From the surface of the earth, it would be impossible for us to find, metamorphic rocks which were formed deep in the crust. However, the metamorphic rocks outcropped above the earth’s surface later because of tectonic movement which resulted in crustal uplift and denudation of the rock formations covering the metamorphic rocks. As a result, metamorphic rocks can bring geologists all kinds of information from the deep crust of the earth.Through the study of metamorphic rocks, we can know a lot about geoscience as well as the composition and evolution of the Earth's crust.