Mount Silverthrone

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Mount Silverthrone is a deeply dissected caldera complex in the Pacific Ranges of the Coast Mountains of British Columbia, located at the northern end of the Garibaldi Volcanic Belt containing rhyolitic, dacitic and andesitic lava domes, lava flows and breccia. The bulk of the complex appears to have been erupted between 0.1 and 0.5 million years ago but postglacial andesitic and basaltic-andesite cones and lava flows are also present. Anomalously old Potassium-Argon dates of 1.0 and 1.1 were obtained from a lava flow in the postglacial Pashleth and Machmel Creek valleys. This flow is clearly much younger than the K-Ar date and high-energy glacial streams have only begun to etch a channel along the margin of the flow. A radiocarbon date from barnacles 8.5 km upstream from the mouth of Machmel River and buried by the flow yielded an age of 12,200 +/- 140 years. This is a maximum age for the lava flow, which could be much younger. Mount Silverthrone is also 3160 m high making it the highest known volcano in Canada.