Whether they're igneous rocks undergoing stress , or sedimentary rocks undergoing changes in heat and pressure , these processes physically change the rock, changing it into something new.
(they; 're; igneous rocks undergoing stress , or sedimentary rocks) (igneous rocks; undergoing; stress , or sedimentary rocks) (sedimentary rocks; undergoing; changes in heat and pressure) (these processes; physically change; the rock; changing it into something new)
they igneous rocks sedimentary rocks these processes
're undergoing undergoing physically change
igneous rocks undergoing stress , or sedimentary rocks
stress , or sedimentary rocks
changes in heat and pressure
the rock changing it into something new