What is the liquid rock on the surface of earth?

Liquid rock can be found on the surface as erupted lava, or in the lithosphere as it attempts to rise toward the surface (molten rock under the surface is called magma). Molten rock originates at the boundary between the lithosphere and the asthenosphere due to the introduction of cold wet oceanic crust into the upper mantle at convergent plate boundaries, or from decompression melting at hot spots and divergent plate boundaries. The asthenosphere is partially molten, but is mostly solid. The outer core is the only liquid layer of the Earth, composed mainly of liquid iron and nickel.