The layered structure of the Earth was developed through the process of differentiation of the earth-forming materials.
The earth was initially a barren, rocky and hot object mostly in a volatile state during its primordial stage. Due to a gradual increase in density, the temperature inside has increased. As s result, the material inside started getting separated depending on their densities.
This allowed heavier materials like iron to sink towards the centre of the earth and the lighter ones to move towards the surface. With the passage of time, it cooled further and solidified and condensed into a smaller size.
This later led to the development of the outer surface in the form of a crust. During the formation of the moon, due to the giant impact, the earth was further heated up. It is through the process of differentiation that the earth-forming material got separated into different layers.
Starting from the surface to the central parts, we have layers like the crust, mantle, outer core and inner core. From the crust to the core, the density of the material increases and each zone has its own different characteristics. This is how the layered structure of the earth was developed.
