The crust is the thinnest layer of the Earth. On the surface of the Earth, the crust can be as deep as 25 km down. While in the ocean it can be as deep as 7 km. The tempuratures in the crust can range from 200° up to 400°C. The crust is composed of granite, diorite and basalt like rocks. The crust is formed of many "plates", these are called tectonic plates. The tectonic plates are constantly moving around in different ways the boundaries in which way they are moving are either divergent, convergent or transforming. The Crust is also a part of the lithosphere which also composes of the upper mantle.