Heavy elements like iron and nickel moved to the Earth's center, forming a dense metallic core and a mantle that can flow slowly, with the crust forming the thin outer layer.
As the Earth formed, heavier elements such as iron and nickel moved to the center of the Earth, a process known as planetary differentiation. This resulted in the formation of the Earth's layers, with a dense metallic core and an overlying mantle.
The core is split into two parts: the solid inner core, made predominantly of an iron and nickel alloy, and the liquid outer core, thought to be responsible for Earth's magnetic field. Surrounding the core is the mantle, which accounts for a significant volume of Earth's structure and is composed of solid rock that can flow slowly due to high temperature and pressure.
This increase in pressure causes the density in the mantle to range from about 3.5 g/cm³ at the top to more than 5 g/cm³ at the base. The Earth's crust forms the thin outer layer, which includes both continental and oceanic types, differing in thickness, composition, and density.