Chapter 6: Major Landforms of the Earth
Social Science - Geography (CBSE Class 6)
Chapter Summary
The Earth's surface is not uniform; it has a variety of landforms. These landforms are a result of two main types of processes:
- Internal Process: This leads to the upliftment and sinking of the Earth’s surface at several places. For example, earthquakes and volcanic eruptions.
- External Process: This involves continuous wearing down (erosion) and rebuilding (deposition) of the land surface. The main agents of erosion and deposition are running water, ice, and wind.
Major Landforms
The major landforms are grouped into Mountains, Plateaus, and Plains.
1. Mountains
- A mountain is any natural elevation of the Earth's surface. It has a small summit and a broad base.
- Some mountains are higher than the clouds. As you go higher, the climate becomes colder.
- In some mountains, there are permanently frozen rivers of ice called glaciers.
- Mountains can be arranged in a line known as a mountain range (e.g., Himalayas, Alps, Andes).
- Mountains are thinly populated due to harsh climate, steep slopes, and difficult farming conditions.
- Types of Mountains:
- Fold Mountains: Formed when two tectonic plates collide, causing the Earth's crust to fold and uplift. Examples: Himalayas (young fold mountains), the Alps, the Andes.
- Block Mountains: Created when large blocks of the Earth are broken and displaced vertically. The uplifted blocks are called horsts, and the lowered blocks are called graben. Examples: The Rhine valley and the Vosges mountain in Europe.
- Volcanic Mountains: Formed due to volcanic activity. Examples: Mount Kilimanjaro (Africa), Mount Fujiyama (Japan).
- Uses of Mountains:
- Mountains are storehouses of water (glaciers, reservoirs).
- They provide rich flora and fauna, forests, and resources like timber, fuel, and fodder.
- Ideal sites for tourism, sports like skiing, river rafting, and paragliding.
- River valleys and terraces are ideal for cultivation.
2. Plateaus
- A plateau is an elevated flat land. It is a flat-topped table land standing above the surrounding area.
- Plateaus are often rich in mineral deposits.
- Some of the oldest plateaus are the Deccan Plateau (India), East African Plateau (Kenya, Tanzania, Uganda), and the Western Plateau of Australia.
- The Tibetan Plateau is the highest plateau in the world, with a height of 4,000 to 6,000 metres above mean sea level.
- The Chhotanagpur Plateau in India is rich in coal, iron, and manganese deposits.
- Many waterfalls are found in plateau areas as rivers fall from great heights.
- Lava plateaus (e.g., Deccan Plateau) are rich in black soil, good for cultivation.
3. Plains
- Plains are large stretches of flat land. They are generally not more than 200 metres above mean sea level.
- Most plains are formed by rivers and their tributaries. Rivers deposit silt, sand, and clay, forming fertile plains.
- Plains are generally very fertile and suitable for agriculture.
- Due to their flat surface, construction of transport networks (roads, railways) is easy.
- Plains are the most densely populated regions of the world.
- Examples: The Ganga Plain in India, the Yangtze Plain in China.
Landforms and people: Humans live differently on different landforms. Life is easier on plains compared to mountains. We must be careful not to pollute the land or harm nature. The different landforms provide diverse conditions for human habitation and development.
Questions and Answers
1. Answer the following questions briefly.
Ques 1 a) What are the major landforms?
Answer: The major landforms are Mountains, Plateaus, and Plains.
Ques 1 b) What is the difference between a mountain and a plateau?
Answer:
- Mountain: A natural elevation of the Earth's surface with a small summit and a broad base. It is considerably higher than the surrounding area.
- Plateau: An elevated flat land, a flat-topped table land standing above the surrounding area. It has a flat top and steep sides.
Ques 1 c) What are the different types of mountains?
Answer: The different types of mountains are:
- Fold Mountains (e.g., Himalayas, Alps)
- Block Mountains (e.g., Rhine valley and the Vosges mountain)
- Volcanic Mountains (e.g., Mount Kilimanjaro, Mount Fujiyama)
Ques 1 d) How are mountains useful to man?
Answer: Mountains are useful to man in several ways:
- They are storehouses of water, providing water for rivers and for irrigation and hydropower.
- They have a rich variety of flora and fauna.
- Forests provide fuel, fodder, shelter, and other products like gum and resin.
- They offer an idyllic site for tourists and provide opportunities for sports like skiing, paragliding, river rafting, and hiking.
- River valleys and terraces are ideal for cultivation.
Ques 1 e) How are plains formed?
Answer: Most plains are formed by rivers and their tributaries. Rivers carry eroded material like silt, sand, and clay from the mountains and deposit them along their courses and in their valleys. These deposits form fertile plains.
Ques 1 f) Why are the river plains thickly populated?
Answer: River plains are thickly populated because:
- They are generally very fertile, making the land suitable for agriculture.
- The flat surface makes it easy to construct transport networks like roads and railways.
- They provide suitable conditions for human habitation and other human activities.
Ques 1 g) Why are mountains thinly populated?
Answer: Mountains are thinly populated because:
- The climate is generally harsh.
- The slopes are steep, making it difficult to build houses and establish transport networks.
- Less land is available for farming, which is the primary occupation in many parts of the world.
2. Tick the correct answer.
Ques 2 a) The mountains differ from the hills in terms of
i) elevation ii) slope iii) aspect
Answer: i) elevation
Ques 2 b) Glaciers are found in
i) the mountains ii) the plains iii) the plateaus
Answer: i) the mountains
Ques 2 c) The Deccan Plateau is located in
i) India ii) Australia iii) Africa
Answer: i) India
Ques 2 d) The river Yangtze flows in
i) South America ii) Australia iii) China
Answer: iii) China
Ques 2 e) An important mountain range of Europe is
i) the Andes ii) the Alps iii) the Rockies
Answer: ii) the Alps
3. Fill in the blanks.
Ques 3 a) A _________ is an unbroken flat or a low-level land.
Answer: A plain is an unbroken flat or a low-level land.
Ques 3 b) The _________ are a group of mountains joined together in a line.
Answer: The range are a group of mountains joined together in a line.
Ques 3 c) The _________ area is rich in mineral deposits.
Answer: The plateau area is rich in mineral deposits.
Ques 3 d) The _________ is a line of hills or mountains.
Answer: The range is a line of hills or mountains.
Ques 3 e) The _________ areas are most productive for farming.
Answer: The plain areas are most productive for farming.
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