Bridge River Cones

Infobox Mountain
Name=Bridge River Cones
Photo= Salal Glacier volcano.jpg
Caption= Satellite image of the Salal Glacier volcanic complex
Elevation=Unit m|2500|0
Location=Upper Bridge River, British Columbia, Canada
Range=Pacific Ranges
Prominence =
Coordinates = coord|50|51|30|N|123|24|00|W|type:mountain_region:CA
Topographic

Type=Volcanic field
Age=Holocene
Last eruption=Unknown, possibly younger than 500
First ascent=
Easiest route=

The Bridge River Cones is the name given to a volcanic field located on the north flank of the upper Bridge River, about 40 kilometres west of the town of Gold Bridge. The cones are in the lee of the Lillooet Icecap and sit astride a group of passes between the Bridge River, which flows W-E to their south, and the Lord River, which flows north to the Taseko Lakes in the Chilcotin District.

Geology

The Bridge River Cones consists of small trachybasaltic and basaltic eruptive centers. Sham Hill (coord|50.09|N|123.52|W|type:mountain), a Unit m|60|0 high steep-sided volcanic plug, is the oldest volcano in the field with a potassium-argon date of one million years.cite book|last=Wood | first=Charles A. | coauthors=Kienle, Jürgen| chapter= | pages= | title=Volcanoes of North America: United States and Canada | year=2001 | edition= | publisher=Cambridge University Press | location=Cambridge, England| isbn= 9780521438117|oclc= 27910629] The plug is approximately Unit km|300|0 wide and its bare glaciated surface, strewn with glacial erratics, consists of large subhorizontal columns formed within the central conduit of an eroded stratovolcano.

The Salal Glacier volcanic complex (coord|50.78|N|123.38|W|type:mountain), with a potassium-argon date of 0.97 to 0.59 million years, contains subaerial tephra and thin scoriaceous flows in the upper part of the pile are surrounded by ice-ponded flows up to Unit m|100|0 thick.

Tuber Hill (coord|50.93|N|123.43|W|type:mountain), a small basaltic stratovolcano with a potassium-argon date of 0.6 million years, was constructed on the Bridge River upland when neighboring valleys were filled by ice. Where distal flows violated on the glaciers a marginal meltwater lake was created in which less than Unit m|150|0 of interbedded hyaloclastite, debris flows, and lacustrine tuff were depositied.

The youngest volcanic rocks in the Bridge River volcanic field lie east of Tuber Hill and are remnants of valley-filling basalt flows. The age of these valley-filling basalt flows is unknown but the presence of unconsolidated glacial till under the flows suggest it is less than 1,500 years old.

ee also

*Bridge River Power Project
*Bridge River, British Columbia
*Bridge River Indian Band
*Bridge River Canyon
*Bridge River Country
*Garibaldi Volcanic Belt
*Cascade Volcanoes
*Cascade Range
*Spruce Lake Protected Area
*Ts'il?os Provincial Park
*Lillooet Icecap
*List of volcanoes in Canada
*Volcanism in Canada

References

External links

* [http://ava.jpl.nasa.gov/volcano.asp?vnum=1200-17- NASA/JPL satellite images] - location only
* [http://www.volcano.si.edu/world/volcano.cfm?vnum=1200-17- Smithsonian Institution description]