Class 6 Geography Notes Chapter 6 (Major Landforms of the Earth) – The Earth Our Habitat

Below is the detailed notes for Chapter 6: Major Landforms of the Earth, from the NCERT Class 6 Geography textbook 'The Earth: Our Habitat', focusing on aspects relevant for government exam preparation.

Chapter 6: Major Landforms of the Earth

1. Introduction to Landforms

• Definition: The surface of the Earth is not uniform. It has an infinite variety of landforms. These different natural features of the Earth's surface are called landforms.
• Formation Processes: Landforms are a result of two main processes:
  • Internal Process (Endogenic Forces): Leads to the upliftment and sinking of the Earth's surface at several places. This creates large-scale landforms like mountains and plateaus. Examples include earthquakes and volcanic activity.
  • External Process (Exogenic Forces): Involves the continuous wearing down and rebuilding of the land surface.
    • Erosion: The wearing away of the Earth's surface by agents like running water, ice, and wind.
    • Deposition: The rebuilding of the surface by the deposition of eroded material carried by the same agents (water, ice, wind).

2. Major Landforms

Based on elevation and slope, landforms can be broadly grouped as Mountains, Plateaus, and Plains.

A. Mountains

• Definition: A mountain is any natural elevation of the Earth's surface, usually rising abruptly from the surrounding level. Mountains are considerably higher than the surrounding areas. They typically have a small summit (top) and a broad base.
• Height: Some mountains are even higher than the clouds. As you go higher, the climate gets colder.
• Glaciers: In some mountains, there are permanently frozen rivers of ice called glaciers. These are often the source of major rivers.
• Ranges: Mountains may be arranged in a line known as a range. Many mountain systems consist of a series of parallel ranges extending over hundreds of kilometers (e.g., the Himalayas, the Alps, the Andes).
• Types of Mountains:
  • Fold Mountains:
    • Formation: Formed due to the folding of rock strata, primarily caused by compressional forces resulting from the movement of tectonic plates.
    • Characteristics: Have rugged relief and high conical peaks.
    • Examples:
      • Young Fold Mountains: The Himalayas (Asia), the Alps (Europe), the Andes (South America). Formed relatively recently in geological time.
      • Old Fold Mountains: The Aravalli Range (India - one of the oldest fold mountain systems in the world), the Appalachians (North America), the Ural Mountains (Russia). These have been considerably worn down by erosion over time.
  • Block Mountains:
    • Formation: Created when large areas are broken and displaced vertically. Uplifted blocks are termed 'horsts', and lowered blocks are called 'graben'.
    • Examples: The Rhine Valley and the Vosges mountain range (Europe).
  • Volcanic Mountains:
    • Formation: Formed due to volcanic activity where magma (molten rock) erupts onto the surface and cools, building up a cone shape over time.
    • Examples: Mt. Kilimanjaro (Africa), Mt. Fujiyama (Japan).
• Importance of Mountains:
  • Storehouse of Water: Many rivers originate from mountain glaciers. Reservoirs are built to harness this water for irrigation, hydroelectricity, and domestic use.
  • Rich Biodiversity: Mountain slopes often have rich flora and fauna. Forests provide fuel, fodder, shelter, and other products like gum and raisins.
  • Tourism and Recreation: Mountains offer scenic beauty and are popular tourist destinations for activities like paragliding, hang gliding, river rafting, and skiing.

B. Plateaus

• Definition: A plateau is an elevated flat land, like a tabletop standing above the surrounding area. It has a large, flat or gently rolling top surface and one or more sides with steep slopes.
• Height: The height of plateaus often varies from a few hundred meters to several thousand meters.
• Types/Age: Plateaus can be young or old.
• Examples:
  • Deccan Plateau (India): One of the oldest plateaus.
  • East African Plateau: In Kenya, Tanzania, and Uganda.
  • Western Plateau of Australia.
  • Tibetan Plateau: The highest plateau in the world, with a height of 4,000 to 6,000 meters above mean sea level.
• Importance of Plateaus:
  • Rich in Mineral Deposits: Many mining areas worldwide are located in plateau regions (e.g., African plateau famous for gold and diamond mining; Chota Nagpur plateau in India is rich in iron, coal, and manganese).
  • Waterfalls: River falls from great heights in plateau areas, creating waterfalls. These sites are often ideal for generating hydro-electric power (e.g., Hundru falls on the Subarnarekha river in the Chota Nagpur plateau; Jog falls in Karnataka).
  • Grasslands & Lava Plateaus: Some plateaus have extensive grasslands suitable for grazing. Lava plateaus (like the Deccan) are rich in black soil, which is fertile and excellent for cotton cultivation.
  • Scenic Spots & Tourism: Many plateaus offer scenic beauty and attract tourists.

C. Plains

• Definition: Plains are large stretches of flat or gently rolling land. They are generally not more than 200 meters above mean sea level.
• Formation: Most plains are formed by rivers and their tributaries. Rivers erode mountains, carry forward the eroded material (silt, clay, sand, stones), and deposit this load along their valleys and in their floodplains, forming extensive, flat, fertile plains.
• Characteristics: Usually very level, though some may be slightly rolling or undulating.
• Examples:
  • Large plains formed by rivers in Asia (e.g., Indo-Gangetic Plains formed by the Indus, Ganga, Brahmaputra and their tributaries in India) and North America.
  • Yangtze River plains in China.
• Importance of Plains:
  • Highly Fertile: Generally very fertile due to alluvial deposits, making them suitable for intensive agriculture.
  • Ease of Transportation: The flat terrain makes it easy to build transport networks (roads, railways).
  • High Population Density: Due to fertile land, availability of water, ease of transport, and construction, plains are usually the most thickly populated regions of the world. Major cities and civilizations often develop in plains.

3. Landforms and People

• Human Habitation: Humans live on different kinds of landforms. Life is generally difficult in mountainous areas compared to plains.
  • Plains: Provide better conditions for agriculture, building houses, and roads. Hence, they are densely populated.
  • Mountains: Sparsely populated due to harsh climate, steep slopes, and less available land for farming.
• Natural Calamities: Sometimes natural calamities like earthquakes, volcanic eruptions, storms, and floods cause widespread destruction and loss of life and property. Awareness about such incidences can help lower the risks.
• Human Impact & Responsibility:
  • Humans often use land and water resources wastefully or carelessly (e.g., constructing settlements on fertile land).
  • Pollution: Garbage, waste materials pollute land and water, making them unsuitable for use.
  • Need for Sustainability: It is crucial to use the Earth's resources (gifts of nature) in a careful, planned, and sustainable manner to ensure they are available for future generations. Protecting our landforms and environment is a key responsibility.

Key Takeaways for Exams:

• Know the definitions of landforms, erosion, and deposition.
• Understand the difference between internal and external processes.
• Memorize the types of mountains (Fold, Block, Volcanic) with specific examples (especially Indian examples like Himalayas, Aravalli). Differentiate between young and old fold mountains.
• Know the definition and characteristics of plateaus. Memorize key examples (Deccan, Tibetan, Chota Nagpur) and their significance (minerals, soil type).
• Understand how plains are formed and why they are densely populated. Know examples (Indo-Gangetic).
• Be aware of the importance/uses of each major landform type (water source, minerals, agriculture, tourism, etc.).
• Understand the relationship between landforms and human settlement patterns.

This detailed breakdown covers the core concepts of Chapter 6 relevant for competitive government exams. Remember to cross-reference with the original NCERT textbook for diagrams and specific phrasing.