Describe the Formation of Erosional Plains.

Plains are large, flat and level pieces of land. They are generally very fertile in nature and support the growth of crops and other plants which are useful to humans. Plains generally have a large amount of population due to various reasons such as easy terrain, more opportunities, fertile land and availability of good lifestyle and climate. Thus plains are an important landform in geography. India has plains to its North and North-East parts which are called the Northern Plains. These plains are very fertile and are formed by the Ganga and Brahmaputra along with their tributaries. These plains stretch from Punjab, Haryana, Uttar Pradesh, Bihar, Jharkhand and West Bengal. Northern plains have nearly 60% of the total population of India. Apart from these India also has coastal plains along the Western and Eastern coasts called the Western and Eastern coastal plains respectively.

Types of Plains

The plains can be broadly classified into the following types:

Structural Plains

• The lifting of a continental shelf or seabed or the diastrophic movements of a large area of land leads to the formation of structural plains.
• Land subsidence may also be one of the factors for the formation of the structural plains.
• They are one of the natural lowland areas of the Earth.
• The plains of the USA and the central highlands of Australia are the finest examples of structural plains.
• Apart from these, they can also be found along the borders of the major continents.

Depositional Plains

• These plains are formed by the deposition of silt, sand, soil and gravel by the flowing rivers, winds or glaciers.
• These plains are very fertile in nature and the soil is rich in organic content as well as nutrients.
• The nutrients of these plains are replenished every year by the rivers that bring a large amount of silt and gravel from the upper mountains and deposit them in the plains as the speed of the rivers reduces on entering the plains.
• The Northern Plains of India is an example of the depositional plains and are also called alluvial plains. These can be further classified as khadar and bhangar. Khadar are the new alluvial plains and are replenished every year by the rivers whereas bhangar are the old alluvial plains, a little away from the river valleys that make up Khadar plains.
• The depositional plains that are made by the action of wind are termed Loess. China has a large area of loess in the world.

Depositional plains are further classified as following depending upon the agent that leads to their formation

• Lava Plain
• Lacustrine Plain
• Glacial Plain
• Scroll Plain
• Abyssal Plain

Erosional Plains

• These plains are the result of the erosion action of various agents such as the wind, air and water. These agents of degradation cause the upper hard rock to erode and expose the plains under the rocks which are called erosional plains.

Formation of Erosional Plains

• As the rivers flow the strong force of the water strikes the rocks and causes the rock material to erode away which forms these plains.
• The combined action of wind and water develops deep cracks in the rocks. As time passes, the cracks deepen and the rocks break into smaller and smaller rocks which are easily carried away by water and, further erosion of rocks transforms them into fine particles which can be easily carried away by the wind. In both cases, the upper rock material is eroded away and the underlying plain is exposed.
• Glaciers take away a large amount of the rocks and other material along with them as they melt and expose the soft soil below it which form the erosional plains. The material carried away by the glaciers is called glacial moraines.
• Erosional Plains can be further classified into 2 types based on the agents of erosion or the agents responsible for their formation. These are as follows:
  • Peneplains: Peneplains are the result of the different agents of erosion such as rivers and glaciers but not wind.
  • Pediplains: The plains that are formed only by the action of wind are termed the Pediplains.
• The Plains of Canada and Niagara Plains of the USA are an example of the erosional plains in the world.

Difference between Erosional and Depositional plains

Depositional Plains	Erosional Plains
These plains are formed by the deposition of the soil and other material by the wind, rivers or glaciers.	These plains are formed by the erosion action of the rivers, wind and glaciers.
They are replenished every year by the rivers and are also called floodplains if they are formed due to the flooding of the rivers.	These plains take a long time to form as the upper rock material erodes very slowly over a long period of time.
The depositional plains formed by the action of wind are called Loess.	The erosional plains formed by the action of wind are called Pediplains.
The depositional plains formed by the action of rivers and glaciers are called flood plains and glacial plains respectively.	The action of rivers and glaciers leads to the formation of erosional plains which are called Peneplains.
The Northern Plains of India is an example of the depositional plains.	The Plains of Canada and the Niagara Plains of the USA are an example of the erosional plains in the world.

Frequently Asked Questions (FAQs)

Que 1. Define erosional plains.

The plains that are formed by the erosional action of various agents such as the wind, rivers and glaciers are called erosional plains. Plains of Canada is an example of erosional plains.

Que 2. Define depositional plains.

Depositional plains are formed by the deposition of the silt, sand, soil and gravel by the flowing rivers, winds or glaciers. These plains are very fertile in nature and the soil is rich in organic content as well as nutrients.

Que 3. Explain the types of Erosional Plains.

• Erosional Plains can be further classified into 2 types based upon the agents of erosion or the agents responsible for their formation. These are as follows:
• Peneplains: Peneplains are the result of the different agents of erosion such as rivers and glaciers but not wind.
• Pediplains: The plains that are formed only by the action of wind are termed as the Pediplains.

Que 4. What do you mean by loess? Give an example of loess.

The depositional plains that are made by the action of wind are termed as Loess. Loess of China is a good example of these type of plains.

Que 5. How are structural plains formed?

Lifting of a continental shelf or seabed or the diastrophic movements of the large area of land leads to the formation of the structural plains.