic complex
Encyclopedia
The Mount Edziza volcanic complex is a large and potentially active north-south trending complex volcano
in Stikine Country
, northwestern British Columbia
, Canada
, located 38 kilometres (23.6 mi) southeast of the small community of Telegraph Creek
. It occupies the southeastern portion of the Tahltan Highland
, an upland area of plateau and lower mountain range
s, lying east of the Boundary Ranges
and south of the Inklin River
, which is the east fork of the Taku River
. As a volcanic complex, it consists of many types of volcanoes, including shield volcano
es, caldera
s, lava dome
s, stratovolcano
es, and cinder cone
s.
Most of the Mount Edziza volcanic complex is encompassed within a large provincial park
called Mount Edziza Provincial Park. Named after Mount Edziza
, this 2660.95 km² (1,027.4 sq mi) park was established in 1972 to preserve the volcanic and cultural treasures unique to the northern British Columbia area. The Mount Edziza volcanic complex is remote, and, without roads, accessible only along trails. The easiest access is from Highway 37 and a spur road from Dease Lake
to Telegraph Creek
. From Kinaskan Lake, on Highway 37, a poorly maintained trail extends west for 30 kilometres (18.6 mi) into the heart of the complex. From Telegraph Creek another trail extends east for 25 kilometres (15.5 mi) to the north slope of Mount Edziza.
The Mount Edziza volcanic complex began forming about 7.5 million years ago and has grown steadily since then. Like other volcanoes in northwestern British Columbia, the Mount Edziza volcanic complex has its origins in continent
al rift
ing—a long divergent plate boundary
where the lithosphere
is being pulled apart. Here, the continental crust
of the North American Plate
is being stretched at a rate of about 2 cm (0.78740157480315 in) per year. This incipient rifting has formed as a result of the Pacific Plate
sliding northward along the Queen Charlotte Fault
, on its way to the Aleutian Trench
, which extends along the southern coastline of Alaska
and the adjacent waters of northeastern Siberia
off the coast of Kamchatka Peninsula
. As the continental crust stretches, the near-surface rocks fracture along steeply dipping cracks parallel to the rift known as faults. Hot basalt
ic magma
rises along these fractures to create passive lava eruptions, known as effusive eruption
s.
The rift zone has existed for at least 20 million years, and has created a line of volcanoes called the Northern Cordilleran Volcanic Province
, also called the Stikine Volcanic Belt, stretching from the Alaska
-Yukon
border to near Prince Rupert, British Columbia
. Several presently dormant volcanoes in the province are potentially active, three of them having erupted in the last few hundred years, two witnessed by First Nations
and placer miners
during the 18th and 19th centuries. The Tseax Cone
, which last erupted in the 18th century, is the southernmost historically active volcano in the province, while Prindle Volcano in easternmost-central Alaska, which erupted during the Pleistocene
period, is generally considered the northernmost.
The Mount Edziza volcanic complex is Canada's second largest volcano of young volcanic activity, with an area of 1000 km² (386.1 sq mi), exceeded only by the Level Mountain Range
north of Edziza, which has an area of 1800 km² (695 sq mi). Four central volcanoes, known as Armadillo Peak
, Spectrum Range
, Ice Peak
, and Mount Edziza
, lie along the northerly trending axis of an oval, composite shield volcano. The composite shield volcano consists of overlapping shields, two of which are clearly noticeable on maps. The composite shield volcano forms a broad lava plateau, 65 kilometres (40.4 mi) long and 20 kilometres (12.4 mi) wide, mainly made of basaltic lava flows; it is dotted with cinder cones and surrounded by steep ridges called escarpment
s, which expose layers of black columnar basaltic lava flows with distal rock fragments and pyroclastic deposits. More light-coloured magmas of mainly trachyte
and comendite
with very little aluminum are mainly confined to the four central volcanoes and associated lava dome. The lava plateau is flanked by Klastline River to the north, Mess Creek and larger Stikine River
to the west and the Iskut River
to the east. Elevations of the lava plateau are 1500 to- with volcanic mountains rising 2590 metres (8,497.4 ft) above sea level. Three sections of the lava plateau have official names; these are the Arctic Lake
, Big Raven
, and Kitsu
plateaus. The history of the Mount Edziza volcanic complex includes at least two periods of regional glaciation, when deep ice sheets covered the land, and several lesser advances of mountain glaciers.
es in the region were built by repeated eruptions of thick, slow-moving lava that have commonly flowed only a few kilometres from the vent. Explosive eruption
s are often associated with these volcanoes, depositing alternating layers of volcanic ash
, cinder
s, blocks, and globes of molten rock called volcanic bomb
s or lava bombs, which are added to its slopes to create the stratovolcano. Edziza's stratovolcanoes contain a fine-grained silica-rich volcanic rock called trachyte
; they have not erupted for thousands of years, allowing erosion
to destroy the original cone, creating craggy ridge
s and rock outcrops of more resistant materials.
s in the Mount Edziza volcanic complex were formed as a result of emptying the magma chamber
beneath a volcano. If enough magma
is erupted, the emptied chamber will not be able to support the weight of the volcanic edifice above it. A roughly circular fracture— a "ring fault"— develops around the edge of the chamber. These ring fractures serve as feeders for fault intrusion
s that are also known as ring dike
s. Secondary volcanic vents form above the ring fracture. As the magma chamber empties, the centre of the volcano within the ring fracture begins to collapse. The collapse may occur as the result of a single cataclysmic eruption, or it may occur in stages as the result of a series of eruptions. These caldera collapses are relatively small compared to most other caldera collapses. The largest caldera at the Mount Edziza volcanic complex is about 6 kilometres (4 mi) in diameter while most calderas are at least 25 kilometres (15.5 mi) in diameter. Volcanic eruptions accompanying these collapses produced trachyte
and a white, sodic rhyolite
called comendite
.
s were built by eruptions of very thick light-coloured magma, including trachyte
. Such magmas are typically too thick to move far from the vent it extrudes from, causing it to solidify quickly and build on previous volcanic extrusions, creating a characteristic dome-like shape. The thickness of the magma is attributed to high levels of silica, a naturally occurring silicon dioxide
found in various crystalline and amorphous forms. Edziza's domes reach heights of several hundred metres, and grew slowly and steadily for months to years. The sides of these structures are composed of unstable rock debris. Due to the possibility of the building of gas pressure, the dome can experience more explosive eruptions over time. When part of a lava dome collapses while it still contains molten rock and gases, it can produce a pyroclastic flow
, a super-heated mix of gas, ash, and pumice
.
Characteristics of lava dome eruptions include shallow, long-period and hybrid seismic activity, which is attributed to excess fluid pressures in the contributing vent chamber. Other characteristics of lava domes include their spherical dome shape, cycles of dome growth over long periods, and sudden onsets of violent explosive activity. The average rate of dome growth may be used as a rough indicator of magma supply, but it shows no systematic relationship to the timing or characteristic of lava dome explosions.
s of Edziza were formed by lava fountain
eruptions, emitting particles and blobs of congealed lava from a single vent. As the gas-charged lava is blown violently into the air, it breaks into small fragments that solidify and fall as cinder
around the vent to form a circular or oval cone. Edziza's cinder cones have bowl-shaped craters at their summits and rise more than a hundred metres above their surroundings. Cinder cones are widespread in British Columbia as well as throughout other volcanic terrains of the world.
Eve Cone
, a black cinder cone of the Mount Edziza volcanic complex, is one the most famous symmetrical and best preserved cinder cones in Canada, reaching a height of 1740 metres (5,708.7 ft) and a topographic prominence
of 150 metres (492.1 ft).
es are built almost entirely of fluid lava flows. They formed as a result of lava flowing out in all directions from central summit vents and from groups of vents, building a broad, gently sloping cone of flat, domical shape. They are built up slowly by the accretion of thousands of lava flows of highly fluid basalt
ic lava, which spread widely over great distances, and then cool as thin, gently dipping sheets. In some shield volcano eruptions, basaltic lava has poured out quietly from fissure vent
s instead of central vents, flooding the surrounding countryside with lava flow upon lava flow, forming Edziza's broad lava plateau.
Lava plateaus similar to Edziza's can be found elsewhere in North America, including the Snake River Plain
in Idaho
, and the Columbia River Basalt Group
in southeastern Washington, and eastern Oregon
, United States
; they can also be found in Iceland
.
s (SUGM) of the Mount Edziza volcanic complex are an unusual type of subglacial volcano
formed when subglacial eruption
s began melting overlying glacial ice at a time when this region was covered by glacial ice during the Pleistocene
and early Holocene
periods. These subglacial eruptions were not hot enough to melt a vertical pipe right through the overlying glacial ice, instead forming mounds of hydrated volcanic rock made up of volcanic fragments called hyaloclastite
and lava that solidified into pillow-shaped masses called pillow lava
deep beneath the glacial ice field. Once the glaciers had retreated, the subglacial volcanoes would be revealed, with a unique shape as a result of their confinement within glacial ice.
The lava dome
s, caldera
s, stratovolcano
es, subglacial mound
s and cinder cone
s forming the volcanic complex were constructed in five phases, each of which began with the effusion of dark olivine
basalt
which formed the flat-lying shield volcano
es and concluded with the eruption of light-coloured magma
. This cyclical behavior is attributed to the episodic rise of basic, mantle
-derived alkali basalt both to the surface and partly into crustal reservoirs where the light-coloured magmas with very little aluminum were created by prolonged crystal fractionation
. The silica-rich trachyte
and comendite lavas are similar to those associated with the most violent eruptions on Earth.
seven million years ago, today represented by an eroded remnant of a small caldera
flanked by steep-sided light-coloured secondary lava domes, including Cartoona Peak
, Tadeda Peak
, IGC Centre
, and Sezill Volcano
, and a thick pile of interlayered light-coloured lava flows, pyroclastic flow
s, air-fall pumice, and epiclastic deposits. It is the most central of the four central volcanoes and its 2210 metres (7,250.7 ft) summit is capped by 180 metres (590.6 ft) of fine-grained silica-rich trachyte
lava flows which were ponded inside the caldera to produce a lava lake
six million years ago during its final stage of activity.
magma 150 metres (492.1 ft) thick and 13 metres (42.7 ft) long during a single event of activity. A broad circular lava dome was eventually created called the Spectrum Range
. This is the southernmost of the four central volcanoes and is over 10 kilometres (6 mi) wide and up to 650 metres (2,132.5 ft) thick on the southwestern flank of Armadillo Peak and north of the Arctic Lake Plateau
. Named for its extensive colourful alteration, it overlies a basal shield volcano and contains deeply carved circular valleys displaying portions of massive silica-rich comendite and trachyte lava flows which comprise the lava dome. The deeply carved circular valleys also display the bounding faults of a buried, cogenetic caldera approximately 4.5 kilometres (2.8 mi) across. More than 100 cubic kilometres (24 cu mi) of rhyolite and trachyte was erupted during the Spectrum Range dome eruptive period, with its activity ending 2,500,000 years ago.
Ice Peak
, 2500 metres (8,202.1 ft) high, which overlaps the northern flank of Armadillo Peak, began to form during Edziza's third phase of activity, starting 1,600,000 years ago when the regional Cordilleran Ice Sheet
began retreating. It is a stratovolcano
that was constructed when large areas of the Edziza lava plateau were free from glacial ice and now enclosed by glacial deposits. However, additional parts of the Mount Edziza volcanic complex were likely still covered by glacial ice. The volcanic activity from Ice Peak during this period produced both basic and intermediate to light-coloured lava flows and pyroclastic rock
s which mixed with meltwater to produce debris flow
s. As Ice Peak began to form, basic lava spread to the flanks of the cone where it formed meltwater
lakes and combines with and forms part of the adjacent shield volcano. As lava continued to flow into these meltwater lakes, pillow lava
and solidified rubble was created. Many of the lava flows with compositions of trachyte
and basalt
were however erupted just below the surface of the soil. Continuous volcanic activity eventually made Ice Peak reach an elevation of 2400 metres (7,874 ft) when three viscous, intermediate, and light-coloured lava flows built up around secondary lava domes parallel with its western side during its final stage of activity 1,500,000 years ago and develops nearly all of the steep, higher flanks of the volcano. These viscous light-coloured lava flows are displayed at two cliffs with broad faces, known as Ornostay Bluff
and Koosick Bluff
and contain basic rock made of solidified rubble overlain by large fractured lava with massive, poorly established pillars.
Two cinder cone
s on Ice Peak's southern flank called Camp Hill
and Cache Hill
and possibly first erupted when glacial ice was still existing on the Edziza lava plateau. As lava flowed into the glacial ice above a vent, pools of meltwater were created. Continuous lava eruptions that flowed into the meltwater pools were cooled and fractured. This fragmental material was interrupted by explosions of steam, water, ash, rock, and volcanic bomb
s called phreatic eruption
s. Camp Hill was eventually developed and over time it grew above water level inside the meltwater lake. Later eruptions produced a pyroclastic cone on top of the original fragmental cone. Cache Hill erupted when nearly all the glacial ice had retreated. The first lava flows from Cache Hill flowed through and dammed a river valley, which eventually ponded to produce a small lake. Subsequent lava flows traveled into the lake to produce pillow lava and solidified rubble. During the long period of Ice Peak activity, high-altitude glaciers developed and melted cutting valleys into the volcano. The current 2500 metres (8,202.1 ft) high summit of Ice Peak is a remnant of the western rim of a small summit caldera, which has been nearly destroyed by erosion
from high-altitude glaciation. Near the end of Ice Peak activity 1,500,000 years ago, this high-altitude glacial ice combined with the regional ice forming part of the Cordilleran Ice Sheet. It is likely that only the tallest mountains might have been visible over the Cordilleran Ice Sheet which was at least 2285 metres (7,496.7 ft) thick. A small volume of intermediate lava was erupted from Ice Peak compared to the other central volcanoes.
The fourth phase of activity began one million years ago when the Cordilleran Ice Sheet retreated from the upper flanks of the adjacent lava plateau, creating Mount Edziza
proper which is the most northerly of the four central volcanoes. It is a steep-sided stratovolcano
and the largest and highest of the peaks that form the volcanic complex with an elevation of 2787 metres (9,143.7 ft), overlapping the northern flank of Ice Peak. The stratovolcano is made up of a fine-grained volcanic rock called trachyte
and is associated with several lava domes which were formed by trachyte lava flows and explosive eruption
s. Its smooth northern and western flanks, only slightly channeled by erosion, curve up to a circular 2700 metres (8,858.3 ft) summit ridge which surrounds a central, ice-filled caldera
2 kilometres (1.2 mi) in diameter. Many glaciers cover Mount Edziza proper, including the Tencho Glacier on its southern flank. Active cirques on the eastern flank have breached the caldera rim, exposing the remnants of numerous lava lake
s which ponded in the caldera 900,000 years ago and rest on hydrothermally altered breccia of the main conduit. Piles of pillow lava
and hyaloclastite
, formed by subglacial eruption
s, are found on the flanks of Mount Edziza and nearby Ice Peak, as well as on the surface of the surrounding shield volcano. Pillow Ridge
on Edziza's northwest flank was formed when basaltic lava erupted beneath the regional Cordilleran Ice Sheet when it was close to its greatest thickness.
The fifth and final phase of eruptive activity occurred from secondary volcanic vents along the flanks of the four central volcanoes starting 10,000 years ago. This phase of activity began at a time when remnants of glacial ice were still present and continued after the glacial period. The initial flank eruptions, quenched by glacial meltwater, formed hyaloclastite
tuff rings, whereas later activity created 30 small cinder cone
s, primarily of basalt
ic composition, including Mess Lake Cone
, Kana Cone
, Cinder Cliff
, Icefall Cone
, Ridge Cone
, Williams Cone
, Walkout Creek Cone
, Moraine Cone
, Sidas Cone
, Sleet Cone
, Storm Cone
, Triplex Cone
, Twin Cone
, Cache Hill
, Camp Hill
, Cocoa Crater, Coffee Crater
, Nahta Cone
, Tennena Cone
, The Saucer
and the well-preserved Eve Cone
. 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 2 metres (6.6 ft) of loose basaltic fragments. These cinder 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
, is one of the areas of young lava flows in the region while the Desolation lava field
, on the northern end of the Big Raven Plateau, is the largest area of young lava flows, covering an area of 150 km2. The longest lava flow is 12 kilometres (7 mi). This volcanic activity was followed by at least two younger, but still undated eruptions, including an undated air-fall pumice
deposit.
The undated air-fall pumice
deposit exists across the southwestern part of the Big Raven Plateau called Sheep Track Pumice
or Sheep Track member. Pumice is a light volcanic rock
full of air spaces and commonly pale in colour, ranging from white, cream, blue or grey, but can be green or black. The Sheep Track Pumice is mysterious because the vent of its origin is unknown, even though it is estimated from its state of preservation to be younger than 500 years old. This pumice deposit emphasizes one of the significant volcanic hazards linked to the Mount Edziza volcanic complex - the likelihood of a violent explosive eruption
. The volcano that produced the pumice might be covered by glacial ice. Collaborators at the University of British Columbia
have started work on samples collected from deposits of Sheep Track Pumice.
The Mount Edziza volcanic complex is one of the eleven Canadian volcanoes associated with recent seismic activity
: the others are Castle Rock
, Mount Garibaldi
, Mount Cayley
, Hoodoo Mountain
, The Volcano
, Crow Lagoon
, Silverthrone Caldera
, Mount Meager
, Wells Gray-Clearwater volcanic field
and Nazko Cone
. Seismic data suggests that these volcanoes still contain live magma
plumbing systems, indicating possible future eruptive activity. Although the available data does not allow a clear conclusion, these observations are further indications that some of Canada's 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 volcanic centres with a history of significant explosive behavior, such as the Mount Edziza volcanic complex.
The most recent volcanic activity at the Mount Edziza volcanic complex have been hot spring
s, several of which are found on the volcano's western flank, including Elwyn springs (36°
C
or 97°F
), Taweh springs (46°C or 115°F), and inactive springs near Mess Lake
. The springs are near the youngest lava fields of the Mount Edziza volcanic complex and are most likely associated with the most recent eruptive activity. These hot springs were highly important to the adjacent Tahltan
people.
Hot springs are closely associated with fumarole
s, which are vents in an active volcanic area releasing steam and hot gases, such as sulfur dioxide
. In general, the water is rotating groundwater that comes into contact with rocks heated by magma and finds openings to the surface. The formation of the springs depends both on the rocks the water has passed through and the profusion of volcanic discharges mixed with the groundwater. Iron oxide
, iron sulfide
s and other substances usually colour pools of boiling mud brilliant yellow, red, brown or green. Hot springs comprising significantly softened silica may deposit it to form siliceous sinter, whereas those comprising softened calcium
carbonate
deposit spongy-looking calcareous rock called tufa
. Overflow of the springs can build masses, spires or stepped terraces of sinter or tufa.
First Nations
people, who now live in Dease Lake
, Telegraph Creek
and the Iskut
, used obsidian
from the Mount Edziza volcanic complex to make tools and weapons for trading material. Most of the obsidian occurs at relatively high elevations at about 1800 to-. This is the main source of obsidian found in northwestern British Columbia, which was traded as far away as Alaska
and northern Alberta
. Obsidian is a type of naturally occurring glass that is highly valued for its cutting qualities and is produced by the rapid cooling of lava. Like all glass and some other types of naturally occurring rocks, obsidian breaks with a characteristic conchoidal fracture
, creating razor sharp edges. A knife made of Edziza obsidian, possibly 2,000 years old, has been recovered in the Stikine River
area. Two exposed columnar basalt formations exist within the volcanic complex: the Tahltan Eagle at the meeting of the Tahltan
and Stikine rivers, and Pipe Organ Mountain. The Tahltan Eagle has significant spiritual and cultural importance to the Tahltan people, while the correct name and cultural significance of Pipe Organ Mountain to the Tahltan people is unknown.
This area of long-lived volcanic activity has been studied and mapped in detail for many years by geoscientists. The first detail studying and mapping of the Mount Edziza volcanic complex was accomplished in the early 1970s by a Geological Survey of Canada society led by Canadian scientist Jack Souther
. Edziza was a significant study area by Souther. While mapping, Souther looked at a mineral tenure map of Stikine Country and was surprised to see that many of the small cinder cones in the area had been maintained by mineral tenures. Upon investigation, the staking had been completed for the British Columbia Railway, then under construction to Dease Lake. The staking was designed to provide a ready source of weight for the railway bed. The Geological Survey of Canada agreed to support a series of Canada-wide lectures by Jack Souther to establish the Mount Edziza Provincial Park to protect the Mount Edziza volcanic complex. Coincidentally, Jack Souther had an opportunity to examine the Red Dog (Spectrum) property gold
veins and he accomplished several section studies of specimens. It was not Souther's intention to include in the park any of the mineralization within near-surface older rocks. However, the British Columbia Ministry of Parks established the Mount Edziza Recreation Area covering 1007.7 km² (389.1 sq mi) on July 27, 1972 as the park proclamation, providing a 1 to 10 km (0.621372736649807 to 6.2 ) wide buffer zone around the park area. On March 21, 1989, all but 40 km² (15.4 sq mi) of the recreation area, covering the Spectrum gold property on its margin, was surreptitiously merged with Mount Edziza Provincial Park, almost doubling its size to 2287 square kilometres (883 sq mi).
Souther's studies in 1992 highlighted the importance and size of the region, and proposed that numerous subglacial eruptions emplaced lava in a sub-ice or ice-contact environment. More recent studies have worked on Souther's contributions with more detailed studies which are funded by colleges and universities. Since colleges and universities started studying the Mount Edziza volcanic complex, it has been an extremely important volcano for subglacial volcanism because its ice-contact lavas record evidence of ice existence and thickness in an area for which there is very little data on ice conditions before the Illinoian Stage of glaciation, which preceded the last glacial, or "Wisconsin", period. Several areas of possible basalt
ic and trachytic
ice-contact products were studied in detail on the western flank of the Mount Edziza volcanic complex, in order to approve their ice-contact nature, and to eventually better constrain former ice existence and thickness. Its lava plateau has also been an important cultural resource. In 2006, Jeff Hungerford, a student of the University of Pittsburgh
in Carlisle, Pennsylvania
, United States
, focused on fieldwork on the region surrounding Edziza's Tennena Cone
, located immediately west of Ice Peak which formed subglacially during the early Holocene
period when this area had remnants of glacial ice from the last ice age. Hungerford's studies in 2006 focused on subglacial volcanism, sampling pillow lavas to be used for degassing studies aimed at determining ice thicknesses during a subglacial eruption, and describing coeval glaciogenic sediments immediately underlying pillow lavas at the distal end of the lava flows. Hungerford also worked on describing glaciogenic sediments immediately underlying lava flows from Ice Peak adjacent to Tennena Cone, which may preserve a record of a one million year old ice sheet.
Kristen LaMoreaux, another student of the University of Pittsburgh, focused on the emplacement of trachyte lava flows and domes. In 2006, LaMoreaux analyzed jointing patterns at Ornostay Bluff
, a viscous series of trachyte lava flows on the western lava plateau of the Mount Edziza volcanic complex. LaMoreaux also examined trachytic lava flows from Koosick Bluff
and Triangle Dome
, a trachytic lava dome which last erupted during the Pleistocene
period. Other studies by LaMoreaux determined criteria for understanding how lava flow thickness may or may not be an indication that the progress of a lava flow was impeded by an ice barrier, resulting in an unusually thick lava flow.
Chira Endress, a student of Dickinson College
in Carlisle, Pennsylvania
, United States, focused on a section of glaciogenic sediments immediately beneath the same Ice Peak trachyte lava flow sampled and described by Jeff Hungerford during his 2006 studies. Endress ettempted to determine if the sediments were deposited immediately before the lava flow was emplaced, or if they are likely to be much older. Endress has quantified the mineralogy of clasts and sand-sized particles from samples in the sediment, and has determined that the mineralogy of several of the trachytic clasts is very similar to that in the overlying lava flow, including the minerals clinopyroxene, magnetite
, alkali feldspar
, and aenigmatite. Endress has also found small lenses of pristine basaltic glass, which could have derived from the Pillow Ridge subglacial mound near Mount Edziza.
Alexander S. Lloyd, a student of Dickinson College, focused on the cooling rates of pillow lavas. Lloyd studied in detail the variation in crystal sizes from the edge pristine pillow lava, which could have derived from nearby Pillow Ridge
which last erupted during the Pleistocene
period.
Courtney Haynes, another student of Dickinson College, focused on mathematics of the pillow lavas in 2007.
A possible way to detect an eruption is studying Edziza's geological history since every volcano has its own pattern of behavior, in terms of its eruption style, magnitude and frequency, so that its future eruption is expected to be similar to its previous eruptions.
While there is a likelihood of Canada being critically affected by local or close by volcanic eruptions argues that some kind of improvement program is required. Benefit-cost thoughts are critical to dealing with natural hazards. However, a benefit-cost examination needs correct data about the hazard types, magnitudes and occurrences. These do not exist for volcanoes in British Columbia or elsewhere in Canada in the detail required.
Other volcanic techniques, such as hazard mapping, displays a volcano's eruptive history in detail and speculates an understanding of the hazardous activity that could possibly be expected in the future. A large volcanic hazard program has never existed within the Geological Survey of Canada. The information has been collected in a lengthy, separate way from the support of several employees, such as volcanologist
s and other geologic scientist
s. Current knowledge is best established at Mount Meager
in the Garibaldi Volcanic Belt
of southwestern British Columbia and is likely to rise considerably with a temporary mapping and monitoring project. Knowledge at the Mount Edziza volcanic complex and other volcanoes in the Northern Cordilleran Volcanic Province is not as established, but certain contributions are being done at least Mount Cayley
, another volcano in the Garibaldi Volcanic Belt. An intensive program classifiying infrastructural exposure near all young Canadian volcanoes and quick hazard assessments at each individual volcanic edifice associated with recent seismic activity would be in advance and would produce a quick and productive determination of priority areas for further efforts.
The existing network of seismographs to monitor tectonic earthquakes has existed since 1975, although it remained small in population until 1985. Apart from a few short-term seismic monitoring experiments by the Geological Survey of Canada, no volcano monitoring has been accomplished at the Mount Edziza volcanic complex or at other volcanoes in Canada at a level approaching that in other established countries with historically active volcanoes. Active or restless volcanoes are usually monitored using at least three seismographs all within approximately 15 kilometres (9.3 mi), and frequently within 5 kilometres (3.1 mi), for better sensitivity of detection and reduced location errors, particularly for earthquake depth. Such monitoring detects the risk of an eruption, offering a forecasting capability which is important to mitigating volcanic risk. Currently the Mount Edziza volcanic complex does not have a seismograph closer than 88 kilometres (54.7 mi). With increasing distance and declining numbers of seismographs used to indicate seismic activity, the prediction capability is reduced because earthquake location accuracy and depth decreases, and the network becomes less accurate. At carefully monitored volcanoes both the located and noticed events are recorded and surveyed immediately to improve the understanding of a future eruption.
In countries like Canada it is possible that small precursor earthquake swarms might go undetected, particularly if no events were observed; more significant events in larger swarms would be detected but only a minor subdivision of the swarm events would be complex to clarify them with confidence as volcanic in nature, or even associate them with an individual volcanic edifice.
Complex volcano
A complex volcano, also called a compound volcano, is a volcano with more than one feature. They form because changes of their eruptive characteristics or the location of multiple vents in an area...
in Stikine Country
Stikine Country
The Stikine Country, also referred to as the Stikine District or simply "the Stikine" , is one of the historical geographic regions of the Canadian province of British Columbia, located inland from the central Alaska Panhandle and comprising the basin of the Stikine River and its tributaries...
, northwestern British Columbia
British Columbia
British Columbia is the westernmost of Canada's provinces and is known for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . Its name was chosen by Queen Victoria in 1858...
, Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
, located 38 kilometres (23.6 mi) southeast of the small community of Telegraph Creek
Telegraph Creek, British Columbia
Telegraph Creek is a small community located off Highway 37 in Northern British Columbia at the confluence of the Stikine River and Telegraph Creek. The only permanent settlement on the Stikine River, it is home to approximately 350 members of the Tahltan First Nation, as well as another 50...
. It occupies the southeastern portion of the Tahltan Highland
Tahltan Highland
The Tahltan Highland is an upland area of plateau and relatively lower mountain ranges in British Columbia, Canada, lying east of the Boundary Ranges and south of the Inklin River...
, an upland area of plateau and lower mountain range
Mountain range
A mountain range is a single, large mass consisting of a succession of mountains or narrowly spaced mountain ridges, with or without peaks, closely related in position, direction, formation, and age; a component part of a mountain system or of a mountain chain...
s, lying east of the Boundary Ranges
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...
and south of the Inklin River
Inklin River
The Inklin River is a river in northern British Columbia, Canada. It flows northwest into the head of the Taku River, which is formed by the convergence of the Inklin with the Nakina River, which flows southwest to meet it at the uninhabited locality of Inklin, which is located at the...
, which is the east fork of the Taku River
Taku River
The Taku River is a river running from British Columbia, Canada, to the northwestern coast of North America, at Juneau, Alaska. Its mouth coincides with the Alaska-British Columbia border...
. As a volcanic complex, it consists of many types of volcanoes, including shield volcano
Shield volcano
A shield volcano is a type of volcano usually built almost entirely of fluid lava flows. They are named for their large size and low profile, resembling a warrior's shield. This is caused by the highly fluid lava they erupt, which travels farther than lava erupted from more explosive volcanoes...
es, caldera
Caldera
A caldera is a cauldron-like volcanic feature usually formed by the collapse of land following a volcanic eruption, such as the one at Yellowstone National Park in the US. They are sometimes confused with volcanic craters...
s, lava dome
Lava dome
|250px|thumb|right|Image of the [[rhyolitic]] lava dome of [[Chaitén Volcano]] during its 2008–2009 eruption.In volcanology, a lava dome is a roughly circular mound-shaped protrusion resulting from the slow extrusion of viscous lava from a volcano...
s, stratovolcano
Stratovolcano
A stratovolcano, also known as a composite volcano, is a tall, conical volcano built up by many layers of hardened lava, tephra, pumice, and volcanic ash. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile and periodic, explosive eruptions...
es, and cinder cone
Cinder cone
According to the , Cinder Cone is the proper name of 1 cinder cone in Canada and 7 cinder cones in the United States:In Canada: Cinder Cone In the United States:...
s.
Most of the Mount Edziza volcanic complex is encompassed within a large provincial park
Provincial park
A provincial park is a park under the management of a provincial or territorial government in Canada.While provincial parks are not the same as national parks, their workings are very similar...
called Mount Edziza Provincial Park. Named after Mount Edziza
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 a complex of multiple peaks and ridges, with several glaciers flowing in all directions. The summit...
, this 2660.95 km² (1,027.4 sq mi) park was established in 1972 to preserve the volcanic and cultural treasures unique to the northern British Columbia area. The Mount Edziza volcanic complex is remote, and, without roads, accessible only along trails. The easiest access is from Highway 37 and a spur road from Dease Lake
Dease Lake, British Columbia
Dease Lake is a small community located in the Cassiar Country of the Northern Interior of British Columbia, Canada. Located only a few hours south of the Yukon border, it is located on Highway 37 at the south end of the lake of the same name. Dease Lake is the last major centre before the Alaska...
to Telegraph Creek
Telegraph Creek, British Columbia
Telegraph Creek is a small community located off Highway 37 in Northern British Columbia at the confluence of the Stikine River and Telegraph Creek. The only permanent settlement on the Stikine River, it is home to approximately 350 members of the Tahltan First Nation, as well as another 50...
. From Kinaskan Lake, on Highway 37, a poorly maintained trail extends west for 30 kilometres (18.6 mi) into the heart of the complex. From Telegraph Creek another trail extends east for 25 kilometres (15.5 mi) to the north slope of Mount Edziza.
Origins
Continent
A continent is one of several very large landmasses on Earth. They are generally identified by convention rather than any strict criteria, with seven regions commonly regarded as continents—they are : Asia, Africa, North America, South America, Antarctica, Europe, and Australia.Plate tectonics is...
al rift
Rift
In geology, a rift or chasm is a place where the Earth's crust and lithosphere are being pulled apart and is an example of extensional tectonics....
ing—a long divergent plate boundary
Divergent boundary
In plate tectonics, a divergent boundary or divergent plate boundary is a linear feature that exists between two tectonic plates that are moving away from each other. Divergent boundaries within continents initially produce rifts which produce rift valleys...
where the lithosphere
Lithosphere
The lithosphere is the rigid outermost shell of a rocky planet. On Earth, it comprises the crust and the portion of the upper mantle that behaves elastically on time scales of thousands of years or greater.- Earth's lithosphere :...
is being pulled apart. Here, the continental crust
Continental crust
The continental crust is the layer of igneous, sedimentary, and metamorphic rocks which form the continents and the areas of shallow seabed close to their shores, known as continental shelves. This layer is sometimes called sial due to more felsic, or granitic, bulk composition, which lies in...
of the North American Plate
North American Plate
The North American Plate is a tectonic plate covering most of North America, Greenland, Cuba, Bahamas, and parts of Siberia, Japan and Iceland. It extends eastward to the Mid-Atlantic Ridge and westward to the Chersky Range in eastern Siberia. The plate includes both continental and oceanic crust...
is being stretched at a rate of about 2 cm (0.78740157480315 in) per year. This incipient rifting has formed as a result of the Pacific Plate
Pacific Plate
The Pacific Plate is an oceanic tectonic plate that lies beneath the Pacific Ocean. At 103 million square kilometres, it is the largest tectonic plate....
sliding northward along the Queen Charlotte Fault
Queen Charlotte Fault
The Queen Charlotte Fault is an active transform fault, located between the North American Plate and the Pacific Plate, Canada's equivalent of the San Andreas Fault. The Queen Charlotte Fault forms a triple junction on its south with the Cascadia subduction zone and the Explorer Ridge...
, on its way to the Aleutian Trench
Aleutian Trench
The Aleutian Trench is a subduction zone and oceanic trench which runs along the southern coastline of Alaska and the adjacent waters of northeastern Siberia off the coast of Kamchatka Peninsula. It is classified as a "marginal trench" in the east as it runs along the margin of the continent, and...
, which extends along the southern coastline of Alaska
Alaska
Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...
and the adjacent waters of northeastern Siberia
Siberia
Siberia is an extensive region constituting almost all of Northern Asia. Comprising the central and eastern portion of the Russian Federation, it was part of the Soviet Union from its beginning, as its predecessor states, the Tsardom of Russia and the Russian Empire, conquered it during the 16th...
off the coast of Kamchatka Peninsula
Kamchatka Peninsula
The Kamchatka Peninsula is a peninsula in the Russian Far East, with an area of . It lies between the Pacific Ocean to the east and the Sea of Okhotsk to the west...
. As the continental crust stretches, the near-surface rocks fracture along steeply dipping cracks parallel to the rift known as faults. Hot basalt
Basalt
Basalt is a common extrusive volcanic rock. It is usually grey to black and fine-grained due to rapid cooling of lava at the surface of a planet. It may be porphyritic containing larger crystals in a fine matrix, or vesicular, or frothy scoria. Unweathered basalt is black or grey...
ic magma
Magma
Magma is a mixture of molten rock, volatiles and solids that is found beneath the surface of the Earth, and is expected to exist on other terrestrial planets. Besides molten rock, magma may also contain suspended crystals and dissolved gas and sometimes also gas bubbles. Magma often collects in...
rises along these fractures to create passive lava eruptions, known as effusive eruption
Effusive eruption
An effusive eruption is a volcanic eruption characterized by the outpouring of lava onto the ground...
s.
The rift zone has existed for at least 20 million years, and has created a line of volcanoes called the Northern Cordilleran Volcanic Province
Northern Cordilleran volcanic province
The Northern Cordilleran Volcanic Province , 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...
, also called the Stikine Volcanic Belt, stretching from the Alaska
Alaska
Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...
-Yukon
Yukon
Yukon is the westernmost and smallest of Canada's three federal territories. It was named after the Yukon River. The word Yukon means "Great River" in Gwich’in....
border to near Prince Rupert, British Columbia
Prince Rupert, British Columbia
Prince Rupert is a port city in the province of British Columbia, Canada. It is the land, air, and water transportation hub of British Columbia's North Coast, and home to some 12,815 people .-History:...
. Several presently dormant volcanoes in the province are potentially active, three of them having erupted in the last few hundred years, two witnessed by First Nations
First Nations
First Nations is a term that collectively refers to various Aboriginal peoples in Canada who are neither Inuit nor Métis. There are currently over 630 recognised First Nations governments or bands spread across Canada, roughly half of which are in the provinces of Ontario and British Columbia. The...
and placer miners
Placer mining
Placer mining is the mining of alluvial deposits for minerals. This may be done by open-pit or by various surface excavating equipment or tunneling equipment....
during the 18th and 19th centuries. The Tseax Cone
Tseax Cone
The Tseax Cone , also called the Tseax River Cone or alternately the Aiyansh Volcano, is a young cinder cone and adjacent lava flows associated with the Nass Ranges and the Northern Cordilleran Volcanic Province...
, which last erupted in the 18th century, is the southernmost historically active volcano in the province, while Prindle Volcano in easternmost-central Alaska, which erupted during the Pleistocene
Pleistocene
The Pleistocene is the epoch from 2,588,000 to 11,700 years BP that spans the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....
period, is generally considered the northernmost.
Structure
Level Mountain Range
The Level Mountain Range, also known as Level Mountain, is a mountain range in Cassiar Country, northwestern British Columbia, Canada, located just northeast of Callison Ranch, southwest of Dease Lake and about north of Mount Edziza. It consists of a massive shield volcano and lies on the Nahlin...
north of Edziza, which has an area of 1800 km² (695 sq mi). Four central volcanoes, known as Armadillo Peak
Armadillo Peak
Armadillo Peak is a 7.5 million year old caldera, located about 3 km north of Bourgeaux Creek and northeast of Raspberry Pass, British Columbia, Canada. It is south of Mount Edziza and is overlapped by the Ice Peak central volcano, which was formed during the early Pleistocene. Its caldera is...
, Spectrum Range
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 Edziza and north of the Arctic Lake Plateau. The...
, Ice Peak
Ice Peak
Ice Peak is a stratovolcano, located west of Tatogga and south of Mount Edziza, British Columbia, Canada. It overlaps the 7.5 million year old Armadillo Peak. It lies on a large volcanic plateau, which is made of basaltic lava flows from the massive Mount Edziza volcanic complex...
, and Mount Edziza
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 a complex of multiple peaks and ridges, with several glaciers flowing in all directions. The summit...
, lie along the northerly trending axis of an oval, composite shield volcano. The composite shield volcano consists of overlapping shields, two of which are clearly noticeable on maps. The composite shield volcano forms a broad lava plateau, 65 kilometres (40.4 mi) long and 20 kilometres (12.4 mi) wide, mainly made of basaltic lava flows; it is dotted with cinder cones and surrounded by steep ridges called escarpment
Escarpment
An escarpment is a steep slope or long cliff that occurs from erosion or faulting and separates two relatively level areas of differing elevations.-Description and variants:...
s, which expose layers of black columnar basaltic lava flows with distal rock fragments and pyroclastic deposits. More light-coloured magmas of mainly trachyte
Trachyte
Trachyte is an igneous volcanic rock with an aphanitic to porphyritic texture. The mineral assemblage consists of essential alkali feldspar; relatively minor plagioclase and quartz or a feldspathoid such as nepheline may also be present....
and comendite
Comendite
Comendite is a hard, peralkaline igneous rock, a type of light blue grey rhyolite. Phenocrysts are sodic sanidine with minor albite and bipyrimidal quartz. Comendite occurs in the mountains Tibrogargan, Coonowrin, Tunbubudla, Coochin, Saddleback, Tibberoowuccum and Ngungun in the Glass House...
with very little aluminum are mainly confined to the four central volcanoes and associated lava dome. The lava plateau is flanked by Klastline River to the north, Mess Creek and larger Stikine River
Stikine River
The Stikine River is a river, historically also the Stickeen River, approximately 610 km long, in northwestern British Columbia in Canada and southeastern Alaska in the United States...
to the west and the Iskut River
Iskut River
The Iskut River is the largest tributary of the Stikine River in northwestern British Columbia, Canada, entering it a few miles above its entry into Alaska....
to the east. Elevations of the lava plateau are 1500 to- with volcanic mountains rising 2590 metres (8,497.4 ft) above sea level. Three sections of the lava plateau have official names; these are the Arctic Lake
Arctic Lake Plateau
The Arctic Lake Plateau is a lava plateau in northern British Columbia, Canada, located northeast of Arctic Lake at the south end of Mount Edziza Provincial Park and Recreation Area....
, Big Raven
Big Raven Plateau
The Big Raven Plateau is a lava plateau in northern British Columbia, Canada, located west of Mount Edziza in Mount Edziza Provincial Park and Recreation Area...
, and Kitsu
Kitsu Plateau
The Kitsu Plateau is a lava plateau in northern British Columbia, Canada, located east of Mess Lake in Mount Edziza Provincial Park and Recreation Area. It is named in association with Kitsu Peak and Kitsu Creek. Kitsu in the Tahltan language is the word for the northern lights.-See...
plateaus. The history of the Mount Edziza volcanic complex includes at least two periods of regional glaciation, when deep ice sheets covered the land, and several lesser advances of mountain glaciers.
Stratovolcano composition
The steep-sided, symmetrical stratovolcanoStratovolcano
A stratovolcano, also known as a composite volcano, is a tall, conical volcano built up by many layers of hardened lava, tephra, pumice, and volcanic ash. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile and periodic, explosive eruptions...
es in the region were built by repeated eruptions of thick, slow-moving lava that have commonly flowed only a few kilometres from the vent. Explosive eruption
Explosive eruption
An explosive eruption is a volcanic term to describe a violent, explosive type of eruption. Mount St. Helens in 1980 was an example. Such an eruption is driven by gas accumulating under great pressure. Driven by hot rising magma, it interacts with ground water until the pressure increases to the...
s are often associated with these volcanoes, depositing alternating layers of volcanic ash
Volcanic ash
Volcanic ash consists of small tephra, which are bits of pulverized rock and glass created by volcanic eruptions, less than in diameter. There are three mechanisms of volcanic ash formation: gas release under decompression causing magmatic eruptions; thermal contraction from chilling on contact...
, cinder
Cinder
A cinder is a pyroclastic material. Cinders are extrusive igneous rocks. Cinders are similar to pumice, which has so many cavities and is such low-density that it can float on water...
s, blocks, and globes of molten rock called volcanic bomb
Volcanic bomb
A volcanic bomb is a mass of molten rock larger than 65 mm in diameter, formed when a volcano ejects viscous fragments of lava during an eruption. They cool into solid fragments before they reach the ground. Because volcanic bombs cool after they leave the volcano, they do not have grains...
s or lava bombs, which are added to its slopes to create the stratovolcano. Edziza's stratovolcanoes contain a fine-grained silica-rich volcanic rock called trachyte
Trachyte
Trachyte is an igneous volcanic rock with an aphanitic to porphyritic texture. The mineral assemblage consists of essential alkali feldspar; relatively minor plagioclase and quartz or a feldspathoid such as nepheline may also be present....
; they have not erupted for thousands of years, allowing erosion
Erosion
Erosion is when materials are removed from the surface and changed into something else. It only works by hydraulic actions and transport of solids in the natural environment, and leads to the deposition of these materials elsewhere...
to destroy the original cone, creating craggy ridge
Ridge
A ridge is a geological feature consisting of a chain of mountains or hills that form a continuous elevated crest for some distance. Ridges are usually termed hills or mountains as well, depending on size. There are several main types of ridges:...
s and rock outcrops of more resistant materials.
Caldera composition
Circular calderaCaldera
A caldera is a cauldron-like volcanic feature usually formed by the collapse of land following a volcanic eruption, such as the one at Yellowstone National Park in the US. They are sometimes confused with volcanic craters...
s in the Mount Edziza volcanic complex were formed as a result of emptying the magma chamber
Magma chamber
A magma chamber is a large underground pool of molten rock found beneath the surface of the Earth. The molten rock in such a chamber is under great pressure, and given enough time, that pressure can gradually fracture the rock around it creating outlets for the magma...
beneath a volcano. If enough magma
Magma
Magma is a mixture of molten rock, volatiles and solids that is found beneath the surface of the Earth, and is expected to exist on other terrestrial planets. Besides molten rock, magma may also contain suspended crystals and dissolved gas and sometimes also gas bubbles. Magma often collects in...
is erupted, the emptied chamber will not be able to support the weight of the volcanic edifice above it. A roughly circular fracture— a "ring fault"— develops around the edge of the chamber. These ring fractures serve as feeders for fault intrusion
Intrusion
An intrusion is liquid rock that forms under Earth's surface. Magma from under the surface is slowly pushed up from deep within the earth into any cracks or spaces it can find, sometimes pushing existing country rock out of the way, a process that can take millions of years. As the rock slowly...
s that are also known as ring dike
Ring dike
A ring dike or ring dyke in geology refers to an intrusive igneous body. Their chemistry, petrology and field appearance precisely match those of dikes or sill, but their concentric or radial geometric distribution around a centre of volcanic activity indicates their subvolcanic origins.-Notable...
s. Secondary volcanic vents form above the ring fracture. As the magma chamber empties, the centre of the volcano within the ring fracture begins to collapse. The collapse may occur as the result of a single cataclysmic eruption, or it may occur in stages as the result of a series of eruptions. These caldera collapses are relatively small compared to most other caldera collapses. The largest caldera at the Mount Edziza volcanic complex is about 6 kilometres (4 mi) in diameter while most calderas are at least 25 kilometres (15.5 mi) in diameter. Volcanic eruptions accompanying these collapses produced trachyte
Trachyte
Trachyte is an igneous volcanic rock with an aphanitic to porphyritic texture. The mineral assemblage consists of essential alkali feldspar; relatively minor plagioclase and quartz or a feldspathoid such as nepheline may also be present....
and a white, sodic rhyolite
Rhyolite
This page is about a volcanic rock. For the ghost town see Rhyolite, Nevada, and for the satellite system, see Rhyolite/Aquacade.Rhyolite is an igneous, volcanic rock, of felsic composition . It may have any texture from glassy to aphanitic to porphyritic...
called comendite
Comendite
Comendite is a hard, peralkaline igneous rock, a type of light blue grey rhyolite. Phenocrysts are sodic sanidine with minor albite and bipyrimidal quartz. Comendite occurs in the mountains Tibrogargan, Coonowrin, Tunbubudla, Coochin, Saddleback, Tibberoowuccum and Ngungun in the Glass House...
.
Lava dome composition
Edziza's rounded, steep-sided lava domeLava dome
|250px|thumb|right|Image of the [[rhyolitic]] lava dome of [[Chaitén Volcano]] during its 2008–2009 eruption.In volcanology, a lava dome is a roughly circular mound-shaped protrusion resulting from the slow extrusion of viscous lava from a volcano...
s were built by eruptions of very thick light-coloured magma, including trachyte
Trachyte
Trachyte is an igneous volcanic rock with an aphanitic to porphyritic texture. The mineral assemblage consists of essential alkali feldspar; relatively minor plagioclase and quartz or a feldspathoid such as nepheline may also be present....
. Such magmas are typically too thick to move far from the vent it extrudes from, causing it to solidify quickly and build on previous volcanic extrusions, creating a characteristic dome-like shape. The thickness of the magma is attributed to high levels of silica, a naturally occurring silicon dioxide
Silicon dioxide
The chemical compound silicon dioxide, also known as silica , is an oxide of silicon with the chemical formula '. It has been known for its hardness since antiquity...
found in various crystalline and amorphous forms. Edziza's domes reach heights of several hundred metres, and grew slowly and steadily for months to years. The sides of these structures are composed of unstable rock debris. Due to the possibility of the building of gas pressure, the dome can experience more explosive eruptions over time. When part of a lava dome collapses while it still contains molten rock and gases, it can produce a pyroclastic flow
Pyroclastic flow
A pyroclastic flow is a fast-moving current of superheated gas and rock , which reaches speeds moving away from a volcano of up to 700 km/h . The flows normally hug the ground and travel downhill, or spread laterally under gravity...
, a super-heated mix of gas, ash, and pumice
Pumice
Pumice is a textural term for a volcanic rock that is a solidified frothy lava typically created when super-heated, highly pressurized rock is violently ejected from a volcano. It can be formed when lava and water are mixed. This unusual formation is due to the simultaneous actions of rapid...
.
Characteristics of lava dome eruptions include shallow, long-period and hybrid seismic activity, which is attributed to excess fluid pressures in the contributing vent chamber. Other characteristics of lava domes include their spherical dome shape, cycles of dome growth over long periods, and sudden onsets of violent explosive activity. The average rate of dome growth may be used as a rough indicator of magma supply, but it shows no systematic relationship to the timing or characteristic of lava dome explosions.
Cinder cone composition
The steep conical cinder coneCinder cone
According to the , Cinder Cone is the proper name of 1 cinder cone in Canada and 7 cinder cones in the United States:In Canada: Cinder Cone In the United States:...
s of Edziza were formed by lava fountain
Lava fountain
A lava fountain is a volcanic phenomenon in which lava is forcefully but non-explosively ejected from a crater, vent, or fissure. Lava fountains may reach heights of up to . They may occur as a series of short pulses, or a continuous jet of lava. They are commonly seen in Hawaiian eruptions.-See...
eruptions, emitting particles and blobs of congealed lava from a single vent. As the gas-charged lava is blown violently into the air, it breaks into small fragments that solidify and fall as cinder
Cinder
A cinder is a pyroclastic material. Cinders are extrusive igneous rocks. Cinders are similar to pumice, which has so many cavities and is such low-density that it can float on water...
around the vent to form a circular or oval cone. Edziza's cinder cones have bowl-shaped craters at their summits and rise more than a hundred metres above their surroundings. Cinder cones are widespread in British Columbia as well as throughout other volcanic terrains of the world.
Eve Cone
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 most recent eruptions on the Big Raven Plateau and in...
, a black cinder cone of the Mount Edziza volcanic complex, is one the most famous symmetrical and best preserved cinder cones in Canada, reaching a height of 1740 metres (5,708.7 ft) and a topographic prominence
Topographic prominence
In topography, prominence, also known as autonomous height, relative height, shoulder drop , or prime factor , categorizes the height of the mountain's or hill's summit by the elevation between it and the lowest contour line encircling it and no higher summit...
of 150 metres (492.1 ft).
Shield volcano composition
Edziza's shield volcanoShield volcano
A shield volcano is a type of volcano usually built almost entirely of fluid lava flows. They are named for their large size and low profile, resembling a warrior's shield. This is caused by the highly fluid lava they erupt, which travels farther than lava erupted from more explosive volcanoes...
es are built almost entirely of fluid lava flows. They formed as a result of lava flowing out in all directions from central summit vents and from groups of vents, building a broad, gently sloping cone of flat, domical shape. They are built up slowly by the accretion of thousands of lava flows of highly fluid basalt
Basalt
Basalt is a common extrusive volcanic rock. It is usually grey to black and fine-grained due to rapid cooling of lava at the surface of a planet. It may be porphyritic containing larger crystals in a fine matrix, or vesicular, or frothy scoria. Unweathered basalt is black or grey...
ic lava, which spread widely over great distances, and then cool as thin, gently dipping sheets. In some shield volcano eruptions, basaltic lava has poured out quietly from fissure vent
Fissure vent
A fissure vent, also known as a volcanic fissure or simply fissure, is a linear volcanic vent through which lava erupts, usually without any explosive activity. The vent is usually a few meters wide and may be many kilometers long. Fissure vents can cause large flood basalts and lava channels...
s instead of central vents, flooding the surrounding countryside with lava flow upon lava flow, forming Edziza's broad lava plateau.
Lava plateaus similar to Edziza's can be found elsewhere in North America, including the Snake River Plain
Snake River Plain
The Snake River Plain is a geologic feature located primarily within the state of Idaho in the United States of America. It stretches about westward from northwest of the state of Wyoming to the Idaho-Oregon border. The plain is a wide flat bow-shaped depression, and covers about a quarter of Idaho...
in Idaho
Idaho
Idaho is a state in the Rocky Mountain area of the United States. The state's largest city and capital is Boise. Residents are called "Idahoans". Idaho was admitted to the Union on July 3, 1890, as the 43rd state....
, and the Columbia River Basalt Group
Columbia River Basalt Group
The Columbia River Basalt Group is a large igneous province that lies across parts of the Western United States. It is found in the U.S. states of Washington, Oregon, Idaho, Nevada, and California...
in southeastern Washington, and eastern Oregon
Oregon
Oregon is a state in the Pacific Northwest region of the United States. It is located on the Pacific coast, with Washington to the north, California to the south, Nevada on the southeast and Idaho to the east. The Columbia and Snake rivers delineate much of Oregon's northern and eastern...
, United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
; they can also be found in Iceland
Iceland
Iceland , described as the Republic of Iceland, is a Nordic and European island country in the North Atlantic Ocean, on the Mid-Atlantic Ridge. Iceland also refers to the main island of the country, which contains almost all the population and almost all the land area. The country has a population...
.
Subglacial mound composition
Subglacial moundSubglacial mound
A subglacial mound is a type of subglacial volcano. This type of volcano forms when lava erupts beneath a thick glacier or ice sheet. The magma forming these volcanoes was not hot enough to melt a vertical pipe right through the overlying glacial ice, instead forming hyaloclastite and pillow lava...
s (SUGM) of the Mount Edziza volcanic complex are an unusual type of subglacial volcano
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...
formed when subglacial eruption
Subglacial eruption
A subglacial eruption is a volcanic eruption that has occurred under ice, or under a glacier. Subglacial eruptions can cause dangerous floods, lahars and create hyaloclastite and pillow lava. Subglacial eruptions sometimes form a subglacial volcano called a tuya. Tuyas in Iceland are called table...
s began melting overlying glacial ice at a time when this region was covered by glacial ice during the Pleistocene
Pleistocene
The Pleistocene is the epoch from 2,588,000 to 11,700 years BP that spans the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....
and early Holocene
Holocene
The Holocene is a geological epoch which began at the end of the Pleistocene and continues to the present. The Holocene is part of the Quaternary period. Its name comes from the Greek words and , meaning "entirely recent"...
periods. These subglacial eruptions were not hot enough to melt a vertical pipe right through the overlying glacial ice, instead forming mounds of hydrated volcanic rock made up of volcanic fragments called hyaloclastite
Hyaloclastite
Hyaloclastite is a hydrated tuff-like breccia rich in black volcanic glass, formed during volcanic eruptions under water, under ice or where subaerial flows reach the sea or other bodies of water. It has the appearance of angular flat fragments sized between a millimeter to few centimeters...
and lava that solidified into pillow-shaped masses called pillow lava
Pillow lava
Pillow lavas are lavas that contain characteristic pillow-shaped structures that are attributed to the extrusion of the lava under water, or subaqueous extrusion. Pillow lavas in volcanic rock are characterized by thick sequences of discontinuous pillow-shaped masses, commonly up to one metre in...
deep beneath the glacial ice field. Once the glaciers had retreated, the subglacial volcanoes would be revealed, with a unique shape as a result of their confinement within glacial ice.
Eruptive history
Lava dome
|250px|thumb|right|Image of the [[rhyolitic]] lava dome of [[Chaitén Volcano]] during its 2008–2009 eruption.In volcanology, a lava dome is a roughly circular mound-shaped protrusion resulting from the slow extrusion of viscous lava from a volcano...
s, caldera
Caldera
A caldera is a cauldron-like volcanic feature usually formed by the collapse of land following a volcanic eruption, such as the one at Yellowstone National Park in the US. They are sometimes confused with volcanic craters...
s, stratovolcano
Stratovolcano
A stratovolcano, also known as a composite volcano, is a tall, conical volcano built up by many layers of hardened lava, tephra, pumice, and volcanic ash. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile and periodic, explosive eruptions...
es, subglacial mound
Subglacial mound
A subglacial mound is a type of subglacial volcano. This type of volcano forms when lava erupts beneath a thick glacier or ice sheet. The magma forming these volcanoes was not hot enough to melt a vertical pipe right through the overlying glacial ice, instead forming hyaloclastite and pillow lava...
s and cinder cone
Cinder cone
According to the , Cinder Cone is the proper name of 1 cinder cone in Canada and 7 cinder cones in the United States:In Canada: Cinder Cone In the United States:...
s forming the volcanic complex were constructed in five phases, each of which began with the effusion of dark olivine
Olivine
The mineral olivine is a magnesium iron silicate with the formula 2SiO4. It is a common mineral in the Earth's subsurface but weathers quickly on the surface....
basalt
Basalt
Basalt is a common extrusive volcanic rock. It is usually grey to black and fine-grained due to rapid cooling of lava at the surface of a planet. It may be porphyritic containing larger crystals in a fine matrix, or vesicular, or frothy scoria. Unweathered basalt is black or grey...
which formed the flat-lying shield volcano
Shield volcano
A shield volcano is a type of volcano usually built almost entirely of fluid lava flows. They are named for their large size and low profile, resembling a warrior's shield. This is caused by the highly fluid lava they erupt, which travels farther than lava erupted from more explosive volcanoes...
es and concluded with the eruption of light-coloured magma
Magma
Magma is a mixture of molten rock, volatiles and solids that is found beneath the surface of the Earth, and is expected to exist on other terrestrial planets. Besides molten rock, magma may also contain suspended crystals and dissolved gas and sometimes also gas bubbles. Magma often collects in...
. This cyclical behavior is attributed to the episodic rise of basic, mantle
Mantle (geology)
The mantle is a part of a terrestrial planet or other rocky body large enough to have differentiation by density. The interior of the Earth, similar to the other terrestrial planets, is chemically divided into layers. The mantle is a highly viscous layer between the crust and the outer core....
-derived alkali basalt both to the surface and partly into crustal reservoirs where the light-coloured magmas with very little aluminum were created by prolonged crystal fractionation
Fractional crystallization (geology)
Fractional crystallization is one of the most important geochemical and physical processes operating within the Earth's crust and mantle. Fractional crystallization is the removal and segregation from a melt of mineral precipitates; except in special cases, removal of the crystals changes the...
. The silica-rich trachyte
Trachyte
Trachyte is an igneous volcanic rock with an aphanitic to porphyritic texture. The mineral assemblage consists of essential alkali feldspar; relatively minor plagioclase and quartz or a feldspathoid such as nepheline may also be present....
and comendite lavas are similar to those associated with the most violent eruptions on Earth.
Armadillo Peak eruptive period
The first phase of activity resulted in the creation of Armadillo PeakArmadillo Peak
Armadillo Peak is a 7.5 million year old caldera, located about 3 km north of Bourgeaux Creek and northeast of Raspberry Pass, British Columbia, Canada. It is south of Mount Edziza and is overlapped by the Ice Peak central volcano, which was formed during the early Pleistocene. Its caldera is...
seven million years ago, today represented by an eroded remnant of a small caldera
Caldera
A caldera is a cauldron-like volcanic feature usually formed by the collapse of land following a volcanic eruption, such as the one at Yellowstone National Park in the US. They are sometimes confused with volcanic craters...
flanked by steep-sided light-coloured secondary lava domes, including Cartoona Peak
Cartoona Peak
Cartoona Peak, also unofficially called Cartoona Ridge, is a volcanic peak in northern British Columbia, Canada, located just southeast of Coffee Crater in Mount Edziza Provincial Park.-See also:*List of volcanoes in Canada...
, Tadeda Peak
Tadeda Peak
Tadeda Peak, also known unofficially as Tadeda Centre, is a volcanic peak in northern British Columbia, Canada, located just southeast of Coffee Crater in Mount Edziza Provincial Park.-See also:* List of volcanoes in Canada...
, IGC Centre
IGC Centre
IGC Centre is a lava dome in Mount Edziza Provincial Park of northern British Columbia, Canada. It is thought to have formed and last erupted during the Miocene period.-See also:*List of volcanoes in Canada*List of Northern Cordilleran volcanoes...
, and Sezill Volcano
Sezill Volcano
Sezill Volcano is a lava dome in Mount Edziza Provincial Park of northern British Columbia, Canada. It is thought to have formed and last erupted during the Miocene period...
, and a thick pile of interlayered light-coloured lava flows, pyroclastic flow
Pyroclastic flow
A pyroclastic flow is a fast-moving current of superheated gas and rock , which reaches speeds moving away from a volcano of up to 700 km/h . The flows normally hug the ground and travel downhill, or spread laterally under gravity...
s, air-fall pumice, and epiclastic deposits. It is the most central of the four central volcanoes and its 2210 metres (7,250.7 ft) summit is capped by 180 metres (590.6 ft) of fine-grained silica-rich trachyte
Trachyte
Trachyte is an igneous volcanic rock with an aphanitic to porphyritic texture. The mineral assemblage consists of essential alkali feldspar; relatively minor plagioclase and quartz or a feldspathoid such as nepheline may also be present....
lava flows which were ponded inside the caldera to produce a lava lake
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...
six million years ago during its final stage of activity.
Spectrum Range eruptive period
The second phase of activity began three million years ago, emplacing rhyoliticRhyolite
This page is about a volcanic rock. For the ghost town see Rhyolite, Nevada, and for the satellite system, see Rhyolite/Aquacade.Rhyolite is an igneous, volcanic rock, of felsic composition . It may have any texture from glassy to aphanitic to porphyritic...
magma 150 metres (492.1 ft) thick and 13 metres (42.7 ft) long during a single event of activity. A broad circular lava dome was eventually created called the Spectrum Range
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 Edziza and north of the Arctic Lake Plateau. The...
. This is the southernmost of the four central volcanoes and is over 10 kilometres (6 mi) wide and up to 650 metres (2,132.5 ft) thick on the southwestern flank of Armadillo Peak and north of the Arctic Lake Plateau
Arctic Lake Plateau
The Arctic Lake Plateau is a lava plateau in northern British Columbia, Canada, located northeast of Arctic Lake at the south end of Mount Edziza Provincial Park and Recreation Area....
. Named for its extensive colourful alteration, it overlies a basal shield volcano and contains deeply carved circular valleys displaying portions of massive silica-rich comendite and trachyte lava flows which comprise the lava dome. The deeply carved circular valleys also display the bounding faults of a buried, cogenetic caldera approximately 4.5 kilometres (2.8 mi) across. More than 100 cubic kilometres (24 cu mi) of rhyolite and trachyte was erupted during the Spectrum Range dome eruptive period, with its activity ending 2,500,000 years ago.
Ice Peak eruptive period
Ice Peak
Ice Peak is a stratovolcano, located west of Tatogga and south of Mount Edziza, British Columbia, Canada. It overlaps the 7.5 million year old Armadillo Peak. It lies on a large volcanic plateau, which is made of basaltic lava flows from the massive Mount Edziza volcanic complex...
, 2500 metres (8,202.1 ft) high, which overlaps the northern flank of Armadillo Peak, began to form during Edziza's third phase of activity, starting 1,600,000 years ago when the regional Cordilleran Ice Sheet
Cordilleran Ice Sheet
The Cordilleran ice sheet was a major ice sheet that covered, during glacial periods of the Quaternary, a large area of North America. This included the following areas:*Western Montana*The Idaho Panhandle...
began retreating. It is a stratovolcano
Stratovolcano
A stratovolcano, also known as a composite volcano, is a tall, conical volcano built up by many layers of hardened lava, tephra, pumice, and volcanic ash. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile and periodic, explosive eruptions...
that was constructed when large areas of the Edziza lava plateau were free from glacial ice and now enclosed by glacial deposits. However, additional parts of the Mount Edziza volcanic complex were likely still covered by glacial ice. The volcanic activity from Ice Peak during this period produced both basic and intermediate to light-coloured lava flows and pyroclastic rock
Pyroclastic rock
Pyroclastic rocks or pyroclastics are clastic rocks composed solely or primarily of volcanic materials. Where the volcanic material has been transported and reworked through mechanical action, such as by wind or water, these rocks are termed volcaniclastic...
s which mixed with meltwater to produce debris flow
Debris flow
A debris flow is a fast moving, liquefied landslide of unconsolidated, saturated debris that looks like flowing concrete. It is differentiated from a mudflow in terms of the viscosity and textural properties of the flow. Flows can carry material ranging in size from clay to boulders, and may...
s. As Ice Peak began to form, basic lava spread to the flanks of the cone where it formed meltwater
Meltwater
Meltwater is the water released by the melting of snow or ice, including glacial ice and ice shelfs over oceans. Meltwater is often found in the ablation zone of glaciers, where the rate of snow cover is reducing...
lakes and combines with and forms part of the adjacent shield volcano. As lava continued to flow into these meltwater lakes, pillow lava
Pillow lava
Pillow lavas are lavas that contain characteristic pillow-shaped structures that are attributed to the extrusion of the lava under water, or subaqueous extrusion. Pillow lavas in volcanic rock are characterized by thick sequences of discontinuous pillow-shaped masses, commonly up to one metre in...
and solidified rubble was created. Many of the lava flows with compositions of trachyte
Trachyte
Trachyte is an igneous volcanic rock with an aphanitic to porphyritic texture. The mineral assemblage consists of essential alkali feldspar; relatively minor plagioclase and quartz or a feldspathoid such as nepheline may also be present....
and basalt
Basalt
Basalt is a common extrusive volcanic rock. It is usually grey to black and fine-grained due to rapid cooling of lava at the surface of a planet. It may be porphyritic containing larger crystals in a fine matrix, or vesicular, or frothy scoria. Unweathered basalt is black or grey...
were however erupted just below the surface of the soil. Continuous volcanic activity eventually made Ice Peak reach an elevation of 2400 metres (7,874 ft) when three viscous, intermediate, and light-coloured lava flows built up around secondary lava domes parallel with its western side during its final stage of activity 1,500,000 years ago and develops nearly all of the steep, higher flanks of the volcano. These viscous light-coloured lava flows are displayed at two cliffs with broad faces, known as Ornostay Bluff
Ornostay Bluff
Ornostay Bluff is a volcanic bluff in northern British Columbia, Canada, located just southwest of Mount Edziza in Mount Edziza Provincial Park and southeast of Telegraph Creek.-See also:*List of volcanoes in Canada*Volcanism of Canada...
and Koosick Bluff
Koosick Bluff
Koosick Bluff is a volcanic bluff in Cassiar Land District in northern British Columbia, Canada. It is located in Mount Edziza Provincial Park and Recreation Area, just northwest of Cocoa Crater and southwest of Mount Edziza.-See also:...
and contain basic rock made of solidified rubble overlain by large fractured lava with massive, poorly established pillars.
Two cinder cone
Cinder cone
According to the , Cinder Cone is the proper name of 1 cinder cone in Canada and 7 cinder cones in the United States:In Canada: Cinder Cone In the United States:...
s on Ice Peak's southern flank called Camp Hill
Camp Hill
-Australia:* Camp Hill, Queensland, a southern suburb of Brisbane* Camp Hill, a prominent hill in Bendigo with public lookout over the CBD-United States:* Camp Hill, Alabama* Camp Hill, Pennsylvania* Camp Hill, Glenn Springs, South Carolina, a historic site...
and Cache Hill
Cache Hill
Cache Hill is a cinder cone in northern British Columbia, Canada. It is thought to have last erupted in the Holocene period. Once used as an airdrop for food and supplies by the Geophysical Survey of Canada, hence its name, it is located north of Raspberry Pass in Mount Edziza Provincial Park.-See...
and possibly first erupted when glacial ice was still existing on the Edziza lava plateau. As lava flowed into the glacial ice above a vent, pools of meltwater were created. Continuous lava eruptions that flowed into the meltwater pools were cooled and fractured. This fragmental material was interrupted by explosions of steam, water, ash, rock, and volcanic bomb
Volcanic bomb
A volcanic bomb is a mass of molten rock larger than 65 mm in diameter, formed when a volcano ejects viscous fragments of lava during an eruption. They cool into solid fragments before they reach the ground. Because volcanic bombs cool after they leave the volcano, they do not have grains...
s called phreatic eruption
Phreatic eruption
A phreatic eruption, also called a phreatic explosion or ultravulcanian eruption, occurs when rising magma makes contact with ground or surface water. The extreme temperature of the magma causes near-instantaneous evaporation to steam, resulting in an explosion of steam, water, ash, rock, and...
s. Camp Hill was eventually developed and over time it grew above water level inside the meltwater lake. Later eruptions produced a pyroclastic cone on top of the original fragmental cone. Cache Hill erupted when nearly all the glacial ice had retreated. The first lava flows from Cache Hill flowed through and dammed a river valley, which eventually ponded to produce a small lake. Subsequent lava flows traveled into the lake to produce pillow lava and solidified rubble. During the long period of Ice Peak activity, high-altitude glaciers developed and melted cutting valleys into the volcano. The current 2500 metres (8,202.1 ft) high summit of Ice Peak is a remnant of the western rim of a small summit caldera, which has been nearly destroyed by erosion
Erosion
Erosion is when materials are removed from the surface and changed into something else. It only works by hydraulic actions and transport of solids in the natural environment, and leads to the deposition of these materials elsewhere...
from high-altitude glaciation. Near the end of Ice Peak activity 1,500,000 years ago, this high-altitude glacial ice combined with the regional ice forming part of the Cordilleran Ice Sheet. It is likely that only the tallest mountains might have been visible over the Cordilleran Ice Sheet which was at least 2285 metres (7,496.7 ft) thick. A small volume of intermediate lava was erupted from Ice Peak compared to the other central volcanoes.
Mount Edziza eruptive period
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 a complex of multiple peaks and ridges, with several glaciers flowing in all directions. The summit...
proper which is the most northerly of the four central volcanoes. It is a steep-sided stratovolcano
Stratovolcano
A stratovolcano, also known as a composite volcano, is a tall, conical volcano built up by many layers of hardened lava, tephra, pumice, and volcanic ash. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile and periodic, explosive eruptions...
and the largest and highest of the peaks that form the volcanic complex with an elevation of 2787 metres (9,143.7 ft), overlapping the northern flank of Ice Peak. The stratovolcano is made up of a fine-grained volcanic rock called trachyte
Trachyte
Trachyte is an igneous volcanic rock with an aphanitic to porphyritic texture. The mineral assemblage consists of essential alkali feldspar; relatively minor plagioclase and quartz or a feldspathoid such as nepheline may also be present....
and is associated with several lava domes which were formed by trachyte lava flows and explosive eruption
Explosive eruption
An explosive eruption is a volcanic term to describe a violent, explosive type of eruption. Mount St. Helens in 1980 was an example. Such an eruption is driven by gas accumulating under great pressure. Driven by hot rising magma, it interacts with ground water until the pressure increases to the...
s. Its smooth northern and western flanks, only slightly channeled by erosion, curve up to a circular 2700 metres (8,858.3 ft) summit ridge which surrounds a central, ice-filled caldera
Caldera
A caldera is a cauldron-like volcanic feature usually formed by the collapse of land following a volcanic eruption, such as the one at Yellowstone National Park in the US. They are sometimes confused with volcanic craters...
2 kilometres (1.2 mi) in diameter. Many glaciers cover Mount Edziza proper, including the Tencho Glacier on its southern flank. Active cirques on the eastern flank have breached the caldera rim, exposing the remnants of numerous lava lake
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...
s which ponded in the caldera 900,000 years ago and rest on hydrothermally altered breccia of the main conduit. Piles of pillow lava
Pillow lava
Pillow lavas are lavas that contain characteristic pillow-shaped structures that are attributed to the extrusion of the lava under water, or subaqueous extrusion. Pillow lavas in volcanic rock are characterized by thick sequences of discontinuous pillow-shaped masses, commonly up to one metre in...
and hyaloclastite
Hyaloclastite
Hyaloclastite is a hydrated tuff-like breccia rich in black volcanic glass, formed during volcanic eruptions under water, under ice or where subaerial flows reach the sea or other bodies of water. It has the appearance of angular flat fragments sized between a millimeter to few centimeters...
, formed by subglacial eruption
Subglacial eruption
A subglacial eruption is a volcanic eruption that has occurred under ice, or under a glacier. Subglacial eruptions can cause dangerous floods, lahars and create hyaloclastite and pillow lava. Subglacial eruptions sometimes form a subglacial volcano called a tuya. Tuyas in Iceland are called table...
s, are found on the flanks of Mount Edziza and nearby Ice Peak, as well as on the surface of the surrounding shield volcano. Pillow Ridge
Pillow Ridge
Pillow Ridge is a ridge of the Tahltan Highland in northern British Columbia, Canada, located southeast of Telegraph Creek. It extends northwest from Mount Edziza in Mount Edziza Provincial Park.-History:...
on Edziza's northwest flank was formed when basaltic lava erupted beneath the regional Cordilleran Ice Sheet when it was close to its greatest thickness.
Central volcano flank eruptive period
Hyaloclastite
Hyaloclastite is a hydrated tuff-like breccia rich in black volcanic glass, formed during volcanic eruptions under water, under ice or where subaerial flows reach the sea or other bodies of water. It has the appearance of angular flat fragments sized between a millimeter to few centimeters...
tuff rings, whereas later activity created 30 small cinder cone
Cinder cone
According to the , Cinder Cone is the proper name of 1 cinder cone in Canada and 7 cinder cones in the United States:In Canada: Cinder Cone In the United States:...
s, primarily of basalt
Basalt
Basalt is a common extrusive volcanic rock. It is usually grey to black and fine-grained due to rapid cooling of lava at the surface of a planet. It may be porphyritic containing larger crystals in a fine matrix, or vesicular, or frothy scoria. Unweathered basalt is black or grey...
ic composition, including Mess Lake Cone
Mess Lake Cone
Mess Lake Cone is a cinder cone in northwestern British Columbia, Canada. It is polygenetic in nature, having erupted more than once throughout its eruptive history. Mess Lake Cone is one of the volcanoes that produced young basaltic lava flows in the central portion of the Mount Edziza volcanic...
, Kana 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.-See also:*List of volcanoes in Canada*List of Northern Cordilleran volcanoes*Volcanism of Canada...
, Cinder Cliff
Cinder Cliff
Cinder Cliff is a cinder cone in northern British Columbia, Canada. It is thought to have last erupted during the Holocene period and is part of the Mount Edziza volcanic complex.-See also:*List of volcanoes in Canada*List of Northern Cordilleran volcanoes...
, Icefall Cone
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.-See also:*List of volcanoes in Canada...
, Ridge Cone
Ridge Cone
Ridge 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.-See also:*List of volcanoes in Canada*List of Northern Cordilleran volcanoes...
, Williams Cone
Williams Cone
Williams Cone is a satellite cone of Mount Edziza, located 36 kilometers 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...
, Walkout Creek Cone
Walkout Creek Cone
Walkout Creek Cone is a cinder cone in northwestern British Columbia, Canada. It is one of the volcanoes that produced young basaltic lava flows in the central portion of the Mount Edziza volcanic complex in the past 10,000 years...
, Moraine Cone
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.-See also:*List of volcanoes in Canada*List of Northern Cordilleran volcanoes...
, Sidas Cone
Sidas Cone
Sidas Cone is one of the cinder cones located north on the Mount Edziza plateau in British Columbia, Canada. Sidas Cone is visible from almost anywhere around the plateau.-See also:* Northern Cordilleran Volcanic Province* Volcanism of Canada...
, Sleet Cone
Sleet Cone
Sleet Cone is a cinder cone in northern British Columbia, Canada. It lies in the Desolation Lava Field and is thought to have last erupted in the Holocene period and is part of the Mount Edziza volcanic complex.-See also:*List of volcanoes in Canada...
, Storm Cone
Storm Cone
Storm Cone is a cinder cone in northern British Columbia, Canada. It is thought to have last erupted in the Holocene period and lies on the Desolation lava field which is part of the Mount Edziza volcanic complex.-See also:*List of volcanoes in Canada...
, Triplex 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.-See also:*List of volcanoes in Canada*List of Northern Cordilleran volcanoes*Volcanism of Canada*Volcanism of Western Canada...
, Twin Cone
Twin Cone
Twin Cone is a cinder cone in northern British Columbia, Canada. It is thought to have last erupted in the Holocene period.-See also:*List of volcanoes in Canada*List of Northern Cordilleran volcanoes*Volcanism of Canada*Volcanism of Western Canada...
, Cache Hill
Cache Hill
Cache Hill is a cinder cone in northern British Columbia, Canada. It is thought to have last erupted in the Holocene period. Once used as an airdrop for food and supplies by the Geophysical Survey of Canada, hence its name, it is located north of Raspberry Pass in Mount Edziza Provincial Park.-See...
, Camp Hill
Camp Hill (British Columbia)
Camp Hill is a cinder cone in northern British Columbia, Canada. It is thought to have last erupted in the Holocene period.-See also:*List of volcanoes in Canada*List of Northern Cordilleran volcanoes*Volcanism of Canada*Volcanism of Western Canada...
, Cocoa Crater, Coffee Crater
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 which in turn form part of the Mount Edziza volcanic complex.-See also:...
, Nahta Cone
Nahta Cone
Nahta Cone is a cinder cone in northern British Columbia, Canada, located southwest of Tatogga, north of Wetalth Ridge and south of Telegraph Creek...
, Tennena Cone
Tennena Cone
Tennena Cone is a subglacial mound in northern British Columbia, Canada, located just southwest of Mount Edziza in Mount Edziza Provincial Park.-See also:*List of volcanoes in Canada*List of Northern Cordilleran volcanoes*Volcanism of Canada...
, The Saucer
The Saucer
The Saucer is a cinder cone in northern British Columbia, Canada. It is thought to have last erupted in the Holocene epoch.-See also:*List of volcanoes in Canada*List of Northern Cordilleran volcanoes*Volcanism of Canada*Volcanism of Western Canada...
and the well-preserved Eve Cone
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 most recent eruptions on the Big Raven Plateau and in...
. 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 2 metres (6.6 ft) of loose basaltic fragments. These cinder cones were built on the basaltic fragments and blocky lava fields surrounding the cones. The Snowshoe lava field
Snowshoe lava field
The Snowshoe Lava Field is a volcanic field associated with the Mount Edziza volcanic complex in northern British Columbia, Canada. It is on the southern end of the Big Raven Plateau and is an area of young lava flows.-Volcanoes:...
, on the southern end of the Big Raven Plateau
Big Raven Plateau
The Big Raven Plateau is a lava plateau in northern British Columbia, Canada, located west of Mount Edziza in Mount Edziza Provincial Park and Recreation Area...
, is one of the areas of young lava flows in the region while the Desolation lava field
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 longest lava flow from the field and the volcanic...
, on the northern end of the Big Raven Plateau, is the largest area of young lava flows, covering an area of 150 km2. The longest lava flow is 12 kilometres (7 mi). This volcanic activity was followed by at least two younger, but still undated eruptions, including an undated air-fall pumice
Pumice
Pumice is a textural term for a volcanic rock that is a solidified frothy lava typically created when super-heated, highly pressurized rock is violently ejected from a volcano. It can be formed when lava and water are mixed. This unusual formation is due to the simultaneous actions of rapid...
deposit.
The undated air-fall pumice
Pumice
Pumice is a textural term for a volcanic rock that is a solidified frothy lava typically created when super-heated, highly pressurized rock is violently ejected from a volcano. It can be formed when lava and water are mixed. This unusual formation is due to the simultaneous actions of rapid...
deposit exists across the southwestern part of the Big Raven Plateau called Sheep Track Pumice
Sheep Track Pumice
Sheep Track Pumice or Sheep Track Member by Canadian volcanologist Jack Souther, is the name for a pumice deposit in northern British Columbia, Canada. It lies in the Snowshoe Lava Field and is thought to have formed in the Holocene period....
or Sheep Track member. Pumice is a light volcanic rock
Volcanic rock
Volcanic rock is a rock formed from magma erupted from a volcano. In other words, it is an igneous rock of volcanic origin...
full of air spaces and commonly pale in colour, ranging from white, cream, blue or grey, but can be green or black. The Sheep Track Pumice is mysterious because the vent of its origin is unknown, even though it is estimated from its state of preservation to be younger than 500 years old. This pumice deposit emphasizes one of the significant volcanic hazards linked to the Mount Edziza volcanic complex - the likelihood of a violent explosive eruption
Explosive eruption
An explosive eruption is a volcanic term to describe a violent, explosive type of eruption. Mount St. Helens in 1980 was an example. Such an eruption is driven by gas accumulating under great pressure. Driven by hot rising magma, it interacts with ground water until the pressure increases to the...
. The volcano that produced the pumice might be covered by glacial ice. Collaborators at the University of British Columbia
University of British Columbia
The University of British Columbia is a public research university. UBC’s two main campuses are situated in Vancouver and in Kelowna in the Okanagan Valley...
have started work on samples collected from deposits of Sheep Track Pumice.
Current activity
Seismology
Seismology is the scientific study of earthquakes and the propagation of elastic waves through the Earth or through other planet-like bodies. The field also includes studies of earthquake effects, such as tsunamis as well as diverse seismic sources such as volcanic, tectonic, oceanic,...
: the others are Castle Rock
Castle Rock
-Islands:*Castle Rock , an island off the coast of the U.S. state of Alaska*Castle Rock, Hong Kong , an island of Hong Kong, part of the Po Toi Islands*Castle Rock , an island in the U.S...
, Mount Garibaldi
Mount Garibaldi
Mount Garibaldi is a potentially active stratovolcano in the Sea to Sky Country of British Columbia, north of Vancouver, Canada. Located in the southernmost Coast Mountains, it is one of the most recognized peaks in the South Coast region, as well as British Columbia's best known volcano...
, Mount Cayley
Mount Cayley
Mount Cayley is a potentially active stratovolcano in Squamish-Lillooet Regional District of southwestern British Columbia, Canada. Located north of Squamish and west of Whistler in the Pacific Ranges of the Coast Mountains, it rises above the Squamish River to the west and above the Cheakamus...
, Hoodoo Mountain
Hoodoo Mountain
Hoodoo Mountain is a potentially active flat-topped stratovolcano in the Stikine Country of northwestern British Columbia, Canada, located northeast of Wrangell, Alaska on the north side of the lower Iskut River and east of its junction with the Stikine River...
, The Volcano
The Volcano (British Columbia)
The Volcano, also known as Lava Fork volcano, is a small cinder cone in the Boundary Ranges of the Coast Mountains in northwestern British Columbia, Canada. It is located approximately northwest of the small community of Stewart near the head of Lava Fork...
, Crow Lagoon
Crow Lagoon
Crow Lagoon is a little-known volcanic center located north of Prince Rupert, British Columbia, Canada. There are beds of thick, basaltic tephra that are of Holocene age....
, Silverthrone Caldera
Silverthrone Caldera
The Silverthrone Caldera is a potentially active caldera complex in southwestern British Columbia, Canada, located over northwest of the city of Vancouver and about west of Mount Waddington in the Pacific Ranges of the Coast Mountains. The caldera is one of the largest of the few calderas in...
, Mount Meager
Mount Meager
Mount Meager, originally known as Meager Mountain, is a complex volcano in the Sea-to-Sky Corridor of southwestern British Columbia, Canada. It is located north of Vancouver at the northern end of the Pemberton Valley. Part of the Cascade Volcanic Arc of western North America, its summit is above...
, Wells Gray-Clearwater volcanic field
Wells Gray-Clearwater volcanic field
The Wells Gray-Clearwater volcanic field, also called the Clearwater Cone Group, is a potentially active monogenetic volcanic field in east-central British Columbia, Canada, located approximately north of Kamloops. It is situated in the Cariboo Mountains of the Columbia Mountains and on the...
and Nazko Cone
Nazko Cone
Nazko Cone is a small potentially active basaltic cinder cone in central British Columbia, Canada, located 75 km west of Quesnel and 150 kilometers southwest of Prince George. It is considered the easternmost volcano in the Anahim Volcanic Belt. The small tree-covered cone rises 120 m above...
. Seismic data suggests that these volcanoes still contain live magma
Magma
Magma is a mixture of molten rock, volatiles and solids that is found beneath the surface of the Earth, and is expected to exist on other terrestrial planets. Besides molten rock, magma may also contain suspended crystals and dissolved gas and sometimes also gas bubbles. Magma often collects in...
plumbing systems, indicating possible future eruptive activity. Although the available data does not allow a clear conclusion, these observations are further indications that some of Canada's 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 volcanic centres with a history of significant explosive behavior, such as the Mount Edziza volcanic complex.
The most recent volcanic activity at the Mount Edziza volcanic complex have been hot spring
Hot spring
A hot spring is a spring that is produced by the emergence of geothermally heated groundwater from the Earth's crust. There are geothermal hot springs in many locations all over the crust of the earth.-Definitions:...
s, several of which are found on the volcano's western flank, including Elwyn springs (36°
Degree (temperature)
The term degree is used in several scales of temperature. The symbol ° is usually used, followed by the initial letter of the unit, for example “°C” for degree Celsius...
C
Celsius
Celsius is a scale and unit of measurement for temperature. It is named after the Swedish astronomer Anders Celsius , who developed a similar temperature scale two years before his death...
or 97°F
Fahrenheit
Fahrenheit is the temperature scale proposed in 1724 by, and named after, the German physicist Daniel Gabriel Fahrenheit . Within this scale, the freezing of water into ice is defined at 32 degrees, while the boiling point of water is defined to be 212 degrees...
), Taweh springs (46°C or 115°F), and inactive springs near Mess Lake
Mess Lake
Mess Lake is a lake in Mount Edziza Provincial Park northern British Columbia, Canada. It is an expansion of Mess Creek....
. The springs are near the youngest lava fields of the Mount Edziza volcanic complex and are most likely associated with the most recent eruptive activity. These hot springs were highly important to the adjacent Tahltan
Tahltan
Tahltan refers to a Northern Athabaskan people who live in northern British Columbia around Telegraph Creek, Dease Lake, and Iskut.-Social Organization:...
people.
Hot springs are closely associated with fumarole
Fumarole
A fumarole is an opening in a planet's crust, often in the neighborhood of volcanoes, which emits steam and gases such as carbon dioxide, sulfur dioxide, hydrochloric acid, and hydrogen sulfide. The steam is created when superheated water turns to steam as its pressure drops when it emerges from...
s, which are vents in an active volcanic area releasing steam and hot gases, such as sulfur dioxide
Sulfur dioxide
Sulfur dioxide is the chemical compound with the formula . It is released by volcanoes and in various industrial processes. Since coal and petroleum often contain sulfur compounds, their combustion generates sulfur dioxide unless the sulfur compounds are removed before burning the fuel...
. In general, the water is rotating groundwater that comes into contact with rocks heated by magma and finds openings to the surface. The formation of the springs depends both on the rocks the water has passed through and the profusion of volcanic discharges mixed with the groundwater. Iron oxide
Iron oxide
Iron oxides are chemical compounds composed of iron and oxygen. All together, there are sixteen known iron oxides and oxyhydroxides.Iron oxides and oxide-hydroxides are widespread in nature, play an important role in many geological and biological processes, and are widely utilized by humans, e.g.,...
, iron sulfide
Iron sulfide
Iron sulfide or Iron sulphide refers to a chemical compound of iron and sulfur with a wide range of stoechiometric formulae and different crystalline structures.-Natural minerals:By increasing order of stability:...
s and other substances usually colour pools of boiling mud brilliant yellow, red, brown or green. Hot springs comprising significantly softened silica may deposit it to form siliceous sinter, whereas those comprising softened calcium
Calcium
Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust...
carbonate
Carbonate
In chemistry, a carbonate is a salt of carbonic acid, characterized by the presence of the carbonate ion, . The name may also mean an ester of carbonic acid, an organic compound containing the carbonate group C2....
deposit spongy-looking calcareous rock called tufa
Tufa
Tufa is a variety of limestone, formed by the precipitation of carbonate minerals from ambient temperature water bodies. Geothermally heated hot-springs sometimes produce similar carbonate deposits known as travertine...
. Overflow of the springs can build masses, spires or stepped terraces of sinter or tufa.
Indigenous people
As early as 10,000 years ago, the TahltanTahltan
Tahltan refers to a Northern Athabaskan people who live in northern British Columbia around Telegraph Creek, Dease Lake, and Iskut.-Social Organization:...
First Nations
First Nations
First Nations is a term that collectively refers to various Aboriginal peoples in Canada who are neither Inuit nor Métis. There are currently over 630 recognised First Nations governments or bands spread across Canada, roughly half of which are in the provinces of Ontario and British Columbia. The...
people, who now live in Dease Lake
Dease Lake, British Columbia
Dease Lake is a small community located in the Cassiar Country of the Northern Interior of British Columbia, Canada. Located only a few hours south of the Yukon border, it is located on Highway 37 at the south end of the lake of the same name. Dease Lake is the last major centre before the Alaska...
, Telegraph Creek
Telegraph Creek, British Columbia
Telegraph Creek is a small community located off Highway 37 in Northern British Columbia at the confluence of the Stikine River and Telegraph Creek. The only permanent settlement on the Stikine River, it is home to approximately 350 members of the Tahltan First Nation, as well as another 50...
and the Iskut
Iskut, British Columbia
Iskut is a small, mostly aboriginal community in the Stikine Country of northwestern British Columbia. It is located on Highway 37, at the north end of Eddontenajon Lake just south of Dease Lake and the crossing of the Stikine River...
, used obsidian
Obsidian
Obsidian is a naturally occurring volcanic glass formed as an extrusive igneous rock.It is produced when felsic lava extruded from a volcano cools rapidly with minimum crystal growth...
from the Mount Edziza volcanic complex to make tools and weapons for trading material. Most of the obsidian occurs at relatively high elevations at about 1800 to-. This is the main source of obsidian found in northwestern British Columbia, which was traded as far away as Alaska
Alaska
Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...
and northern Alberta
Alberta
Alberta is a province of Canada. It had an estimated population of 3.7 million in 2010 making it the most populous of Canada's three prairie provinces...
. Obsidian is a type of naturally occurring glass that is highly valued for its cutting qualities and is produced by the rapid cooling of lava. Like all glass and some other types of naturally occurring rocks, obsidian breaks with a characteristic conchoidal fracture
Conchoidal fracture
Conchoidal fracture describes the way that brittle materials break when they do not follow any natural planes of separation. Materials that break in this way include flint and other fine-grained minerals, as well as most amorphous solids, such as obsidian and other types of glass.Conchoidal...
, creating razor sharp edges. A knife made of Edziza obsidian, possibly 2,000 years old, has been recovered in the Stikine River
Stikine River
The Stikine River is a river, historically also the Stickeen River, approximately 610 km long, in northwestern British Columbia in Canada and southeastern Alaska in the United States...
area. Two exposed columnar basalt formations exist within the volcanic complex: the Tahltan Eagle at the meeting of the Tahltan
Tahltan River
The Tahltan River is a river in northern British Columbia, Canada. It flows southwest into the Stikine River. The First Nations community of Tahltan is located at the confluence....
and Stikine rivers, and Pipe Organ Mountain. The Tahltan Eagle has significant spiritual and cultural importance to the Tahltan people, while the correct name and cultural significance of Pipe Organ Mountain to the Tahltan people is unknown.
Geologic studies
Jack Souther
Jack Souther is an Bancroft Award winning American-Canadian volcanologist of the Geological Survey of Canada. He is a leading authority on geothermal resources and volcanism in the Canadian Cordillera. Souther has long been in demand as a professor to lay audiences because of his ability to give...
. Edziza was a significant study area by Souther. While mapping, Souther looked at a mineral tenure map of Stikine Country and was surprised to see that many of the small cinder cones in the area had been maintained by mineral tenures. Upon investigation, the staking had been completed for the British Columbia Railway, then under construction to Dease Lake. The staking was designed to provide a ready source of weight for the railway bed. The Geological Survey of Canada agreed to support a series of Canada-wide lectures by Jack Souther to establish the Mount Edziza Provincial Park to protect the Mount Edziza volcanic complex. Coincidentally, Jack Souther had an opportunity to examine the Red Dog (Spectrum) property gold
Gold
Gold is a chemical element with the symbol Au and an atomic number of 79. Gold is a dense, soft, shiny, malleable and ductile metal. Pure gold has a bright yellow color and luster traditionally considered attractive, which it maintains without oxidizing in air or water. Chemically, gold is a...
veins and he accomplished several section studies of specimens. It was not Souther's intention to include in the park any of the mineralization within near-surface older rocks. However, the British Columbia Ministry of Parks established the Mount Edziza Recreation Area covering 1007.7 km² (389.1 sq mi) on July 27, 1972 as the park proclamation, providing a 1 to 10 km (0.621372736649807 to 6.2 ) wide buffer zone around the park area. On March 21, 1989, all but 40 km² (15.4 sq mi) of the recreation area, covering the Spectrum gold property on its margin, was surreptitiously merged with Mount Edziza Provincial Park, almost doubling its size to 2287 square kilometres (883 sq mi).
Basalt
Basalt is a common extrusive volcanic rock. It is usually grey to black and fine-grained due to rapid cooling of lava at the surface of a planet. It may be porphyritic containing larger crystals in a fine matrix, or vesicular, or frothy scoria. Unweathered basalt is black or grey...
ic and trachytic
Trachyte
Trachyte is an igneous volcanic rock with an aphanitic to porphyritic texture. The mineral assemblage consists of essential alkali feldspar; relatively minor plagioclase and quartz or a feldspathoid such as nepheline may also be present....
ice-contact products were studied in detail on the western flank of the Mount Edziza volcanic complex, in order to approve their ice-contact nature, and to eventually better constrain former ice existence and thickness. Its lava plateau has also been an important cultural resource. In 2006, Jeff Hungerford, a student of the University of Pittsburgh
University of Pittsburgh
The University of Pittsburgh, commonly referred to as Pitt, is a state-related research university located in Pittsburgh, Pennsylvania, United States. Founded as Pittsburgh Academy in 1787 on what was then the American frontier, Pitt is one of the oldest continuously chartered institutions of...
in Carlisle, Pennsylvania
Carlisle, Pennsylvania
Carlisle is a borough in and the county seat of Cumberland County, Pennsylvania, United States. The name is traditionally pronounced with emphasis on the second syllable. Carlisle is located within the Cumberland Valley, a highly productive agricultural region. As of the 2010 census, the borough...
, United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
, focused on fieldwork on the region surrounding Edziza's Tennena Cone
Tennena Cone
Tennena Cone is a subglacial mound in northern British Columbia, Canada, located just southwest of Mount Edziza in Mount Edziza Provincial Park.-See also:*List of volcanoes in Canada*List of Northern Cordilleran volcanoes*Volcanism of Canada...
, located immediately west of Ice Peak which formed subglacially during the early Holocene
Holocene
The Holocene is a geological epoch which began at the end of the Pleistocene and continues to the present. The Holocene is part of the Quaternary period. Its name comes from the Greek words and , meaning "entirely recent"...
period when this area had remnants of glacial ice from the last ice age. Hungerford's studies in 2006 focused on subglacial volcanism, sampling pillow lavas to be used for degassing studies aimed at determining ice thicknesses during a subglacial eruption, and describing coeval glaciogenic sediments immediately underlying pillow lavas at the distal end of the lava flows. Hungerford also worked on describing glaciogenic sediments immediately underlying lava flows from Ice Peak adjacent to Tennena Cone, which may preserve a record of a one million year old ice sheet.
Ornostay Bluff
Ornostay Bluff is a volcanic bluff in northern British Columbia, Canada, located just southwest of Mount Edziza in Mount Edziza Provincial Park and southeast of Telegraph Creek.-See also:*List of volcanoes in Canada*Volcanism of Canada...
, a viscous series of trachyte lava flows on the western lava plateau of the Mount Edziza volcanic complex. LaMoreaux also examined trachytic lava flows from Koosick Bluff
Koosick Bluff
Koosick Bluff is a volcanic bluff in Cassiar Land District in northern British Columbia, Canada. It is located in Mount Edziza Provincial Park and Recreation Area, just northwest of Cocoa Crater and southwest of Mount Edziza.-See also:...
and Triangle Dome
Triangle Dome
Triangle Dome is a trachytic lava dome in northern British Columbia, Canada. It is thought to have formed in the Pleistocene period.-See also:*List of volcanoes in Canada*List of Northern Cordilleran volcanoes*Volcanism of Canada...
, a trachytic lava dome which last erupted during the Pleistocene
Pleistocene
The Pleistocene is the epoch from 2,588,000 to 11,700 years BP that spans the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....
period. Other studies by LaMoreaux determined criteria for understanding how lava flow thickness may or may not be an indication that the progress of a lava flow was impeded by an ice barrier, resulting in an unusually thick lava flow.
Chira Endress, a student of Dickinson College
Dickinson College
Dickinson College is a private, residential liberal arts college in Carlisle, Pennsylvania. Originally established as a Grammar School in 1773, Dickinson was chartered September 9, 1783, five days after the signing of the Treaty of Paris, making it the first college to be founded in the newly...
in Carlisle, Pennsylvania
Pennsylvania
The Commonwealth of Pennsylvania is a U.S. state that is located in the Northeastern and Mid-Atlantic regions of the United States. The state borders Delaware and Maryland to the south, West Virginia to the southwest, Ohio to the west, New York and Ontario, Canada, to the north, and New Jersey to...
, United States, focused on a section of glaciogenic sediments immediately beneath the same Ice Peak trachyte lava flow sampled and described by Jeff Hungerford during his 2006 studies. Endress ettempted to determine if the sediments were deposited immediately before the lava flow was emplaced, or if they are likely to be much older. Endress has quantified the mineralogy of clasts and sand-sized particles from samples in the sediment, and has determined that the mineralogy of several of the trachytic clasts is very similar to that in the overlying lava flow, including the minerals clinopyroxene, magnetite
Magnetite
Magnetite is a ferrimagnetic mineral with chemical formula Fe3O4, one of several iron oxides and a member of the spinel group. The chemical IUPAC name is iron oxide and the common chemical name is ferrous-ferric oxide. The formula for magnetite may also be written as FeO·Fe2O3, which is one part...
, alkali feldspar
Feldspar
Feldspars are a group of rock-forming tectosilicate minerals which make up as much as 60% of the Earth's crust....
, and aenigmatite. Endress has also found small lenses of pristine basaltic glass, which could have derived from the Pillow Ridge subglacial mound near Mount Edziza.
Alexander S. Lloyd, a student of Dickinson College, focused on the cooling rates of pillow lavas. Lloyd studied in detail the variation in crystal sizes from the edge pristine pillow lava, which could have derived from nearby Pillow Ridge
Pillow Ridge
Pillow Ridge is a ridge of the Tahltan Highland in northern British Columbia, Canada, located southeast of Telegraph Creek. It extends northwest from Mount Edziza in Mount Edziza Provincial Park.-History:...
which last erupted during the Pleistocene
Pleistocene
The Pleistocene is the epoch from 2,588,000 to 11,700 years BP that spans the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....
period.
Courtney Haynes, another student of Dickinson College, focused on mathematics of the pillow lavas in 2007.
Monitoring
Currently the Mount Edziza volcanic complex is not monitored closely enough by the Geological Survey of Canada to ascertain how active the volcano's magma system is. The existing network of seismographs has been established to monitor tectonic earthquakes and is too far away to provide a good indication of what is happening beneath the volcanic complex. The network may sense an increase in activity if the volcano becomes very restless, but this may only provide a warning for a large eruption. It might detect activity only once the volcano has started erupting.A possible way to detect an eruption is studying Edziza's geological history since every volcano has its own pattern of behavior, in terms of its eruption style, magnitude and frequency, so that its future eruption is expected to be similar to its previous eruptions.
While there is a likelihood of Canada being critically affected by local or close by volcanic eruptions argues that some kind of improvement program is required. Benefit-cost thoughts are critical to dealing with natural hazards. However, a benefit-cost examination needs correct data about the hazard types, magnitudes and occurrences. These do not exist for volcanoes in British Columbia or elsewhere in Canada in the detail required.
Volcanologist
A volcanologist is a person who studies the formation of volcanoes, and their current and historic eruptions. Volcanologists frequently visit volcanoes, especially active ones, to observe volcanic eruptions, collect eruptive products including tephra , rock and lava samples...
s and other geologic scientist
Scientist
A scientist in a broad sense is one engaging in a systematic activity to acquire knowledge. In a more restricted sense, a scientist is an individual who uses the scientific method. The person may be an expert in one or more areas of science. This article focuses on the more restricted use of the word...
s. Current knowledge is best established at Mount Meager
Mount Meager
Mount Meager, originally known as Meager Mountain, is a complex volcano in the Sea-to-Sky Corridor of southwestern British Columbia, Canada. It is located north of Vancouver at the northern end of the Pemberton Valley. Part of the Cascade Volcanic Arc of western North America, its summit is above...
in the Garibaldi Volcanic Belt
Garibaldi Volcanic Belt
The Garibaldi Volcanic Belt, also called the Canadian Cascade Arc, 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 southwestern...
of southwestern British Columbia and is likely to rise considerably with a temporary mapping and monitoring project. Knowledge at the Mount Edziza volcanic complex and other volcanoes in the Northern Cordilleran Volcanic Province is not as established, but certain contributions are being done at least Mount Cayley
Mount Cayley
Mount Cayley is a potentially active stratovolcano in Squamish-Lillooet Regional District of southwestern British Columbia, Canada. Located north of Squamish and west of Whistler in the Pacific Ranges of the Coast Mountains, it rises above the Squamish River to the west and above the Cheakamus...
, another volcano in the Garibaldi Volcanic Belt. An intensive program classifiying infrastructural exposure near all young Canadian volcanoes and quick hazard assessments at each individual volcanic edifice associated with recent seismic activity would be in advance and would produce a quick and productive determination of priority areas for further efforts.
In countries like Canada it is possible that small precursor earthquake swarms might go undetected, particularly if no events were observed; more significant events in larger swarms would be detected but only a minor subdivision of the swarm events would be complex to clarify them with confidence as volcanic in nature, or even associate them with an individual volcanic edifice.
See also
- List of volcanoes in Canada
- List of Northern Cordilleran volcanoes
- Mountain peaks of CanadaMountain peaks of CanadaThis article comprises three sortable tables of major mountain peaks of Canada.Topographic elevation is the vertical distance above the reference geoid, a precise mathematical model of the Earth's sea level as an equipotential gravitational surface. Topographic prominence is the elevation...
- Mountain peaks of North AmericaMountain peaks of North AmericaThis article comprises three sortable tables of major mountain peaks of greater North America.This article defines greater North America as the portion of the continental landmass of the Americas extending northward from Panama plus the islands surrounding that landmass...
- Volcanism of Canada
- Volcanism of Western CanadaVolcanism of Western CanadaVolcanism of Western Canada produces lava flows, lava plateaus, lava domes, cinder cones, stratovolcanoes, shield volcanoes, submarine volcanoes, calderas, diatremes and maars, along with examples of more less common volcanic forms such as tuyas and subglacial mounds.-Volcanic belts:*Anahim...
- Geology of the Pacific NorthwestGeology of the Pacific NorthwestThe geology of the Pacific Northwest refers to the study of the composition , structure, physical properties and the processes that shape the Pacific Northwest region of the United States and Canada...
External links
- Volcanoes of Canada Stikine Volcanic Belt (Mount Edziza area)
- Catalogue of Canadian volcanoes - Mount Edziza