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WEATHER
Mount Thielsen
Shield Volcano
on
Mt. Thielsen Trail
in
Umpqua NF
,
Mount Thielsen Wilderness
,
Cascade Range
near
Diamond Lake Information Center
,
OR
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On Wikipedia
Mount Thielsen, or Big Cowhorn (Klamath: hisc’akwaleeʔas), is an extinct shield volcano in the Oregon High Cascades, near Mount Bailey. Because eruptive activity ceased 250,000 years ago, glaciers have heavily eroded the volcano's structure, creating precipitous slopes and a horn-like peak. The spire-like shape of Thielsen attracts lightning strikes and creates fulgurite, an unusual mineral. The prominent horn forms a centerpiece for the Mount Thielsen Wilderness, a reserve for recreational activities such as skiing and hiking. Thielsen was produced by subduction of the Juan de Fuca Plate under the North American Plate. Volcanism near the Cascades dates back to 55 million years ago (mya), and extends from British Columbia to California. Thielsen is part of the High Cascades, a branch of…
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Classified As
Shield Volcano
Geologic Formation
Mafic vent complexes (ORQTmv;0)
Geologic Formation
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