BharatNotes 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.
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 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.
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 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.
[Additional] 1a. Great Nicobar Island Holistic Development Project — Development vs Ecology
The chapter mentions A&N Islands' tribal significance and strategic position, but a massive ongoing project on Great Nicobar Island — ₹75,000–92,000 crore for a port, airport, township, and power plant — is a defining current-affairs intersection of physiography, tribal rights, and ecology.
Key Terms — Great Nicobar Project:
| Term | Meaning |
|---|---|
| ANIIDC | Andaman and Nicobar Islands Integrated Development Corporation — implementing agency for the project |
| Galathea Bay | A bay on Great Nicobar Island's southern coast; site of the proposed International Container Transhipment Terminal; formerly a Wildlife Sanctuary (denotified January 2021) |
| Leatherback sea turtle | World's largest turtle (Dermochelys coriacea); Critically Endangered; Galathea Bay is one of their critical nesting beaches |
| Shompen | A PVTG on Great Nicobar Island; fewer than 300 individuals; interior forest-dwelling; the project overlaps their territory |
| FRA 2006 | Forest Rights Act — requires free, prior, and informed consent of tribal communities before any project affecting their habitat |
| NGT | National Green Tribunal — environment-focused court; upheld the Environmental Clearance on February 16, 2026 |
[Additional] Great Nicobar Holistic Development Project (GS2 — Tribal Rights / GS3 — Environment & Infrastructure / GS4 — Ethics):
The NCERT chapter mentions the Andaman & Nicobar Islands' tribal significance and strategic position, but a massive ongoing infrastructure project on Great Nicobar Island is a major UPSC current-affairs intersection with physiography, tribal rights, and ecology.
What is the project? The Holistic Development of Great Nicobar Island is a mega-infrastructure project conceived by NITI Aayog and being implemented by the Andaman and Nicobar Islands Integrated Development Corporation (ANIIDC). It covers 166.1 sq km on the island's southern tip and comprises four components:
- An International Container Transhipment Terminal at Galathea Bay
- A Greenfield International Airport (dual-use, civil and military)
- A gas and solar power plant
- A township to support a planned population of 350,000
Project cost: Originally estimated at ₹75,000 crore (approx. US$ 9.4 billion, 2022); revised to ₹81,000 crore by 2025. Some reports cite a figure of ₹92,000 crore as of early 2026.
Approval timeline:
- January 2021: The Standing Committee of the National Board for Wildlife (NBWL) approved the denotification of the Galathea Bay Wildlife Sanctuary (created in 1997) to enable the port — done even before a formal government proposal was filed.
- November 2022: The Ministry of Environment, Forest and Climate Change (MoEFCC) granted the final Environmental Clearance (EC).
- February 16, 2026: The National Green Tribunal (NGT) upheld the EC, ruling that "adequate safeguards have been provided" and citing the project's "strategic importance." Challenges to the forest clearance under the Forest Rights Act (FRA) remain pending before the Calcutta High Court.
Environmental concerns:
- 130.75 sq km of the 166 sq km project area is dense tropical rainforest — approximately 964,000 trees will be felled (critics argue the real figure may be several million, as official density estimates are considered underestimates).
- Galathea Bay is a critical nesting site for the leatherback sea turtle (Dermochelys coriacea), the world's largest turtle. The port is proposed on the nesting beach.
- The project affects the Nicobar megapode and saltwater crocodile, both endemic/vulnerable species.
- The NGT directed "no net loss of sandy nesting beaches" as a safeguard condition.
Shompen tribal rights: The Shompen are a Particularly Vulnerable Tribal Group (PVTG) numbering fewer than 300 individuals, living in the interior forests of Great Nicobar. The project zone overlaps three Shompen settlements and destroys forests used for foraging, hunting, and freshwater access. In February 2024, 39 genocide experts from 13 countries warned the UN that the development "will be a death sentence for the Shompen, tantamount to the international crime of genocide" — citing their lack of immunity to outside diseases and the destruction of their habitat. A petition before the Calcutta High Court (filed by Meena Gupta, former Secretary, Ministry of Tribal Affairs) argues that consent was not obtained under Section 5(c) of the Forest Rights Act — a Tribal Welfare officer was wrongly authorised to represent the Shompen, for whom no such proxy consent mechanism exists under law.
UPSC synthesis: Key exam facts: Great Nicobar project = 166.1 sq km; Rs 75,000–92,000 crore; ANIIDC implementing agency; NITI Aayog conceived; Galathea Bay = port site + leatherback nesting; NBWL denotified sanctuary January 2021; EC granted November 2022; NGT upheld February 16 2026; Calcutta HC FRA challenge pending; Shompen = PVTG <300 individuals; 39 genocide experts warned February 2024; INS Baaz = India's southernmost naval base (Great Nicobar). This is GS1 + GS2 + GS3 + GS4 intersection.
[Additional] 1b. 4th Global Coral Bleaching Event (2024) — India's Reefs in Crisis
The chapter notes Lakshadweep has a "coral atoll ecosystem threatened by coral bleaching." The 2024 global bleaching event — confirmed by NOAA on April 15, 2024 — is the most severe in recorded history, hitting 84.4% of the world's reefs, including ~75% of Lakshadweep's corals.
Coral Bleaching — Key Terms:
| Term | Meaning |
|---|---|
| Coral bleaching | When water is too warm, corals expel the symbiotic algae (zooxanthellae) living in their tissues; the coral turns white ("bleaches"); without algae, corals lose their food source and can die |
| Degree Heating Weeks (DHW) | NOAA's measure of coral thermal stress; 4°C-weeks = significant bleaching; 8°C-weeks = widespread mortality |
| SST (Sea Surface Temperature) | Ocean surface water temperature; Lakshadweep bleaching threshold ≈ 30.5°C; SST reached 36°C in 2024 |
| NOAA Alert Level 5 | New category introduced during GCBE4 — indicates near-complete coral mortality; did not exist before 2024 |
| GCBE | Global Coral Bleaching Event — only 4 declared in recorded history: 1998, 2010, 2014-17, 2024 (ongoing) |
| ICRI | International Coral Reef Initiative — NOAA's partner in declaring global bleaching events |
[Additional] 4th Global Coral Bleaching Event and India's Reefs (GS3 — Environment / Biodiversity / Climate):
The NCERT chapter notes that Lakshadweep has a "coral atoll ecosystem" threatened by coral bleaching. The 2024–25 global bleaching event gives this a precise, examinable face.
The Fourth Global Coral Bleaching Event (GCBE4): On April 15, 2024, NOAA (National Oceanic and Atmospheric Administration) and the International Coral Reef Initiative (ICRI) officially confirmed the Fourth Global Coral Bleaching Event — only the fourth in recorded history (earlier events: 1998, 2010, 2014–17). From January 2023 to September 2025, bleaching-level heat stress has impacted approximately 84.4% of the world's coral reef area, a scale so extreme that NOAA had to introduce a new Alert Level 5 category (indicating near-complete mortality) that did not previously exist. Bleaching has been recorded in over 53 countries across all major ocean basins.
Impact on India's coral reefs: India's four coral reef zones were all affected:
| Reef Zone | Impact | Key Data |
|---|---|---|
| Lakshadweep (Arabian Sea) | Worst hit; severe bleaching | SST reached 36°C (bleaching threshold ~30.5°C); Degree Heating Weeks (DHW) exceeded 4°C-weeks; ~75% of corals bleached |
| Andaman & Nicobar Islands (Bay of Bengal) | Moderate; ~15–18% bleaching in South Andaman | Most reefs showed recovery potential |
| Gulf of Mannar (Tamil Nadu) | Significant bleaching reported | Monitoring by NCCR, Chennai |
| Gulf of Kachchh (Gujarat) | Bleaching impacted | India's largest coral translocation project (16,000+ corals relocated) ongoing here |
Lakshadweep — the crisis in detail: ICAR-Central Marine Fisheries Research Institute (CMFRI) scientists recorded widespread bleaching from late October 2023 onwards, as the Lakshadweep Sea experienced sea surface temperatures consistently more than 1°C above the climatological norm. SST peaked at 36°C against the bleaching threshold of ~30.5°C. The Indian Ocean Dipole and subsequent La Nina patterns sustained these elevated temperatures. Long-term coral cover data tells the structural story: coral cover in Lakshadweep fell from 37.24% (1998) to 19.6% (2022) — already halved before the 2024 event struck.
Government response (acknowledged in Parliament, December 2024):
- INCOIS (Indian National Centre for Ocean Information Services) provides satellite-based coral bleaching alerts for all Indian reef zones.
- NCCR (National Centre for Coastal Research) conducts regular monitoring, remote-sensing mapping, and in-situ reef-health surveys in Lakshadweep, Palk Bay, and Andaman.
- Coral translocation/restoration projects active in Gulf of Mannar, Gulf of Kachchh, and Palk Bay.
- Legal protection under Wildlife Protection Act, 1972 and CRZ (Coastal Regulation Zone) notifications.
UPSC synthesis: Key exam facts: GCBE4 confirmed April 15 2024 (NOAA + ICRI); 4th ever (previous: 1998, 2010, 2014-17); 84.4% of world's reefs hit; NOAA Alert Level 5 = new category (near-complete mortality); Lakshadweep SST reached 36°C (threshold 30.5°C); ~75% of Lakshadweep corals bleached; DHW exceeded 4°C-weeks; long-term cover: 37.24% (1998) → 19.6% (2022); Andaman = moderate 15-18% bleaching; INCOIS = bleaching alerts; NCCR = monitoring; coral translocation active in Gulf of Kachchh (16,000+ corals relocated). India's 4 reef zones: Lakshadweep, A&N, Gulf of Mannar, Gulf of Kachchh.
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; India is also the 2nd largest coal producer globally (FY 2024-25: 1,047.67 MT — first time crossing 1 billion tonnes).
- 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 → Great Nicobar Holistic Development Project (₹81,000 crore; NGT cleared Feb 2026; Calcutta HC challenge on FRA pending; Shompen genocide warning by 39 experts, Feb 2024)
- Lakshadweep coral reefs → GCBE4 (NOAA, April 15, 2024) → 84.4% global reefs hit → Lakshadweep SST 36°C; coral cover 37.24% (1998) → 19.6% (2022) → climate change impacts on Indian Ocean biodiversity
- Gondwana coalfields → India's energy security → Just Transition challenges
Practice Questions
Prelims:
Which of the following is the southernmost point of India?
(a) Kanyakumari
(b) Point Calimere
(c) Indira Point
(d) Port BlairWith reference to India's island territories, which of the following statements is/are correct?
- Barren Island is India's only active volcano.
- Lakshadweep is the smallest Union Territory of India by area.
- 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
- Barren Island is India's only active volcano.
Mains:
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)
"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)
