Earth's crust is made up of huge
slabs called plates.
>
The plates move constantly.
>
At times, the plates move away
from each other, creating gaps.
>
Molten magma flowing beneath
Earth's surface finds its way
out of the gaps.
>
Magma comes out of Earth, creating
a heap of lava, ash, and rocks.
>
The heap grows bigger and bigger
as the volcano erupts, creating a
huge mound.
>
The mound cools down over
thousands of years to form
a mountain.