The surface of this layer is called the crust. The theory of plate tectonics explains the nature, origin and function of the Earth's outer crust. Continental plates which are composed of granite and are very old. It is destroyed at the areas where plates collide and one plate is subducted under another. The creation of oceanic crust and its collision with continental crust cause the continents to move across the Earth's surface over geologic time.
Mountain building is the result of plate collisions.
For example, the Himalayas were created when the Indian plate crashed into the Eurasian plate. In the collision oceanic sedimentary deposits were pushed vertically to great altitudes. This explains why you can find marine fossils in mountain environments. Earthquakes are also a result of plate tectonics. They occur at faults, tectonic plate boundaries, and at the mid-oceanic ridge.