Mount Price (British Columbia) - Geology

Geology

Mount Price is one of the three principal volcanoes in the southern segment of the Garibaldi Volcanic Belt. In contrast to most stratovolcanoes in Canada, Mount Price has a nearly symmetrical structure. It is one of the several Garibaldi Belt volcanoes that have been active in the Quaternary period. Clinker Peak, a breached volcanic crater on its western flank, was formed during a period of volcanic activity about 10,000 years ago. Oxidation of Price's volcanic rocks has given the mountain a red colour.

Like other volcanoes in the Garibaldi Volcanic Belt, Mount Price formed as a result of subduction zone volcanism. As the Juan de Fuca Plate subducts under the North American Plate at the Cascadia subduction zone, it forms volcanoes and volcanic eruptions. Unlike most subduction zones worldwide, there is no deep oceanic trench present along the continental margin in Cascadia. There is also very little seismic evidence that the Juan de Fuca Plate is actively subducting. As a result, the existence of active volcanism in the Cascade Volcanic Arc is the best evidence for ongoing subduction. However, volcanic activity along the Cascade Arc has been declining over the last few million years. The probable explanation lies in the rate of convergence between the Juan de Fuca and North American plates. These two tectonic plates currently converge at a rate of 3 cm (1.2 in) to 4 cm (1.6 in) per year, only about half the rate of convergence from seven million years ago. This slowed convergence likely accounts for reduced seismicity and lack of an oceanic trench.