What caused the interior of earth to separte into layers?

The interior of the Earth separated into layers due to a process called planetary differentiation, which occurred during the planet's early formation. As the Earth was still molten, denser materials like iron and nickel sank toward the center, while lighter materials rose to form the crust. This gravitational separation led to the distinct layering we see today: the core, mantle, and crust. Heat from radioactive decay and residual energy from the planet's formation also contributed to this differentiation process.