Lithosphere
The lithosphere provides a conductive lid on top of the convecting mantle: it reduces heat transport through the Earth. A lithosphere (Ancient Greek: λίθος [lithos] for "rocky", and σφαίρα [sphaira] for "sphere") is the rigid,[1] outermost shell of a terrestrial-type planet or natural satellite which is defined by its rigid mechanical properties. On Earth, it is composed of the crust and that portion of the upper mantle which behaves elastically on time scales of thousands of years or greater. The outermost shell of a rocky planet, the crust, is defined on the basis of its chemistry and mineralogy.