6 Geography

Major Landforms of Earth

Learning Goals:

  • Mountains
  • Plateau
  • Plains
  • Landforms and People

Landform is a natural feature of the earth’s surface. The surface of the earth varies from one place to another. The main landforms are; mountains, plateau and plains.

There are two processes which lead to formation of different landforms. These processes are; internal process and external process.

Internal Process: The earth beneath your feet is continuously moving. The movement of earth’s surface results in internal process. The internal process results in a portion of the earth’s surface getting elevated or getting sunk.


External Process: Continuous wearing down and rebuilding of the earth’s surface is the result of external process.

Erosion: Removal of materials is called erosion. Erosion results in lowering of the earth’s surface. Erosion is carried out by various agents; like wind and water.

Deposition: Deposition of materials results in rebuild of the earth’s surface. It also results in the surface getting elevated. Wind and water are the main agents of deposition.

Mountains

A mountain is the natural elevation of the earth’s surface. A mountain may be narrow at top and broad at the base. The elevation of mountain is considerably more than that of surrounding area.

We know that temperature reduces with increase in altitude. Due to this, very high mountains are usually covered with snow.

Glacier: Permanently frozen rivers of ice are called glaciers. Glaciers are found in some of the very high mountains.

Population at Mountains: Because of steep slopes, less amount of land is available for farming on mountains. This is also difficult to build houses on steep slopes. Hence, less number of people lives on the mountains.

Mountain Range: When mountains are arranged in a line, then it is called a mountain range. Some of the mountain systems contain ranges spread over hundreds of kilometers.



Types of Mountains

There are three types of mountains, viz. fold mountains, block mountains and volcanic mountains.

fold mountain
Fig: Fold Mountain

Fold Mountains: When a tectonic plate gets pressure from two sides, it gets folded. Some of its portion becomes elevated and forms the mountains. The depressions form the valleys. The Himalayas, The Andes and the Alps are examples of Fold Mountain. They are the young mountains of the world and hence they have some of the highest peaks of the world. The Aravali is also an example of Fold Mountain. Because of constant erosion, the Aravali has considerably worn down.

block mountain
Fig: Block Mountain

Block Mountains: When large areas are broken and displaced vertically, Block Mountains are formed. In this case, the uplifted blocks are called horsts. On the other hand, the lowered blocks are called graben. Examples of Block Mountains are; the Rhine Valley and the Vosges mountain in Europe.

Volcanic Mountains: A mountain formed due to volcanic activity is called Volcanic Mountain. Examples of Volcanic Mountains are; Mt. Kilimanjaro and Mt. Fujiyama.

Importance of Mountains:

  • Mountains are rich sources of water. Many important rivers originate from glaciers on mountains. Water from the mountains is used for irrigation and also for power generation.
  • River valleys and terraces are ideal for cultivation.
  • Mountains are rich in flora and fauna. The plant species of a place is called flora. The animal species of a place is called fauna.
  • Mountains provide many forest produce; like wood, herbs, medicinal plants, honey, catechu, etc.
  • Mountains are ideal tourist spots. Many adventure sports are only possible in the mountains; like river rafting, paragliding, hang gliding, skiing, etc.




Plateau

A plateau is a flat and elevated land. A plateau is at higher elevation than the surrounding areas. A plateau may have one or more sides with steep slopes. A plateau can be young or old. The height of plateau can be from a few hundred meters to several thousand meters.

Examples: The Deccan Plateau (India) is one of the oldest plateaus in the world. Other examples of plateau are; the East African Plateau in Kenya, Tanzania and Uganda and the Western Plateau in Australia. The Tibet plateau is the highest plateau in the world and its elevation is between 4,000 to 6,000 m above sea level.

Importance of Plateau

  • Plateaus are rich in mineral deposits. Many mining belts in the world are located in the plateau areas.
  • Most of the mining areas in India are in the Chhotanagpur Plateau in Jharkhand, Orissa and Chhattisgarh.
  • The African plateau is famous for mines of gold and diamond.
  • Many waterfalls are present in plateau areas. For example; the Hundru falls in the Chhotanagpur and Jog falls in Karnataka.
  • The lava plateaus are rich in black soil. Black soil is fertile and is good for cultivation.
  • Plateau areas are great tourist attractions because of lot of scenic spots.

Plains

Plains are flat lands and are generally not more than 200 m above mean sea level. Some plains are extremely level, while others may be slightly rolling and undulating.

Formation of Plains: Plains are usually formed by rivers and their tributaries. When a river flows down a mountain, it erodes the mountain. The river carries forward the eroded material. Then the river deposits the load in its valley. The load consists of stones, sand and silt. Plains are formed from these deposits.

Importance of Plains:
  • Plains are usually highly fertile and hence most ideal for cultivation.
  • It is very easy to make transport network in the plains.
  • Due to above mentioned factors; plains are the best areas for human habitation.
  • Most of the densely populated areas of the world are in the plains.
  • The Indo-Gangetic Plains in India is among the most densely populated regions of the world.

Landforms and the People

  • Humans have been living in most of the terrains.
  • Life is difficult in mountain areas because of rugged terrain. Hence, mountain areas are sparsely populated.
  • Life is somewhat easier in the plateaus; compared to in mountains.
  • Life is the easiest in the plains.
  • In all types of terrains, natural calamities always pose threat. Earthquakes, storms and floods can hit any area. Volcanic eruption can be potential risk in areas near volcanic activity.
  • But people need to learn to live with natural disasters. Proper precautions can help save life and property; in case of natural disasters.