At a subduction
zone one plate is forced underneath another.When the two plates collide, the younger of the two plates will rise
over the edge of the older plate. This will happen because the younger plate is less dense. At a subduction sone, sedimentary
rock can be pushed down into the earth, and one of two things can happen.
it will be put under heat and pressure, and over time be turned into a different form of rock. This new form of rock is metamorphic.
The rock will be melted and turned into magma. And the rock cycle will begin all over again.