Catalogue of Canadian volcanoes |
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Catalogue of Canadian volcanoes Stikine volcanic belt: Mount Edziza
![Figure A23. Mount EdzizaMount Edziza is the remnant of a large shield volcano, now heavily eroded by overriding glaciers. The peak is 2590 m high. (Photograph by C.J. Hickson (Geological Survey of Canada)) Figure A23. Mount EdzizaMount Edziza is the remnant of a large shield volcano, now heavily eroded by overriding glaciers. The peak is 2590 m high. (Photograph by C.J. Hickson (Geological Survey of Canada))](/web/20061103010711im_/http://www.gsc.nrcan.gc.ca/volcanoes/cat/images/a23_.jpg) Figure A23. Mount EdzizaMount Edziza is the remnant of a large shield volcano, now heavily eroded by overriding glaciers. The peak is 2590 m high.
(Photograph by C.J. Hickson (Geological Survey of Canada))
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Mount Edziza, the second largest volcanic complex in Canada, is in northwestern
British Columbia. Its glacier covered peaks are visible from
the Stewart-Cassiar highway, 40 km to the west. This area of
long-lived volcanic activity was studied in detail for many
years by Dr. Jack Souther of the Geological Survey of Canada.
Souther's (1992) on Mount Edziza and the surrounding volcanoes
highlighted the importance and size of the region, one of the
largest areas of young volcanic activity in Canada. The complex
comprises a large plateau of predominantly basaltic lava flows;
four large stratovolcanoes built on top of the plateau. The
plateau is about 65 km long and a maximum of 20 km wide. The
higher peaks of the complex were built upon a base of fluid
basalt lava flows and are now glacier covered (Figure A23).
Throughout the length of the volcanic complex, numerous eruptions
have occurred within the last 10 000 years (or since the end
of the last ice age). The most recent activity formed two large
lava fields and several smaller, isolated cinder cones surrounded
by lava flows (Figure A24, Figure A25).
Desolation lava field, covering 150 km² on the northern
end of the volcanic plateau, is the largest area of young lava
flows. The longest lava flow from the Desolation field, and
the youngest in the volcanic complex, is 12 km long. Eve cone,
in the middle of the Desolation lava field, is one of the most
symmetrical and best preserved cinder cones in Canada. Other
young lava flows and cinder cones at Mount Edziza include Kana
cone, Cinder cliff, Icefall cone, Ridge cone, Walkout Creek,
the Mess Lake and Snowshoe lava fields, and two isolated cones
at the southern end of the volcanic plateau. Many of the young
cinder cones and lava flows at Mount Edziza are covered by light
yellow pumice, referred to as the 'Sheep Track Member' by Souther
(1992). The volcano that produced the pumice has not been discovered,
but probably has been covered by glacier ice.
![Figure A24. Pyramid DomePyramid Dome is a relatively young dome on the northwest flank of Mount Edziza. The dome represents just one of the several different styles of volcanism found in the Mount Edziza volcanic complex. (Photograph by C.J. Hickson (Geological Survey of Canada)) Figure A24. Pyramid DomePyramid Dome is a relatively young dome on the northwest flank of Mount Edziza. The dome represents just one of the several different styles of volcanism found in the Mount Edziza volcanic complex. (Photograph by C.J. Hickson (Geological Survey of Canada))](/web/20061103010711im_/http://www.gsc.nrcan.gc.ca/volcanoes/cat/images/a24_.jpg) Figure A24. Pyramid DomePyramid Dome is a relatively young dome on the northwest flank of Mount Edziza. The dome represents just one of the several different styles of volcanism found in the Mount Edziza volcanic complex.
(Photograph by C.J. Hickson (Geological Survey of Canada))
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![Figure A25. Williams ConeWilliams cone is one of numerous postglacial cinder cones dotting the landscape around Mount Edziza. The most recent of these has been dated at 1350 radiocarbon years ago. (Photograph by C.J. Hickson (Geological Survey of Canada)) Figure A25. Williams ConeWilliams cone is one of numerous postglacial cinder cones dotting the landscape around Mount Edziza. The most recent of these has been dated at 1350 radiocarbon years ago. (Photograph by C.J. Hickson (Geological Survey of Canada))](/web/20061103010711im_/http://www.gsc.nrcan.gc.ca/volcanoes/cat/images/a25_.jpg) Figure A25. Williams ConeWilliams cone is one of numerous postglacial cinder cones dotting the landscape around Mount Edziza. The most recent of these has been dated at 1350 radiocarbon years ago.
(Photograph by C.J. Hickson (Geological Survey of Canada))
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Active or recently active warm springs are found in several areas
along the western flank of the volcanic plateau, including
Elwyn springs (36°C), Taweh springs (46°C), and inactive
springs near Mess Lake. All three hydrothermal areas are near
the youngest lava fields on the plateau and are probably associated
with the most recent volcanic activity at Mount Edziza. The
vast plateau has also been an important cultural resource.
The Tahltan people, who now live largely near Telegraph Creek,
British Columbia, used volcanic glass (obsidian) from Mount
Edziza to make tools and for trading material. More recently,
most of the plateau has been made into a provincial park to
preserve the volcanic and culture treasures unique to the
northern British Columbia area.
Track Bench pumice deposit highlights one of the important volcanic
hazards associated with the Mount Edziza volcanic complex -
the possibility of a large, explosive volcanic eruption. Mount
Edziza has a history of producing not only fluid and relatively
passive basaltic lava flows, but also more silica-rich trachytic
and rhyolitic lava flows and explosive eruptions. The silica-rich
compositions are similar to those associated with the most violent
eruptions on Earth, and scientists believe that the ice cap
on top of Mount Edziza might be covering at least one volcanic
caldera or crater. An explosive eruption could produce an ash
cloud that would affect parts of northwestern Canada. As well,
in the past, lava flows from Mount Edziza and closely related
volcanoes to the north have dammed the Stikine River, which
now has a major salmon fishery. Forest fires started by volcanic
eruptions are also a possibility in this part of the world.
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