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
- Fold Mountains: Formed by continental collision (e.g., Himalayas)
- Block Mountains: Created by faulting (e.g., Vosges, France)
- Volcanic Mountains: Built from lava accumulation (e.g., Mt. Fuji)
- Dome Mountains: Formed by magma pushing up crust (e.g., Black Hills, USA)
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)
- India: Zoji La, Nathu La, Shipki La
- World: Khyber (Pakistan-Afghanistan), Brenner (Austria-Italy)
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
- Elevated flat-topped areas with steep sides
- Also called "tablelands"
- Average elevation: 300-900m (some higher)
- Formed by volcanic activity, crustal uplift, or erosion
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
- Deccan Plateau: Volcanic, covers 8 states
- Chota Nagpur Plateau: Mineral-rich (Jharkhand)
- Malwa Plateau: Between Aravallis and Vindhyas
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
- Alluvial Plains: River deposits (e.g., Indo-Gangetic)
- Structural Plains: Bedrock uplift (e.g., Great Plains, USA)
- Erosional Plains: Leveled by erosion (e.g., Canadian Shield)
- Abyssal Plains: Ocean floor (deepest flattest areas)
Characteristics
- Generally below 200m elevation
- Gentle slopes (<5°)
- Fertile soils (especially alluvial plains)
- Densely populated (50% of world population)
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
- Indo-Gangetic Plain: From Punjab to Bengal (alluvial)
- Coastal Plains: Eastern and Western (formed by marine deposits)
- Punjab Plain: Between Indus and Ganges systems
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).
India's Physiographic Divisions
- Northern Mountains: Himalayas (young fold)
- Northern Plains: Indo-Gangetic (alluvial)
- Peninsular Plateau: Deccan (volcanic) + Central Highlands
- Coastal Plains: Eastern and Western
- 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
- Water sources (rivers, glaciers)
- Biodiversity hotspots
- Tourism (adventure, pilgrimage)
- Mineral resources
Plateaus
- Mineral wealth (metals, precious stones)
- Hydropower potential (steep edges)
- Black soil regions (volcanic plateaus)
Plains
- Agriculture (fertile soils)
- Transportation networks
- Urban centers
- Cultural hearths (ancient civilizations)
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
- Classification of landforms (formation processes)
- Indian landforms (Himalayas, Deccan, Coastal plains)
- Global examples (major ranges, plateaus, plains)
- Economic and ecological significance
Preparation Strategy
- Create comparative tables (e.g., young vs. old mountains)
- Mark important landforms on maps (especially Indian)
- Relate landforms to climate, soils, and human activities
- Practice previous years' questions on physiography
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.