Photograph by B. Edwards
Photograph by B. Edwards
Lava Fork volcano, which is probably the youngest volcano in Canada,
is a small cinder pile on top of a remote mountain ridge in the Coast Mountains
of British Columbia. The volcano's vent, shown above, is a pile of loose
ash, lapilli-sized tephra and volcanic bombs. Lava Fork is the southernmost
of ten volcanoes in the Iskut volcanic field, which includes volcanoes
at Hoodoo Mountain and Iskut
River. All volcanoes in the Iskut volcanic field are part of the northern
Cordilleran volcanic province (Edwards & Russell 2000).
Photograph by B. Edwards
The valley-filling lava flows (shown above) traveled south 5 km where
they crossed the border into Alaska and dammed the Blue River, forming
several small lakes. In total the lava flows are approximately 22 km long.
Photograph by B. Edwards
The surface of the lava flows still have well-preserved flow features
(pressure ridges and lava channels), pits formed when the overlying solidified
lava collapsed into underlying lava tubes, and tree molds (seen in the
picture above). Also seen in the picture above, locally large trees are
embedded in the top of the lava flows. Based on dating of tree-ring cores
and radiometric ages from 14C dating, the youngest of these lava flows
is probably only 150 years old (Hauksdottir et al., 1994).
-summary by Ben Edwards, Grand Valley State University, MI
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.
Elliot, R.L., Koch, R.D., and Robinson, S.W., 1981, Age of basalt flows
in the Blue River Valley, Bradfield Canal quadrangle,
in The United States Geological Survey in Alaska; Accomplishments
during 1979: USGS Circ. 823-B, B115-B116.
Grove, E.W., 1974, Deglaciation-A possible triggering mechanism for
recent volcanism: Internat. Assn. Volc. Chem.
Earth's Interior, Proc. Symp. Andean Antartic Volcanology Problems,
Santiago Chile, Sept. 1974.
Hauksdottir, S. 1994. Petrography, geochemistry and petrogenesis of
the Iskut-Unuk rivers volcanic centres,
NW British Columbia. Unpub. M.Sc. Thesis, University of British Columbia,
253 p.
Hauksdottir, S., Enegren, E.G., & Russell, J.K. 1994. Recent basaltic
volcanism in the Iskut-Unuk rivers area,
northwestern British Columbia. In Current Research 1994-1A, Geological
Survey of Canada, p. 57-67.
Russell, J.K. & Hauksdottir, S. 2000. Estimates of crustal assimilation
in Quaternary lavas from the northern cordillera, British Columbia.
Canadian Mineralogist, 39, 361-383.
Souther, J.G., 1990. Iskut-Unuk River Cones, Canada. In Wood, C.A.,
& Kienle, J. (eds.). Volcanoes of North
America, Cambridge Univ. Press: Cambridge, p. 128-29.
