Why this chapter matters for UPSC: The types of landforms, how they form (plate tectonics), and their significance for climate, agriculture, and human settlement are all tested in UPSC GS1 Physical Geography. India has classic examples of each type — the Himalayas (young fold mountains), the Deccan Plateau, and the Indo-Gangetic Plain.

PART 1 — Quick Reference Tables

Types of Mountains

Type Formation Examples Characteristics
Fold Mountains Tectonic plates collide; rock strata fold upward Himalayas, Alps, Andes, Rockies Highest mountains; young = steep peaks; formed by convergent plate boundaries
Block Mountains (Horst) Rock block lifted between two parallel faults Vosges (France), Satpura (India), Rhine Valley sides Flat top; steep sides; associated with rift valleys
Volcanic Mountains Lava accumulation from volcanic eruptions Kilimanjaro (Africa), Fujiyama (Japan), Deccan Trap (India — lava plateau) Conical shape; can be active, dormant, or extinct
Residual Mountains Ancient mountains eroded over time Aravalli (India), Eastern/Western Ghats, Nilgiris Older, worn down; India's Aravalli is ~3.5 billion years old

Major Landforms — Comparative

Landform Definition India Example Global Example
Mountain Elevated land > 600 m with narrow summit Himalayas, Karakoram Alps, Andes
Hill Elevated land < 600 m with rounded top Shivalik Hills English Lake District
Plateau Elevated flat land with steep sides Deccan Plateau, Chota Nagpur Tibetan Plateau, Colorado Plateau
Plain Flat, low-lying land Indo-Gangetic Plain, Brahmaputra Valley Amazon Basin, Mississippi Valley
Valley Low land between mountains/hills Kashmir Valley, Brahmaputra Valley Rhine Valley
Glacier Slow-moving river of ice Gangotri, Siachen Antarctic ice sheet

PART 2 — Detailed Notes

Fold Mountains — Formation

Explainer

How fold mountains form:

  1. Two continental tectonic plates collide (convergent boundary)
  2. Sedimentary rocks (often deposited at the bottom of ancient seas between the plates) are squeezed and folded upward
  3. Over millions of years, these folds build into high mountain ranges

The Himalayas — Case Study:

  • ~50 million years ago, the Indian tectonic plate was separate from the Asian plate, with the Tethys Sea between them
  • The Indian plate moved northward (~40–50 million years ago), the Tethys Sea floor sediments were compressed and folded upward → the Himalayas
  • The Indian plate is still moving north at ~5 cm per year → the Himalayas are still rising (~5 mm per year)
  • The Himalayas are therefore the world's youngest and highest fold mountains

Other fold mountain ranges: Alps (Europe; formed by African + Eurasian plate collision), Andes (South America; South American + Nazca plate), Rockies (North America; Pacific plate subduction)

Significance of Landforms

Explainer

Mountains:

  • Source of rivers: The Himalayas feed the Indus, Ganga, Brahmaputra — critical for India's water supply and agriculture
  • Climate modification: Block cold Central Asian winds from North India in winter; force monsoon winds to rise and rain (orographic rainfall); create the rain shadow (leeward side gets less rain — Rajasthan is in the rain shadow of the Aravalli)
  • Biodiversity: Altitude creates multiple ecological zones from tropical forests (foothills) to alpine meadows to glaciers
  • Barriers: The Himalayas provided India historical protection from Central Asian invasions — though mountain passes (Khyber, Bolan) allowed exchange

Plateaus:

  • Rich in mineral resources — the Deccan Plateau has basalt (from ancient lava flows), Chota Nagpur has iron ore, coal, manganese, mica
  • Generally poor agricultural land (hard rock, thin soil, irregular rainfall)
  • Good for grazing; some plateau areas (like parts of Maharashtra) are productive with proper irrigation

Plains:

  • Best for agriculture — flat land, deep alluvial soil, irrigation easier
  • High population density — the Indo-Gangetic Plain supports ~700 million people (highest population density region in the world)
  • Good for transport — flat land → roads, railways cheap and efficient
  • Limited mineral resources (alluvial soil covers rock; mines on plains are rare)

India's Major Landforms

UPSC Connect

UPSC Physical Geography of India:

Himalayan Region:

  • Young fold mountains (~50 million years old)
  • Three parallel ranges: Greater Himalayas (Himadri), Lesser Himalayas (Himachal), Outer Himalayas (Shivaliks)
  • Highest peak in India: Kangchenjunga (8,586 m) — in Sikkim; Highest peak overall accessible from India region: K2 (8,611 m) in Pakistan; Everest (8,849 m, 2023 revised measurement) — Nepal/China border

Indo-Gangetic Plain:

  • Formed by alluvial deposits from Himalayan rivers (Indus, Ganga, Brahmaputra system)
  • Most fertile agricultural land; "granary of India"
  • Extends from Punjab to Assam
  • Depth of alluvium: 1,000–2,000 metres in some places

Deccan Plateau:

  • Ancient, geologically stable (Archaean age, some parts ~3 billion years old)
  • Composed of basalt (Deccan Traps — volcanic lava plateau, ~65 million years old; formed by massive volcanic activity possibly triggered by the Chicxulub asteroid impact)
  • Black cotton soil (regur) = excellent for cotton cultivation → Maharashtra + Gujarat + MP cotton belt

Coastal Plains:

  • Western Coastal Plain: Narrow (50–80 km); between Western Ghats and Arabian Sea; Kerala, Goa, Karnataka, Maharashtra; receives very heavy rainfall; good for coconut, spices, fishing
  • Eastern Coastal Plain: Wider (80–200 km); between Eastern Ghats and Bay of Bengal; Coromandel Coast (Tamil Nadu), Andhra, Odisha; deltaic plains of Krishna, Godavari, Mahanadi, Ganga, Brahmaputra

PART 3 — Frameworks & Analysis

India's Landform Diversity and Its Consequences

Landform Region Economic Activity Environmental Issue
Himalayas Tourism, hydropower, apple/temperate horticulture Glacial retreat, GLOF (Glacial Lake Outburst Floods), earthquake risk
Indo-Gangetic Plain Agriculture (wheat, rice, sugarcane), industry Flooding, groundwater depletion, air pollution (Punjab/UP)
Deccan Plateau Cotton, mining (iron, coal, manganese), industry Drought risk, mining pollution, displacement of tribal communities
Western Coastal Plain Fisheries, spices, tourism, ports Coastal erosion, flooding, sea-level rise threat
Eastern Coastal Plain Rice, aquaculture, ports Cyclones, storm surge, delta sinking
Northeast Tea, timber, biodiversity Floods, erosion, ethnic conflicts over land

Exam Strategy

Prelims traps:

  • Aravalli: Oldest mountain range in India (~3.5 billion years); NOT the Himalayas (they are the youngest, ~50 million years)
  • Deccan Plateau: Formed by lava flows (Deccan Traps) ~65 million years ago — NOT by plate collision; it is NOT a fold mountain
  • India's highest peak: Kangchenjunga (8,586 m) is the highest peak entirely within India's borders (in Sikkim); K2 (8,611 m) is the 2nd highest in the world but in Pakistan-administered Kashmir; Everest is on Nepal-China border
  • Block mountain: The Satpura range in India is a horst (block mountain); the Narmada and Tapi rivers flow in rift valleys (graben) on either side

Previous Year Questions

Prelims:

  1. The Himalayas are an example of which type of mountains?
    (a) Fold mountains
    (b) Block mountains
    (c) Volcanic mountains
    (d) Residual mountains

  2. The oldest mountain range in India is:
    (a) Aravalli
    (b) Himalayas
    (c) Satpura
    (d) Eastern Ghats

  3. The Deccan Plateau is primarily composed of which rock type?
    (a) Granite (ancient) only
    (b) Basalt (from ancient lava flows — Deccan Traps)
    (c) Limestone
    (d) Sandstone

  4. Which river flows in a rift valley between the Vindhya and Satpura ranges?
    (a) Narmada
    (b) Tapti
    (c) Godavari
    (d) Mahanadi