<span>Foliated rocks show different minerals or grains that have been segregated into layers or aligned nonrandomly. Quartzite is an example of a nonfoliated metaphoric rock. The main factor that changes rocks during contact metamorphism is both heat and pressure, but if had to choose one I would select pressure. When shale undergoes metamorphism it becomes slate!</span>
A subduction zone is also generated when twooceanic plates collide — the older plate is forced under the younger one — and it leads to the formation of chains of volcanic islands known as island arcs.
