Layers Of Earth | Earth’s Structure

Key Concepts

• Earth
• Crust
• Mantle
• Inner core
• Outer core

Introduction: 

Earth is the place where we live, and it is the third planet from the sun. 70% of the earth is covered by water. Earth is a unique planet. It has supported life for many years. Earth is round in shape, and it’s not a solid piece of rock. It is made up of various layers. Each layer of the earth has different physical and chemical characteristics. Earth is also called a water planet or blue planet due to the presence of water on it. The only planet that has water on its surface is earth. 

There are many features on the earth’s surface. These features are called landforms.  

Earth’s structure 

The Earth’s structure consists of four distinct layers: the crust, mantle, outer core, and inner core.

Crust: 

• It is the thinnest outermost layer of the earth. It is known as the lithosphere. 
• It is a sphere of solid rock. 
• It is brittle and hence can crack very easily. 
• Earth’s landforms such as mountains, plains, plateau, ocean, river, desert are found on the crust. 
• The oceanic crust is 5 km thick and consists of silica and alumina, and the continental crust consists of rocks. 

• Continental crust is land where we live, and it is 70 km thick. 

Mantle :

• This layer of rock is present below the crust. 

• It expands up to a depth of 2900 km below the crust. 
• Mantle is divided into upper and lower mantle.  
• Mantle is mainly comprised of silicate rocks that are rich in iron and magnesium. 
• In some places, rock is in the molten state called magma or aesthenosphere. When the magma reaches near the crust, it comes out in the form of lava from the volcano.  
• In the mantle, rocks move continuously up and down due to inter heat from the core area and form convective currents. 

• These currents cause rock plates to move and collide with each other that results in earthquakes. 
• Tectonic plates are formed by the combination of the upper mantle and crust. These plates move very slowly. The point where plates touch each other is called a fault. 

Outer core :

• This layer is next to the mantle.  
• It is present in liquid state at the 5000 degree centigrade temperature. 
• The outer core comprises nickel and iron. These two metals are in a liquid state due to tremendous heat in the outer core. 
• The outer core creates a magnetic field around the earth due to its constant circulatory motion. 
• The benefit of this magnetic field is that it protects the earth from the sun’s damaging solar wind. 

• This layer is very important because without this layer, the earth will not have a magnetic field, and without a magnetic field, the earth will not have life, ocean and atmosphere on it. 

Inner core :

• This layer is the hottest layer of the earth, with a temperature of 7000 degrees centigrade. It is hotter than the sun’s surface. 

• It is below the outer core. 
• It comprises iron and nickel. 
• Though it is the innermost layer, it is present in the solid state because it is under high pressure of the weight of layers present above it. 

Summary:

• Earth is the place where we live. It is the third planet from the sun.
• Earth is made up of various layers-crust, mantle, outer core and inner core.
• B Earth is also called a water planet or blue planet due to the presence of water on it.
• The crust is the thinnest outermost layer of the earth.
• B Mantle is mainly made up of silicate rocks that are rich in iron and magnesium.
• The outer core is present in the liquid state at the 5000-degree centigrade temperature.
• The inner core is the hottest layer of the earth, with a temperature of 7000 degrees centigrade.