The document describes the different layers of the Earth, including the crust, mantle, outer core and inner core, along with their thicknesses and primary compositions. It explains that the mantle is the thickest layer and is separated into the upper and lower mantle, with most of the Earth's internal heat located in the mantle. The core is divided into the liquid outer core and solid inner core, with the Earth's magnetic field believed to be controlled by the outer core.