They form when magma crystallizes within the neck of a volcano, and are exposed for us to see as weathering and erosion remove the rock comprising the volcano.
(They; form; T:when magma crystallizes within the neck of a volcano, and are exposed) (the rock; comprising; the volcano) (magma; crystallizes; within the neck of a volcano) (magma; are exposed; ) (us; to see; as weathering and erosion) (us; to remove; the rock comprising the volcano)
They the rock magma magma us us
form comprising crystallizes are exposed to see to remove
T:when magma crystallizes within the neck of a volcano, and are exposed
the volcano
within the neck of a volcano
as weathering and erosion
the rock comprising the volcano