The lithosphere (IPA: [ˈlɪθ.ə.sfiɹ], from the Greek λίθος [líthos] for "rocky" + σφαίρα [sfaíra] for "sphere")'s the rigid outermost shell of a rocky planet. Earth's lithosphere In the Earth, the lithosphere includes the crust and the uppermost mantle, which constitute the hard and rigid outer layer of the planet. The lithosphere's underlain by the asthenosphere, the weaker, hotter, and deeper part of th… (More on Lithosphere)