Metamorphic rocks are sedimentary or igneous rocks that have been altered by the action of heat or pressure.
(Metamorphic rocks; are; sedimentary or igneous rocks that have been altered by the action of heat or pressure) (sedimentary or igneous rocks; have been altered; by the action of heat or pressure)
Metamorphic rocks sedimentary or igneous rocks
are have been altered
sedimentary or igneous rocks that have been altered by the action of heat or pressure
by the action of heat or pressure