The portion of the interior beyond the crust is called the mantle.
(i)The mantle extends from Moho’s discontinuity to a depth of 2,900 km. The upper portion of the mantle is called asthenosphere. The word astheno means weak. It is considered to be extending upto 400 km.
(ii)It is the main source of magma that finds its way to the surface during volcanic eruptions. It has a density higher than the crust’s (3.4 g/cm3).
(iii)The crust and the uppermost part of the mantle are called lithosphere. Its thickness ranges from 10-200 km. The lower mantle extends beyond the asthenosphere. It is in solid state.
