Why are the layers of earth sorted by density?

The layers of Earth are sorted by density due to the process of gravitational differentiation that occurred during the planet's formation. Heavier materials, such as iron and nickel, sank toward the center, forming the core, while lighter materials like silicates rose to form the mantle and crust. This sorting is driven by the force of gravity, which causes denser materials to move inward and less dense materials to stay outward. As a result, the Earth has a layered structure with distinct compositions and densities.