|
What about volcanoes? ¿Habla español?
|
|
|
There are different kinds of volcanoes, just like there are different kinds of trees. Here are some of
the different kinds:
Composite cones (stratovolcanos): steep-sided, consist of layers of both pyroclastic material and lava. Rocks comprising composite cones range from silica-poor varieties (basalt) through intermediate types (i.e. andesite), to silica-rich types (rhyolites), ex: Cascade Range of California, Oregon, Washington, and British Columbia. Pyroclastic Cones (cinder cones): small, steep-sided, composed largely of pyroclasts of various sizes with little, if any, lava., Occur in groups and are associated either with major volcanos in arcs or with isolated, local volcanic terranes. ex: Wizard Island at Crater Lake; San Francisco Mountain volcanic field, Arizona Volcanic Domes: small, steep-sided, shaped like inverted cups or domes, Formed by the intrusion, extrusion, or both of thick (viscous) siliceous magma, typically associated with major volcanos, but can also occur in independent fields of intermediate to siliceous volcanic structures that lack a single major volcano. ex: Long Valley Caldera (Mono Lake area, California) Shield cones: low rounded profiles (2-10°), cone-shaped accumulations of lava containing minor amounts of interlayered pyroclastic materials, ex: Snake River Plain in western North America |