What are the subtypes of metamorphic rocks?
Metamorphic rocks can be classified by type of metamorphism. Regional metamorphism is caused by pressures and heat derived from plate movement processes. Contact metamorphism is caused from proximity to an intrusive plutonic body. Metamorphic rocks are also classified by degree of metamorphism, expressed as a grade (low, medium, high), as a rock experiences higher and higher heat and pressure until it eventually melts.
