The preexisting rock that is subsequently altered to form a metamorphic rock is termed a
A) xenolith.
B) source rock.
C) protolith.
D) phenocryst.

Question

Quizplus · Accepted Answer

A protolith, also known as a parent rock or source rock, is the preexisting rock that undergoes metamorphism to form a metamorphic rock. Choice A, xenolith, refers to a foreign rock fragment that is incorporated into another rock during its formation. Choice D, phenocryst, refers to a large crystal that is typically found in an igneous rock.

The Preexisting Rock That Is Subsequently Altered to Form a Metamorphic