The thickness of the Earth's crust varies with location and ranges from 1 to 80 kilometers thick. The continental crust is 50 kilometers thick on average, while the oceanic crust typically reaches no more than 20 kilometers thick.
The Earth's crust is the outermost of its three main layers. It rests above a layer of semisolid rock known as the mantle, which surrounds the Earth's core. The crust has oceanic and continental layers. The continental layer is typically older and thicker than the oceanic crust. The oceanic crust continually renews itself by sinking into the mantle and reforming through a process called subduction.