Indian Geography: Complete UPSC Notes 2026
Physical Features of India
Comprehensive notes on all 6 physiographic divisions of India — Himalayas, Northern Plains, Peninsular Plateau, Indian Desert, Coastal Plains, and Islands. Includes PYQs, comparison tables, and Mains answer hints.
1. Overview — India's Physiographic Divisions
India, the 7th largest country in the world, covers an area of approximately 3.28 million sq km. It is bounded by the Himalayas in the north and extends southward to the Indian Ocean, flanked by the Arabian Sea in the west and the Bay of Bengal in the east. This unique geographic setting has resulted in extraordinary physical diversity.
India is divided into six major physiographic divisions based on its varied landforms, geological structure, and physical features:
2. The Himalayan Mountains
The Himalayas are the youngest, highest, and most extensive mountain system in India. They were formed due to the collision of the Indian Plate with the Eurasian Plate, as the Tethys Sea closed. This is a continuing geological process, which is why the Himalayas are still rising — and why they are associated with frequent earthquakes.
The Himalayan mountain wall stretches over a distance of about 2,400 km in length, with a varying width of 240 to 320 km. The Himalayas comprise three almost parallel ranges from north to south:
| Range Name | Also Known As | Average Altitude | Key Features | Important Peaks/Passes |
|---|---|---|---|---|
| Greater Himalayas | Himadri | 6,000 m | Highest range; perennially snow-covered; permanent glaciers; asymmetrical in cross-section | Mt. Everest (8,849m), Kanchenjunga (8,586m), Nanda Devi (7,817m) |
| Middle Himalayas | Himachal / Lesser Himalayas | 3,700–4,500 m | Famous hill stations; important valleys; Pir Panjal & Dhauladhar ranges | Shimla, Mussoorie, Nainital; Kashmir Valley, Kullu Valley |
| Outer Himalayas | Shiwaliks | 600–1,500 m | Outermost range; widest in west, absent in east; marshy valleys called Duns (e.g., Dehradun) | Doon Valley (Dehradun); foothills covered with dense forests |
Table 1: Three Himalayan Ranges — Comparative Overview
Himalayan Divisions (West to East)
The Himalayas can also be divided longitudinally based on river systems and regional geography:
- Punjab Himalaya: Between the Indus and Sutlej rivers (560 km)
- Kumaon Himalaya: Between the Sutlej and Kali rivers
- Nepal Himalaya: Between the Kali and Teesta rivers (800 km) — highest peaks here
- Assam Himalaya: Between the Teesta and Dihang rivers
Purvanchal (Eastern Hills)
Beyond the Dihang gorge (where the Brahmaputra enters India), the Himalayas bend sharply southward, forming the Purvanchal ranges. These run along India's northeastern boundary and include:
- Patkai Hills — Arunachal Pradesh (also called Patkai Bum)
- Naga Hills — Nagaland (highest peak: Saramati, 3,826 m)
- Manipur Hills — Manipur (contains Loktak Lake)
- Mizo Hills (Lushai Hills) — Mizoram (highest: Blue Mountain / Phawngpui, 2,157 m)
"Himadri — Himachal — Shiwalik" — Remember: H-H-S → "Higher than Him is Silly" (Greatest → Middle → Outer/Lowest)
Significance of the Himalayas
- Climatic barrier: Blocks cold Central Asian winds, protecting India; also forces the southwest monsoon to rise and cause rainfall
- Perennial rivers: Glaciers feed the Indus, Ganga, and Brahmaputra systems — critical for India's water security
- Biodiversity: Diverse flora and fauna across altitudinal zones
- Strategic importance: Acts as India's natural northern border; key strategic passes (Nathula, Shipkila)
- Agriculture: Fertile valleys like Kashmir and Kullu support horticulture
- Tourism: Hill stations, trekking routes, and pilgrimage centres
3. The Northern Plains of India
The Northern Plains, also called the Indo-Gangetic-Brahmaputra Plains, stretch approximately 3,200 km in length with a width of 150–300 km. They were formed by the gradual filling of the depression between the Himalayas and the Peninsular Plateau with alluvial deposits brought by three major river systems: Indus, Ganga, and Brahmaputra.
These plains are among the most densely populated and agriculturally productive regions on Earth. The average depth of alluvial deposits is 1,000–2,000 metres, indicating the enormous geological timescale of their formation (Pleistocene and Holocene periods).
Types of Alluvial Deposits
- Largest part of the Northern Plains
- Lies above the floodplains (terrace-like)
- Contains calcareous deposits (Kankar)
- Less fertile than Khadar
- Darker in colour
- Younger deposits of floodplains
- Renewed by fresh silt deposits every monsoon
- Extremely fertile — ideal for agriculture
- Lower lying than Bhangar
- Lighter in colour
Sub-Divisions of the Northern Plains
| Sub-Region | Location | Key Feature | States |
|---|---|---|---|
| Punjab Plains | West — Indus tributaries | Land of 5 rivers; Doabs prominent; good agricultural land | Punjab, Haryana |
| Ganga Plains | Centre — largest unit | Upper, Middle, Lower subdivisions; most fertile; dense population | UP, Bihar, WB |
| Brahmaputra Plains | East — Assam | Marshy tracts; meandering river; oxbow lakes; braided channels | Assam |
| Terai Region | Foothills of Himalayas | Marshy, forested belt between plains and Shiwaliks; rich biodiversity | UP, Bihar, Uttarakhand |
Bist Doab (Beas–Sutlej) → Bari Doab (Beas–Ravi) → Rechna Doab (Ravi–Chenab) → Chaj Doab (Chenab–Jhelum) → Sindh Sagar Doab (Jhelum+Chenab–Indus, now in Pakistan)
Mnemonic: "B-B-R-C-S" → "Boys Bear Rains Cold Sometimes"
4. The Peninsular Plateau
The Peninsular Plateau is the oldest and most stable landform of India. It is part of the ancient Gondwana land — the supercontinent that existed before the breakup of Pangaea. Covering an area of about 16 lakh sq km, it forms the largest physiographic division of India.
It is triangular in shape, with a general elevation of 600–900 metres. It is composed primarily of ancient crystalline, igneous, and metamorphic rocks. The plateau tilts slightly towards the east, which is why most major peninsular rivers (Godavari, Krishna, Mahanadi, Cauvery) flow eastward into the Bay of Bengal.
Major Divisions of the Peninsular Plateau
| Division | Location | Key Ranges/Features | Soil Type |
|---|---|---|---|
| Central Highlands | North of Narmada River | Malwa Plateau, Chotanagpur Plateau; Vindhya, Satpura, Aravalli ranges; bordered by Vindhyan escarpment | Red & yellow soil; some black soil |
| Deccan Plateau | South of Narmada | Higher in west, slopes east; basaltic lava flows (Deccan Traps); Western & Eastern Ghats on flanks | Black cotton soil (regur) |
| Chotanagpur Plateau | Eastern extension | Richest mineral belt of India (coal, iron ore, manganese, bauxite); Damodar River basin | Laterite soil; highly mineralized |
| Meghalaya Plateau | Northeast — detached block | Garo, Khasi, Jaintia hills; separated from main plateau by Brahmaputra depression; wettest place on Earth (Mawsynram) nearby | Laterite soil |
Important Hill Ranges of the Plateau
- Aravalli Range: One of the world's oldest folded mountains; highest peak = Guru Shikhar (1,722 m), Mount Abu; runs NE–SW in Rajasthan
- Vindhya Range: Separates North India from South India; bounded by Satpura in the south
- Satpura Range: Runs east-west; highest peak = Dhupgarh (1,350 m), Pachmarhi; rich in forests
- Rajmahal Hills: Eastern extension; basaltic; associated with the Gondwana fossil plant Glossopteris
The Deccan Plateau was formed by enormous lava flows (Deccan Traps) about 65–66 million years ago — around the time of the dinosaur extinction. The weathering of this basaltic rock over millions of years created the famous black cotton soil (regur), ideal for growing cotton. Maharashtra and parts of Gujarat, MP, and AP have this soil.
5. The Indian Desert (Thar Desert)
The Thar Desert, also called the Great Indian Desert, is the 7th largest desert in the world and the most densely populated desert in the world. It is located in the northwestern part of India, primarily in Rajasthan, and extends into parts of Gujarat, Punjab, and Haryana, as well as Pakistan's Sindh and Punjab provinces.
Key Features of the Thar Desert
- Area: About 200,000 sq km in India
- Rainfall: Less than 150 mm per year (most gets less than 100 mm)
- Sand dunes (Barchans): Crescent-shaped dunes formed by wind action; longitudinal sand ridges also present
- Luni River: The only significant river in this region; drains into the Rann of Kutch
- Salt lakes: Sambhar Lake (largest salt lake in India), Didwana, Pachpadra
- Temperature extremes: Very hot in summer (50°C) and very cold in winter (0°C or below)
- West of Luni River
- Extends to Rann of Kutch northward
- Mostly sandy desert
- Lies along Rajasthan-Pakistan border
- Between Jaisalmer and Jodhpur
- East of Luni River
- Rocky land with limestone ridges
- More vegetation than great desert
The Aravalli Hills run parallel to the direction of the Arabian Sea branch of the southwest monsoon, providing no barrier. As a result, the moisture-laden winds pass over Rajasthan without releasing rainfall, creating the desert conditions. Had the Aravalli been perpendicular to the monsoon, Rajasthan would have received rain!
6. The Coastal Plains of India
India has a total coastline of 7,516.6 km (mainland + islands). The coastal plains lie on either side of the Peninsular Plateau, extending along the western and eastern coasts. These plains are narrow, but immensely important for trade, fishing, ports, and climate regulation.
| Feature | Western Coastal Plains | Eastern Coastal Plains |
|---|---|---|
| Extent | Gujarat to Kerala (1,500 km) | West Bengal to Tamil Nadu (1,500 km) |
| Width | Narrow (10–25 km) | Wider (100–130 km) |
| Sub-divisions | Konkan (N), Kanara (middle), Malabar (S) | Northern Circar (N), Coromandel (S) |
| Drainage | Rivers short, swift; no deltas | Large deltas (Mahanadi, Godavari, Krishna, Cauvery) |
| Rainfall | Heavy — exposed to SW monsoon | NE monsoon brings Oct–Dec rainfall |
| Lagoons / Backwaters | Prominent — Vembanad Lake, Kayals (Kerala) | Chilika Lake (Odisha), Pullicat Lake (AP/TN) |
| Soil | Red laterite + alluvial | Alluvial and deltaic |
| Ports | Mumbai, Kochi, Marmagoa, Kandla | Kolkata, Visakhapatnam, Chennai, Paradip |
Table 2: Eastern vs Western Coastal Plains — Comparative Analysis
7. The Islands of India
India has 1,382 islands in total (including smaller ones), of which the two main groups are the Andaman & Nicobar Islands in the Bay of Bengal and the Lakshadweep Islands in the Arabian Sea.
- Located in Bay of Bengal
- About 836 islands (572 named)
- Capital: Port Blair
- Volcanic origin — extension of Arakan Yoma
- Barren Island — only active volcano in India
- Narcondam Island — dormant volcano
- Southernmost point: Indira Point (submerged in 2004 tsunami)
- Rich tropical rainforest; tribal populations
- UT — administered by Centre
- Located in Arabian Sea
- 36 islands (10 inhabited)
- Capital: Kavaratti
- Coral origin — formed on coral reefs (atolls)
- Smallest UT of India by area
- Minicoy Island — closest to Maldives; home to Minicoy lighthouse
- Nine Degree Channel separates Minicoy from main islands
- Eight Degree Channel separates Lakshadweep from Maldives
- No rivers; groundwater dependent; fragile ecology
- Ten Degree Channel → separates Andaman Islands from Nicobar Islands
- Duncan Passage → between South Andaman and Little Andaman
- Nine Degree Channel → separates Minicoy Island from main Lakshadweep group
- Eight Degree Channel → separates Lakshadweep from Maldives
8. Major River Systems of India
India's rivers can be divided into two major groups based on their origin and characteristics:
- Originate in glaciers — perennial
- Long, large basins
- V-shaped valleys, gorges, waterfalls
- High sediment load → fertile deltas
- Example: Ganga, Indus, Brahmaputra
- Eastward-flowing Himalayan rivers in India were antecedent to the mountains
- Originate in Western Ghats or plateau — seasonal
- Shorter, shallower valleys
- Mostly flow east → Bay of Bengal
- Few flow west: Narmada, Tapi (in rift valleys)
- Example: Godavari, Krishna, Cauvery, Narmada
- Narmada and Tapi flow through rift valleys
| River | Origin | Flows Into | Length (km) | Key Tributaries |
|---|---|---|---|---|
| Ganga | Gangotri Glacier, Uttarakhand | Bay of Bengal | 2,525 | Yamuna, Ghaghra, Gandak, Kosi, Son |
| Indus | Mansarovar Lake, Tibet | Arabian Sea (Pakistan) | 3,180 (total) | Sutlej, Beas, Ravi, Chenab, Jhelum |
| Brahmaputra | Chemayungdung Glacier, Tibet | Bay of Bengal (via Bangladesh) | 2,900 (total) | Teesta, Subansiri, Lohit, Dibang |
| Godavari | Nasik, Maharashtra (Western Ghats) | Bay of Bengal | 1,465 | Indravati, Pranhita, Manjira — "Dakshin Ganga" |
| Krishna | Near Mahabaleshwar, Maharashtra | Bay of Bengal | 1,400 | Tungabhadra, Bhima, Musi |
| Cauvery | Brahmagiri Hills, Coorg, Karnataka | Bay of Bengal | 805 | Kabini, Bhavani — "Dakshin Ganga" / "Ganga of South" |
| Narmada | Amarkantak, MP | Arabian Sea (Gulf of Khambhat) | 1,312 | Hiran, Orsang — flows through rift valley |
| Tapi (Tapti) | Betul district, MP | Arabian Sea (Gulf of Khambhat) | 724 | Purna, Girna — twin of Narmada in rift valley |
Table 3: Major Rivers of India — Key Facts for UPSC
9. Western Ghats & Eastern Ghats
The Western Ghats (Sahyadri) and Eastern Ghats are the two major mountain ranges that flank the Deccan Plateau, forming the backbone of the peninsula's drainage system.
| Feature | Western Ghats (Sahyadri) | Eastern Ghats |
|---|---|---|
| Continuity | Continuous, unbroken range | Discontinuous, dissected by rivers |
| Length | ~1,600 km | ~1,300 km (discontinuous) |
| Height | 915–1,220 m avg; rises to 2,695 m (Anamudi) | ~610 m avg; Mahendragiri = 1,501 m (highest) |
| Highest Peak | Anamudi (2,695 m) — highest point south of Himalayas | Mahendragiri (1,501 m) — Odisha |
| UNESCO Status | World Heritage Site (2012) | Not UNESCO listed |
| Passes | Thalghat, Bhorghat, Palakkad Gap (Palghat Pass) | No major passes (dissected, not continuous) |
| Rainfall | Windward side = very heavy rain; leeward = rain shadow | Less rainfall; leeward of Western Ghats |
| Biodiversity | One of world's 8 "hottest hotspots" of biodiversity | Less biodiverse; mixed forest |
| Rivers originating | Godavari, Krishna, Cauvery originate here | Eastern Ghats dissected by Mahanadi, Godavari, Krishna |
Anamudi (2,695 m) — Western Ghats, Kerala — Highest peak south of Himalayas
Doddabetta (2,637 m) — Nilgiris, Tamil Nadu/Kerala
Guru Shikhar (1,722 m) — Aravalli, Rajasthan — Highest in Aravalli
Dhupgarh (1,350 m) — Satpura, MP — Highest in Satpura
Mahendragiri (1,501 m) — Eastern Ghats, Odisha — Highest in Eastern Ghats
10. UPSC PYQs & Revision Points
Chaj Doab — between Chenab and Jhelum; Bari Doab — between Beas and Ravi (Answer: Both are correct)
Mains Hints — Important Topics for GS-I
- Role of Himalayas in India's climate and economy — Climate barrier, perennial rivers, tourism, agriculture, biodiversity
- Significance of Northern Plains for Indian civilization — Fertile soil, dense population, agriculture, early civilizations (Indus Valley), river systems
- Compare Eastern and Western Coastal Plains — Width, rainfall, drainage patterns, lagoons, ports, fishing
- Why does the Thar Desert exist? — Orientation of Aravalli, Arabian Sea branch bypass, low rainfall
- Western Ghats as a biodiversity hotspot — UNESCO Heritage, endemic species, source of rivers, rain shadow effect
- Peninsular Plateau — mineral wealth and economic importance — Coal, iron ore in Chotanagpur; cotton in Deccan; basaltic rock origin
- Always study with an outline map of India — mark every range, river, and plateau
- Practice map-based MCQs regularly — 2–3 questions from maps appear every year
- Read NCERT Class 9 Chapter 2 (Physical Features) and NCERT Class 11 India: Physical Environment thoroughly
- For PYQs, solve the last 10 years of UPSC Prelims — topics like channels, passes, and passes repeat
- For Mains, practice writing 200-word answers linking physical features to economic/climate significance
- Remember: comparative questions (Himalayan vs Peninsular rivers, East vs West Ghats) are very common
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