How is a
volcano formed?
A volcano is
a special kind of mountain that actually builds itself. Scientists think that
far down in the Earth, where it is fiercely hot, there are pockets of melted
rock. It is thought that the pressure of gas pushes this melted rock, called
magma, up out of the ground. Once magma comes out of the ground it is known as
lava. Lava may be thick like syrup or thin as watery soup, but it cools into a
black, gritty rock. It is this rock that builds the volcano. As the lava pours
out of the earth, it piles up into the shape of a cone, with a tunnel running
down its middle. The more lava that comes out, the higher and wider the volcano
gets. Volcanoes can erupt in different ways. One kind shoots a stream of
glowing lava high into the air, like a giant, fiery fountain. Another shoots
out solid chunks of red-hot rock and cinders. Some volcanoes pour rivers of
lava through cracks in their sides. And some blow themselves to pieces.
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