A
volcano is an
opening on the
surface of the
earth where
melted
rock (called
magma) is
ejected above the surface of the
earth as
lava.
volcanoes occur where
tectonic plates come into
contact with one another. there are
approximately 1,000
active volcanoes in the
world, many of them in an area known as the "
Ring of Fire" which circles the
Pacific Ocean.