Photograph by B. Edwards
Photograph by B. Edwards
The Mountain Edziza complex, as seen above from the Cassiar-Stewart
Hwy, is a large volcanic plateau that has been an area of active volcanism
for the last 7-10 million years (Souther, 1992). This is the second
largest area of volcanic activity in the northern Cordilleran volcanic
province (Edwards & Russell 2000) as well as in Canada. The complex
comprises a large plateau (65 km long and < 20 km wide) made of predominantly
basaltic lava flows, with four large stratovolcanoes built on top of the
plateau. Numerous eruptions have occurred within the last 10 000 years
(Holocene) including: Desolation (150 km2), Mess Lake and Snowshoe
lava fields; Kana cone; Eve cone; Cinder cliff; Icefall cone; Ridge cone;
and Walkout Creek. Dr. J. Souther of the Geological Survey of Canada spent
several years studying this area of volcanic activity and published an
exhaustive bulletin on his work in 1992 (see Sources of Information below).
Many of the volcanic features in the volcanic complex are protected as
part of Mount
Edziza Provincal Park, one of the larger provincial parks in British
Columbia.
Photograph by C.
Hickson
Mount Edziza, the ice covered peak in the center of the photograph, is one of the main volcanic vents of the Mount Edziza volcanic complex, located in northwestern British Columbia.
Photograph by C.
Hickson
Many of the young lava flows and cinder cones, such as Eve cone shown above, are covered by light yellow pumice (Sheep Track member) from a close by but unkown volcanic vent. Age constraints on Holocene eruptions include dates of 1340 years BP for Williams cone, between 1 000 and 10 000 years for Sheep Track pumice, and ~8500 years BP for lavas flows of the Big Raven Formation, west of Edziza (Souther, 1992).
-summary by Ben Edwards and Andy McCarthy, Grand Valley State University
Edwards, B.R. & Russell, J.K. 2000. The distribution, nature and
origin of Neogene-Quaternary magmatism
in the Northern Cordilleran Volcanic Province, northern Canadian Cordillera.
Geological Society of America Bulletin, v. 112, no. 8, 1280-1295.
Souther, J.G., 1992. The Late Cenozoic Mount Edziza Volcanic Complex,
British Columbia.
Geological Survey of Canada Memoir 420, 319 p.
Souther, J.G., 1990. Edziza, Canada. In Wood, C.A., & Kienle, J.
(eds.). Volcanoes of North
America, Cambridge Univ. Press: Cambridge, p. 124-26.
Souther, J.G. & Hickson, C.J. 1984. Crystal fractionation of the basalt comendite series of the Mount Edziza volcanic complex, British Columbia: major and trace elements. Journal of Volcanology and Geothermal Research, v. 21, 79-106.
Souther, J.G., Armstrong, R.L., & Harakal, J. 1984. Chronology of
the peralkaline, late Cenozoic
Mount Edziza volcanic complex. Geol. Soc. America Bull., V. 95, p.
337-349.
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