The brittle outer part of the earth, consisting of the crust and the upper mantle.

It is made up of six major and several minor tectonic plates that move around on the softer asthenosphere or the relatively plastic layer of the upper mantle of the earth on which the tectonic plates of the lithosphere move.

It is about 55 km (34 mi) thick beneath the oceans and up to about 200 km (124 mi) thick beneath the continents and is composed of rigid plates.

The high velocity with which seismic waves propagate through the lithosphere suggests that it is completely solid.

The movement of the plates of the lithosphere results in convergence, or collisions, that can form mountain belts and subduction zones, and divergence of the plates and the creation of new crust as material wells up from below separating plates. The lithosphere and asthenosphere are distinguished from the crust, mantle and core of the earth on the basis of their mechanical behavior and not their composition.

The chemical boundary layer between the surface of the earth and the asthenosphere that contains the material differentiated or extracted from the mantle.