View source for Volcanic history of the Northern Cordilleran Volcanic Province

{{Short description|Geologic region in British Columbia and Yukon, Canada}}
[[File:NCVP map.png|thumb|right|250px|alt=Map of the Northern Cordilleran Volcanic Province and location of nearby fault zones. The volcanoes fall into the region between the two faults.|Minor and major volcanoes of the Northern Cordilleran Volcanic Province, including the [[Queen Charlotte Fault|Queen Charlotte]], [[Denali Fault|Denali]] and [[Tintina Fault|Tintina]] fault zones]]
The '''volcanic history of the Northern Cordilleran Volcanic Province''' presents a record of volcanic activity in northwestern [[British Columbia]], central [[Yukon]] and the [[U.S. state]] of easternmost [[Alaska]]. The volcanic activity lies in the northern part of the [[Western Cordillera (North America)|Western Cordillera]] of the [[Pacific Northwest]] region of [[North America]]. [[Rift|Extensional cracking]] of the [[North American Plate]] in this part of North America has existed for millions of years. Continuation of this continental rifting has fed scores of [[volcano]]es throughout the [[Northern Cordilleran Volcanic Province]] over at least the past 20&nbsp;million years (see [[Geology of the Pacific Northwest]]) and occasionally continued into geologically recent times.<ref name="SI">{{cite web|title=Stikine volcanic belt |work=Catalogue of Canadian volcanoes |publisher=[[Geological Survey of Canada]] |date=2008-02-13 |url=http://gsc.nrcan.gc.ca/volcanoes/cat/belt_stikine_e.php |access-date=2009-12-20 |url-status=dead |archive-url=https://web.archive.org/web/20080615214726/http://gsc.nrcan.gc.ca/volcanoes/cat/belt_stikine_e.php |archive-date=2008-06-15 }}</ref>
Eruptive activity in the Northern Cordilleran Volcanic Province throughout its 20&nbsp;million year history has been mainly the production of [[alkaline]] [[lava]]s, including alkaline [[basalt]]s. A range of alkaline rock types not commonly found in the Western Cordillera are regionally widespread in the Northern Cordilleran Volcanic Province. These include [[nephelinite]], [[basanite]] and [[peralkaline]] [[phonolite]], [[trachyte]] and [[comendite]] lavas.<ref name="CH">{{cite web|author=Edwards, Benjamin R.|author2=Russell, James K. |title=Distribution, nature, and origin of Neogene-Quaternary magmatism in the northern Cordilleran volcanic province, Canada|publisher=[[Geological Society of America Bulletin]]|pages=1280, 1281, 1282, 1284|date=August 2000|url=http://www.eos.ubc.ca/~krussell/epapers/GSAB_ER2000.pdf|access-date=2009-10-02}}</ref> The trachyte and comendite lavas are understood to have been created by fractionation of mainly alkali basalt magma in crustal reservoirs. An area of continental rifting, such as the Northern Cordilleran Volcanic Province, would aid the formation of high-level reservoirs of capable size and thermal activity to maintain long-lived fractionation.<ref name="JK">{{cite book|last=Wood|first=Charles A.|author2=Kienle, Jürgen | pages=109, 114, 121, 123, 125, 126, 129|title=Volcanoes of North America: United States and Canada|year=1990|publisher=[[Cambridge University Press]]|location=[[Cambridge]], [[England]]|isbn=0-521-43811-X}}</ref>
In the past 15&nbsp;million years, at least four large volcanoes have formed their way through dense [[igneous rock|igneous]] and [[metamorphic rock|metamorphic]] composed [[bedrock]] of this part of North America. This includes [[Hoodoo Mountain]], the [[Mount Edziza volcanic complex]], [[Level Mountain]] and [[Heart Peaks]], which are primarily located in northwestern British Columbia. Most notable of these is the 7.5&nbsp;million year old Mount Edziza volcanic complex, which has had more than 20 eruptions in the past 10,000&nbsp;years. The only activity present in the Northern Cordilleran Volcanic Province has been occasional [[earthquake]]s and constant boiling of [[hot spring]]s. However, a high potential exists for renewed eruptive activity that could threaten life and property in the volcanic zone.<ref name="SI"/>
==Production and rates in volcanism==
More than 100&nbsp;eruptions have occurred in the past 20&nbsp;million years with a broad range of eruptive styles.<ref name="CH"/> These volcanic processes have created a range of different volcanic landforms, including [[stratovolcano]]es,<ref>{{cite web|title=Mount Edziza|work=Catalogue of Canadian volcanoes|publisher=[[Geological Survey of Canada]]|date=2009-03-10|url=http://gsc.nrcan.gc.ca/volcanoes/cat/volcano_e.php?id=svb_mez_081|access-date=2009-01-22|archive-url=https://web.archive.org/web/20090607071853/http://gsc.nrcan.gc.ca/volcanoes/cat/volcano_e.php?id=svb_mez_081|archive-date=2009-06-07|url-status=dead}}</ref> [[shield volcano]]es,<ref>{{cite web|title=Heart Peak |work=Catalogue of Canadian volcanoes |publisher=[[Geological Survey of Canada]] |date=2009-03-10 |url=http://gsc.nrcan.gc.ca/volcanoes/cat/volcano_e.php?id=svb_hpk_025 |access-date=2009-01-22 |url-status=dead |archive-url=https://web.archive.org/web/20101211081526/http://gsc.nrcan.gc.ca/volcanoes/cat/volcano_e.php?id=svb_hpk_025 |archive-date=2010-12-11 }}</ref> [[lava dome]]s<ref>{{cite web|title=Cartoona Ridge|work=Catalogue of Canadian volcanoes|publisher=[[Geological Survey of Canada]]|date=2009-03-10|url=http://gsc.nrcan.gc.ca/volcanoes/cat/volcano_e.php?id=svb_ctr_138|access-date=2009-01-22|archive-url=https://web.archive.org/web/20071112095652/http://gsc.nrcan.gc.ca/volcanoes/cat/volcano_e.php?id=svb_ctr_138|archive-date=2007-11-12|url-status=dead}}</ref> and cinder cones,<ref name="VI"/> along with a few isolated examples of rarer volcanic forms such as [[tuya]]s.<ref>{{cite web|title=Tuya Butte|work=Catalogue of Canadian volcanoes|publisher=[[Geological Survey of Canada]]|date=2009-03-10|url=http://gsc.nrcan.gc.ca/volcanoes/cat/volcano_e.php?id=svb_tbu_111|access-date=2009-01-22|archive-url=https://web.archive.org/web/20101212053819/http://gsc.nrcan.gc.ca/volcanoes/cat/volcano_e.php?id=svb_tbu_111|archive-date=2010-12-12|url-status=dead}}</ref> Large persistent volcanoes of the Northern Cordilleran Volcanic Province can remain dormant for hundreds or thousands of years between eruptions and therefore the greatest risk caused by volcanic activity is not always readily apparent. Volcanics older than 14&nbsp;million years are mainly found in the northern portion of the volcanic province while volcanics ranging from nine to four million years old exist only in the middle of the volcanic province.<ref name="CH"/> At least three types of volcanic zones are present in the Northern Cordilleran Volcanic Province, including large persistent [[lava plateau]]s like those found at the Mount Edziza volcanic complex, [[polygenetic volcanic field|polygenetic volcanoes]] such as Hoodoo Mountain and [[monogenetic volcanic field|monogenetic volcanoes]] like the basaltic cinder cones found throughout the volcanic province.<ref name="CH"/> When Northern Cordilleran volcanoes do erupt, [[pyroclastic flow]]s, lava flows and [[landslide]]s can devastate areas {{convert|10|km|mi|abbr=on}} away and [[mudflow]]s of [[volcanic ash]] and [[debris]] can inundate valleys {{convert|10|km|mi|abbr=on}} downstream. Falling ash from [[explosive eruption]]s can disrupt human activities hundreds of kilometres downwind, and drifting clouds of fine volcanic ash can cause severe damage to [[jet aircraft]] even hundreds of kilometres away. Volcanic deposits in the Northern Cordilleran Volcanic Province include lava flows, welded and unwelded pyroclastic deposits, hydroclastic deposits and other ice-contact volcanic deposits.<ref name="CH"/> The variety of different volcanic deposits is partly due to changes in eruption characteristics from mainly [[subaerial eruption]]s to broadly [[subglacial eruption]]s throughout the history of the Northern Cordilleran Volcanic Province.<ref name="CH"/>
[[File:Lava fountain at Kilauea.jpg|thumb|left|alt=A jet of fluid lava spraying into the air on an island. Smoke rises behind it.|Lava fountains like those associated with [[Kīlauea]] in Hawaii are a common eruption style in the Northern Cordilleran Volcanic Province.]]
There is evidence of a decline in volcanic activity over the past few million years. This decline in volcanic activity can be grouped into two phases. From eight to four million years ago, volcanism rates were higher than they are at present.<ref name="CK">{{cite journal |journal=Geology|volume=27|issue=3|pages=243–246|doi=10.1130/0091-7613(1999)027<0243:NCVPAN>2.3.CO;2|url=http://geology.geoscienceworld.org/cgi/content/abstract/27/3/243|title=Northern Cordilleran volcanic province: A northern Basin and Range?|last1=Edwards |first1=Benjamin R.|last2=Russell|first2=James K.|date=March 1999|publisher=[[Geological Society of America]]|access-date=2009-11-16|bibcode = 1999Geo....27..243E }}</ref> Magma production during this volcanic phase was most active from seven to five million years ago and was related to a period of rifting along the Pacific and North American Plate boundary.<ref name="CK"/> Between four and three million years ago in the Pliocene epoch, a pause in volcanic activity began to happen.<ref name="CH"/> The most recent magmatic phase ranging from two million years ago to present resulted from nearby areas of rifting during a period of compression between the Pacific and North American plates.<ref name="CK"/> Volcanism rates during this volcanic phase was most active from two to one million years ago with the construction of 25&nbsp;volcanic zones then decreased one million years ago with the construction of 11&nbsp;volcanic zones.<ref name="CH"/> To date, the most recent volcanic phase has produced {{convert|100|km3|mi3|abbr=on}} of volcanic material whereas the first phase produced {{convert|250|km3|mi3|abbr=on}} of volcanic material.<ref name="CK"/> Even though the rate in volcanism throughout the Northern Cordilleran Volcanic Province has changed considerably, there is no correlation between the rate in magma production and the number of active volcanoes during any interval of time.<ref name="CH"/> The present day volcanism rate for the Northern Cordilleran Volcanic Province is considerably lower than the [[Cascade Volcanoes|Cascade Volcanic Arc]] and [[Hawaii (island)|Hawaiian]] volcanism rates.<ref name="CH"/> However, geologists are aware the temporal volcanic patterns known for the Northern Cordilleran Volcanic Province should be looked at carefully because volcanics that pre-date the [[last glacial period]] have been eroded by glacial ice and many of the volcanics have not been directly dated or have not been dated in significant detail to identify more individual temporal patterns.<ref name="CH"/> [[Lava fountain]]s can occur in the Northern Cordilleran Volcanic Province roughly every 100&nbsp;years.<ref name="HEPO"/>
[[File:Level Mountain Range.png|thumb|right|250px|alt=A massive open volcano situated on a plateau consisting of a series of buttes and ridges.|Level Mountain, the largest volcano of the Northern Cordilleran Volcanic Province. The large brown area in the middle is a dissected stratovolcano and the surrounding light brown is the broad shield volcano comprising a lava plateau.]]
Large basaltic shield volcanoes throughout the central Northern Cordilleran Volcanic Province form large lava plateaus and are the largest volcanoes of the volcanic zone.<ref name="CH"/> These extensive volcanoes are generally larger and more long-lived than volcanoes of adjacent volcanic zones, including the stratovolcanoes of the Cascade and Aleutian arcs. [[Mount Shasta]], the largest stratovolcano in the Cascade Arc and [[Mount Veniaminof]], one of the largest and most active volcanoes in the Aleutian Arc, have volumes of at least {{convert|350|km3|mi3|abbr=on}}, less than half of that of the Level Mountain and Edziza shield complexes.<ref>{{cite web|publisher=[[United States Geological Survey]]|url=http://vulcan.wr.usgs.gov/Volcanoes/Shasta/description_shasta.html|title=Mount Shasta and Vicinity, California|date=2007-10-26|access-date=2009-10-02}}</ref><ref>{{cite journal|title=History and Eruptive Style of Mount Veniaminof, a Huge Alaskan Basalt-to-Dacite Volcano With Pleistocene and Holocene Caldera-Forming Eruptions|last1=C.R.|first1=Bacon|last2=Calvert|first2=Calvert|last3=Nye|first3=Nye|last4=Sisson|first4=Sisson|date=December 2003|bibcode=2003AGUFM.V32D1048B|volume=32|pages=1048|journal=American Geophysical Union, Fall Meeting}}</ref> The massive Level Mountain shield, occupying an area of {{convert|1800|km2|mi2|abbr=on}} and a volume of more than {{convert|860|km3|mi3|abbr=on}}, is the most voluminous and most long-lived volcano of the Northern Cordilleran Volcanic Province.<ref name="ZKQ">{{cite gvp|vn=320050|title=Level Mountain|access-date=2009-03-30}}</ref> Further south, the Mount Edziza volcanic complex resides as the seconed most voluminous volcano with an area of {{convert|1000|km2|mi2|abbr=on}} and a volume of {{convert|670|km3|mi3|abbr=on}}.<ref name="CH"/> Just west of Level Mountain lies Heart Peaks, the third most voluminous volcano of the Northern Cordilleran Volcanic Province with an area of {{convert|275|km2|mi2|abbr=on}}.<ref name="CH"/> However, remains of a shield volcano that once covered an area of more than {{convert|900|km2|mi2|abbr=on}} are present in the western [[Cassiar Mountains]] as [[Maitland Volcano]].<ref name="CH"/><ref name="JK"/>
All of the known most recent eruptions have occurred in British Columbia, although there is evidence for volcanic activity in Yukon in the past thousand years.<ref name="CR"/> The two most recent were lava flow eruptions at [[Tseax Cone]] in the 18th century and at [[The Volcano (British Columbia)|The Volcano]] in 1904. Reports of an eruption {{convert|80|km|mi|abbr=on}} south of [[Gladys Lake]] in northern British Columbia were made by placer miners at the end of the 19th century, but no evidence for this eruption has been found, leading researchers to speculate the eruption as uncertain.<ref name="HK">{{cite gvp|vn=320030|title=Atlin Volcanic Field|access-date=2009-10-02}}</ref>
==Volcanic activity begins==
[[File:Level Mountain valley.jpg|thumb|left|250px|alt=Landscape of a mountain range.|Level Mountain with extensive elevated plateau in the foreground]]
The first volcanic activity in the Northern Cordilleran Volcanic Province 20&nbsp;million years ago was infrequent, creating small amounts of volcanic material.<ref name="CH"/> This infrequent volcanic activity was interrupted when considerable volcanism began to form the large Level Mountain shield volcano 15&nbsp;million years ago.<ref name="CH"/> The {{convert|1800|km2|mi2|abbr=on}} shield volcano forms a broad cliff-bounded lava plateau {{convert|70|km|mi|abbr=on}} long and {{convert|45|km|mi|abbr=on}} wide, with an average thickness of {{convert|750|m|ft|abbr=on}}.<ref name="JK"/> Ropy [[pāhoehoe]] lava flows predominate over blocky [[ʻaʻā]] lava flows, breccias and tuffs, attesting to a fluid and effusive character for the volcanism.<ref name="JK"/>
When the Mount Edziza volcanic complex began to form 7.5&nbsp;million years ago, volcanism rates in the Northern Cordilleran Volcanic Province increased again.<ref name="CH"/> Early volcanic activity of the Mount Edziza volcanic complex seven million years ago constructed [[Armadillo Peak]], the oldest and most central of the four central volcanoes comprising the complex.<ref name="JK"/> Its {{convert|2194|m|abbr=on}} summit is capped by {{convert|180|m|abbr=on}} thick fine-grained silica-rich trachyte lava flows that ponded inside the [[caldera]] to produce a [[lava lake]] six million years ago during its final stage of activity.<ref name="JK"/> A massive stratovolcano was also formed on top of the Level Mountain shield volcano 7.1&nbsp;to 5.3&nbsp;million years ago during this increased period of volcanism when viscous peralkaline trachyte and comendite lavas were erupted.<ref name="JK"/> The stratovolcano has a volume of {{convert|860|km3|mi3|abbr=on}} and comprises several volcanic vents, some of which were formally more than {{convert|2500|m|ft|abbr=on}} in elevation.<ref name="JK"/><ref name="ZKQ"/> Glacial ice and streams have since dissected the stratovolcano into a series of valleys with intervening ridges, forming the so-named Level Mountain Range on the central summit of Level Mountain.<ref name="JK"/>
More Miocene age volcanics of {{nowrap|27.5 ± 4.3}} and {{nowrap|16.2 ± 2 million}} years are present at the [[Anderson Bay|Anderson]] and [[Moose Bay (British Columbia)|Moose]] bays of [[Atlin Lake]] in northern British Columbia that represent remnants of columnar-jointed basalt lava flows.<ref name="XL">{{cite web|author=B.R. Edwards |author2=J.K. Russell |author3=R.G. Anderson |author4=M. Harder|title=Overview of Neogene to Recent volcanism in the Atlin volcanic district, Northern Cordilleran volcanic province, northwestern British Columbia|publisher=[[Geological Survey of Canada]]|year=2003|url=http://dsp-psd.pwgsc.gc.ca/Collection/GSC-CGC/M44-2003/Articles/a08.pdf|access-date=2009-10-02}}</ref> This indicates these volcanics are older than the Edziza and Level Mountain shields and they might represent the oldest volcanic events in the Northern Cordilleran Volcanic Province.<ref name="XL"/> However, their distinctive chemical characteristics and apparent large age differences compared to other volcanics in the Atlin area could also indicate that these columnar-jointed basalt lava flows are not part of the Northern Cordilleran Volcanic Province assemblage.<ref name="XL"/> In northern Yukon, similar aged volcanics can be found, including {{nowrap|19.9 ± 0.5}} million year old volcanics at [[Forty Mile, Yukon|Forty Mile]] and {{nowrap|17.2 ± 0.3}} million year old volcanics at Sixty Mile.<ref name="CH"/> However, the type of volcanic landforms these volcanics represent are unknown.<ref name="CH"/>
==Volcanism 5.3 to 1.6 million years ago==
In northern British Columbia, remnants of a shield volcano are found throughout the western Cassiar Mountains.<ref name="JK"/> This prehistoric shield volcano, known as [[Maitland Volcano]], was erupted from five to four million years ago on a mature eroded surface as thin hawaiite and basaltic lava flows engulfed the surrounding landscape.<ref name="JK"/> Remnants of this prehistoric shield volcano include a cluster of 14&nbsp;volcanic plugs and scattered cliff-bounded basaltic lava flows.<ref name="JK"/>
At the southern end of the Mount Edziza volcanic complex, volcanism constructed the [[Spectrum Range]] three to 2.5&nbsp;million years ago.<ref name="JK"/> Named for its extensive colouration, this nearly circular lava dome is up to {{convert|650|m|ft|abbr=on}} thick and more than {{convert|10|km|mi|abbr=on}} wide with a basaltic shield volcano forming its broad base.<ref name="JK"/><ref>{{cite gvp|vn=320070|title=Spectrum Range|access-date=2009-03-30}}</ref> Since its formation, the Spectrum Range lava dome has been deeply cut by erosion, forming an extensive valley system. This valley system exposes large comendite and trachyte lava flows of the dome, including faults of a hidden {{convert|4.5|km|mi|abbr=on}} wide caldera.<ref name="JK"/>
A series of lava domes were constructed in the Level Mountain Range alpine valley system 4.5&nbsp;to 2.5&nbsp;million years ago.<ref name="JK"/> These domes intrude the glacially eroded core of the {{convert|860|km3|mi3|abbr=on}} stratovolcano and headward erosion has further modified the Level Mountain shield by incising youthful V-shaped stream canyons into the lava plateau margin.<ref name="JK"/>
==Volcanism 1.6 million to 10,000 years ago==
Throughout the [[Pleistocene]] epoch 1.6&nbsp;million to 10,000&nbsp;years ago, volcanism in the Northern Cordilleran Volcanic Province was broadly associated with glacial ice and ice sheets during glacial periods, including the large [[Cordilleran Ice Sheet]]. This volcano-ice association can be recognized in three different physiographic settings, each displaying unique relationships between topography, volcanism and glacial ice.<ref name="ZI">{{cite web |last=Edwards |first=B. |author2=Osborn J. |author3=Russell J.K. |author4=Skilling I.P. |author5=Evenchick C. |author6=Spooner I. |author7=Simpson K. |author8=Cameron B. |title=Physiographic Controls on Glaciovolcanism and the Cordilleran Ice Sheet in the northern Cordilleran volcanic province, western Canada |url=http://volcanoes.dickinson.edu/VIWG/meetings/abstracts/edwards1.doc |access-date=2009-10-02 }}{{Dead link|date=November 2018 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> The first volcano-ice interaction is displayed as tuyas, including [[Tuya Butte]], on the [[Tanzilla Plateau]] in the [[British Columbia Interior|Northern Interior of British Columbia]].<ref name="ZI"/> This sub-section of the [[Stikine Plateau]] consists of large flatlands with hills of low relief, and might have been one of the areas of ice accumulation for the Cordilleran Ice Sheet.<ref name="ZI"/> Tanzilla Plateau volcanism throughout the Pleistocene epoch was basaltic [[subglacial eruption]]s.<ref name="ZI"/> The most generally known [[subglacial volcano]]es are distinctive tuyas, which commonly reach more than {{convert|100|m|ft|abbr=on}} in elevation.<ref name="ZI"/> Other volcanic forms also exist, some of which are basic and others that are probably the products of weathering.<ref name="ZI"/> The subdued relief on the Tanzilla Plateau strongly influenced edifice morphologies, favoring broad-based tuyas.<ref name="ZI"/> The hydrological conditions in these areas likely were controlled by relatively uniform ice thickness and gentle topography.<ref name="ZI"/>
The seconed type of volcano-ice interaction is located only to the east, south and southwest of the Tanzilla Plateau, in the Cassiar Mountains, [[Skeena Mountains]] and in the Boundary Ranges.<ref name="ZI"/> Volcanic activity in these locations is also largely mafic in composition, but the extensive elevations of these areas had a much more impressive influence on glaciation and subglacial volcanism.<ref name="ZI"/> High altitude glaciation took over when the Cordilleran Ice Sheet was not present and even when buried by the Cordilleran Ice Sheet, basal ice movement was strongly influenced by the deep, pre-glacial drainages.<ref name="ZI"/> Accordingly, the erosional remnants of subglacial volcanoes are minor and intermittent.<ref name="ZI"/> In the Skeena Mountains, separated outcrops of pillow lava and volcanic breccia are generally found side by side on the summits of sharp rugged mountain ridges, with presumably temporally-associated pyroclastic rocks having collected downslope.<ref name="ZI"/>
[[File:Hoodoo Mountain.jpg|thumb|left|250px|alt=A snow-covered mountain with a jagged flattish top|Hoodoo Mountain in the Boundary Ranges of the Coast Mountains, whose flat-topped summit likely originated from frequent interactions between volcanic activity and ice of the Cordilleran Ice Sheet]]
The third type of volcano-ice interaction is geographically restricted to three volcanoes, including Level Mountain, the Mount Edziza volcanic complex and Hoodoo Mountain.<ref name="ZI"/> All three volcanoes are broad enough to hold ice caps that likely altered regional ice flow while still being altered by the Cordilleran Ice Sheet at individual periods.<ref name="ZI"/> The Mount Edziza and Level Mountain complexes have shelves of older lava with elevations more than {{convert|1|km|mi|abbr=on}} and have been zones of volcanic activity long enough that their geothermal activities might have had effects on movements of the Cordilleran Ice Sheet much like the [[Grímsvötn]] caldera in Iceland, which has been a significant heat source beneath the vast [[Vatnajökull]] icecap.<ref name="ZI"/> At the Edziza complex, most of the subglacial products were formed on top of the main lava plateau, which now rises at least {{convert|1000|m|ft|abbr=on}} in elevation above adjacent stream valleys.<ref name="ZI"/> The Edziza complex consists of a collection of mafic subglacial products, but more unusually, including Hoodoo Mountain and Level Mountain, comprises some of the largest deposits of peralkaline felsic subglacial volcanics known.<ref name="ZI"/> At the Edziza and Level Mountain complexes, glacier hydrology of the Cordilleran Ice Sheet was possibly dominated by a complicated interaction between drainage on the flat plateaus under relatively thinner ice and drainage within nearby steep valleys filled with much thicker ice.<ref name="ZI"/>
[[File:Heart Peaks and Level Mountain.jpg|thumb|right|250px|alt=Landscape of a flat plain with two groups of mountains.|Heart Peaks in the upper-left corner and the central and largest, is the treeless plateau of the Level Mountain shield volcano whose stratovolcano and domes are etched out by a light snowfall. Intermontane lowland lakes are shown as irregular dark blue patches.]]
Just northwest of Level Mountain, the [[Heart Peaks]] shield volcano rises with a [[topographic prominence]] of {{convert|1025|m|ft|abbr=on}} above the [[Nahlin Plateau]] with rhyolitic lava domes capping its summit. Heart Peaks is made of flat-lying basaltic and trachybasaltic lava flows and pyroclastic rocks.<ref name="XK">{{cite gvp|vn=320040|title=Heart Peaks|access-date=2009-03-30}}</ref> The most recent eruption at the shield is of dominantly Pleistocene age and late-stage Holocene activity is uncertain.<ref name="XK"/>
On the divide between the head of the [[Omineca River|Omineca]] and [[Bear River (Sustut River)|Bear]] rivers, [[The Thumb (Omineca)|The Thumb]] rises with a [[topographic prominence]] of {{convert|180|m|ft|abbr=on}} above gently sloping benchland near the crest of the [[Connelly Range]].<ref name="JK"/> It is the largest among a cluster of seven steep-sided volcanic plugs associated with dikes, lava flows and remnants of cinder cones.<ref name="JK"/>
[[Ne Ch'e Ddhawa]], an extinct volcano in the Fort Selkirk Volcanic Field of central Yukon, reaches a height of {{convert|300|m|ft|abbr=on}} near the junction of the [[Pelly River|Pelly]] and [[Yukon River|Yukon]] rivers.<ref name="ZP"/> It was erupted subglacially under the Cordilleran Ice Sheet between 0.8 and one million years ago, depositing [[hyaloclastite]] [[tuff]]s, breccias and pillow breccias that now form the volcano.<ref name="CR"/><ref name="ZP">{{cite web|title=Northern Landscapes|publisher=IPY GeoNorth 2007|date=2007-04-25|url=http://ess-sst.nrcan-rncan.gc.ca/ipygeonorth/land_e.php|access-date=2009-10-02}} {{Dead link|date=October 2010|bot=H3llBot}}</ref>
In the Boundary Ranges of northwestern British Columbia, Hoodoo Mountain began its formation at least 100,000&nbsp;years ago mostly under glacial ice of the Cordilleran Ice Sheet.<ref name="ZIO">{{cite gvp|vn=320080|title=Hoodoo Mountain|access-date=2009-10-23}}</ref> More than 90% of Hoodoo Mountain was formed during this eruptive period and interlayed peralkaline phonolitic and trachytic lava flows and hyaloclastites are the main volcanics comprising the volcano.<ref name="ZIO"/> On the northern flank of Hoodoo Mountain lies the smaller [[Little Bear Mountain]], a tuya which also formed in the Pleistocene epoch.<ref name="ZIO"/>
[[Ice Peak]], which overlaps the northern flank of Armadillo Peak, began to form when the regional Cordilleran Ice Sheet began retreating from the Mount Edziza volcanic complex 1,600,000&nbsp;years ago.<ref name="JK"/> It is a stratovolcano that was constructed when large areas of the Edziza lava plateau were free from glacial ice, but additional parts of the Mount Edziza volcanic complex were likely still covered by glacial ice. Volcanic activity at Ice Peak during this period produced lava flows and pyroclastic rocks, which mixed with [[meltwater]] to produce [[debris flow]]s. As Ice Peak began to form, basic lava spread to the flanks of Ice Peak where it formed meltwater lakes and combines with and forms part of the adjacent shield volcano. [[Mount Edziza]], a steep-sided stratovolcano overlapping the northern flank of Ice Peak and the most northerly of the four central volcanoes comprising the Mount Edziza volcanic complex, began to form a million years ago when the Cordilleran Ice Sheet retreated from the upper flanks of the Edziza lava plateau. Its smooth northern and western flanks are only slightly channeled by erosion and they curve up to a circular {{convert|2700|m|ft|abbr=on}} summit ridge which surrounds a central ice-filled caldera {{convert|2|km|mi|abbr=on}} in diameter.<ref name="JK"/> Active [[cirque]]s on Edziza's eastern flank have breached the caldera rim, exposing the remnants of several lava lakes that ponded in the caldera 900,000&nbsp;years ago.<ref name="JK"/> As well, subglacial eruptions around the flanks of Mount Edziza and Ice Peak constructed piles of pillow lava and hyaloclastite.<ref name="JK"/>
Prindle Volcano, the northernmost volcano of the Northern Cordilleran Volcanic Province and one of the most isolated volcanoes in Alaska, was formed on the Yukon-Tanana upland during the Pleistocene epoch. It is a small cinder cone made of basanite with a {{convert|90|m|ft|abbr=on}} deep breached volcanic crater at its summit.<ref name="JK"/> Extending from Prindle's breached volcanic crater is a {{convert|11.2|km|mi|abbr=on}} long basanite lava flow that flowed southeast of the cone then flowed southwest into a river valley.<ref name="JK"/>
The Cassiar Mountains and Tanzilla Plateau in northern British Columbia are dominated by tuyas of the broad [[Tuya Volcanic Field]]. These flat-topped, steep-sided subglacial volcanoes were formed when magma intruded into and melted a vertical pipe in the overlying Cordilleran Ice Sheet. At least six volcanoes formed beneath glacial ice close to [[Tuya Lake]], including [[Ash Mountain (British Columbia)|Ash Mountain]], [[South Tuya]], [[Tuya Butte]], [[Mathews Tuya]].<ref name="AJ">{{cite web|last=Edwards|first=Ben|title=South Tuya, Canada|work=VolcanoWorld|date=November 2000|url=http://volcano.oregonstate.edu/vwdocs/volc_images/north_america/canada/Final-STuya.html|access-date=2009-10-02|archive-url=https://web.archive.org/web/20100216131737/http://volcano.oregonstate.edu/vwdocs/volc_images/north_america/canada/Final-STuya.html|archive-date=2010-02-16|url-status=dead}}</ref> Ash Mountain at the head of [[Parallel Creek]] consists of pillow lava and hyaloclastite, South Tuya consists of loose volcanic debris with basaltic dikes intruding into the volcano and Tuya Butte and Mathews Tuya consist of pillow lava and hyaloclastite on its lower flanks with subaerially erupted lava flows at their flat-topped summits.<ref name="AJ"/><ref>{{cite web|last=Edwards|first=Ben|author2=Andy McCarthy|title=Ash Mountain, Canada|work=VolcanoWorld|date=November 2000|url=http://volcano.oregonstate.edu/vwdocs/volc_images/north_america/canada/Final-Ash.html|access-date=2009-10-02|archive-url=https://web.archive.org/web/20100216122620/http://volcano.oregonstate.edu/vwdocs/volc_images/north_america/canada/Final-Ash.html|archive-date=2010-02-16|url-status=dead}}</ref><ref>{{cite web|last=Edwards|first=Ben|title=Tuya Butte, Canada|work=VolcanoWorld|date=November 2000|url=http://volcano.oregonstate.edu/vwdocs/volc_images/north_america/canada/Final-TuyaButte.html|access-date=2009-10-02|archive-url=https://web.archive.org/web/20100216131742/http://volcano.oregonstate.edu/vwdocs/volc_images/north_america/canada/Final-TuyaButte.html|archive-date=2010-02-16|url-status=dead}}</ref><ref>{{cite web|last=Edwards|first=Ben|title=Mathew's Tuya, Canada|work=VolcanoWorld|date=November 2000|url=http://volcano.oregonstate.edu/vwdocs/volc_images/north_america/canada/Final-MathewsTuya.html|access-date=2009-10-02|archive-url=https://web.archive.org/web/20100216131731/http://volcano.oregonstate.edu/vwdocs/volc_images/north_america/canada/Final-MathewsTuya.html|archive-date=2010-02-16|url-status=dead}}</ref>
==Volcanism in the past 10,000 years==
Numerous eruptions have occurred since the beginning of the [[Holocene]] epoch 10,000&nbsp;years ago, when the vast Cordilleran Ice Sheet retreated rapidly at the end of the [[last glacial period]]. The majority of volcanic eruptions throughout the Holocene have occurred in British Columbia while fewer Holocene eruptions have occurred in Yukon.
In the early Holocene epoch, volcanism at Hoodoo Mountain produced lava flows with well-preserved [[lava channel]]s on its northwestern and southwestern flanks and are largely unglaciated, suggesting the last eruptive activity at Hoodoo Mountain occurred in an ice-free environment.<ref name="ZIO"/><ref name="PP">{{cite web|url=http://www.eos.ubc.ca/~krussell/epapers/ER_GSL_2002.pdf|title=Glacial influence on morphology and eruptive products of Hoodoo Mountain volcano, Canada|author=B. R. Edwards and J. K. Russell|work=Analysis of influence by glaciers on Hoodoo Mountain|publisher=The University of British Columbia EOS-Earth and Ocean Sciences|page=181|access-date=2009-04-15}}</ref><ref name="AAB">{{cite web|last=Edwards |first=Ben |title=Hoodoo Mountain, NW British Columbia, Canada |work=VolcanoWorld |date=November 2000 |url=http://volcano.oregonstate.edu/vwdocs/volc_images/north_america/canada/Final-Hoodoo.html |access-date=2009-04-02 |url-status=dead |archive-url=https://web.archive.org/web/20090411062636/http://volcano.oregonstate.edu/vwdocs/volc_images/north_america/canada/Final-Hoodoo.html |archive-date=2009-04-11 }}</ref> These lava flows originated from the mountain's flat-topped summit and volcanic vents on its flanks. Geologists do not always agree on the dates of these more recent eruptions, some dating them to nice thousand years ago, others to as recently as seven thousand years ago.<ref name="ZIO"/><ref name="AAB"/>
[[File:Blue River lava flow, British Columbia.jpg|thumb|right|250px|alt=A valley filled with rugged rock in a mountainous area.|Recently erupted pahoehoe lava flow in the Iskut-Unuk River Cones volcanic field]]
At the southern end of the Northern Cordilleran Volcanic Province near the border between British Columbia and the [[Alaska Panhandle]], lava flows and eight small volcanoes form a volcanic field known as the [[Iskut-Unuk River Cones]].<ref name="CI">{{cite gvp|vn=320090|title=Iskut-Unuk River Cones|access-date=2009-03-30}}</ref> Lava flows date back 70,000 years ago during the Pleistocene epoch, but the eight volcanoes were likely formed between nine thousand and a few hundred years ago.<ref name="CI"/> At least five volcanoes sent lava {{convert|20|km|mi|abbr=on}} down the Iskut and Unuk River valleys and their tributaries.<ref name="CI"/> The other three volcanoes were formed when glacial ice existed adjacent to the associated volcanic vents, creating scoria, pillow lava and hyaloclastite breccia.<ref name="CI"/> Volcanism in the Iskut River area has created at least ten lava flows and Lava Fork at least three.<ref name="CI"/> The most recent eruption of the Iskut-Unuk River Cones at The Volcano (also called Lava Fork volcano) in 1904 is also the most recent volcanic eruption in Canada.<ref>{{cite web|publisher=BC Parks |url=http://www.env.gov.bc.ca/bcparks/explore/parkpgs/lava_forks/|title=Lava Forks Provincial Park |access-date=2009-10-02}}</ref>
Immediately north of the junction of the Pelly and Yukon rivers, [[Volcano Mountain]] in central Yukon consists of a cinder cone and a series of lava flows.<ref name="KW">{{cite web|title=Stikine volcanic belt: Volcano Mountain |work=Catalogue of Canadian volcanoes |publisher=[[Geological Survey of Canada]] |date=2009-04-01 |url=http://gsc.nrcan.gc.ca/volcanoes/cat/feature_volcano_e.php |access-date=2009-10-31 |url-status=dead |archive-url=https://web.archive.org/web/20090307140121/http://gsc.nrcan.gc.ca/volcanoes/cat/feature_volcano_e.php |archive-date=2009-03-07 }}</ref> It is the youngest volcano in the Fort Selkirk Volcanic Field and lava flows originated from fractures in the volcano's flank.<ref name="KW"/> These lava flows extend northeast and southwest of the volcano.<ref name="KW"/> The northeastern lava flow extends {{convert|5.5|km|mi|abbr=on}} from Volcano Mountain whereas the southwestern lava flow extends {{convert|3|km|mi|abbr=on}} from the volcano.<ref name="KW"/> These lava flows are composed of olivine nephelinite, a type of lava not commonly found on Earth.<ref name="KW"/> Nephelinite lavas are usually interpreted to have originated much deeper in the Earth's mantle unlike the typical basaltic lava found throughout the Northern Cordilleran Volcanic Province.<ref name="KW"/> The nephelinite lava flows at Volcano Mountain remain clear from vegetation and seem to be only a few hundred years old.<ref name="CR">{{cite gvp|vn=320010|title=Fort Selkirk|access-date=2009-03-30}}</ref> However, dating of sediments in a lake dammed by the nephelinite lavas suggest the lava flows could not be younger than mid-Holocene and could be early Holocene or older.<ref name="CR"/> Therefore, the exact age for the most recent eruptions at Volcano Mountain are unknown.<ref name="CR"/>
[[File:Nass Valley Lava Beds.jpg|thumb|left|250px|alt=Open area of lava beds right by a road.|Nass valley lava beds]]
At the southernmost end of the Northern Cordilleran Volcanic Province, Tseax Cone lies in a valley above and east of the [[Tseax River]]. It is a young Holocene age cinder cone that was the source for a major basalt lava flow eruption around the years 1750 and 1775 that travelled into the Tseax River, damming it and forming [[Lava Lake (British Columbia)|Lava Lake]].<ref name="AU">{{cite gvp|vn=320100|title=Tseax River Cone|access-date=2009-01-19}}</ref> The lava flow subsequently travelled {{convert|11|km|mi|abbr=on}} north to the [[Nass River]], where it filled the flat valley floor for an additional {{convert|10|km|mi|abbr=on}}, making the entire lava flow {{convert|22.5|km|mi|abbr=on}} long.<ref name="AU"/><ref name="UY">{{cite web|title=Tseax Cone |work=Catalogue of Canadian volcanoes |publisher=[[Geological Survey of Canada]] |date=2005-08-19 |url=http://gsc.nrcan.gc.ca/volcanoes/cat/volcano_e.php?id=svb_tsx_107 |access-date=2009-01-19 |url-status=dead |archive-url=https://web.archive.org/web/20060219232127/http://gsc.nrcan.gc.ca/volcanoes/cat/volcano_e.php?id=svb_tsx_107 |archive-date=2006-02-19 }}</ref> Native legends from [[Nisga'a]] people in the area tell of a prolonged period of disruption by the volcano, including the destruction of two Nisga'a villages known as [[Lax Ksiluux, British Columbia|Lax Ksiluux]] and Wii Lax K'abit.<ref name="AU"/><ref>{{cite web|publisher=Government of British Columbia|url=https://apps.gov.bc.ca/pub/bcgnws/names/40740.html |archive-url=https://web.archive.org/web/20070102034732/http://ilmbwww.gov.bc.ca/bcgn-bin/bcg10?name=40740 |url-status=live |archive-date=January 2, 2007 |title=BCGNIS Query Results|access-date=2009-01-19}} </ref> Nisga'a people dug pits for shelter but at least 2,000&nbsp;Nisga'a people were killed due to [[volcanic gas]]es and poisonous smoke (most likely [[carbon dioxide]]).<ref name="AU"/><ref name="UY"/><ref name="IK">{{cite web|last=Hickson |first=C.J. |author2=Ulmi, M. |title=Volcanoes of Canada |publisher=Natural Resources Canada |date=2006-01-03 |url=http://www.bcminerals.ca/pdf/CanadianVolcanoes-CH2005.pdf |page=97 |access-date=2009-01-19 |url-status=dead |archive-url=https://web.archive.org/web/20060528051236/http://www.bcminerals.ca/pdf/CanadianVolcanoes-CH2005.pdf |archive-date=2006-05-28 }}</ref> This is Canada's worst known geophysical disaster and is the only eruption in Canada for which legends of [[First Nations in Canada|First Nations]] people have been proven true.<ref name="UY"/><ref name="IK"/> As of 1993, the Tseax Cone quietly rests in [[Nisga'a Memorial Lava Bed Provincial Park]].<ref name="UY"/>
More than 20&nbsp;eruptions have occurred at the Mount Edziza volcanic complex in the past 10,000&nbsp;years, including [[Mess Lake Cone]],<ref>{{cite web|title=Mess Lake |work=Catalogue of Canadian volcanoes |publisher=[[Geological Survey of Canada]] |date=2005-08-19 |url=http://gsc.nrcan.gc.ca/volcanoes/cat/volcano_e.php?id=svb_msl_097 |access-date=2009-01-22 |url-status=dead |archive-url=https://web.archive.org/web/20101211101239/http://gsc.nrcan.gc.ca/volcanoes/cat/volcano_e.php?id=svb_msl_097 |archive-date=2010-12-11 }}</ref> [[Kana Cone]],<ref name="QQP">{{cite web|title=Kana Cone |work=Catalogue of Canadian volcanoes |publisher=[[Geological Survey of Canada]] |date=2005-08-19 |url=http://gsc.nrcan.gc.ca/volcanoes/cat/volcano_e.php?id=svb_kcn_011 |access-date=2009-01-22 |url-status=dead |archive-url=https://web.archive.org/web/20071110044017/http://gsc.nrcan.gc.ca/volcanoes/cat/volcano_e.php?id=svb_kcn_011 |archive-date=2007-11-10 }}</ref> [[Cinder Cliff]],<ref>{{cite web|title=Cinder Cliff |work=Catalogue of Canadian volcanoes |publisher=[[Geological Survey of Canada]] |date=2005-08-19 |url=http://gsc.nrcan.gc.ca/volcanoes/cat/volcano_e.php?id=svb_ccl_073 |access-date=2009-01-22 |url-status=dead |archive-url=https://web.archive.org/web/20110719225429/http://gsc.nrcan.gc.ca/volcanoes/cat/volcano_e.php?id=svb_ccl_073 |archive-date=2011-07-19 }}</ref> [[Icefall Cone]],<ref>{{cite web|title=Icefall Cone |work=Catalogue of Canadian volcanoes |publisher=[[Geological Survey of Canada]] |date=2005-08-19 |url=http://gsc.nrcan.gc.ca/volcanoes/cat/volcano_e.php?id=svb_ifc_034 |access-date=2009-01-22 |url-status=dead |archive-url=https://web.archive.org/web/20101211101116/http://gsc.nrcan.gc.ca/volcanoes/cat/volcano_e.php?id=svb_ifc_034 |archive-date=2010-12-11 }}</ref> [[Ridge Cone]],<ref>{{cite web|title=Ridge Cone |work=Catalogue of Canadian volcanoes |publisher=[[Geological Survey of Canada]] |date=2005-08-19 |url=http://gsc.nrcan.gc.ca/volcanoes/cat/volcano_e.php?id=svb_rcn_035 |access-date=2009-01-22 |url-status=dead |archive-url=https://web.archive.org/web/20101211101401/http://gsc.nrcan.gc.ca/volcanoes/cat/volcano_e.php?id=svb_rcn_035 |archive-date=2010-12-11 }}</ref> [[Williams Cone]],<ref name="QQX">{{cite web | title = Williams Cone | work = Catalogue of Canadian volcanoes | publisher = [[Geological Survey of Canada]] | date = 2005-08-19 | url = http://gsc.nrcan.gc.ca/volcanoes/cat/volcano_e.php?id=svb_wic_018 | access-date = 2009-01-22 | archive-url = https://web.archive.org/web/20071110044052/http://gsc.nrcan.gc.ca/volcanoes/cat/volcano_e.php?id=svb_wic_018 | archive-date = 2007-11-10 | url-status = dead }}</ref> [[Walkout Creek Cone]],<ref name="CCD">{{cite web | title = Walkout Creek | work = Catalogue of Canadian volcanoes | publisher = [[Geological Survey of Canada]] | date = 2005-08-19 | url = http://gsc.nrcan.gc.ca/volcanoes/cat/volcano_e.php?id=svb_wcr_092 | access-date = 2009-01-22 | archive-url = https://web.archive.org/web/20101212061045/http://gsc.nrcan.gc.ca/volcanoes/cat/volcano_e.php?id=svb_wcr_092 | archive-date = 2010-12-12 | url-status = dead }}</ref> [[Moraine Cone]],<ref name="QQR">{{cite web | title = Moraine Cone | work = Catalogue of Canadian volcanoes | publisher = [[Geological Survey of Canada]] | date = 2005-08-19 | url = http://gsc.nrcan.gc.ca/volcanoes/cat/volcano_e.php?id=svb_moc_012 | access-date = 2009-01-22 | archive-url = https://web.archive.org/web/20071112095708/http://gsc.nrcan.gc.ca/volcanoes/cat/volcano_e.php?id=svb_moc_012 | archive-date = 2007-11-12 | url-status = dead }}</ref> [[Sidas Cone]],<ref name="QQS">{{cite web|title=Sidas Cone |work=Catalogue of Canadian volcanoes |publisher=[[Geological Survey of Canada]] |date=2005-08-19 |url=http://gsc.nrcan.gc.ca/volcanoes/cat/volcano_e.php?id=svb_sic_013 |access-date=2009-01-22 |url-status=dead |archive-url=https://web.archive.org/web/20071112095719/http://gsc.nrcan.gc.ca/volcanoes/cat/volcano_e.php?id=svb_sic_013 |archive-date=2007-11-12 }}</ref> [[Sleet Cone]],<ref name="QQT">{{cite web | title = Sleet Cone | work = Catalogue of Canadian volcanoes | publisher = [[Geological Survey of Canada]] | date = 2005-08-19 | url = http://gsc.nrcan.gc.ca/volcanoes/cat/volcano_e.php?id=svb_sic_014 | access-date = 2009-01-22 | archive-url = https://web.archive.org/web/20071112095724/http://gsc.nrcan.gc.ca/volcanoes/cat/volcano_e.php?id=svb_sic_014 | archive-date = 2007-11-12 | url-status = dead }}</ref> [[Storm Cone]],<ref name="QQU">{{cite web | title = Storm Cone | work = Catalogue of Canadian volcanoes | publisher = [[Geological Survey of Canada]] | date = 2005-08-19 | url = http://gsc.nrcan.gc.ca/volcanoes/cat/volcano_e.php?id=svb_stc_015 | access-date = 2009-01-22 | archive-url = https://web.archive.org/web/20071111155130/http://gsc.nrcan.gc.ca/volcanoes/cat/volcano_e.php?id=svb_stc_015 | archive-date = 2007-11-11 | url-status = dead }}</ref> [[Triplex Cones]],<ref name="QQV">{{cite web | title = Triplex Cone | work = Catalogue of Canadian volcanoes | publisher = [[Geological Survey of Canada]] | date = 2005-08-19 | url = http://gsc.nrcan.gc.ca/volcanoes/cat/volcano_e.php?id=svb_trc_016 | access-date = 2009-01-22 | archive-url = https://web.archive.org/web/20071110044042/http://gsc.nrcan.gc.ca/volcanoes/cat/volcano_e.php?id=svb_trc_016 | archive-date = 2007-11-10 | url-status = dead }}</ref> [[Twin Cone]],<ref name="QQW">{{cite web|title=Twin Cone |work=Catalogue of Canadian volcanoes |publisher=[[Geological Survey of Canada]] |date=2005-08-19 |url=http://gsc.nrcan.gc.ca/volcanoes/cat/volcano_e.php?id=svb_twc_017 |access-date=2009-01-22 |url-status=dead |archive-url=https://web.archive.org/web/20071112095734/http://gsc.nrcan.gc.ca/volcanoes/cat/volcano_e.php?id=svb_twc_017 |archive-date=2007-11-12 }}</ref> [[Cache Hill]],<ref>{{cite web|title=Cache Hill |work=Catalogue of Canadian volcanoes |publisher=[[Geological Survey of Canada]] |date=2005-08-19 |url=http://gsc.nrcan.gc.ca/volcanoes/cat/volcano_e.php?id=svb_cah_036 |access-date=2009-01-22 |url-status=dead |archive-url=https://web.archive.org/web/20110604164829/http://gsc.nrcan.gc.ca/volcanoes/cat/volcano_e.php?id=svb_cah_036 |archive-date=2011-06-04 }}</ref> [[Camp Hill (British Columbia)|Camp Hill]],<ref>{{cite web|title=Camp Hill |work=Catalogue of Canadian volcanoes |publisher=[[Geological Survey of Canada]] |date=2005-08-19 |url=http://gsc.nrcan.gc.ca/volcanoes/cat/volcano_e.php?id=svb_cah_037 |access-date=2009-01-22 |url-status=dead |archive-url=https://web.archive.org/web/20110604170115/http://gsc.nrcan.gc.ca/volcanoes/cat/volcano_e.php?id=svb_cah_037 |archive-date=2011-06-04 }}</ref> [[Cocoa Crater]],<ref name="CCA">{{cite web | title = Cocoa Cone | work = Catalogue of Canadian volcanoes | publisher = [[Geological Survey of Canada]] | date = 2005-08-19 | url = http://gsc.nrcan.gc.ca/volcanoes/cat/volcano_e.php?id=svb_ccn_088 | access-date = 2009-01-22 | archive-url = https://web.archive.org/web/20101212060930/http://gsc.nrcan.gc.ca/volcanoes/cat/volcano_e.php?id=svb_ccn_088 | archive-date = 2010-12-12 | url-status = dead }}</ref> [[Coffee Crater]],<ref name="CCB">{{cite web | title = Coffee Crater | work = Catalogue of Canadian volcanoes | publisher = [[Geological Survey of Canada]] | date = 2005-08-19 | url = http://gsc.nrcan.gc.ca/volcanoes/cat/volcano_e.php?id=svb_ccr_089 | access-date = 2009-01-22 | archive-url = https://web.archive.org/web/20101211081030/http://gsc.nrcan.gc.ca/volcanoes/cat/volcano_e.php?id=svb_ccr_089 | archive-date = 2010-12-11 | url-status = dead }}</ref> [[Nahta Cone]],<ref>{{cite web|title=Nahta Cone |work=Catalogue of Canadian volcanoes |publisher=[[Geological Survey of Canada]] |date=2005-08-19 |url=http://gsc.nrcan.gc.ca/volcanoes/cat/volcano_e.php?id=svb_ncn_095 |access-date=2009-01-22 |url-status=dead |archive-url=https://web.archive.org/web/20101211093755/http://gsc.nrcan.gc.ca/volcanoes/cat/volcano_e.php?id=svb_ncn_095 |archive-date=2010-12-11 }}</ref> [[Tennena Cone]],<ref>{{cite web | title = Tennena Cone | work = Catalogue of Canadian volcanoes | publisher = [[Geological Survey of Canada]] | date = 2005-08-19 | url = http://gsc.nrcan.gc.ca/volcanoes/cat/volcano_e.php?id=svb_tcn_094 | access-date = 2009-01-22 | archive-url = https://web.archive.org/web/20101211101432/http://gsc.nrcan.gc.ca/volcanoes/cat/volcano_e.php?id=svb_tcn_094 | archive-date = 2010-12-11 | url-status = dead }}</ref> [[The Saucer]]<ref name="CCC">{{cite web|title=The Saucer |work=Catalogue of Canadian volcanoes |publisher=[[Geological Survey of Canada]] |date=2005-08-19 |url=http://gsc.nrcan.gc.ca/volcanoes/cat/volcano_e.php?id=svb_tsu_091 |access-date=2009-01-22 |url-status=dead |archive-url=https://web.archive.org/web/20101211102020/http://gsc.nrcan.gc.ca/volcanoes/cat/volcano_e.php?id=svb_tsu_091 |archive-date=2010-12-11 }}</ref> and the well-preserved [[Eve Cone]].<ref name="VI">{{cite web|title=Stikine volcanic belt: Mount Edziza|work=Catalogue of Canadian volcanoes|publisher=[[Geological Survey of Canada]]|date=2008-02-13|url=http://gsc.nrcan.gc.ca/volcanoes/cat/feature_edziza_e.php|access-date=2008-12-20|archive-url=https://web.archive.org/web/20080610154204/http://gsc.nrcan.gc.ca/volcanoes/cat/feature_edziza_e.php|archive-date=2008-06-10|url-status=dead}}</ref><ref>{{cite web|title=Eve Cone |work=Catalogue of Canadian volcanoes |publisher=[[Geological Survey of Canada]] |date=2005-08-19 |url=http://gsc.nrcan.gc.ca/volcanoes/cat/volcano_e.php?id=svb_evc_010 |access-date=2009-01-22 |url-status=dead |archive-url=https://web.archive.org/web/20071112010028/http://gsc.nrcan.gc.ca/volcanoes/cat/volcano_e.php?id=svb_evc_010 |archive-date=2007-11-12 }}</ref> These cinder cones were formed no more than the year 700 based on the age of burnt plant stems still rooted in former soil under {{convert|2|m|ft|abbr=on}} of loose basaltic fragments.<ref name="JK"/> The cones were built on the basaltic fragments and blocky lava fields surrounding the cones.<ref name="JK"/> The [[Snowshoe Lava Field]] on the southern end of the [[Big Raven Plateau]] is one of the areas of young lava flows in the region while the [[Desolation Lava Field]] on the northern end of the Big Raven Plateau is the largest area of young lava flows, covering an area of {{convert|150|km2|mi2|abbr=on}}.<ref name="VI"/> The longest lava flow is {{convert|12|km|mi|abbr=on}}.<ref name="VI"/> This volcanic activity was followed by at least two younger, but still undated eruptions.<ref name="JK"/>
[[File:Alligator Lake.jpg|thumb|right|250px|alt=Jagged landscape of mountains.|The Alligator Lake volcanic complex. The two small reddish brown areas in the middle are cinder cones.]]
Two well-preserved reddish-brown basaltic cinder cones cap a small shield volcano of the [[Alligator Lake volcanic complex]] in southcentral Yukon.<ref name="NW">{{cite gvp|vn=320020|title=Alligator Lake|access-date=2009-03-30}}</ref> These cinder cones are likely younger than the adjacent Holocene glaciation and both cones were erupting at the same time.<ref name="NW"/> These cinder cones produced alkaline olivine basalt to basanitic lava flows that extend to the north.<ref name="NW"/> Lava flows from the northeast cone are the largest, extending {{convert|6|km|mi|abbr=on}} from the cone and expanding to a width of {{convert|10|km|mi|abbr=on}} at the end.<ref name="NW"/> Sections of the lava flows comprise spinel lherzolite, [[xenolith]]s composed of granite and megacrysts of olivine, pyroxene and spinel.<ref name="NW"/>
An eruption was reported in the [[Atlin Volcanic Field]] by [[placer mining|placer miners]] on November 8, 1898.<ref name="HK"/><ref>{{cite gvp|vn=320030|vtab=Eruptions|title=Atlin Volcanic Field|access-date=2009-11-01}}</ref> Miners working in the area reportedly were able to work during the dark nights due to the glow of the eruption.<ref name="HK"/> A news report published on December 1, 1898 by the American newspaper publisher [[The New York Times]] stated:
{{Cquote|Dr. W. D. Kinslee and T. P. James, Denver mining men who with Col. Hughes of Rossland have just returned from Alaska, report that a volcano is in active eruption about fifty miles from Atlin City. No name has yet been given to the volcano, but the officials of Atlin are preparing for a trip of inspection and will christen it. It is said to be the second in a string of four mountains lying fifty miles due south of Lake Gladys, all of which are more than 1,400 feet high.<ref>{{cite journal|url=https://timesmachine.nytimes.com/timesmachine/1898/12/01/102091355.pdf|title=Active Volcano Near Atlin, Alaska|journal=[[The New York Times]]|date=1898-12-01|access-date=2009-11-27 }}</ref>}}
In 1898 the [[Atlin, British Columbia|Atlin]] area was in [[Alaska boundary dispute|dispute with the Alaska-British Columbia boundary]], leading American news broadcasters stating the Atlin area was in Alaska rather than in northwestern British Columbia. This Alaska-British Columbia boundary dispute was eventually resolved by arbitration in 1903 and no evidence for the 1898 eruption has been found, leading researchers to speculate the eruption and report as uncertain.<ref name="HK"/> However, given the location of the placer operations from which the eruption was supposedly visible (Pine, Birch, Discovery, and McKee creeks) and the reported location of the volcano {{convert|80|km|mi|abbr=on}} south of Gladys Lake, the vent might possibly be in the very rugged and inaccessible Coast Mountains south or southwest of Atlin Lake.<ref name="XL"/>
On the south side of the [[Khutzeymateen Inlet]] north of [[Prince Rupert, British Columbia|Prince Rupert]], thick basaltic [[Plinian eruption]] tephra deposits are recognized at [[Crow Lagoon]].<ref name="XB">{{cite gvp|vn=320110|title=Crow Lagoon|access-date=2009-03-30}}</ref> These volcanics originated from a volcanic vent that remains unidentified.<ref name="XB"/> However, existence of [[volcanic bomb]]s at the Plinian tephra deposits indicates the volcanic vent of its origin is located nearby.<ref name="XB"/> The age of these volcanics is unknown but they were deposited throughout the Holocene epoch.<ref name="XB"/>
In the Pleistocene Tuya Volcanic Field, small subaerial shield volcanoes and postglacial cinder cones and lava flows can be recognized.<ref name="NE">{{cite gvp|vn=320031|title=Tuya Volcanic Field|access-date=2009-03-30}}</ref> At least one of these volcanoes is of Holocene age.<ref name="NE"/> [[Gabrielse Cone]] near the headwaters of [[Iverson Creek (British Columbia)|Iverson Creek]] in the [[Stikine Ranges]] rises with an elevation of {{convert|1600|m|ft|abbr=on}} and a diameter of {{convert|400|m|ft|abbr=on}}. It is mostly made of loose basaltic [[scoria]] with a [[volcanic crater]] {{convert|30|m|ft|abbr=on}} deep at its summit.<ref name="QK">{{cite web|author=K. Simpson|author2=B. Edwards |author3=K. Wetherell |title=Documentation of a Holocene volcanic cone in the Tuya-Teslin volcanic field, northern British Columbia|publisher=[[Geological Survey of Canada]]|year=2006|url=http://dsp-psd.pwgsc.gc.ca/Collection/M44-2006-A1E.pdf|page=2|access-date=2009-10-02}}</ref> The northeastern flank of Gabrielse Cone is ruptured where remnants of a basaltic lava flow exists.<ref name="QK"/> This basalt lava flow extends more than {{convert|400|m|ft|abbr=on}} from the volcano and there is no proof Gabrielse Cone was formed during or before the Cordilleran Ice Sheet.<ref name="QK"/> As a result, Gabrielse Cone is unmistakably younger than 11,000&nbsp;years and it was formed in the Holocene epoch.<ref name="QK"/>
===Recent activity and hazards===
At least five volcanoes have had seismic activity since 1985, including the Mount Edziza volcanic complex (eight events),<ref name="AA"/> Castle Rock (two events),<ref name="AA"/> Hoodoo Mountain (eight events),<ref name="AA"/> Crow Lagoon (four events)<ref name="AA"/> and The Volcano (five events).<ref name="AA"/> Seismic data suggests that these volcanoes still contain living [[magma chamber]]s, indicating possible future eruptive activity.<ref>{{cite web|publisher=[[Geological Survey of Canada]] |url=http://gsc.nrcan.gc.ca/volcanoes/gscvol_e.php |title=Volcanology in the Geological Survey of Canada |work=Volcanoes of Canada |access-date=2008-05-09 |url-status=dead |archive-url=https://web.archive.org/web/20080513003833/http://gsc.nrcan.gc.ca/volcanoes/gscvol_e.php |archive-date=2008-05-13 }}</ref> Although the available data does not allow a clear conclusion, these observations are further indications that some Northern Cordilleran volcanoes are potentially active and that their associated hazards may be significant.<ref name="AA">{{cite book | last = Etkin | first = David |author2=Haque, C.E. |author3=Brooks, Gregory R. | title = An Assessment of Natural Hazards and Disasters in Canada | publisher = Springer | date = 2003-04-30 | pages =569, 582, 583 | url = https://books.google.com/books?id=kaJz_SNNuKMC&q=wells+%22gray+clearwater%22+volcanic+field+earthquakes&pg=PA569
| isbn = 978-1-4020-1179-5}}</ref> The seismic activity correlates both with some of Canada's most youthful volcanoes and with long-lived volcanoes with a history of significant explosive activity, such as Hoodoo Mountain and the Mount Edziza volcanic complex.<ref name="AA"/> To date, Edziza and Hoodoo pose the greatest threats in the Northern Cordilleran Volcanic Province.<ref name="QBO">{{cite web|url=http://132.203.220.37/cgi-bin/consultau.cgi?527&529&|archive-url=https://web.archive.org/web/19991111193556/http://132.203.220.37/cgi-bin/consultau.cgi?527&529&|url-status=dead|archive-date=1999-11-11|title=Holocene volcanism, Holocene tephras, and future volcanic hazards in Western Canada|last1=Hickson|first1=C.J.|last2=Edwards|first2=B.R.|date=March 1999|publisher=[[Geological Survey of Canada]]|access-date=2009-11-16}}</ref> A large [[pumice]] deposit scattered throughout the Edziza complex highlights one of the significant volcanic hazards associated with the complex, including the possibility of a large explosive eruption.<ref name="IOV">{{cite web|title=Stikine volcanic belt: Mount Edziza|work=Catalogue of Canadian volcanoes|publisher=[[Geological Survey of Canada]]|date=2008-02-13|url=http://gsc.nrcan.gc.ca/volcanoes/cat/feature_edziza_e.php|access-date=2008-09-11|archive-url=https://web.archive.org/web/20080610154204/http://gsc.nrcan.gc.ca/volcanoes/cat/feature_edziza_e.php|archive-date=2008-06-10|url-status=dead}}</ref> This large pumice deposit indicates that the Mount Edziza volcanic complex has a history of producing not only fluid and passive basaltic lava flows, but also more silica-rich trachytic and rhyolitic lava flows and explosive eruptions.<ref name="IOV"/> The silica-rich compositions are similar to those associated with the most catastrophic eruptions on Earth.<ref name="IOV"/>  A large explosive eruption at the Edziza complex could produce an [[eruption column]] that would affect parts of the [[Pacific Northwest]].<ref name="IOV"/> Similarly, high eruption columns from Hoodoo Mountain would disrupt air traffic between Canada, Alaska and Asia.<ref>{{cite web|title=Stikine volcanic belt: Hoodoo Mountain |work=Catalogue of Canadian volcanoes |publisher=[[Geological Survey of Canada]] |date=2008-02-13 |url=http://gsc.nrcan.gc.ca/volcanoes/cat/feature_hoodoo_e.php |access-date=2009-03-30 |url-status=dead |archive-url=https://web.archive.org/web/20090608030101/http://gsc.nrcan.gc.ca/volcanoes/cat/feature_hoodoo_e.php |archive-date=2009-06-08 }}</ref> The flat summit of Hoodoo Mountain is also covered by an ice cap more than {{convert|100|m|ft|abbr=on}} thick.<ref name="SS">{{cite web|title=The Hoodoo Mountain project|work=Volcanoes of Canada|publisher=[[Geological Survey of Canada]]|date=2008-02-12|url=http://gsc.nrcan.gc.ca/volcanoes/hoodoo_e.php|access-date=2009-12-03|archive-url=https://web.archive.org/web/20090211124206/http://gsc.nrcan.gc.ca/volcanoes/hoodoo_e.php|archive-date=2009-02-11|url-status=dead}}</ref> An eruption from Hoodoo's summit would cause considerable melting of the ice cap to create large [[flood]]s and [[lahar]]s, which would have significant effects on adjacent river valleys.<ref name="SS"/> This includes the [[Iskut River]] just on the southern flank of Hoodoo Mountain, which is the host for a large amount of [[salmon]], logging operations and a large mining and mineral exploration camp.<ref name="SS"/> Edziza and Hoodoo Mountain are two of the three most hazardous volcanoes in Western Canada that have been active in the past 10,000 years, the other being the [[Mount Meager massif]] in the [[Garibaldi Volcanic Belt]] of southwestern British Columbia which produced a large-scale eruption 2,350&nbsp;years ago that sent ash as far as central [[Alberta]].<ref name="QBO"/>
Lava flows in the Northern Cordilleran Volcanic Province are among the least hazardous, even though they can be enormously destructive to property in their path.<ref name="ZLE">{{cite web|publisher=[[Geological Survey of Canada]] |url=http://gsc.nrcan.gc.ca/volcanoes/haz_e.php |title=Volcanic hazards |work=Volcanoes of Canada |access-date=2009-11-22 |url-status=dead |archive-url=https://web.archive.org/web/20080516040529/http://gsc.nrcan.gc.ca/volcanoes/haz_e.php |archive-date=2008-05-16 }}</ref> This is because lava generally moves slowly enough for people to get out of their way, though this is dependent on the viscosity of the lava.<ref name="ZLE"/> Lava flows typically have secondary hazards, including the destruction of buildings and ejection of [[volcanic gas]]es.<ref name="ZLE"/> Forest fires started by lava flows are also a possibility in this part of Canada.<ref name="ZLE"/> The typical lava fountains in the Northern Cordilleran Volcanic Province are commonly associated with lava flows, but these do not normally reach heights more than a few hundred metres.<ref name="ZLE"/> Therefore, the dangers caused by lava fountains are only adjacent to the erupting volcano.<ref name="ZLE"/>
Currently, no volcanoes in the Northern Cordilleran Volcanic Province are monitored closely enough by the [[Geological Survey of Canada]] to ascertain how active their magma chambers are.<ref name="ZPQ">{{cite web|title=Monitoring volcanoes |work=Volcanoes of Canada |publisher=[[Geological Survey of Canada]] |date=2008-02-12 |url=http://gsc.nrcan.gc.ca/volcanoes/mon_e.php |access-date=2009-01-22 |url-status=dead |archive-url=https://web.archive.org/web/20080507152523/http://gsc.nrcan.gc.ca/volcanoes/mon_e.php |archive-date=2008-05-07 }}</ref> An existing network of [[seismometer|seismographs]] has been established to monitor tectonic earthquakes and is too far away to provide a good indication of what is happening beneath them.<ref name="ZPQ"/> It may sense an increase in activity if a volcano becomes very restless, but this may only provide a warning for a large eruption.<ref name="ZPQ"/> It might detect activity only once a volcano has started erupting.<ref name="ZPQ"/> The [[Interagency Volcanic Event Notification Plan]], Canada's volcanic emergency notification program, was established to outline the notification procedure of some of the main agencies that would be involved in response to a volcanic eruption in Canada, an eruption close to Canada's borders, or an eruption significant enough to have an effect on Canada and its people.<ref>{{cite web|title=Interagency Volcanic Event Notification Plan: Western Canada |publisher=[[Natural Resources Canada]] |date=2008-05-01 |url=http://gsc.nrcan.gc.ca/volcanoes/pdf/ivenp_e.pdf |page=7 |access-date=2009-02-19 |url-status=dead |archive-url=https://web.archive.org/web/20110604174944/http://gsc.nrcan.gc.ca/volcanoes/pdf/ivenp_e.pdf |archive-date=2011-06-04 }}</ref> It focuses primarily on aviation safety because jet aircraft can quickly enter areas of volcanic ash.<ref name="HEPO">{{cite web|title=Volcanoes |publisher=[[Natural Resources Canada]] |date=2007-09-05 |url=http://atlas.nrcan.gc.ca/site/english/maps/environment/naturalhazards/volcanoes/1 |access-date=2009-01-22 |url-status=dead |archive-url=https://web.archive.org/web/20090217001048/http://atlas.nrcan.gc.ca/site/english/maps/environment/naturalhazards/volcanoes/1 |archive-date=2009-02-17 }}</ref> The program notifies all impacted agencies that have to deal with volcanic events.<ref name="HEPO"/> Aircraft are rerouted away from hazardous ash and people on the ground are notified of potential ash fall.<ref name="HEPO"/>
==See also==
*[[Volcanology of Canada]]
*[[Volcanology of Northern Canada]]
*[[Volcanology of Western Canada]]
==References==
{{reflist|26em}}
[[Category:Northern Cordilleran Volcanic Province|*V]]
[[Category:Volcanism of Alaska]]
[[Category:Volcanism of British Columbia]]
[[Category:Volcanism of Yukon]]
[[Category:Cenozoic geology of North America]]
[[Category:North American Cordillera|V]]
[[Category:Natural history of British Columbia]]
[[Category:Natural history of Yukon]]
[[Category:Natural history of Alaska]]
[[Category:Natural hazards in British Columbia]]
[[Category:Cenozoic Alaska]]
[[Category:Cenozoic British Columbia]]
[[Category:Cenozoic Yukon]]