The state of the mantle, the layer of Earth between the crust and the core, depends on its depth. Near the surface, the rock is very hard and dense. Deeper in, immense heat and pressure render the rock into a semisolid, or plastic, state.
The mantle is roughly 1,802 miles thick and consists of four layers: the lithosphere, the asthenosphere, the upper mantle and the lower mantle. The layer closest to the surface of the Earth is the lithosphere, and the rock there is very similar to that of the crust. The layer closest to the core is the lower mantle, where the rock is the most dense and hotter than the rest of the mantle.
