Garibaldi Volcanic Belt

Mount Cayley as seen from its southeast slopes

Mount Fee as seen from its north side

Black Tusk viewed from the southeast

The Garibaldi Volcanic Belt is a north-south range of volcanoes in southwestern British Columbia. It is the northern extension of the Cascades Volcanic Belt in the United States (which includes Mount Baker and Mount St. Helens) and contains the most explosive young volcanoes in Canada. The Garibaldi Volcanic Belt includes the Bridge River Cones, Mount Cayley, Mount Fee, Mount Garibaldi, Mount Price, Mount Meager, Mount Silverthrone and the Squamish Volcanic Field. The eruption styles in the belt range from effusive to explosive, with compositions from basalt to rhyolite. Morphologically, centers include calderas, cinder cones, stratovolcanoes and small isolated lava masses. Due to repeated continental and alpine glaciations, many of the volcanic deposits in the belt reflect complex interactions between magma composition, topography, and changing ice configurations. The most recent major catastrophic eruption in the Garibaldi Volcanic Belt was from Mount Meager 2,350 BP. The most recent eruption from Mount Silverthrone, at the northern tip of the belt, is probably younger then 1,000 AD.

The Chilcotin Plateau Basalts east of the Garibaldi Volcanic Belt, is thought to have formed as a result of extension of the crust behind the Cascadia subduction zone.

[edit] Cascadia subduction zone

Main article: Cascadia subduction zone

Area of the Cascadia subduction zone, including Cascade volcanoes (red triangles)

The Garibaldi Volcanic Belt was formed by the subduction of the Juan de Fuca Plate and the Explorer Plate to its west, which are remnants of the much larger Farallon Plate, under the North American Plate and has produced the Cascadia subduction zone. It is a 680-mile long fault, running 50 miles off the west-coast of the Pacific Northwest. It starts from Northern California and stretches to northern Vancouver Island, British Columbia. The subduction zone has created large earthquakes, including the Cascadia earthquake, which took place at the evening of January 26, 1700 by a magnitude 8.7 - 9.2 megathrust earthquake. Unlike in most subduction zones, there is no trench present along the continental margin. Instead, terranes and the accretionary wedge have been uplifted to form a series of coast ranges and exotic mountains. The subduction zone moves at rate of over 10 mm per year in a north-easterly direction and the outer margin is slowly being compressed, similar to a giant spring.