VOLCANOES, Eruptions and Igneous Features



Redoubt VolcanoVolcanoes Volcanoes.htm





Locations of volcanoes


  • a mountain that forms when magma reaches the earth’s surface

Cascade Range from Northern California to Washington

Mt. St. Helens, May 1980

Kilauea in Hawaii

Formation of volcano

Type of eruption

Location and types of volcanoes


Most volcanoes occur along plate boundaries or at hot spots in the crust

Hot spots – a region where hot rock extends from deep within the mantle to the surface

Shield volcano – flat, wide volcano formed by quiet eruption of low-viscosity lava

Cinder cone volcano-small, steep sided volcano formed by ash and cinders

Composite volcano – formed from explosive eruptions, that produce a combination of lava and ash

Other Igneous Features

batholith – largest type of intrusive igneous rock mass, often form the core of a mountain range, such as the Sierra Nevada range in California

sill – magma that hardens in rock cracks parallel to existing rock

dike – magma that hardens in rock cracks perpendicular to existing rock

volcanic neck – when magma hardens in a volcano’s pipe


back to top