Mount Meager
Encyclopedia
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 sea level
, and is capped by several eroded volcanic edifices. This includes mounds of viscous lava
, columns of volcanic rock
and overlapping piles of lava flows. Hydrothermal exploration is present at Mount Meager and it is one of the several geothermal
sites in British Columbia.
Mount Meager is responsible for the largest volcanic eruption in Canada in the past 10,000 years. About 2,350 years ago, an explosive eruption
formed a volcanic crater
on its northeastern flank and sent avalanches of hot ash, rock fragments and volcanic gas
es down the northern flank of the volcano, creating a geological formation in the Lillooet River
valley. Evidence for more recent volcanic activity has been documented at the volcano, such as hot spring
s and earthquake
s. Mount Meager has also been the source for several large landslide
s in the past, including a massive debris flow
in 2010 that swept down Meager Creek
and the Lillooet River.
The Garibaldi Volcanic Belt
has a long history of eruptions and poses a threat to the surrounding region. Any volcanic hazard
—ranging from landslides to eruptions—could pose a significant risk to humans and wildlife. Even though Mount Meager has not erupted for over 2,000 years, it could again produce a major eruption; if this were to happen, relief efforts would probably be quickly organized. Teams such as the Interagency Volcanic Event Notification Plan
(IVENP) are prepared to notify people threatened by volcanic eruptions.
Volcanism
in the Cascade Volcanic Arc is caused by subduction
of the Juan de Fuca Plate
under the North American Plate
at the Cascadia subduction zone. This is a long fault zone running off the Pacific Northwest
from Northern California
to southwestern British Columbia. The plates move at a relative rate of over per year at an oblique angle to the subduction zone. Because of the very large fault area, the Cascadia subduction zone can produce large earthquake
s of magnitude
7.0 or greater. The interface between the Juan de Fuca and North American plates remains locked for periods of roughly 500 years. During these periods, stress builds up on the interface between the plates and causes uplift of the North American margin. When the plate finally slips, the 500 years of stored energy are released in a massive earthquake.
Unlike most subduction zones worldwide, there is no deep oceanic trench
present along the continental margin
in Cascadia. The reason is that the mouth of the Columbia River
empties directly into the subduction zone and deposits silt at the bottom of the Pacific Ocean
, burying the oceanic trench. Massive floods from prehistoric Glacial Lake Missoula
during the Late Pleistocene
also deposited large amounts of sediment
into the trench. However, in common with other subduction zones, the outer margin is slowly being compressed, similar to a giant spring. When the stored energy is suddenly released by slippage across the fault at irregular intervals, the Cascadia subduction zone can create very large earthquakes, such as the magnitude 9.0 Cascadia earthquake on January 26, 1700. However, earthquakes along the Cascadia subduction zone are fewer than expected and there is evidence of a decline in volcanic activity over the past few million years. The probable explanation lies in the rate of convergence between the Juan de Fuca and North American plates. These two tectonic plates currently converge 3 cm (1.2 in) to 4 cm (1.6 in) per year. This is only about half the rate of convergence from seven million years ago.
Mount Meager is part of the Garibaldi Volcanic Belt, an extension of the Cascade Volcanic Arc, which extends from the Watts Point volcano
in the south to the Silverthrone Caldera
in the north. This volcanic belt
includes cinder cone
s, caldera
s, stratovolcano
es and subglacial volcano
es that have been active in the Holocene
period (10,000 years ago to present). The latest explosive eruption in the Garibaldi Volcanic Belt occurred at a crater on the northeastern flank of Mount Meager, which forms a clearly-defined depression. At least eight volcanic vents constitute Meager, which erupted mafic
, intermediate
and felsic
magma
. Streams and glaciers have played a significant role in dissecting the massif and its upper slopes are covered by snow and ice. Numerous feeder dikes
to older units are exposed by deep erosion. Perkin's Pillar
, a vertical tower of breccia
ted lava, represented an erosional remnant of Meager until its collapse in June 2005. More than 10 streams drain meltwater from Mount Meager, including Capricorn Creek, Job Creek, No Good Creek, Angel Creek, Devastation Creek, Canyon Creek and Affliction Creek.
The geomorphology
of Mount Meager is similar to Glacier Peak
, another Cascade Arc volcano, located in the U.S. state
of Washington. It consists of at least four overlapping stratovolcanoes that become progressively younger from south to north. As a result, Meager can be classified as a compound/complex volcano, which consists of two or more vents. With a total volume of , Mount Meager is a long-lived feature, tracing its history back to 2,200,000 years ago. This indicates that it is relatively old compared to most volcanoes in the Cascade Arc. In the Cascade Range
, the oldest volcanoes are generally no more than a million years old. This includes Mount Rainier
(500,000 years), Lassen Peak
(27,000 years), Mount Jefferson
(680,000 years), Mount St. Helens
(50,000 years) and many more. However, portions of Mount Meager formed in the past million years. The volcano is made of volcanic rock
s ranging from rhyodacite
to basalt
. Rhyodacite forms a series of eroded volcanic plugs, which represent the highest peaks of Meager. Their flanks are covered by their eruptive products and are the surface expressions of intrusion
s. As a result, they provide a unique opportunity to study the relationships between magma chamber
s and their lavas.
Although some scientists speculate the Silverthrone Caldera as the northernmost volcano of the Garibaldi Volcanic Belt, others prefer Mount Meager as the northernmost. This controversy is because little is known about the volcanoes north of Meager, such as Silverthrone and the Franklin Glacier volcanic complex
. It is also unclear whether the Milbanke Sound Cones are part of the Garibaldi Belt or they are volcanoes formed by different tectonic processes than those in the Garibaldi Belt. However, there is evidence the Silverthrone and Franklin Glacier complexes are related to Cascadia subduction. Geologically, these two volcanoes contain the same rock types as those found elsewhere in the Cascade Arc, including rhyolite
s, dacite
s, andesite
s and basaltic andesite
s. Such rock types are produced by subduction zone volcanism, indicating volcanism at Silverthrone and Franklin Glacier is probably related to subduction. If these two volcanoes are true Cascade Arc volcanoes, Mount Meager is not the northernmost volcano of the Garibaldi Belt or the Cascade Arc.
A number of summits constitute the Mount Meager massif. The highest and northernmost is Plinth Peak
with an elevation of . Mount Meager itself is in elevation. Capricorn Mountain
west of Mount Meager proper rises with an elevation of . Mount Job
, , is situated just west of Capricorn Mountain. Pylon Peak
with an elevation of is south of Capricorn Mountain and Mount Meager proper. Devastator Peak
, also known as The Devastator, has an elevation of and is the lowest and southernmost summit of Mount Meager.
s, lahar
s and lava flows. Eastward migration of the eruption column
spread material across Western Canada
to deposit the Bridge River Ash
. In the Bridge River
and Lillooet River area, the ash occurs as a coarse-textured deposit with blocks of pumice
up to in diameter. The texture rapidly becomes finer eastward from the Bridge River. At Big Bar on the Fraser River
, pellets are up to in diameter while pellets in the Messiter area have a maximum diameter of .
Situated on the northeastern flank of Plinth Peak, the Bridge River Vent has an elevation of . It has oversteepened walls covered with ice and debris from volcanic activity and slope collapses. The crater is roughly bowl-shaped, although it is breached on the northern side. Because the Bridge River Vent is located on the northern flank of Meager, it represents a satellite vent. The eruption that formed the Bridge River Vent was probably fed through a conduit from the magma chamber below Meager. A stress field
controlled by regional tectonics
has been commonly invoked to explain the dynamics of lateral flow of magma from a reservoir to produce such eruptions.
, a long mountain range
extending from Vancouver
to the Alaskan Panhandle. It is about wide, cut by fjord
s created by glacial erosion. Because the Coast Mountains are just east of the Pacific Ocean, they have a profound effect on British Columbia's climate by forcing moisture-laden air off the ocean. This drops heavy rainfalls on the western slopes where lush forests exist. The precipitation is among the heaviest in North America.
Valleys surrounding Mount Meager contain old-growth forests. The area also has wetland
habitats, plants of the cottonwood-willow
-thimbleberry
family and glaucous willowherb
s. Wildlife such as wolves
, wolverine
, moose
, raptors
, black-tailed deer
, mountain goat
s and waterfowl
inhabit the area, as well as grizzly
and black
bear
s.
Meager's subsidiary peak names were submitted by Canadian mountaineer Neal M. Carter, who was a member of the British Columbia Mountaineering Club
. Devastator Peak was officially named on August 3, 1977 in association with Devastation Glacier. Plinth Peak was officially named on September 6, 1951 as identified in Carter's 1932 sketch map and article "Explorations in the Lillooet River Watershed". Mount Job and Pylon Peak were both officially named on January 17, 1957 as labelled on Carter's 1954 sketch map of the Lillooet River. Capricorn Mountain was originally identified as Mount Capricorn in the 1932 Canadian Alpine Journal
, Vol XXI. According to Carter's 1932 Canadian Alpine Journal, Vol XXI, "the name chosen for the 8440-foot mountain was Mt. Capricorn, a variation of the all-too-common appellation "Goat Mountain", applied by Bert [Perkins] to the stream which drains the Capricorn glacier at its base". Subsequently, the peak was renamed to Capricorn Mountain on June 22, 1967.
more than 2000 m (6,561.7 ft) long and 1000 m (3,280.8 ft) wide has been the subject of mining
operations since at least the 1970s. The deposit was first hired by J. MacIsaac, who died in the late 1970s. In the mid 1970s the second hirer, W.H. Willes, investigated and mined the pumice. It was crushed, removed then stored close to the village of Pemberton. Later, the bridge that was used to access the pumice deposit was washed out and mining operations were not renewed. Mining resumed in 1988 when the deposit was staked by L.B. Bustin. In 1990, the pumice outcrop was bought by D.R. Carefoot from the owners B. Chore and M. Beaupre. In a program from 1991 to 1992, workers evaluated the deposit for its properties as a construction material and as an absorber for oil and stonewash
. About 7500 cubic metre of pumice was mined in 1998 by the Great Pacific Pumice Incoporation.
Mount Meager has been investigated as a potential hydrothermal energy resource. At least 16 geothermal sites have been identified in British Columbia, the Mount Meager area being one of the five areas most capable for commercial development. Others include the Lakelse Hot Springs
near the community of Terrace
, Mount Cayley
near the community of Squamish
, Mount Edziza
on the Tahltan Highland
and the Lillooet Fault Zone between Harrison Lake
and the community of Lillooet
. At Meager Creek, there is potential for commercial development of a 100-200 megawatt power station
. Nearby Pebble Creek also has "very good" potential for a 200 megawatt plant. Because the two creeks offer the greatest potential for commercial development, the Mount Meager area is the most promising site for geothermal power development in British Columbia.
to explosive. Four primary eruptive periods in the history of Mount Meager have been identified, with individual eruptions separated by thousands of years. Large northwest-southeast trending structures paralleling Harrison Lake
and the Pemberton Valley may control volcanic activity at Mount Meager or at least create zones of crustal
weakness that are exploited by rising magma batches.
s were erupted at the southern end of the massif. Basal breccia, which may be an exhumed vent, underlies andesite and tuff
s, flows, lava domes and breccia of Devastator Peak. It has a maximum thickness of and overlies a high ridge of bedrock
that formed between 251,000,000 and 65,500,000 years ago of the Mesozoic
era.
At the southwestern end of Meager, dacite with sparse phenocryst
s of quartz
, plagioclase
and hornblende
, represents a thick remnant of subhorizontal lava flows.
. This thick geological formation is located on the south and west flanks of Pylon Peak and Devastator Peak. Its western portion consists of roughly layered tephra
while its eastern end represents the lava flows and subvolcanic
intrusions of a partly preserved vent. Here, The Devastator Assemblage is massive and steeply truncates basal breccia from the first eruptive period.
Between 1,000,000 and 500,000 years ago, a thick sequence of andesite lava flows were erupted from the volcanic plug of Devastator Peak, creating the Pylon Assemblage
. With a maximum thickness of over , the Pylon Assemblage is the largest rock unit comprising Mount Meager. The lava flows are normally layered, separated by a thin layer of lapilli
tuff and reddened breccia. A concentration of subvolcanic intrusions and coarse volcanic breccia clasts over in length suggest that Devastator Peak is a major vent.
hornblende, biotite
and quartz rhyodacite lava flows of the Job Assemblage
were erupted. They are prominently layered and locally columnar jointed. On the east side of Affliction Glacier, they overlie porphyritic andesite lava flows of the Pylon Assemblage. Later, rhyodacite lava flows of the Capricorn Assemblage
were erupted and flowed over biotite rhyodacite of the Job Assemblage. The upper of Capricorn Mountain and Mount Job are formed by these lava flows.
Another sequence of rhyodacite lava flows were subsequently erupted and form the Plinth Assemblage
. Mount Meager proper, a massive lava dome or volcanic plug, consists of steeply inclined flow layering and was the southern source of Plinth Assemblage lava flows and breccias. Plinth Peak was also formed during the Plinth Assemblage eruptive stage and is mostly composed of prominent columnar or partly jointed lava flows. Its north ridge and flat-topped summit contain three areas of steep flow layering and subhorizontally-oriented columnar jointing. These areas are possibly the remains of volcanic plugs or lava domes that were the northern source of Plinth Assemblage lava flows. The Mosaic Assemblage
, a sparsely porphyritic plagioclase-augite
-olivine
basalt and trachybasalt
formation, also formed during the fourth eruptive period. It is the remains of scoria
ceous lava flows, breccias, volcanic bomb
s and pillow lava
s.
The best known and most documented eruption of Mount Meager is a large explosive eruption that occurred about 2,350 years ago. This eruption, which likely reached 5 on the Volcanic Explosivity Index
(VEI), was similar to the 1980 eruption of Mount St. Helens
. It sent a massive Plinian column
at least high into the atmosphere. Prevailing winds carried volcanic ash
from this explosion eastwards to as far as Alberta
. Nearby areas were devastated by heavy pyroclastic fall
when parts of the Plinian column collapsed. Later, a series of pyroclastic flow
s were erupted and travelled from their source. After this happened, a lava flow was erupted that repeatedly collapsed on Meager's steep flanks, creating a thick welded breccia deposit that blocked the Lillooet River. This created a lake just upstream and later collapsed to produce a massive outburst flood. Large boulders were carried downstream for over , but the destructive floodwaters continued further. After this took place, a small dacite lava flow was erupted, which cooled into well preserved columnar joints. The entire eruption cycle was erupted from the Bridge River Vent on the northeastern flank of Plinth Peak. This is the latest known eruption of Mount Meager, as well as the largest known Holocene explosive eruption in Canada. However, it is unknown when this eruption ended.
In 1977, J. A. Westgate of the University of Toronto
suggested that a smaller eruption may have occurred at the Bridge River Vent after the eruption 2,350 years ago, sending tephra to the southeast. A tephra deposit overlying the Bridge River Ash at Otter Creek shows strong genetic relationships with the Bridge River Ash, differing only by its absence of biotite. In earlier publications, this tephra is classified as part of the Bridge River Ash. However, it has been dated to be about 2,000 radiocarbon years old, indicating that this tephra is a few hundred years younger than the Bridge River Ash. Apparent absence of biotite and occurrence well to the south of the Bridge River Ash likewise favour a separate identity. Large volume, fine grained, debris flows north of the volcano might have been caused by volcanic activity. If this is correct, the knowledge of eruptions at Mount Meager in the past 10,000 years is insufficient.
Two small hot spring clusters are found at Mount Meager, indicating magmatic heat is still present. These two clusters of hot springs, known as the Meager Creek Hot Springs and Pebble Creek Hot Springs, are most likely related to recent volcanic activity at Mount Meager. Meager Creek Hot Springs, the largest in British Columbia, remain free of snow for most of the year. The springs at Mount Meager might be evidence of a shallow magma chamber beneath the surface.
Between 1970 and 2005, over 20 small earthquakes were recorded at the volcano. The magnitude
of these events were generally no higher than 2.0 on the Richter magnitude scale
and they originated to less than below the surface. Other volcanoes in the Garibaldi Volcanic Belt with recorded seismicity include Mount Garibaldi
, Mount Cayley
and Silverthrone Caldera. Seismic data suggest that these volcanoes still contain active magma chambers, indicating that some Garibaldi Belt volcanoes are probably active, with significant potential hazards. The seismic activity corresponds with some of Canada's recently formed volcanoes and with persistent volcanoes that have had major explosive activity throughout their history, such as Mount Garibaldi, Mount Cayley and Mount Meager.
, a community some downstream from Meager, is also significantly threatened by the volcano. Because of these concerns, the Geological Survey of Canada is planning to create hazard map
s and emergency plans for Mount Meager, as well as Mount Cayley to the south. If the volcano were to erupt again violently, it would have large-scale effects on the Lillooet River fishery. Another significant eruption would also have massive effects on nearby mining
and logging
activity. In addition, Mount Meager is situated in the immediate proximity of a major air traffic route
. Volcanic ash reduces visibility and can cause jet engine failure, as well as damage to other aircraft systems.
Jack Souther
, a leading authority on geothermal resources and volcanism in the Canadian Cordillera, has stated "at present the volcanoes of the Garibaldi Belt are quiet, presumed dead but still not completely cold. But the flare-up of Meager Mountain 2,500 years ago raises the question, "Could it happen again?" Was the explosive eruption of Meager Mountain the last gasp of the Garibaldi Volcanic Belt or only the most recent event in its on-going life? The short answer is nobody really knows for sure. So just in case I sometimes do a quick check of the old hot-spots when I get off the Peak Chair".
Even though very few eruptions in Canada have been witnessed by people, Canada is geologically an area of intense volcanic activity. According to the Geologic Hazards '91 Workshop, "priority should be given to eruption impact studies of the two recently active volcanic centres closest to urban areas, Mount Baker and Mount Meager. The former case will require a combined US-Canada-Washington State-B.C. effort". In addition, Mount Meager is not monitored closely enough by the Geological Survey of Canada to ascertain how active its magma system is. If it were to erupt, relief efforts could be orchestrated. The Interagency Volcanic Event Notification Plan (IVENP) was created to outline the notification procedure of some of the main agencies that would be involved in response to an erupting volcano in Canada, an eruption close to the Canada – United States border or any eruption that will have effects in Canada.
Although Mount Meager is a potentially active volcano, as of 2003 there was no evidence of an imminent eruption. Many shallow earthquakes normally occur before a volcano erupts. As magma rises to the surface, it will probably create much more vigour and heat at the regional hot springs, as well as the formation of new springs or fumarole
s. These signs generally occur well in advance of a potential eruption, although the possibility of an eruption occurring in the near future is low.
Volcano-associated debris flows, known as lahars, are one of the most dangerous hazards associated with volcanoes. They can occur both during an eruption and when a volcano is not erupting. The water that creates lahars can come from melting snow and ice, intense rainfall or the breakout of a summit crater lake
. Large lahars are a potential hazard to many communities downstream from glaciated volcanoes. In addition, Pemberton is vulnerable to lahars from Mount Meager. Lahars are also a major hazard at Mount Rainier, a younger but heavily glaciated stratovolcano southeast of Seattle
in the central Cascade Volcanic Arc. More than 25 landslides have occurred at Mount Meager in the past 8,000 years.
On August 6, 2010, a massive lahar cascaded down from Capricorn Glacier with a speed of per second. With a volume of , it is the second largest landslide in Canadian history, exceeded by the Hope Slide
, which removed of rock from Johnson Peak. The 2010 landslide at Mount Meager was wide and long, creating a dam across Meager Creek and the Lillooet River. This resulted in the creation of a lake just upstream. Fears of the dam collapsing and flooding the Lillooet River valley ended a day after the landslide when part of the dam ruptured and slowly released water. An evacuation alert was rescinded and nearly 1,500 residents were allowed to return to their homes on the weekend after the landslide occurred. No injuries were reported from this landslide.
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 the Sea-to-Sky Corridor
Sea-to-Sky Corridor
The Sea-to-Sky Corridor, often referred to as the Corridor, or the Sea to Sky Country, is a region in British Columbia spreading from Horseshoe Bay through Whistler to the Pemberton Valley and sometimes beyond to include Birken and D'Arcy...
of southwestern 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. It is located north of Vancouver
Vancouver
Vancouver is a coastal seaport city on the mainland of British Columbia, Canada. It is the hub of Greater Vancouver, which, with over 2.3 million residents, is the third most populous metropolitan area in the country,...
at the northern end of the Pemberton Valley
Pemberton Valley
The Pemberton Valley is a valley flanking the Lillooet River upstream from Lillooet Lake, including the communities of Mount Currie, Pemberton, British Columbia and the agricultural district surrounding them and flanking the river as far upstream as the Pemberton Meadows area...
. Part of the Cascade Volcanic Arc
Cascade Volcanoes
The Cascade Volcanoes are a number of volcanoes in a volcanic arc in western North America, extending from southwestern British Columbia through Washington and Oregon to Northern California, a distance of well over 700 mi ...
of western North America, its summit is above sea level
Sea level
Mean sea level is a measure of the average height of the ocean's surface ; used as a standard in reckoning land elevation...
, and is capped by several eroded volcanic edifices. This includes mounds of viscous lava
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...
, columns of volcanic rock
Volcanic plug
A volcanic plug, also called a volcanic neck or lava neck, is a volcanic landform created when magma hardens within a vent on an active volcano. When forming, a plug can cause an extreme build-up of pressure if volatile-charged magma is trapped beneath it, and this can sometimes lead to an...
and overlapping piles of lava flows. Hydrothermal exploration is present at Mount Meager and it is one of the several geothermal
Geothermal
Geothermal is related to energy and may refer to:* The geothermal gradient and associated heat flows from within the Earth- Renewable technology :...
sites in British Columbia.
Mount Meager is responsible for the largest volcanic eruption in Canada in the past 10,000 years. About 2,350 years ago, an 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...
formed a volcanic crater
Volcanic crater
A volcanic crater is a circular depression in the ground caused by volcanic activity. It is typically a basin, circular in form within which occurs a vent from which magma erupts as gases, lava, and ejecta. A crater can be of large dimensions, and sometimes of great depth...
on its northeastern flank and sent avalanches of hot ash, rock fragments and volcanic gas
Volcanic gas
|250px|thumb|right|Image of the [[rhyolitic]] [[lava dome]] of [[Chaitén Volcano]] during its 2008-2010 eruption.Volcanic gases include a variety of substances given off by active volcanoes...
es down the northern flank of the volcano, creating a geological formation in the Lillooet River
Lillooet River
The Lillooet River is a major river of the southern Coast Mountains of British Columbia. It begins at Silt Lake, on the southern edge of the Lillooet Crown Icecap about 80 kilometres northwest of Pemberton and about 85 kilometres northwest of Whistler...
valley. Evidence for more recent volcanic activity has been documented at the volcano, such as 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 and earthquake
Earthquake
An earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves. The seismicity, seismism or seismic activity of an area refers to the frequency, type and size of earthquakes experienced over a period of time...
s. Mount Meager has also been the source for several large landslide
Landslide
A landslide or landslip is a geological phenomenon which includes a wide range of ground movement, such as rockfalls, deep failure of slopes and shallow debris flows, which can occur in offshore, coastal and onshore environments...
s in the past, including a massive 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...
in 2010 that swept down Meager Creek
Meager Creek
Meager Creek is a creek in the southern Pacific Ranges of the Coast Mountains in British Columbia, Canada. It flows northeast into the Lillooet River....
and the Lillooet River.
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...
has a long history of eruptions and poses a threat to the surrounding region. Any volcanic hazard
Volcanic hazards
Volcanic hazards are threats to life and/or infrastructure due to volcanic activity and related phenomena such as floods and landslides at volcanoes.-Lava flows:...
—ranging from landslides to eruptions—could pose a significant risk to humans and wildlife. Even though Mount Meager has not erupted for over 2,000 years, it could again produce a major eruption; if this were to happen, relief efforts would probably be quickly organized. Teams such as the Interagency Volcanic Event Notification Plan
Interagency Volcanic Event Notification Plan
The Interagency Volcanic Event Notification Plan is a program in Canada established to outline the notification procedure of some of the main agencies that would be involved in response to a volcanic eruption in Canada, an eruption close to Canada's borders, or significant enough that a volcanic...
(IVENP) are prepared to notify people threatened by volcanic eruptions.
Regional setting
Volcanism
Volcanism is the phenomenon connected with volcanoes and volcanic activity. It includes all phenomena resulting from and causing magma within the crust or mantle of a planet to rise through the crust and form volcanic rocks on the surface....
in the Cascade Volcanic Arc is caused by subduction
Subduction
In geology, subduction is the process that takes place at convergent boundaries by which one tectonic plate moves under another tectonic plate, sinking into the Earth's mantle, as the plates converge. These 3D regions of mantle downwellings are known as "Subduction Zones"...
of the Juan de Fuca Plate
Juan de Fuca Plate
The Juan de Fuca Plate, named after the explorer of the same name, is a tectonic plate, generated from the Juan de Fuca Ridge, and subducting under the northerly portion of the western side of the North American Plate at the Cascadia subduction zone...
under 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...
at the Cascadia subduction zone. This is a long fault zone running off the Pacific Northwest
Pacific Northwest
The Pacific Northwest is a region in northwestern North America, bounded by the Pacific Ocean to the west and, loosely, by the Rocky Mountains on the east. Definitions of the region vary and there is no commonly agreed upon boundary, even among Pacific Northwesterners. A common concept of the...
from Northern California
Northern California
Northern California is the northern portion of the U.S. state of California. The San Francisco Bay Area , and Sacramento as well as its metropolitan area are the main population centers...
to southwestern British Columbia. The plates move at a relative rate of over per year at an oblique angle to the subduction zone. Because of the very large fault area, the Cascadia subduction zone can produce large earthquake
Earthquake
An earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves. The seismicity, seismism or seismic activity of an area refers to the frequency, type and size of earthquakes experienced over a period of time...
s of magnitude
Magnitude (mathematics)
The magnitude of an object in mathematics is its size: a property by which it can be compared as larger or smaller than other objects of the same kind; in technical terms, an ordering of the class of objects to which it belongs....
7.0 or greater. The interface between the Juan de Fuca and North American plates remains locked for periods of roughly 500 years. During these periods, stress builds up on the interface between the plates and causes uplift of the North American margin. When the plate finally slips, the 500 years of stored energy are released in a massive earthquake.
Unlike most subduction zones worldwide, there is no deep oceanic trench
Oceanic trench
The oceanic trenches are hemispheric-scale long but narrow topographic depressions of the sea floor. They are also the deepest parts of the ocean floor....
present along the continental margin
Continental margin
The continental margin is the zone of the ocean floor that separates the thin oceanic crust from thick continental crust. Continental margins constitute about 28% of the oceanic area....
in Cascadia. The reason is that the mouth of the Columbia River
Columbia River
The Columbia River is the largest river in the Pacific Northwest region of North America. The river rises in the Rocky Mountains of British Columbia, Canada, flows northwest and then south into the U.S. state of Washington, then turns west to form most of the border between Washington and the state...
empties directly into the subduction zone and deposits silt at the bottom of the Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
, burying the oceanic trench. Massive floods from prehistoric Glacial Lake Missoula
Glacial Lake Missoula
Glacial Lake Missoula was a prehistoric proglacial lake in western Montana that existed periodically at the end of the last ice age between 15,000 and 13,000 years ago...
during the Late Pleistocene
Late Pleistocene
The Late Pleistocene is a stage of the Pleistocene Epoch. The beginning of the stage is defined by the base of the Eemian interglacial phase before the final glacial episode of the Pleistocene 126,000 ± 5,000 years ago. The end of the stage is defined exactly at 10,000 Carbon-14 years BP...
also deposited large amounts of sediment
Sediment
Sediment is naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of fluids such as wind, water, or ice, and/or by the force of gravity acting on the particle itself....
into the trench. However, in common with other subduction zones, the outer margin is slowly being compressed, similar to a giant spring. When the stored energy is suddenly released by slippage across the fault at irregular intervals, the Cascadia subduction zone can create very large earthquakes, such as the magnitude 9.0 Cascadia earthquake on January 26, 1700. However, earthquakes along the Cascadia subduction zone are fewer than expected and there is evidence of a decline in volcanic activity over the past few million years. The probable explanation lies in the rate of convergence between the Juan de Fuca and North American plates. These two tectonic plates currently converge 3 cm (1.2 in) to 4 cm (1.6 in) per year. This is only about half the rate of convergence from seven million years ago.
Local setting
Watts Point volcanic centre
The Watts Point volcanic centre is a small outcrop of Pleistocene age volcanic rock at Watts Point in British Columbia, Canada, about south of Squamish and north of Vancouver, and just north of Britannia Beach. It is the southernmost volcanic zone in the Squamish volcanic field and of the...
in the south to the 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...
in the north. This volcanic belt
Volcanic belt
A volcanic belt is a large volcanically active region. Other terms are used for smaller areas of activity, such as volcanic fields. Volcanic belts are found above zones of unusually high temperature where magma is created by partial melting of solid material in the Earth's crust and upper mantle....
includes 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, 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 and 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...
es that have been active in the 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 (10,000 years ago to present). The latest explosive eruption in the Garibaldi Volcanic Belt occurred at a crater on the northeastern flank of Mount Meager, which forms a clearly-defined depression. At least eight volcanic vents constitute Meager, which erupted mafic
Mafic
Mafic is an adjective describing a silicate mineral or rock that is rich in magnesium and iron; the term is a portmanteau of the words "magnesium" and "ferric". Most mafic minerals are dark in color and the relative density is greater than 3. Common rock-forming mafic minerals include olivine,...
, intermediate
Intermediate composition
In igneous petrology an intermediate composition refers to the chemical composition of a rock that has 52-63 wt% SiO2 being an intermediate between felsic and mafic compositions. Typical intermediate rocks include andesite, dacite and trachyandesite among volcanic rocks and diorite and granodiorite...
and felsic
Felsic
The word "felsic" is a term used in geology to refer to silicate minerals, magma, and rocks which are enriched in the lighter elements such as silicon, oxygen, aluminium, sodium, and potassium....
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...
. Streams and glaciers have played a significant role in dissecting the massif and its upper slopes are covered by snow and ice. Numerous feeder dikes
Dike (geology)
A dike or dyke in geology is a type of sheet intrusion referring to any geologic body that cuts discordantly across* planar wall rock structures, such as bedding or foliation...
to older units are exposed by deep erosion. Perkin's Pillar
Perkin's Pillar
Perkin's Pillar was a vertical pillar of volcanic rock of the Mount Meager massif in southwestern British Columbia, Canada. It existed on the steep north flank of Capricorn Mountain...
, a vertical tower of breccia
Breccia
Breccia is a rock composed of broken fragments of minerals or rock cemented together by a fine-grained matrix, that can be either similar to or different from the composition of the fragments....
ted lava, represented an erosional remnant of Meager until its collapse in June 2005. More than 10 streams drain meltwater from Mount Meager, including Capricorn Creek, Job Creek, No Good Creek, Angel Creek, Devastation Creek, Canyon Creek and Affliction Creek.
The geomorphology
Geomorphology
Geomorphology is the scientific study of landforms and the processes that shape them...
of Mount Meager is similar to Glacier Peak
Glacier Peak
Glacier Peak is the most isolated of the five major stratovolcanoes of the Cascade Volcanic Arc in Washington...
, another Cascade Arc volcano, located in the U.S. state
U.S. state
A U.S. state is any one of the 50 federated states of the United States of America that share sovereignty with the federal government. Because of this shared sovereignty, an American is a citizen both of the federal entity and of his or her state of domicile. Four states use the official title of...
of Washington. It consists of at least four overlapping stratovolcanoes that become progressively younger from south to north. As a result, Meager can be classified as a compound/complex volcano, which consists of two or more vents. With a total volume of , Mount Meager is a long-lived feature, tracing its history back to 2,200,000 years ago. This indicates that it is relatively old compared to most volcanoes in the Cascade Arc. In the Cascade Range
Cascade Range
The Cascade Range is a major mountain range of western North America, extending from southern British Columbia through Washington and Oregon to Northern California. It includes both non-volcanic mountains, such as the North Cascades, and the notable volcanoes known as the High Cascades...
, the oldest volcanoes are generally no more than a million years old. This includes Mount Rainier
Mount Rainier
Mount Rainier is a massive stratovolcano located southeast of Seattle in the state of Washington, United States. It is the most topographically prominent mountain in the contiguous United States and the Cascade Volcanic Arc, with a summit elevation of . Mt. Rainier is considered one of the most...
(500,000 years), Lassen Peak
Lassen Peak
Lassen Peak is the southernmost active volcano in the Cascade Range. It is part of the Cascade Volcanic Arc which is an arc that stretches from northern California to southwestern British Columbia...
(27,000 years), Mount Jefferson
Mount Jefferson (Oregon)
Mount Jefferson is a stratovolcano in the Cascade Volcanic Arc, part of the Cascade Range, and is the second highest mountain in Oregon. Situated in the far northeastern corner of Linn County on the Jefferson County line, about east of Corvallis, Mount Jefferson is in a rugged wilderness and is...
(680,000 years), Mount St. Helens
Mount St. Helens
Mount St. Helens is an active stratovolcano located in Skamania County, Washington, in the Pacific Northwest region of the United States. It is south of Seattle, Washington and northeast of Portland, Oregon. Mount St. Helens takes its English name from the British diplomat Lord St Helens, a...
(50,000 years) and many more. However, portions of Mount Meager formed in the past million years. The volcano is made of 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...
s ranging from rhyodacite
Rhyodacite
Rhyodacite is an extrusive volcanic rock intermediate in composition between dacite and rhyolite. It is the extrusive equivalent of granodiorite. Phenocrysts of sodium rich plagioclase, sanidine, quartz, and biotite or hornblende are typically set in an aphanitic to glassy light to intermediate...
to 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...
. Rhyodacite forms a series of eroded volcanic plugs, which represent the highest peaks of Meager. Their flanks are covered by their eruptive products and are the surface expressions of 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. As a result, they provide a unique opportunity to study the relationships between 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...
s and their lavas.
Although some scientists speculate the Silverthrone Caldera as the northernmost volcano of the Garibaldi Volcanic Belt, others prefer Mount Meager as the northernmost. This controversy is because little is known about the volcanoes north of Meager, such as Silverthrone and the Franklin Glacier volcanic complex
Franklin Glacier Volcano
Franklin Glacier Volcano is a deeply eroded and huge long and wide caldera complex in southwestern British Columbia, Canada, located east-southeast of the Silverthrone Caldera in the Hoodoo Creek and Franklin Glacier area on the northwest flank of the Waddington Massif of the Pacific Ranges...
. It is also unclear whether the Milbanke Sound Cones are part of the Garibaldi Belt or they are volcanoes formed by different tectonic processes than those in the Garibaldi Belt. However, there is evidence the Silverthrone and Franklin Glacier complexes are related to Cascadia subduction. Geologically, these two volcanoes contain the same rock types as those found elsewhere in the Cascade Arc, including 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...
s, dacite
Dacite
Dacite is an igneous, volcanic rock. It has an aphanitic to porphyritic texture and is intermediate in composition between andesite and rhyolite. The relative proportions of feldspars and quartz in dacite, and in many other volcanic rocks, are illustrated in the QAPF diagram...
s, andesite
Andesite
Andesite is an extrusive igneous, volcanic rock, of intermediate composition, with aphanitic to porphyritic texture. In a general sense, it is the intermediate type between basalt and dacite. The mineral assemblage is typically dominated by plagioclase plus pyroxene and/or hornblende. Magnetite,...
s and basaltic andesite
Basaltic andesite
Basaltic andesite is a black volcanic rock containing about 55% silica. Minerals in basaltic andesite include olivine, augite and plagioclase. Basaltic andesite can be found in volcanoes around the world, including in Central America and the Andes of South America. Basaltic andesite is common in...
s. Such rock types are produced by subduction zone volcanism, indicating volcanism at Silverthrone and Franklin Glacier is probably related to subduction. If these two volcanoes are true Cascade Arc volcanoes, Mount Meager is not the northernmost volcano of the Garibaldi Belt or the Cascade Arc.
A number of summits constitute the Mount Meager massif. The highest and northernmost is Plinth Peak
Plinth Peak
Plinth Peak, sometimes called Plinth Mountain, is the highest satellite cone of Mount Meager, and one of four overlapping volcanic cones which together form the northernmost volcanic complex in the Cascade Volcanic Arc and the Garibaldi Volcanic Belt...
with an elevation of . Mount Meager itself is in elevation. Capricorn Mountain
Capricorn Mountain
Capricorn Mountain is one of the several volcanic peaks of the Mount Meager massif in southwestern British Columbia, Canada. The slopes of Capricorn Mountain appear to be more gentle than other volcanic peaks of the massif...
west of Mount Meager proper rises with an elevation of . Mount Job
Mount Job
Mount Job is one of the six named volcanic peaks of Mount Meager in British Columbia, Canada. It is a pile of rubble held together by volcanic ash and sand...
, , is situated just west of Capricorn Mountain. Pylon Peak
Pylon Peak
Pylon Peak is the southernmost summit of the six named volcanic peaks of Mount Meager in British Columbia, Canada. Two pinnacled ridges extend out from Pylon and are named respectively the Pylons and the Marionettes. Pylon Peak overlooks the Meager Creek Hot Springs.Erosional remnants of flows from...
with an elevation of is south of Capricorn Mountain and Mount Meager proper. Devastator Peak
Devastator Peak
Devastator Peak, also known as The Devastator, is the lowest and southernmost of the six subsidiary peaks that form the Mount Meager massif in southwestern British Columbia, Canada. It is located west of Bralorne.-Geology:...
, also known as The Devastator, has an elevation of and is the lowest and southernmost summit of Mount Meager.
Bridge River Vent
The Bridge River Vent is a relatively young volcanic crater that formed during an eruption about 2,350 years ago. This eruption ranged in character from explosive to effusive, involving lava dome extrusion, pyroclastic flowPyroclastic 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, lahar
Lahar
A lahar is a type of mudflow or debris flow composed of a slurry of pyroclastic material, rocky debris, and water. The material flows down from a volcano, typically along a river valley. The term is a shortened version of "berlahar" which originated in the Javanese language of...
s and lava flows. Eastward migration of the eruption column
Eruption column
An eruption column consists of hot volcanic ash emitted during an explosive volcanic eruption. The ash forms a column rising many kilometres into the air above the peak of the volcano. In the most explosive eruptions, the eruption column may rise over 40 km, penetrating the stratosphere...
spread material across Western Canada
Western Canada
Western Canada, also referred to as the Western provinces and commonly as the West, is a region of Canada that includes the four provinces west of the province of Ontario.- Provinces :...
to deposit the Bridge River Ash
Bridge River Ash
The Bridge River Ash is a large geologically recent volcanic ash deposit that spans from southwestern British Columbia to central Alberta, Canada. The ash consists of dust-sized shards ellipsoidal fragments of pumice. It overlaps the Mount St. Helens Yn Ash and the Mazama Ash which were erupted...
. In the Bridge River
Bridge River
The Bridge River is, or was, a major tributary of British Columbia's Fraser River, entering that stream about six miles upstream from the town of Lillooet.-Name:Its name in the Lillooet language is Xwisten , sometimes spelled Nxwisten or Nxo-isten)...
and Lillooet River area, the ash occurs as a coarse-textured deposit with blocks of 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...
up to in diameter. The texture rapidly becomes finer eastward from the Bridge River. At Big Bar on the Fraser River
Fraser River
The Fraser River is the longest river within British Columbia, Canada, rising at Fraser Pass near Mount Robson in the Rocky Mountains and flowing for , into the Strait of Georgia at the city of Vancouver. It is the tenth longest river in Canada...
, pellets are up to in diameter while pellets in the Messiter area have a maximum diameter of .
Situated on the northeastern flank of Plinth Peak, the Bridge River Vent has an elevation of . It has oversteepened walls covered with ice and debris from volcanic activity and slope collapses. The crater is roughly bowl-shaped, although it is breached on the northern side. Because the Bridge River Vent is located on the northern flank of Meager, it represents a satellite vent. The eruption that formed the Bridge River Vent was probably fed through a conduit from the magma chamber below Meager. A stress field
Stress field
A stress field is a region in a body for which the stress is defined at every point. Stress fields are widely used in fluid dynamics and materials science....
controlled by regional tectonics
Tectonics
Tectonics is a field of study within geology concerned generally with the structures within the lithosphere of the Earth and particularly with the forces and movements that have operated in a region to create these structures.Tectonics is concerned with the orogenies and tectonic development of...
has been commonly invoked to explain the dynamics of lateral flow of magma from a reservoir to produce such eruptions.
Climate and vegetation
Mount Meager is situated in the Coast MountainsCoast Mountains
The Coast Mountains are a major mountain range, in the Pacific Coast Ranges, of western North America, extending from southwestern Yukon through the Alaska Panhandle and virtually all of the Coast of British Columbia. They are so-named because of their proximity to the sea coast, and are often...
, a long 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...
extending from Vancouver
Vancouver
Vancouver is a coastal seaport city on the mainland of British Columbia, Canada. It is the hub of Greater Vancouver, which, with over 2.3 million residents, is the third most populous metropolitan area in the country,...
to the Alaskan Panhandle. It is about wide, cut by fjord
Fjord
Geologically, a fjord is a long, narrow inlet with steep sides or cliffs, created in a valley carved by glacial activity.-Formation:A fjord is formed when a glacier cuts a U-shaped valley by abrasion of the surrounding bedrock. Glacial melting is accompanied by rebound of Earth's crust as the ice...
s created by glacial erosion. Because the Coast Mountains are just east of the Pacific Ocean, they have a profound effect on British Columbia's climate by forcing moisture-laden air off the ocean. This drops heavy rainfalls on the western slopes where lush forests exist. The precipitation is among the heaviest in North America.
Valleys surrounding Mount Meager contain old-growth forests. The area also has wetland
Wetland
A wetland is an area of land whose soil is saturated with water either permanently or seasonally. Wetlands are categorised by their characteristic vegetation, which is adapted to these unique soil conditions....
habitats, plants of the cottonwood-willow
Willow
Willows, sallows, and osiers form the genus Salix, around 400 species of deciduous trees and shrubs, found primarily on moist soils in cold and temperate regions of the Northern Hemisphere...
-thimbleberry
Thimbleberry
Rubus parviflorus, commonly called thimbleberry or salmonberry, is a species of Rubus, native to western and northern North America, from Alaska east to Ontario and Michigan, and south to northern Mexico...
family and glaucous willowherb
Epilobium glaberrimum
Epilobium glaberrimum is a species of willowherb known by the common name glaucous willowherb. This clumping perennial wildflower is native to western North America from central Canada to northern Mexico. It generally grows at some elevation in moist places. This plant is somewhat variable in...
s. Wildlife such as wolves
Gray Wolf
The gray wolf , also known as the wolf, is the largest extant wild member of the Canidae family...
, wolverine
Wolverine
The wolverine, pronounced , Gulo gulo , also referred to as glutton, carcajou, skunk bear, or quickhatch, is the largest land-dwelling species of the family Mustelidae . It is a stocky and muscular carnivore, more closely resembling a small bear than other mustelids...
, moose
Moose
The moose or Eurasian elk is the largest extant species in the deer family. Moose are distinguished by the palmate antlers of the males; other members of the family have antlers with a dendritic configuration...
, raptors
Bird of prey
Birds of prey are birds that hunt for food primarily on the wing, using their keen senses, especially vision. They are defined as birds that primarily hunt vertebrates, including other birds. Their talons and beaks tend to be relatively large, powerful and adapted for tearing and/or piercing flesh....
, black-tailed deer
Black-tailed Deer
Two forms of black-tailed deer or blacktail deer occupying coastal temperate rainforest on North America's Pacific coast are subspecies of the mule deer. They have sometimes been treated as a species, but virtually all recent authorities maintain they are subspecies...
, mountain goat
Mountain goat
The Mountain Goat , also known as the Rocky Mountain Goat, is a large-hoofed mammal found only in North America. Despite its vernacular name, it is not a member of Capra, the genus of true goats...
s and waterfowl
Waterfowl
Waterfowl are certain wildfowl of the order Anseriformes, especially members of the family Anatidae, which includes ducks, geese, and swans....
inhabit the area, as well as grizzly
Grizzly Bear
The grizzly bear , also known as the silvertip bear, the grizzly, or the North American brown bear, is a subspecies of brown bear that generally lives in the uplands of western North America...
and black
American black bear
The American black bear is a medium-sized bear native to North America. It is the continent's smallest and most common bear species. Black bears are omnivores, with their diets varying greatly depending on season and location. They typically live in largely forested areas, but do leave forests in...
bear
Bear
Bears are mammals of the family Ursidae. Bears are classified as caniforms, or doglike carnivorans, with the pinnipeds being their closest living relatives. Although there are only eight living species of bear, they are widespread, appearing in a wide variety of habitats throughout the Northern...
s.
Naming
The name Meager Mountain was adopted on May 6, 1924 as labelled on the 1923 British Columbia map 2D. In 1966, the volcano was renamed to Mount Meager. According to a letter written in March 1983, "the local name, Cathedral, was duplicated elsewhere, so the mountain was renamed Meager after the creek of that name which lies to the south of it". Meager Creek is in turn named after J.B. Meager, who was an owner of timber licences on the creek. Despite its official name, Mount Meager is sometimes mistakenly spelled Mount Meagre or Mount Meagher.Meager's subsidiary peak names were submitted by Canadian mountaineer Neal M. Carter, who was a member of the British Columbia Mountaineering Club
British Columbia Mountaineering Club
The British Columbia Mountaineering Club is a mountaineering organization, based in Vancouver, British Columbia. Founded on October 28, 1907 as the Vancouver Mountaineering Club, it became one of the centres of Canadian Mountaineering, particularly in the Coast Mountains of British Columbia...
. Devastator Peak was officially named on August 3, 1977 in association with Devastation Glacier. Plinth Peak was officially named on September 6, 1951 as identified in Carter's 1932 sketch map and article "Explorations in the Lillooet River Watershed". Mount Job and Pylon Peak were both officially named on January 17, 1957 as labelled on Carter's 1954 sketch map of the Lillooet River. Capricorn Mountain was originally identified as Mount Capricorn in the 1932 Canadian Alpine Journal
Canadian Alpine Journal
The Canadian Alpine Journal is the yearly magazine of the Alpine Club of Canada. It serves as a worldwide journal of record for achievements in climbing, mountaineering, ski mountaineering, and exploration of mountains....
, Vol XXI. According to Carter's 1932 Canadian Alpine Journal, Vol XXI, "the name chosen for the 8440-foot mountain was Mt. Capricorn, a variation of the all-too-common appellation "Goat Mountain", applied by Bert [Perkins] to the stream which drains the Capricorn glacier at its base". Subsequently, the peak was renamed to Capricorn Mountain on June 22, 1967.
Occupation
A large pumice outcropOutcrop
An outcrop is a visible exposure of bedrock or ancient superficial deposits on the surface of the Earth. -Features:Outcrops do not cover the majority of the Earth's land surface because in most places the bedrock or superficial deposits are covered by a mantle of soil and vegetation and cannot be...
more than 2000 m (6,561.7 ft) long and 1000 m (3,280.8 ft) wide has been the subject of mining
Mining
Mining is the extraction of valuable minerals or other geological materials from the earth, from an ore body, vein or seam. The term also includes the removal of soil. Materials recovered by mining include base metals, precious metals, iron, uranium, coal, diamonds, limestone, oil shale, rock...
operations since at least the 1970s. The deposit was first hired by J. MacIsaac, who died in the late 1970s. In the mid 1970s the second hirer, W.H. Willes, investigated and mined the pumice. It was crushed, removed then stored close to the village of Pemberton. Later, the bridge that was used to access the pumice deposit was washed out and mining operations were not renewed. Mining resumed in 1988 when the deposit was staked by L.B. Bustin. In 1990, the pumice outcrop was bought by D.R. Carefoot from the owners B. Chore and M. Beaupre. In a program from 1991 to 1992, workers evaluated the deposit for its properties as a construction material and as an absorber for oil and stonewash
Stone washing
Stone washing is a textile manufacturing process used to give a newly manufactured cloth garment a worn-out appearance. Stone-washing also helps to increase the softness and flexibility of otherwise stiff and rigid fabrics such as canvas and denim....
. About 7500 cubic metre of pumice was mined in 1998 by the Great Pacific Pumice Incoporation.
Mount Meager has been investigated as a potential hydrothermal energy resource. At least 16 geothermal sites have been identified in British Columbia, the Mount Meager area being one of the five areas most capable for commercial development. Others include the Lakelse Hot Springs
Lakelse Hot Springs
The Lakese Hot Springs, also known as the Mount Layton Hot Springs, are a group of hot springs in the Kalum-Kitimat valley of northern British Columbia, Canada, located on the eastern shore of Lakelse Lake in Lakelse Lake Provincial Park south of Terrace along Highway 37...
near the community of Terrace
Terrace, British Columbia
Terrace is a city on the Skeena River in British Columbia, Canada. The Kitselas people, a tribe of the Tsimshian Nation, have lived in the Terrace area for thousands of years. The community population fell between 2001 and 2006 from 12,109 with a regional population of 19,980 to 11,320 and...
, 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...
near the community of Squamish
Squamish, British Columbia
Squamish is a community and a district municipality in the Canadian province of British Columbia, located at the north end of Howe Sound on the Sea to Sky Highway...
, 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...
on 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...
and the Lillooet Fault Zone between Harrison Lake
Harrison Lake
Harrison Lake is the largest lake in the southern Coast Mountains of Canada, being about 250 square kilometres in area. It is about 60 km in length and at its widest almost 9 km across. Its southern end, at the resort community of Harrison Hot Springs, is c. 95 km east of...
and the community of Lillooet
Lillooet, British Columbia
Lillooet is a community on the Fraser River in western Canada, about up the British Columbia Railway line from Vancouver. Situated at an intersection of deep gorges in the lee of the Coast Mountains, it has a dry climate- of precipitation is recorded annually at the town's weather station,...
. At Meager Creek, there is potential for commercial development of a 100-200 megawatt power station
Power station
A power station is an industrial facility for the generation of electric energy....
. Nearby Pebble Creek also has "very good" potential for a 200 megawatt plant. Because the two creeks offer the greatest potential for commercial development, the Mount Meager area is the most promising site for geothermal power development in British Columbia.
Volcanic history
At least 54 eruptions have occurred at Mount Meager in the past 2,600,000 years, ranging in character from effusiveEffusive eruption
An effusive eruption is a volcanic eruption characterized by the outpouring of lava onto the ground...
to explosive. Four primary eruptive periods in the history of Mount Meager have been identified, with individual eruptions separated by thousands of years. Large northwest-southeast trending structures paralleling Harrison Lake
Harrison Lake
Harrison Lake is the largest lake in the southern Coast Mountains of Canada, being about 250 square kilometres in area. It is about 60 km in length and at its widest almost 9 km across. Its southern end, at the resort community of Harrison Hot Springs, is c. 95 km east of...
and the Pemberton Valley may control volcanic activity at Mount Meager or at least create zones of crustal
Crust (geology)
In geology, the crust is the outermost solid shell of a rocky planet or natural satellite, which is chemically distinct from the underlying mantle...
weakness that are exploited by rising magma batches.
First record of activity
During the first eruptive period 2,200,000 to 1,900,000 years ago, intermediate to felsic pyroclastic rockPyroclastic 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 were erupted at the southern end of the massif. Basal breccia, which may be an exhumed vent, underlies andesite and tuff
Tuff
Tuff is a type of rock consisting of consolidated volcanic ash ejected from vents during a volcanic eruption. Tuff is sometimes called tufa, particularly when used as construction material, although tufa also refers to a quite different rock. Rock that contains greater than 50% tuff is considered...
s, flows, lava domes and breccia of Devastator Peak. It has a maximum thickness of and overlies a high ridge of bedrock
Bedrock
In stratigraphy, bedrock is the native consolidated rock underlying the surface of a terrestrial planet, usually the Earth. Above the bedrock is usually an area of broken and weathered unconsolidated rock in the basal subsoil...
that formed between 251,000,000 and 65,500,000 years ago of the Mesozoic
Mesozoic
The Mesozoic era is an interval of geological time from about 250 million years ago to about 65 million years ago. It is often referred to as the age of reptiles because reptiles, namely dinosaurs, were the dominant terrestrial and marine vertebrates of the time...
era.
At the southwestern end of Meager, dacite with sparse phenocryst
Phenocryst
thumb|right|300px|[[Granite]]s often have large [[feldspar|feldspatic]] phenocrysts. This granite, from the [[Switzerland|Swiss]] side of the [[Mont Blanc]] massif, has large white [[plagioclase]] phenocrysts, [[triclinic]] [[mineral]]s that give [[trapezium|trapezoid]] shapes when cut through)...
s of quartz
Quartz
Quartz is the second-most-abundant mineral in the Earth's continental crust, after feldspar. It is made up of a continuous framework of SiO4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall formula SiO2. There are many different varieties of quartz,...
, plagioclase
Plagioclase
Plagioclase is an important series of tectosilicate minerals within the feldspar family. Rather than referring to a particular mineral with a specific chemical composition, plagioclase is a solid solution series, more properly known as the plagioclase feldspar series...
and hornblende
Hornblende
Hornblende is a complex inosilicate series of minerals .It is not a recognized mineral in its own right, but the name is used as a general or field term, to refer to a dark amphibole....
, represents a thick remnant of subhorizontal lava flows.
The Devastator and Pylon assemblage eruptive periods
The second eruptive period between 1,900,000 and 500,000 years ago produced rhyodacite tuff, breccia, lavas and domes of The Devastator AssemblageThe Devastator Assemblage
The Devastator Assemblage is a geological formation comprising a portion of the Mount Meager massif in southwestern British Columbia, Canada. It is named after Devastator Peak , the lowest and southernmost subsidiary peak of Meager...
. This thick geological formation is located on the south and west flanks of Pylon Peak and Devastator Peak. Its western portion consists of roughly layered tephra
Tephra
200px|thumb|right|Tephra horizons in south-central [[Iceland]]. The thick and light coloured layer at center of the photo is [[rhyolitic]] tephra from [[Hekla]]....
while its eastern end represents the lava flows and subvolcanic
Subvolcanic rock
A subvolcanic rock, also known as a hypabyssal rock, is an igneous rock that originates at medium to shallow depths within the crust and contain intermediate grain size and often porphyritic texture. They have textures between volcanic and plutonic rocks. Subvolcanic rocks include diabase and...
intrusions of a partly preserved vent. Here, The Devastator Assemblage is massive and steeply truncates basal breccia from the first eruptive period.
Between 1,000,000 and 500,000 years ago, a thick sequence of andesite lava flows were erupted from the volcanic plug of Devastator Peak, creating the Pylon Assemblage
Pylon Assemblage
The Pylon Assemblage is an accreted terrane of igneous rocks in southwestern British Columbia, Canada, located about north of Vancouver. It is named after Pylon Peak, a subsidiary summit of the Mount Meager massif...
. With a maximum thickness of over , the Pylon Assemblage is the largest rock unit comprising Mount Meager. The lava flows are normally layered, separated by a thin layer of lapilli
Lapilli
Lapilli is a size classification term for tephra, which is material that falls out of the air during a volcanic eruption or during some meteorite impacts. Lapilli means "little stones" in Latin. They are in some senses similar to ooids or pisoids in calcareous sediments.By definition lapilli range...
tuff and reddened breccia. A concentration of subvolcanic intrusions and coarse volcanic breccia clasts over in length suggest that Devastator Peak is a major vent.
Formation of the Plinth, Job, Capricorn and Mosaic assemblages
The fourth and final eruptive period 150,000 to less than 3,000 years ago produced rhyodacite lava flows, domes, breccias and subvolcanic intrusions of the Plinth, Job and Capricorn assemblages. Around Mount Job, porphyriticPorphyritic
Porphyritic is an adjective used in geology, specifically for igneous rocks, for a rock that has a distinct difference in the size of the crystals, with at least one group of crystals obviously larger than another group...
hornblende, biotite
Biotite
Biotite is a common phyllosilicate mineral within the mica group, with the approximate chemical formula . More generally, it refers to the dark mica series, primarily a solid-solution series between the iron-endmember annite, and the magnesium-endmember phlogopite; more aluminous endmembers...
and quartz rhyodacite lava flows of the Job Assemblage
Job Assemblage
The Job Assemblage is a geological formation comprising a portion of the Mount Meager massif in southwestern British Columbia, Canada. It is named after Mount Job, a subsidiary peak of Meager. The rock unit was formed during a period of rhyodacite volcanism during the Pleistocene epoch.Around Mount...
were erupted. They are prominently layered and locally columnar jointed. On the east side of Affliction Glacier, they overlie porphyritic andesite lava flows of the Pylon Assemblage. Later, rhyodacite lava flows of the Capricorn Assemblage
Capricorn Assemblage
The Capricorn Assemblage is a geological formation comprising the central portion of the Mount Meager massif in southwestern British Columbia, Canada. It is named after Capricorn Mountain, the third highest subsidiary peak of Meager...
were erupted and flowed over biotite rhyodacite of the Job Assemblage. The upper of Capricorn Mountain and Mount Job are formed by these lava flows.
Another sequence of rhyodacite lava flows were subsequently erupted and form the Plinth Assemblage
Plinth Assemblage
The Plinth Assemblage, also known as the Plinth Formation, is an accreted terrane of igneous rocks in southwestern British Columbia, Canada, located just north of the Lillooet River and on the northern flank of the Mount Meager massif...
. Mount Meager proper, a massive lava dome or volcanic plug, consists of steeply inclined flow layering and was the southern source of Plinth Assemblage lava flows and breccias. Plinth Peak was also formed during the Plinth Assemblage eruptive stage and is mostly composed of prominent columnar or partly jointed lava flows. Its north ridge and flat-topped summit contain three areas of steep flow layering and subhorizontally-oriented columnar jointing. These areas are possibly the remains of volcanic plugs or lava domes that were the northern source of Plinth Assemblage lava flows. The Mosaic Assemblage
Mosaic Assemblage
The Mosaic Assemblage is a rock unit of the Pacific Ranges of the Coast Mountains in southwestern British Columbia, Canada. It is the namesake of Mosaic Glacier, which is drained by Mosaic Creek. This geological formation formed 140,000 to less than 90,000 years ago when porphyritic...
, a sparsely porphyritic plagioclase-augite
Augite
Augite is a single chain inosilicate mineral, 2O6. The crystals are monoclinic and prismatic. Augite has two prominent cleavages, meeting at angles near 90 degrees.-Characteristics:Augite is a solid solution in the pyroxene group...
-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 and trachybasalt
Trachybasalt
Trachybasalt is a volcanic rock with a composition between trachyte and basalt. Minerals included in trachybasalt include alkali feldspar, calcic plagioclase, olivine, clinopyroxene and likely very small amounts of leucite or analcime. It contains high alkali content ....
formation, also formed during the fourth eruptive period. It is the remains of scoria
Scoria
Scoria is a volcanic rock containing many holes or vesicles. It is most generally dark in color , and basaltic or andesitic in composition. Scoria is relatively low in mass as a result of its numerous macroscopic ellipsoidal vesicles, but in contrast to pumice, all scoria has a specific gravity...
ceous lava flows, breccias, 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 and 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...
s.
The best known and most documented eruption of Mount Meager is a large explosive eruption that occurred about 2,350 years ago. This eruption, which likely reached 5 on the Volcanic Explosivity Index
Volcanic Explosivity Index
The Volcanic Explosivity Index was devised by Chris Newhall of the U.S. Geological Survey and Stephen Self at the University of Hawaii in 1982 to provide a relative measure of the explosiveness of volcanic eruptions....
(VEI), was similar to the 1980 eruption of Mount St. Helens
1980 eruption of Mount St. Helens
The 1980 eruption of Mount St. Helens, a stratovolcano located in Washington state, in the United States, was a major volcanic eruption. The eruption was the only significant one to occur in the contiguous 48 U.S. states since the 1915 eruption of Lassen Peak in California...
. It sent a massive Plinian column
Plinian eruption
Plinian eruptions, also known as 'Vesuvian eruptions', are volcanic eruptions marked by their similarity to the eruption of Mount Vesuvius in AD 79 ....
at least high into the atmosphere. Prevailing winds carried 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...
from this explosion eastwards to as far as 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...
. Nearby areas were devastated by heavy pyroclastic fall
Pyroclastic fall
A pyroclastic fall is a uniform deposit of material which has been ejected from a volcanic eruption or plume such as an ash fall or tuff. Pyroclastic air fall deposits are a result of:...
when parts of the Plinian column collapsed. Later, a series of 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 were erupted and travelled from their source. After this happened, a lava flow was erupted that repeatedly collapsed on Meager's steep flanks, creating a thick welded breccia deposit that blocked the Lillooet River. This created a lake just upstream and later collapsed to produce a massive outburst flood. Large boulders were carried downstream for over , but the destructive floodwaters continued further. After this took place, a small dacite lava flow was erupted, which cooled into well preserved columnar joints. The entire eruption cycle was erupted from the Bridge River Vent on the northeastern flank of Plinth Peak. This is the latest known eruption of Mount Meager, as well as the largest known Holocene explosive eruption in Canada. However, it is unknown when this eruption ended.
In 1977, J. A. Westgate of the University of Toronto
University of Toronto
The University of Toronto is a public research university in Toronto, Ontario, Canada, situated on the grounds that surround Queen's Park. It was founded by royal charter in 1827 as King's College, the first institution of higher learning in Upper Canada...
suggested that a smaller eruption may have occurred at the Bridge River Vent after the eruption 2,350 years ago, sending tephra to the southeast. A tephra deposit overlying the Bridge River Ash at Otter Creek shows strong genetic relationships with the Bridge River Ash, differing only by its absence of biotite. In earlier publications, this tephra is classified as part of the Bridge River Ash. However, it has been dated to be about 2,000 radiocarbon years old, indicating that this tephra is a few hundred years younger than the Bridge River Ash. Apparent absence of biotite and occurrence well to the south of the Bridge River Ash likewise favour a separate identity. Large volume, fine grained, debris flows north of the volcano might have been caused by volcanic activity. If this is correct, the knowledge of eruptions at Mount Meager in the past 10,000 years is insufficient.
Recent activity
Between 1970 and 2005, over 20 small earthquakes were recorded at the volcano. The magnitude
Surface wave magnitude
The surface wave magnitude scale is one of the magnitude scales used in seismology to describe the size of an earthquake. It is based on measurements in Rayleigh surface waves that travel primarily along the uppermost layers of the earth...
of these events were generally no higher than 2.0 on the Richter magnitude scale
Richter magnitude scale
The expression Richter magnitude scale refers to a number of ways to assign a single number to quantify the energy contained in an earthquake....
and they originated to less than below the surface. Other volcanoes in the Garibaldi Volcanic Belt with recorded seismicity include 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...
and Silverthrone Caldera. Seismic data suggest that these volcanoes still contain active magma chambers, indicating that some Garibaldi Belt volcanoes are probably active, with significant potential hazards. The seismic activity corresponds with some of Canada's recently formed volcanoes and with persistent volcanoes that have had major explosive activity throughout their history, such as Mount Garibaldi, Mount Cayley and Mount Meager.
Eruptions
Because Mount Meager is capable of producing highly explosive eruptions, it is, overall, a dangerous volcano. Many populated areas throughout southern British Columbia and Alberta are threatened by Mount Meager. PembertonPemberton, British Columbia
Pemberton is a village north of Whistler in the Pemberton Valley of British Columbia in Canada, with a population of 2,192. Until the 1960s the village could be accessed only by train but that changed when Highway 99 was built through Whistler and Pemberton.-Climate:The climate of Pemberton is...
, a community some downstream from Meager, is also significantly threatened by the volcano. Because of these concerns, the Geological Survey of Canada is planning to create hazard map
Hazard map
A hazard map is a map that highlights areas that are affected or vulnerable of a particular hazard. They are typically created for natural hazards, such as earthquakes, volcanoes, landslides, flooding and tsunamis. Hazard maps help prevent serious damage and deaths....
s and emergency plans for Mount Meager, as well as Mount Cayley to the south. If the volcano were to erupt again violently, it would have large-scale effects on the Lillooet River fishery. Another significant eruption would also have massive effects on nearby mining
Mining
Mining is the extraction of valuable minerals or other geological materials from the earth, from an ore body, vein or seam. The term also includes the removal of soil. Materials recovered by mining include base metals, precious metals, iron, uranium, coal, diamonds, limestone, oil shale, rock...
and logging
Logging
Logging is the cutting, skidding, on-site processing, and loading of trees or logs onto trucks.In forestry, the term logging is sometimes used in a narrow sense concerning the logistics of moving wood from the stump to somewhere outside the forest, usually a sawmill or a lumber yard...
activity. In addition, Mount Meager is situated in the immediate proximity of a major air traffic route
Airway
The pulmonary airway comprises those parts of the respiratory system through which air flows, conceptually beginning at the nose and mouth, and terminating in the alveoli...
. Volcanic ash reduces visibility and can cause jet engine failure, as well as damage to other aircraft systems.
Jack Souther
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...
, a leading authority on geothermal resources and volcanism in the Canadian Cordillera, has stated "at present the volcanoes of the Garibaldi Belt are quiet, presumed dead but still not completely cold. But the flare-up of Meager Mountain 2,500 years ago raises the question, "Could it happen again?" Was the explosive eruption of Meager Mountain the last gasp of the Garibaldi Volcanic Belt or only the most recent event in its on-going life? The short answer is nobody really knows for sure. So just in case I sometimes do a quick check of the old hot-spots when I get off the Peak Chair".
Even though very few eruptions in Canada have been witnessed by people, Canada is geologically an area of intense volcanic activity. According to the Geologic Hazards '91 Workshop, "priority should be given to eruption impact studies of the two recently active volcanic centres closest to urban areas, Mount Baker and Mount Meager. The former case will require a combined US-Canada-Washington State-B.C. effort". In addition, Mount Meager is not monitored closely enough by the Geological Survey of Canada to ascertain how active its magma system is. If it were to erupt, relief efforts could be orchestrated. The Interagency Volcanic Event Notification Plan (IVENP) was created to outline the notification procedure of some of the main agencies that would be involved in response to an erupting volcano in Canada, an eruption close to the Canada – United States border or any eruption that will have effects in Canada.
Although Mount Meager is a potentially active volcano, as of 2003 there was no evidence of an imminent eruption. Many shallow earthquakes normally occur before a volcano erupts. As magma rises to the surface, it will probably create much more vigour and heat at the regional hot springs, as well as the formation of new springs or 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. These signs generally occur well in advance of a potential eruption, although the possibility of an eruption occurring in the near future is low.
Landslides
Mount Meager has been the source for many large landslides in the past 8,000 years. These have flowed down the Lillooet River valley to areas that have become populated in the past 100 years and are now experiencing rapid urban growth. For example, the town of Pemberton has doubled in size since 2003. In addition, it has been argued by scientists that Mount Meager is the most unstable mountain massif in Canada. It may also be the most active landslide area in Canada. Because Mount Meager is capable of producing large landslides, Meager Creek valley is probably the most dangerous valley in the Canadian Cordillera. Debris flows, mainly from Mount Meager, have filled the valley to a depth of .Volcano-associated debris flows, known as lahars, are one of the most dangerous hazards associated with volcanoes. They can occur both during an eruption and when a volcano is not erupting. The water that creates lahars can come from melting snow and ice, intense rainfall or the breakout of a summit crater lake
Crater lake
A crater lake is a lake that forms in a volcanic crater or caldera, such as a maar; less commonly and with lower association to the term a lake may form in an impact crater caused by a meteorite. Sometimes lakes which form inside calderas are called caldera lakes, but often this distinction is not...
. Large lahars are a potential hazard to many communities downstream from glaciated volcanoes. In addition, Pemberton is vulnerable to lahars from Mount Meager. Lahars are also a major hazard at Mount Rainier, a younger but heavily glaciated stratovolcano southeast of Seattle
Seattle, Washington
Seattle is the county seat of King County, Washington. With 608,660 residents as of the 2010 Census, Seattle is the largest city in the Northwestern United States. The Seattle metropolitan area of about 3.4 million inhabitants is the 15th largest metropolitan area in the country...
in the central Cascade Volcanic Arc. More than 25 landslides have occurred at Mount Meager in the past 8,000 years.
Prehistoric
| Event | Source | Reference | |
|---|---|---|---|
| Rock avalanche/debris flow | Pylon Peak | 7900 | Friele and Clague (2004) |
| Rock avalanche/debris flow | Job Creek | 6250 | Friele et al. (2005) |
| Rock avalanche/debris flow | Capricorn Creek | 5250 | McNeely and McCuaig (1991) |
| Rock avalanche/debris flow/hyperconcentrated flow | Pylon Peak | 4400 | Friele and Clague (2004); Friele et al. (2005) |
| Rock avalanche/debris flow | Job Creek, eruption precursor | 2600 | Friele et al. (2005); Simpson et al. (2006) |
| Pyroclastic flow | Syn-eruptive | 2400 | Stasiuk et al. (1996); Stewart (2002) |
| Rock avalanche/outburst flood/debris flow/hyperconcentrated flow | Syn-eruptive | 2400 | Stasiuk et al. (1996); Stewart (2002) |
| Rock avalanche | Syn- to post-eruptive | 2400 | Stasiuk et al. (1996); Stewart (2002) |
| Debris flow | Job Creek | 2240 | Pierre, Jakob and Clague (2008) |
| Debris flow | Devastation Creek | 2170 | McNeely and McCuaig (1991) |
| Debris flow | Angel Creek | 1920 | McNeely and McCuaig (1991) |
| Debris flow | Job Creek | 1860 | McNeely and McCuaig (1991) |
| Debris flow | Job Creek | 870 | Jordan (1994) |
| Debris flow | No Good Creek | 800 | McNeely and McCuaig (1991) |
| Debris flow | Job Creek | 630 | Pierre, Jakob and Clague (2008) |
| Debris flow | No Good Creek | 370 | McNeely and McCuaig (1991) |
| Debris flow | Angel Creek | 210 | McNeely and McCuaig (1991) |
Historic
| Event | Source | Reference | |
|---|---|---|---|
| Debris flow | Devastation Creek | 1931 | Carter (1931); Decker et al. (1977); Jordan (1994) |
| Rock avalanche | Capricorn Creek | <100 years | Croft (1983) |
| Rock avalanche | Devastation Creek | 1947 | Read (1978) |
| Debris flow | Capricorn Creek | 1972 | Jordan (1994) |
| Rock avalanche 1975 Devastation Glacier landslide The 1975 Devastation Glacier landslide was a massive rock avalanche that originated from Devastation Glacier on the southern flank of the Mount Meager massif on July 22, 1975. It had a volume of and buried and killed a group of four geologists at the confluence of Devastation Creek and Meager... |
Devastation Creek | 1975 | Mokievsky-Zubot (1977); Evans (2001) |
| Debris flow | Affliction Creek | 1984 | Jordan (1994) |
| Rock avalanche | Mount Meager | 1986 | Evans (1987) |
| Debris flow | Capricorn Creek | 1998 | Bovis and Jakob (2000) |
| Debris flow | Capricorn Creek | 2010 | McKinnon (2010) |
2010 landslide
On August 6, 2010, a massive lahar cascaded down from Capricorn Glacier with a speed of per second. With a volume of , it is the second largest landslide in Canadian history, exceeded by the Hope Slide
Hope Slide
The Hope Slide was the largest landslide ever recorded in Canada. It occurred in the morning hours of January 9, 1965 in the Nicolum Valley near Hope, British Columbia, and killed four people...
, which removed of rock from Johnson Peak. The 2010 landslide at Mount Meager was wide and long, creating a dam across Meager Creek and the Lillooet River. This resulted in the creation of a lake just upstream. Fears of the dam collapsing and flooding the Lillooet River valley ended a day after the landslide when part of the dam ruptured and slowly released water. An evacuation alert was rescinded and nearly 1,500 residents were allowed to return to their homes on the weekend after the landslide occurred. No injuries were reported from this landslide.
See also
- List of volcanoes in Canada
- List of Cascade volcanoes
- 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...