The Bridge River Ash is a large geologically recent volcanic ash deposit that spans from southwestern British Columbia to central Alberta , Canada . The ash consists of dust-sized shards ellipsoidal fragments of pumice . It overlaps the Mount St. Helens Yn Ash and the Mazama Ash which were erupted from Mount St. Helens and Mount Mazama about 3,400 and 6,800 years ago.
6-748: Even though the name Bridge River Ash is consistent with the Bridge River Cones , the ash did not originate from these volcanoes. The Bridge River Ash was created by the Bridge River eruption of the Mount Meager massif about 2,350 years ago as prevailing winds carried the ash eastward during eruption. This is the most recent major eruption in Canada. 52°09′04″N 118°43′19″W / 52.151°N 118.722°W / 52.151; -118.722 This volcanism article
12-518: A 60 m (197 ft) high steep-sided volcanic plug , is the oldest volcano in the field with a potassium-argon date of one million years. The plug is approximately 300 m (984 ft) 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 ( 50°47′N 123°23′W / 50.79°N 123.38°W / 50.79; -123.38 ), with
18-408: 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 100 m (328 ft) thick. Tuber Hill ( 50°56′N 123°26′W / 50.93°N 123.44°W / 50.93; -123.44 ), a small basaltic stratovolcano with a potassium-argon date of 0.6 million years,
24-525: Is a stub . You can help Misplaced Pages by expanding it . This article about a location in the Interior of British Columbia , Canada is a stub . You can help Misplaced Pages by expanding it . This Alberta location article is a stub . You can help Misplaced Pages by expanding it . Bridge River Cones The Bridge River Cones , sometimes referred to as the Lillooet Cones and Salal Creek Cones ,
30-910: Is the name given to a volcanic field located on the north flank of the upper Bridge River , about 40 km (25 mi) 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 . The Bridge River Cones consist of small trachybasaltic and basaltic eruptive centers. Sham Hill ( 50°54′N 123°31′W / 50.90°N 123.51°W / 50.90; -123.51 ),
36-484: 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 150 m (492 ft) of interbedded hyaloclastite , debris flows , and lacustrine tuff were deposited. 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
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