Structure of the Earth Cutaway computer artwork showing the internal structure of the Earth From the centre outwards the five layers shown are inner and outer core inner and outer mantle and crust The core is around of the volume of the Earth and the mantle is around The crust is a thin kilometres thick rock layer over the kilometrediameter Earth The core is heavy iron and nickel metal that sank to Earths centre The inner core is solid but the liquid outer core generates the Earths magnetic field The mantle is molten rock and the inner mantle is more fluid than the outer mantle due to higher temperatures which exceed degrees Celsius in the core