The mantle is a layer between the crust and the outer core. Earth's mantle is a silicate rocky shell with an average thickness of 2,886 kilometres (1,793 mi).
Themantle makes up about 84% of Earth's volume. It is predominantly solid but in geological time it behaves as a very viscous fluid.
The planetary core consists of the innermost layer(s) of a planet; which may be composed of solid and liquid layers. Cores of specific planets may be entirely solid or entirely liquid. In the Solar System, core size can range from about 20% (Moon) to 85% of a planet's radius (Mercury).
The crust of the Earth is composed of a great variety of igneous, metamorphic, and sedimentary rocks. The crust is underlain by the mantle. The upper part of the mantle is composed mostly of peridotite, a rock denser than rocks common in the overlying crust. The boundary between the crust and mantle is conventionally placed at the Mohorovičić discontinuity, a boundary defined by a contrast in seismic velocity. The crust occupies less than 1% of Earth's volume