Why this chapter matters for UPSC: India's physiographic diversity is a foundational GS1 topic. Prelims ask direct questions on peak heights, physiographic divisions, and island features. Mains links physiography to climate, agriculture, mineral distribution, disaster vulnerability, tribal rights, and strategic significance of islands. The Deccan Traps and Gondwana geology underpin questions on soils and coalfields.

PART 1 — Quick Reference Tables

Physiographic Region Key Features UPSC Relevance
The Himalayas Young fold mountains; ~50 million years old; three parallel ranges Water security, glaciers, border disputes, biodiversity
Northern Plains Alluvial deposits; Indus-Ganga-Brahmaputra; 2,400 km long Food security, population density, river systems
Peninsular Plateau Oldest landmass (Gondwanaland); Deccan Plateau; Aravallis Minerals, soils, Deccan Traps, coal fields
Coastal Plains Western (narrow, 10–25 km); Eastern (wider, 100–130 km) Ports, fisheries, monsoon, backwaters, deltas
Islands A&N (Bay of Bengal, 572); Lakshadweep (Arabian Sea, 36) Strategic importance, tribal rights, coral reefs
Himalayan Range Local Name Elevation Notable Features
Greater Himalaya Himadri Above 6,000 m Perennial snow; Kangchenjunga (8,586 m) — highest in India
Lesser Himalaya Himachal 3,700–4,500 m Famous hill stations: Shimla, Mussoorie, Darjeeling, Ooty
Outer Himalaya Shiwaliks 900–1,100 m Foothills; doon valleys; landslide-prone; Doon valley (Dehradun)
Island Group Location Total Islands Inhabited Key Facts
Andaman & Nicobar Bay of Bengal 572 37 Indira Point (southernmost); Barren Island (active volcano); Jarawa, Sentinelese tribes; Seismic Zone V
Lakshadweep Arabian Sea 36 11 Coral atolls; smallest UT by area; exclusive coral reef ecosystem; no rivers

PART 2 — Detailed Notes

India's Physical Identity

India is the 7th largest country in the world by area (~3.28 million km²). It spans approximately 30° of latitude (8°4'N to 37°6'N) and 30° of longitude (68°7'E to 97°25'E). This vast extent gives India an extraordinary range of physical landscapes — from the world's highest mountain ranges to sea-level coral atolls, and from the wettest places on Earth to hyper-arid cold deserts.

Key Term

Physiographic Region: A large area of land with broadly similar relief, geological history, and physical characteristics. India is divided into five major physiographic divisions: the Himalayas, Northern Plains, Peninsular Plateau, Coastal Plains, and Islands.

The Himalayas

The Himalayas are young fold mountains formed approximately 50 million years ago when the northward-drifting Indian tectonic plate collided with the Eurasian plate. This collision buckled and folded the ancient Tethys Sea sediments into the world's highest mountain system. Because the collision is still ongoing, the Himalayas continue to rise and remain seismically active.

The Himalayas consist of three parallel ranges running from northwest to southeast:

  • Greater Himalaya (Himadri): The northernmost and highest range; peaks permanently snow-capped and above 6,000 m; contains India's highest peak Kangchenjunga (8,586 m, Sikkim). Note: the world's highest peak is Mount Everest (8,848.86 m, Nepal-Tibet, re-measured 2020); K2 (8,611 m, Pakistan-administered Kashmir) is the second highest in the world.
  • Lesser Himalaya (Himachal): Middle range, elevation 3,700–4,500 m; contains famous hill stations (Shimla, Mussoorie, Darjeeling, Nainital); important source of rivers; some of India's major hydroelectric projects.
  • Outer Himalaya (Shiwaliks): Southernmost and lowest range, 900–1,100 m; highly susceptible to erosion and landslides; separated from Lesser Himalaya by longitudinal valleys called duns (e.g., Doon Valley, Dehra Dun).
UPSC Connect

UPSC GS1 — Himalayan Glaciers and Water Security: The Himalayas are called Asia's "water tower" — their glaciers feed the Indus, Ganga, Brahmaputra, and other river systems that support over 1.5 billion people. Climate change is accelerating glacial melt, initially increasing river flows but threatening long-term water security. The IPCC AR6 report (2021) flagged Himalayan glacier retreat as a critical risk for South Asia. Glacial Lake Outburst Floods (GLOFs) — as seen in Uttarakhand (2021) — are an emerging disaster risk.

The Northern Plains

The Northern Plains were formed by the deposition of alluvial material carried by the Indus, Ganga, and Brahmaputra river systems over millions of years. These plains are approximately 2,400 km long and 240–320 km wide, making them one of the most extensive alluvial plains in the world.

Two types of alluvium are found here:

  • Khadar: New alluvium deposited by rivers in flood plains; finer texture; renewed annually; more fertile.
  • Bhangar: Old alluvium; slightly elevated above flood plain; coarser; contains lime nodules called kankar; less fertile than khadar.

The Northern Plains are the most densely populated and agriculturally productive region of India — the heartland of wheat, rice, and sugarcane cultivation.

The Peninsular Plateau

The Peninsular Plateau is the oldest landmass of India, a fragment of the ancient supercontinent Gondwanaland. This makes it geologically stable (no fold mountains, few earthquakes). The plateau is composed of hard crystalline rocks.

Key sub-regions:

  • Deccan Plateau: The main triangular plateau south of the Vindhyas; slopes gently eastward (rivers flow eastward into Bay of Bengal).
  • Western Ghats: Continuous range along the western edge; average height ~1,000 m; UNESCO World Heritage Site for biodiversity; acts as orographic barrier receiving heavy SW monsoon rainfall on windward (western) side; creates rain shadow on eastern (leeward) side.
  • Eastern Ghats: Discontinuous, lower (~600 m); cut through by rivers (Mahanadi, Godavari, Krishna, Cauvery) forming fertile deltas on the eastern coast.
  • Chota Nagpur Plateau: Part of Jharkhand; India's mineral heartland — coal, iron ore, copper, bauxite, mica.
  • Aravalli Range: One of the world's oldest fold mountains (Rajasthan); acts as a climatic divide between the Thar Desert and the eastern plains.
Explainer

Deccan Traps: About 65–66 million years ago, massive volcanic eruptions covered the Deccan region in thick layers of basalt lava — now forming the Deccan Traps (covering much of Maharashtra, parts of MP, Gujarat). This coincided with the Chicxulub asteroid impact, both events contributing to the mass extinction of dinosaurs. The basalt weathered into black cotton soil (Regur) — the best soil in India for growing cotton. Maharashtra's Vidarbha cotton belt owes its agricultural character to this geological event.

Coastal Plains

Western Coastal Plains: Narrow strip (10–25 km) between the Western Ghats and the Arabian Sea. Sub-divided into:

  • Konkan Coast (Maharashtra, Goa)
  • Malabar Coast (Kerala) — famous for backwaters (lagoons and canals parallel to the sea; houseboat tourism; paddy fields on reclaimed land called kole wetlands) Receives heavy SW monsoon rainfall (2,000–4,000 mm/year).

Eastern Coastal Plains: Wider (100–130 km) between the Eastern Ghats and the Bay of Bengal. Contains the deltas of major rivers: Mahanadi, Godavari, Krishna, and Cauvery. These deltas are India's rice bowls. Receives less rainfall than western coast — the NE monsoon provides most rain (October–December).

The Islands

Andaman and Nicobar Islands (Bay of Bengal): 572 islands; only 37 are inhabited. Located in a seismically active zone (Zone V) — highly vulnerable to earthquakes and tsunamis (devastating 2004 Indian Ocean Tsunami). Barren Island is India's only confirmed active volcano. Narcondam is a dormant volcano. Indira Point (Great Nicobar Island) is India's southernmost tip. Home to particularly vulnerable tribal groups — the Jarawa and Sentinelese (Particularly Vulnerable Tribal Groups, PVTGs) — protected under the Andaman and Nicobar Protection of Aboriginal Tribes Regulation, 1956.

Lakshadweep (Arabian Sea): 36 coral atolls; only 11 are inhabited. Smallest Union Territory of India by area (32 sq km). India's only coral atoll ecosystem — ecologically fragile and threatened by coral bleaching (ocean warming). No rivers; freshwater from wells and rainwater harvesting.

UPSC Connect

UPSC GS1/GS2 — Strategic Importance of Islands: India's island territories are critical for its maritime strategy. The Andaman and Nicobar Islands sit astride the Strait of Malacca — through which 80% of China's oil imports pass. INS Baaz (naval air station, Great Nicobar) is India's southernmost military base. The proposed Great Nicobar holistic development project (Niti Aayog) and tribal rights (Forest Rights Act, 2006) are active policy tensions. Lakshadweep's Exclusive Economic Zone (EEZ) extends India's maritime reach deep into the Arabian Sea.

India's Geological Heritage

  • Gondwana Coal Fields: Eastern India's coal belt (Jharkhand, West Bengal, Odisha, Chhattisgarh, Madhya Pradesh) lies in ancient Gondwana rock formations. India holds the 4th largest coal reserves in the world, almost entirely in Gondwana strata.
  • Deccan Traps: Basalt lava plateau; Regur (black cotton soil) formed from its weathering.
  • Fossil Parks: The Rajmahal Hills (Jharkhand) preserve fossil forests from the Gondwana period.

Exam Strategy

Prelims traps:

  • Kangchenjunga (8,586 m) is India's highest peak, NOT Everest or K2. Everest is in Nepal-Tibet; K2 is in Pakistan-administered Kashmir.
  • Barren Island = active volcano; Narcondam = dormant. Both in Andaman group.
  • Lakshadweep = smallest UT by area; Chandigarh = smallest UT by area after Lakshadweep is often confused — Lakshadweep (32 sq km) is correct.
  • Eastern Ghats are discontinuous; Western Ghats are continuous — often reversed in options.
  • Khadar = newer, more fertile; Bhangar = older, slightly elevated, less fertile.
  • Deccan Traps = ~65–66 million years old (Cretaceous-Paleogene boundary); NOT 50 million years like Himalayas.

Mains angles:

  • Himalayan glaciers → water security → geopolitics (India-China-Pakistan river disputes)
  • Western Ghats → biodiversity → Gadgil vs Kasturirangan panel debates → development vs ecology
  • Island territories → strategic importance → tribal rights → development pressures (Great Nicobar project)
  • Gondwana coalfields → India's energy security → Just Transition challenges

Previous Year Questions

Prelims:

  1. Which of the following is the southernmost point of India?
    (a) Kanyakumari
    (b) Point Calimere
    (c) Indira Point
    (d) Port Blair

  2. With reference to India's island territories, which of the following statements is/are correct?

    1. Barren Island is India's only active volcano.
    2. Lakshadweep is the smallest Union Territory of India by area.
    3. The Andaman and Nicobar Islands are located in the Arabian Sea.
      (a) 1 only
      (b) 1 and 2 only
      (c) 2 and 3 only
      (d) 1, 2, and 3

Mains:

  1. Discuss the significance of the Western Ghats as a biodiversity hotspot and examine the conflicts between conservation and development in the region. (CSE Mains 2019, GS Paper 3, 15 marks)

  2. "The Himalayan ecosystem is intrinsically linked to the water security of peninsular India." Critically examine this statement in the context of climate change. (CSE Mains 2022, GS Paper 1, 15 marks)