Volcano

Snow-covered Kanaga Volcano in Alaska erupts a small column of tephra, gas, and steam. Kanaga is a stratovolcano. View is toward the west.

A volcano forms when magma, in the form of lava, is able to breach the surface of the Earth. Many volcanoes tend to resemble mountains, although some are so large that they form entire islands, as is the case of Mauna Loa. Volcanoes come in three main types, stratovolcano (also composite cone), shiled volcano, and cinder cone.