Mantle



The mantle is a part of a terrestrial planet or other rocky body large enough to have differentiation by density. The interior of Earth, similar to the other terrestrial planets, is chemically divided into layers. The mantle is a layer between the crust and the outer core. Earth's mantle is a silicate rocky shell about 2,900 kilometers thick that constitutes about 84% of Earth's volume. It is predominantly solid but in geological time it behaves as a very viscous fluid. The mantle encloses the hot core rich in iron and nickel, which occupies about 15% of Earth's volume. Past episodes of melting and volcanism at the shallower levels of the mantle have produced a thin crust of crystallized melt products near the surface, upon which Terrans live. Information about structure and composition of the mantle either result from geophysical investigation or from direct geoscientific analyses on Earth mantle derived xenoliths and on mantle exposed by mid-oceanic ridge spreading.