MOUNT SILVERTHRONE

'Mount Silverthrone' (officially gazetted as 'Silverthrone Mountain') is a circular wide, deeply dissected caldera complex in Regional District of Mount Waddington, British Columbia, in the Pacific Northwest region of Canada. It is located over northwest of the city of Vancouver and about west of Mount Waddington. It is the highest summit in the Ha-Iltzuk Icefield, which is the largest icefield in the Coast Mountains south of the Alaskan Panahandle.
Silverthrone may be the northernmost member of the Cascade Volcanic Arc, but scientific study has been very limited due to its extremely remote location. Its relationship to volcanism caused by the Cascadia subduction zone (ie. the Cascade Volcanic Arc) has not been firmly established.
Mount Silverthrone may also be the highest volcano in Canada, but even its elevation is not definitely known. Some references state an elevation as high as , but the current topographic map shows contours only as high as , and no spot elevation is given. It addition, it is unclear whether the highest point is of volcanic origin or not, since the summit is covered with permanent snow and ice, and the composition of the underlying rock is unknown.
The first mountaineering visit at Mount Silverthrone was by the famous pioneering climbing group of Don and Phyllis Munday in 1936 by walking up the Klinakini Glacier from the head of Knight Inlet.

Geology and eruptive history

The Mount Silverthrone caldera complex contains rhyolitic, dacitic and andesitic lava domes, lava flows and breccia. Most of the caldera's eruptions occurred during the last ice age. Mount Silverthrone was episodically active during both Pemberton and Garibaldi Volcanic Belt stages of volcanism. 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 million years 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 upstream from the mouth of the 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. The last eruption from Mount Silverthrone ran up against ice in Chernaud Creek. The lava was dammed by the ice and made a cliff with a waterfall up against it.

Volcanic hazards

Mount Silverthrone is in a heavily glaciated area west of the Klinaklini River. Melting of the Ha-Iltzuk Icefield by volcanic activity could produce floods, lahars, or debris flows. Mount Silverthrone is one of the top 10 Canadian volcanoes with recent seismic activity, the others include: Castle Rock, Mount Edziza, Mount Cayley, Hoodoo Mountain, Lava Fork Valley, Crow Lagoon, Mount Meager, Wells Gray-Clearwater Volcanic Field and Mount Garibaldi.

Easiest access

The easiest access to Mount Silverthrone is by air travel, starting from the rural community of Tatla Lake, landing on the major part of the Ha-Iltzuk Icefield. Air travels can also be made into logging camps at Owikeno Lake to the west or at the start of Knight Inlet to the southwest, followed by long hiking and skiing methods.