When magma beneath the Earth's surface is forced up through any opening in Earth's crust, it is called a volcano. Some pour or explode molten rock, ash, cinders, and poisonous gases. Volcanoes are also types of mountains made up of hardened layers of lava and cinders. There are three general types of volcanoes: the composite volcano, the shield volcano, and the cinder cone.

The composite volcano has the most powerful eruptions of all the volcanoes, Its steeply sloping cone is made up of alternating layers of cinders, ash, and lava. Gases that are trapped in silica rich magma cause eruptions switching between quiet flows of lava and violent eruptions of gas-rich lava. Mount St. Helens, Washington State and Japan's Mt. Fuji are examples of composite volcanoes. Mount St. Helens killed 57 people in less than 1 mintue on May 18, 1980!

Shield volcanoes are formed in the shape of a large round-like...