The Earth is made up of a total of 7 layers which are- crust, lithosphere (crust and uppermost mantle), asthenosphere (upper mantle directly below the lithosphere), lower mantle, outer core and ...

Here the mantle melts to form molten magma which rises as the plates move apart and then cools to form new oceanic lithosphere. This new material is less dense than the asthenosphere, but cools and ...