Crust

Earth has three main layers: the crust, mantle and core. These names distinguish materials with different compositions. The crust contains relatively light rocks, the mantle contains silicate rocks rich in iron and magnesium, and the core is dense metal, mainly iron with nickel.

The Earth has four main layers: crust, mantle, outer core and inner core. The crust is the thin, solid outermost layer. Beneath it lies the mantle, a layer of mostly solid rock about 2,900 km thick.