Volcanoes

This is a volcanic "cone". Click on image for full size version (40K GIF) Image from: U.S. Geological Survey

There are several ways in which a volcano can form, just as there are several different kinds of volcanoes. Volcanism is part of the process by which a planet cools off.

Hot magma, rising from lower reaches of the Earth, eventually, but not always, erupts onto the surface. During the eruptionlava and ash form a cone. This cone is what we know as a volcano. Strong earthquakes accompany rising magma just before an eruption, as illustrated in this picture.

Among the different kinds of volcanoes are:

• shield volcanoes
• cinder cones
• composite volcanoes