How scientist thought earths dour layers were formed?

Scientists believe Earth's four layers—crust, mantle, outer core, and inner core—formed through processes related to planetary differentiation. As the young Earth cooled, heavier materials like iron sank towards the center, forming the core, while lighter materials remained near the surface, creating the crust. The mantle developed as semi-solid rock, accommodating convection currents that drive tectonic activity. This layered structure reflects the planet's thermal history and the dynamics of its formation over billions of years.