What are the differences between the lithosphere and the asthenosphere?
The lithosphere, Greek for “rocky sphere,” is the outermost shell of the Earth. The term is also used to refer to the outermost rocky shell of other solid planets. It is a relatively thin layer, 50-100 km thick under the oceans, 150 km thick on the continents. The lithosphere is composed of the upper crust, 5 km thick in the oceans and 65 km thick on the continents, and the upper mantle, which makes up the remainder. Separating the crust and the upper mantle is the Mohorovičić discontinuity, the point at which rocks become plastic rather than solid. Beneath the lithosphere is the asthenosphere, which continues the upper mantle, and is approximately the point at which the mantle becomes liquid. Asthenosphere is a zone of the earth’s mantle that lies beneath the lithosphere and consists of several hundred kilometers of deformable rock.
