Earth material becomes denser as you move closer to the core. Once you move past the lithosphere and the asthenosphere and get deep into the mantle, you get into magma like material flowing at a very thick consistency. When you get into the outer core the density thickens and the material consists of melted nickel and iron. Then once you move deep into the inner core the iron and nickel has such a high density it solidifies into a solid state. So, in general, as you go deeper into the Earth, the material gets denser and eventually the particles get so compacted they beome a solid again.