The earth is made up of three main layers. 

A) Crust:

1. The outer part of the earth on which we live is called the crust. 

2. While the earth was boiling in a molten form the lighter particles cooled at the top and formed the layer of crust. 

3. The curst mostly consists of various kinds of rocks. 

4. This layer goes up to a depth of 30 to 100 kms.

B) Mantle: 

1. While the earth was boiling in a molten form the less heavier particles settled in the middle and formed the mantle. 

2. The upper part of the mantle is a pliable layer over which the crust floats. 

3. This layer consists mainly of chemicals called silicates.

4. It exists at the depths from 100 kms to 2900 kms. 

C) Core: 

1. While the earth was boiling in a molten form the heaviest substances formed core. 

2. It is composed of dense and heavy substances like Iron and Nickel. 

3. It exists at the depths from 2,900 kms to 6,376 kms. 

4. It can be divided into two sub-layers.

a) Outer core : 

This layer is composed of liquid metallic material like nickel and iron. It is 2,900 – 5,100 kms in thickness. 

b) Inner core : 

The solid inner core is made up of iron compounds and heavy substances like gold. It is 5,100 – 6,376 kms in thickness.