Volcano: n. an opening in the Earth's crust through which molten lava, ash, and gases are ejected.
A volcano is an opening in the
earth’s surface through which hot lava, hot gases, and rock fragments erupt.
Volcanic eruptions sometimes take place on volcanic islands, which are made up
of cool, dried lava. Eruptions on volcanic islands are a spectacular sight.
Volcanoes are not always on
volcanic mountains, which is what many people think a volcano is. A volcano can
also be volcanic vents or just cracks in the earth’s surface.
There are three main types of
volcanoes. They are:
I. Shield volcano – a shield
volcano is low and dome-shaped. One is formed when large amounts of free flowing
lava spills from a vent and spreads widely.
II. Cinder volcano – a cinder
volcano is a cone-shaped mountain. One builds up when tephra erupts from a vent
and falls back to the earth around the vent.
III. Composite volcano – a
composite volcano is a cone shaped mountain. One is formed when both lava and
tephra erupt from a central vent.