The document describes the layers of the Earth. It has a crust that is 5 to 25 miles thick, a mantle that is 1,800 miles thick below the crust, an outer core that is 1,400 miles thick below the mantle, and an inner core that is 800 miles thick at the center of the Earth. The crust is composed of igneous, metamorphic and sedimentary rocks, while the mantle and cores are composed of hot molten rock and liquid metal respectively.