Final answer:
Metamorphic rocks are formed when sedimentary and igneous rocks change under heat and pressure. The minerals in the rocks rearrange into bands or form new minerals.
Step-by-step explanation:
Metamorphic rock is formed when sedimentary and igneous rocks change over time under heat and pressure. Pressure from the weight of overlying rocks or from stresses of mountain building rearranges the minerals in rocks into bands or rearranges the atoms of the minerals into new minerals. Heat from the intrusion of a large igneous mass can also metamorphose a large area. Metamorphism can occur when rocks are buried deeply during the process of mountain building or when molten rock intrudes other rocks and bakes the contact zone where the molten rock touches the preexisting rock.