The document describes the three main layers of the Earth - crust, mantle, and core. The crust is the thinnest layer and is broken into tectonic plates that move atop the mantle. The mantle, made of hot dense rock, flows via convection currents which cause plate movement at the asthenosphere. Temperature, density and pressure all increase with depth in the Earth. The core is the center-most layer and hottest part of Earth.