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Landforms: Mountains, Plateaus, and Plains for UPSC Prelims

1. Introduction to Landforms

Landforms are natural features on Earth's surface shaped by geological processes like tectonic activity, erosion, and deposition. The three major landform types—mountains, plateaus, and plains—differ in elevation, slope, and formation processes. Understanding these is crucial for UPSC as they influence climate, human settlement, and resource distribution.

Key Facts

  • Mountains: High elevation (>600m), steep slopes, tectonic origins
  • Plateaus: Elevated flat-topped areas (>300m), volcanic or erosional origins
  • Plains: Low-lying flat lands (<200m), formed by deposition or erosion
  • Formation Processes: Tectonic activity, volcanism, erosion, deposition

Important Facts for UPSC

  • Landforms are classified based on elevation, slope, and formation process.
  • India has examples of all three types: Himalayas (mountains), Deccan (plateau), Indo-Gangetic (plains).
  • Landforms influence population distribution and economic activities.

2. Mountains: Formation and Types

Formation Processes

Classification by Age

Type Age Characteristics Examples
Young Fold <50 million years High, rugged, seismically active Himalayas, Andes, Alps
Old Fold 200-300 million years Lower, rounded, mineral-rich Appalachians, Ural, Aravalli

Important Facts for UPSC

  • The Himalayas are the youngest and highest fold mountains.
  • Orogenesis refers to mountain-building processes.
  • Mountains are "water towers" providing 60-80% of freshwater globally.

3. Major Mountain Ranges of the World

Range Location Highest Peak Significance
Himalayas Asia Mt. Everest (8,848m) Youngest, highest; influences Indian monsoon
Andes South America Aconcagua (6,961m) Longest continental range (7,000km)
Rockies North America Mt. Elbert (4,401m) Major watershed; mineral resources
Alps Europe Mont Blanc (4,809m) Tourism; source of major rivers

Important Mountain Passes (UPSC Focus)

Important Facts for UPSC

  • The Himalayas contain three parallel ranges: Greater, Lesser, and Shiwalik.
  • Mountains create rain shadows (e.g., Tibetan Plateau in Himalayas' rain shadow).
  • The Western Ghats are fault-block mountains, not fold mountains.

4. Plateaus: Characteristics and Formation

Key Features

Types of Plateaus

Type Formation Process Examples
Tectonic Crustal uplift Tibetan, Deccan
Volcanic Lava accumulation Columbia (USA), Deccan (India)
Dissected Erosion of uplifted areas Colorado (USA), Chota Nagpur (India)

Important Facts for UPSC

  • The Deccan Plateau covers 43% of India's land area.
  • Plateaus are often rich in minerals (e.g., African plateaus have gold/diamonds).
  • The Tibetan Plateau is called the "Roof of the World" (avg. elevation 4,500m).

5. Major Plateaus of the World

Plateau Location Significance
Tibetan Central Asia Highest/largest; source of major rivers
Deccan India Volcanic basalt; black soil regions
Colorado USA Grand Canyon shows stratified layers
Brazilian South America Rich in minerals (iron, manganese)

Indian Plateaus

Important Facts for UPSC

  • The Deccan Traps formed from massive volcanic eruptions 66 million years ago.
  • Chota Nagpur Plateau is called the "Ruhr of India" for its minerals.
  • Plateaus often have inverted relief - hills become valleys due to erosion.

6. Plains: Formation and Importance

Formation Processes

Characteristics

Important Facts for UPSC

  • Plains cover 55% of Earth's land surface.
  • The Indo-Gangetic Plain is the world's most extensive alluvial plain.
  • Plains are agriculturally productive but vulnerable to flooding.

7. Major Plains of the World

Plain Location Significance
Indo-Gangetic South Asia World's largest alluvial plain; fertile
Great Plains North America "Breadbasket"; wheat/maize production
West Siberian Russia World's largest unbroken lowland
Pampas Argentina Major cattle-rearing region

Indian Plains

Important Facts for UPSC

  • The Indo-Gangetic Plain is divided into Khadar (new alluvium) and Bangar (old alluvium).
  • Coastal plains are classified as emergent (rising) or submergent (sinking).
  • Plains often have fertile loess soils (wind-deposited silt).

8. Indian Landforms: Mountains, Plateaus, and Plains

India's Physiographic Divisions

  1. Northern Mountains: Himalayas (young fold)
  2. Northern Plains: Indo-Gangetic (alluvial)
  3. Peninsular Plateau: Deccan (volcanic) + Central Highlands
  4. Coastal Plains: Eastern and Western
  5. Islands: Andaman & Nicobar, Lakshadweep

Key Features

Landform Region Significance
Himalayas North Climate barrier; perennial rivers
Deccan Plateau South Black soil; mineral resources
Indo-Gangetic Plain North Agricultural heartland; dense population

Important Facts for UPSC

  • India has 10% of world's mountains, 2.4% of land area.
  • The Western Ghats are older than the Himalayas.
  • The Aravallis are India's oldest fold mountains (Proterozoic era).

9. Economic and Ecological Significance

Mountains

Plateaus

Plains

Important Facts for UPSC

  • The Himalayas influence India's climate by blocking cold winds.
  • Plateaus often have inverted topography due to erosion.
  • Flood plains are both productive and hazardous.

10. UPSC Preparation Tips

Focus Areas

Preparation Strategy

Important Facts for UPSC

  • Previous questions have asked about Deccan Trap formation, Himalayan ranges, and plain types.
  • Understand the difference between Doab (land between rivers) and Terai (wetlands).
  • Note how landforms influence settlement patterns in India.