The term 'LAYERS OF EARTH' can be summarized by the four-letter word 'SODS, ' which stands for the four main layers of the Earth: the solid inner core, the outer core, the mantle, and the crust. The inner core is composed of solid iron and nickel, while the outer core is made up of liquid iron and nickel. The mantle is a thick layer of hot rock, and the crust is the thin layer of solid rock that makes up the surface of the Earth.