Metamorphic rocks formed when either sedimentary, igneous, or earlier formed metamorphic rocks were put under pressure and heat deep in the earth's crust.
(Metamorphic rocks; formed; T:when either sedimentary, igneous, or earlier formed metamorphic rocks were put under pressure and heat deep in the earth's crust) (metamorphic rocks; were put; under pressure; L:deep in the earth's crust)
Metamorphic rocks metamorphic rocks
formed were put
T:when either sedimentary, igneous, or earlier formed metamorphic rocks were put under pressure and heat deep in the earth's crust
under pressure L:deep in the earth's crust