Photograph by B. Edwards
Photograph by B. Edwards
Ash Mountain, the mountain in the center of the picture immediately
north of High Tuya Lake, is one of six subglacial
volcanoes clustered close to Tuya Lake, in northcentral British Columbia.
The other volcanoes in the area include Tuya
Butte, South Tuya, and Mathew's
Tuya. The base of the volcano comprises pillow lavas and hyaloclastite,
indicating that the volcano formed either beneath ice or with a large lake.
The cone seen above comprises loose volcanic debris as well as dikes of
basaltic rock intruded into the volcanic pile. The volcanoes in the Tuya
region of northwestern British Columbia form part of the northern Cordilleran
volcanic province of northwestern Canada (Edwards & Russell 2000).
Photograph by B. Edwards
Basaltic lavas from Ash Mountain sometimes contain partly melted fragments
of crustal rocks, refered to as "xenoliths" (white area shown in basaltic
lava above).
-Ben Edwards and Andy McCarthy, Grand Valley State University, MI
Allen, C.C., Jercinovic, M.J. and Allen, J.S.B., 1982. Subglacial volcanism
in north-central
British Columbia and Iceland. Journal of Geology, 90, 699-715.
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.
Mathews, W.H., 1947, Tuyas, flat-topped volcanoes in northern British
Columbia. American
Journal of Science, v. 245, p. 560-570.
Moore, J.G., Hickson, C.J., and Calk, L. 1995. Tholeiitic-alkalic transition
at subglacial
volcanoes, Tuya region, B.C., Canada, Journal of Geophysical Research,
v.100, p. 24, 577-24, 592.
