Layers of earth

We have already studied in evolution of earth that the earth is made up of three layers. These are:

1. Crust
2. Mantle and
3. Core

Crust

Crust is the outermost solid and rocky layer of earth. The chief component of crust is silicon, which is present in the form of silicates. The thickness of crust varies from place to place. Its thickness is minimum (about 5 km) under the oceans and maximum (about 80 km) under the mountains.

Mantle

Mantle is the central layer of earth. It is mainly a solid layer having thickness of about 2900 km. the chief components of mantle are silicates or iron and magnesium. Inside the mantle, the temperature is in the range of 700 – 800⁰C. The pressure is also very high in mantle. Due to presence of high temperature and high pressure inside the mantle some rocks of mantle starts to flow. These flowing rocks are called magma.

Core

Core is the innermost layer of the earth. Core is composed mainly of iron and some nickel. The core of earth is divided into two parts; outer core and inner core. The inner core is made up of solid iron, whereas outer core is made up of liquid molten iron. The temperature at the centre of core is estimated to be in the range of 4000⁰– 5000⁰C.

Test Your Understanding and Answer These Questions:

1. What is the structure of earth?
2. Name three layers of earth.
3. What is the meaning of magma?
4. What is the temperature of core?
5. Name the outermost layer of earth?
6. Name the innermost layer of earth?