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Monday, July 20, 2020

NCERT Chapter Summary and Solutions For Class 6 Social Science Geography Chapter 6 - Major Landforms of the Earth



MajorLandforms of the Earth - The landform is a natural or artificial feature of the solid surface of the Earth or the planetary body.
  • The Major type of landform is - 1. Mountains, 2. Hills, 3. Plateau, 4. Plains
  •  The Minor type of landform is - 1. Buttes, 2. Canyons, 3. Valleys, 4. Basins

The Landforms are results of 2 processes:- 1. Internal process, 2. External process

  • Internal Process - It is a type of continuous movement within the earth that lead to the upliftment and sinking of the earth's surface at several places. The earth beneath the feet is continuously moving and it is driven by the heat (in the form of energy) in the earth's interior. E.g. Convection, Tectonic plate movement, Rock formation, Earthquake, Volcanic eruptions, etc.

  • External Process - It is the continuous wearing off and rebuilding of the land surface. They are powered by solar energy. E.g. Soil erosion, deposition, etc.
Fig. Landforms

ErosionThe wearing off the earth's surface. It is being lowered by the external process.            

  Fig. Soil Erosion

DepositionWhen the river loses its energy, it drops any of the material it has been carrying. The surface is being rebuilt by the external process.            
Fig. The force of moving river water - Erosion & Deposition 

The major type of landform (Depending on Elevation & Slope):-

A. Mountains: 

  • Mountains are natural elevations of the earth's surface. They vary in shape and size.
  • They are higher than in the surrounding area. Some of them are even higher than the clouds.
  • Glaciers, a permanently frozen river of ice. 
  • Rivers have their sources in the mountains and it is used for irrigation and the generation of hydro-electricity.
  • The climate of the mountain is harsh, which makes them less suitable for human habitation.
  • The river valley and terraces are ideal for crop cultivation, though some mountains have steep slopes. Hence, farming is quite difficult there.
  • Mountains have a rich variety of flora and fauna. Fuel, food, fodder, shelter, timber, and other products like gum, raisins, etc. can easily get from mountain and forest.
  • Mountain provides an idyllic scene and their scenic beauty for tourists. They can enjoy recreational activities like paragliding, hang gliding, river rafting, and skiing.
  • The mountain may be arranged in a series of parallel extending over hundreds of kilometers known as, Range. E.g. the Himalayas (in Asia), the Alps (in Europe), the Andes (in South America).

There are 3 types of Mountains: 1. Fold mountain, 2. Block mountain, 3. Volcanic mountain

  1. Fold Mountain: It is created by where two or more of Earth's tectonic plates are pushed together. As this colliding, compressing boundaries of rocks, and debris are wrapped and folded into rocky outcrops, hills, mountains, and the entire mountain ranges.
  2. It is divided into 3 types of fold mountains.
  3. Young fold mountain: Age- 10 to 25 million years old. They have rugged relief and high conical peaks. E.g. The Himalaya mountain (in Asia) and the Alps mountain (in Europe), the Rocky (in North America)
  4. Old mountain: Age- 200 million years old. They do not have pointed high peaks due to erosional activities of exogenic forces. E.g. The Aravali range (in India), The Appalachians (in North America), Ural mountain (in Russia).

Fig. Young Fold Mountain                                                                     Fig. Old Fold Mountain 

2. Block Mountain: These are created when a block of bedrock is broken and split into vertically by tectonic activity. It is also called Fault block mountains.

  1. The upliftment blocks are - horsts.
  2. The lower blocks are - graben.
  3. Example: Satpura= seven mountain, and Vindhya range= group of the discontinuous chain of mountain ridges, plateau escarpment, highland, hill ranges (in India), The Great American rift valley (graben, valley floor)Vosges mountain in Europe (horst).