Catalogue of Canadian volcanoes |
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Catalogue of Canadian volcanoes Lava Fork Figure A17. Black Scoria at Lava ForkA helicopter sits upon thick, black scoria deposited from the eruption of Lava Fork volcano. The surrounding ridges are also covered with tephra and scoria deposits. The cone itself is poorly formed and, even though it is very young, has been eroded by the perpetual ice found at this elevation and latitude.
(Photo by Kelly Russell (UBC))
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Lava Fork volcano is located immediately north of the British Columbia-Alaska
border in northwestern British Columbia, approximately 60 km
northwest of the town of Stewart. The volcano is one of 10 found
along or near the Iskut River. The deposits at Lava Fork comprise
mainly basaltic lava flows (Figure A17),
which erupted from a vent high up on the side of a glaciated,
U-shaped valley and flowed 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 (Figure A18).
The vent area has small deposits of sulfur precipitated from
volcanic gases and volcanic bombs up to 0.5 m long. The surface
of the lava flows still have well preserved flow features such
as pressure ridges and lava channels (Figure A18),
as well as pits formed when the overlying solidified lava collapsed
into underlying lava tubes. In many areas, large trees were
engulfed by the lava flows and are now found embedded in the
top of the flows (Figure A19).
Figure A19. Trees engulfed by lava flowsNear the distal end of the Lava Fork flows, trees were engulfed by the laval flows, but preserved as lava quenched against massive trunks or groups of trees. The bases of the trees then burned, and the upper trunks and branches fell to the still-cooling lava surface below. These hulks can be seen littering the lower reaches of the flow in curious crisscross patterns. View looking south, in the flow direction; the large tree is lying parallel to the flow direction.
(Photograph by C.J. Hickson (Geological Survey of Canada))
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Figure A18. Lava levees at Lava ForkWell defined lava levees and flow features can be seen on the surface of lava flows emanating from Lava Fork volcano. Although the vent area is relatively nondescript, significant quantities of lava poured down the steep slopes into the valley below, travelling over 15 km.
(Photo by Kelly Russell (UBC))
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At least two different episodes of eruption produced the basaltic lava
flows at the Lava Fork vent. On the basis of tree-ring-core
dating and 14C dating, the youngest of these lava flows is probably
only 150 years old. This makes Lava Fork the youngest known
volcano in Canada. Because the Iskut region is so remote and
the style of eruption involves basically passive, fluid lava
flows, future eruptions from Lava Fork pose little threat. Damming
of local water courses may disrupt fish habitat and spawning
grounds, but ash clouds are unlikely to be high enough to disrupt
international jet traffic. They could potentially threaten lower
flying aircraft along the northern coastal corridor between
Vancouver and Alaska.
List all List by type Map Lava Fork |
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Type of volcanic feature: | Cinder cone | Additional volcanic features: | Scoria cone, air-fall deposits, and lava flows | Region: | British Columbia | Volcanic belt: | Stikine volcanic belt | Area: | Iskut-unuk River Cones | Latitude: | 56.42 N | Longitude: | 130.85 W | Age of last eruption: | < 150 Years Ago | Oldest known eruption: | > 350 Years ago | Summit elevation: | 1330 m | Base elevation: | 100 m | Estimated volume erupted: | 2.2 km3 |
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