Final answer:
The separation of Earth into layers of different densities is an example of differentiation, which is the process of sorting the major components of a planet by density.
Step-by-step explanation:
The separation of Earth into layers of different densities is an example of differentiation, the process of sorting the major components of a planet by density. The fact that Earth is differentiated suggests that it was once warm enough for its interior to melt, permitting the heavier metals to sink to the center and form the dense core. Evidence for differentiation comes from comparing the planet's bulk density (5.5 g/cm³) with the surface materials (3 g/cm³) to suggest that denser material must be buried in the core.