Stratovolcano Stratovolcano A stratovolcano, also known as a composite volcano, is a conical volcano built up by many layers (strata) of hardened lava, tephra, pumice and ash. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile with a summit crater and periodic intervals of explosive eruptions and effusive eruptions, although some have collapsed summit craters called calderas. The lava flowing from stratovolcanoes typically cools and hardens before spreading far due to high viscosity. The magma forming this lava is often felsic, having high-to-intermediate levels of silica (as in rhyolite, dacite, or andesite), with lesser amounts of less-viscous mafic magma. Extensive
Canadian Cascade Arc and a group of basaltic and andesitic volcanoes known as the Bridge River Cones. Mount Meager is composed of at least four overlapping stratovolcanoes that become progressively younger from south to north. These were formed in the last 2.2 million years, with the latest eruption having been about 2,350 years ago. The mafic, intermediate and felsic volcanic rocks comprising Meager were erupted from at least eight volcanic vents. Extending north of the Mount Meager massif almost to the Interior Plateau are the Bridge River Cones. This group of small volcanoes on the upper Bridge River includes stratovolcanoes, volcanic plugs and