Physiographic Divisions of India in Depth

Why physiography is the base of Indian geography

India covers about 3.28 million square kilometres, roughly 2.4 per cent of the world's land, yet it holds almost every major landform: the youngest fold mountains on Earth, one of the largest alluvial plains, an ancient plateau that is part of the old Gondwana landmass, a hot desert, long coastlines and two groups of islands. Each of these units was formed by a different geological history, and each shapes the soils, rivers, climate, crops, minerals and population that sit on it. UPSC asks both direct map-based Prelims questions (passes, ranges, hills, plateaus) and Mains questions on how physiography influences economy and society. The standard NCERT classification divides India into six physiographic divisions.

1. The Northern and North-Eastern Mountains

The Himalayas were formed by the collision of the Indian plate with the Eurasian plate after the closure of the Tethys Sea. They stretch about 2,400 km from the Indus in the west to the Brahmaputra in the east, and their width varies from about 400 km in Kashmir to about 150 km in Arunachal Pradesh. Because the plate is still pushing north, they are still rising and are seismically very active.

Longitudinal divisions (north to south):

• Trans-Himalaya – the Karakoram, Ladakh and Zaskar ranges behind the Great Himalaya. K2 (Godwin Austen, 8,611 m), India's highest peak, lies in the Karakoram. The Siachen and Baltoro are among the longest glaciers outside the polar regions.
• Greater Himalaya (Himadri) – the highest and most continuous range, average height about 6,000 m, with peaks such as Kangchenjunga (8,586 m), Nanda Devi and Kamet. Its core is made of granite, and it is perennially snow-bound.
• Lesser Himalaya (Himachal) – heights of 3,700–4,500 m; includes the Pir Panjal, Dhauladhar and Mahabharat ranges. Most hill stations – Shimla, Mussoorie, Nainital, Darjeeling – are here, along with valleys such as Kashmir, Kangra and Kullu.
• Shiwaliks (Outer Himalaya) – the youngest and lowest range (900–1,100 m), made of unconsolidated sediments brought down by rivers. Flat-floored valleys between the Lesser Himalaya and Shiwaliks are called duns – Dehradun, Kotli Dun and Patli Dun.

Regional divisions (from west to east) are based on the rivers that cut through them: the Punjab (Kashmir) Himalaya between the Indus and Sutlej, the Kumaon Himalaya between the Sutlej and Kali, the Nepal Himalaya between the Kali and Teesta, and the Assam Himalaya between the Teesta and Dihang (Brahmaputra).

Eastern hills (Purvanchal): after the Dihang gorge, the mountains bend sharply south as the Patkai Bum, Naga hills, Manipur hills and Mizo (Lushai) hills, made mostly of sandstone and covered with dense forest. Loktak Lake in Manipur, with its floating islands (phumdis) and the Keibul Lamjao National Park, lies here.

Important passes: Zoji La (Srinagar–Leh), Banihal (Jammu–Srinagar, now bypassed by the Jawahar and Navyug tunnels), Shipki La (Sutlej valley to Tibet), Lipulekh (Kailash-Mansarovar route), Nathu La (Sikkim–Tibet trade route), Bomdi La and Rohtang (now bypassed by the Atal Tunnel).

2. The Northern Plains

The Indo-Gangetic-Brahmaputra plain is formed by the alluvial deposits of three great river systems. It covers about 7 lakh square kilometres, is about 2,400 km long and 240–320 km wide, and has a very thick layer of alluvium – in places more than 1,000 m deep. It is among the most densely populated and intensively farmed areas in the world.

From north to south, the plain shows four belts:

Regionally, the plain is divided into the Punjab plains (doabs between the five rivers), the Ganga plains (upper, middle and lower), and the Brahmaputra plain of Assam. The Sundarbans delta at the mouth of the Ganga–Brahmaputra is the largest delta in the world. River islands such as Majuli in the Brahmaputra are also features of this plain.

3. The Peninsular Plateau

The Peninsular Plateau is the oldest and most stable landmass of India, made of ancient crystalline, igneous and metamorphic rocks of the Gondwana block. It is roughly triangular and rises from about 150 m in the north to about 600–900 m in the south.

• Central Highlands – north of the Narmada; include the Malwa plateau, Bundelkhand, Baghelkhand and the Chotanagpur plateau. The Aravallis, among the oldest fold mountains in the world, are heavily eroded; their highest peak is Guru Shikhar (1,722 m) on Mount Abu.
• Deccan Plateau – south of the Narmada; bounded by the Satpura in the north, the Western Ghats in the west and the Eastern Ghats in the east. The north-western part is covered by basalt lava flows (the Deccan Traps), which weather into black soil.
• North-eastern extension – the Meghalaya (Shillong) plateau, with the Garo, Khasi and Jaintia hills, and the Karbi Anglong plateau are separated from the main plateau by the Malda gap.

Western vs Eastern Ghats:

The Western and Eastern Ghats meet at the Nilgiri Hills, whose highest peak is Doddabetta. South of the Palghat gap, the Anaimalai, Cardamom and Palani hills continue the Western Ghats.

4. The Indian (Thar) Desert

North-west of the Aravallis lies the Thar desert, an undulating sandy plain with barchans (crescent-shaped dunes) and longitudinal dunes. Rainfall is below 150 mm a year. Luni is the only large river, and it ends in the Rann of Kachchh. Saline lakes such as Sambhar produce salt. Much of the desert was under the sea during the Mesozoic era, as shown by the wood fossils park at Akal near Jaisalmer. The Indira Gandhi Canal has turned parts of the desert into farmland.

5. The Coastal Plains

India has a mainland coastline of about 6,100 km (official recalculation in 2023–24 puts the total coastline, including islands, at about 11,098 km).

• Western coastal plain – narrow, a submerged coast; divided into the Kachchh and Kathiawar, Konkan, Kanara (Karnataka) and Malabar coasts. The Malabar coast has kayals (backwaters) such as Vembanad Lake, and natural harbours like Mumbai, Mormugao and Kochi. Rivers form estuaries, not deltas.
• Eastern coastal plain – broad, an emergent coast; the Utkal, Andhra and Coromandel coasts. Rivers Mahanadi, Godavari, Krishna and Kaveri build large deltas. Lagoons such as Chilika (the largest brackish-water lagoon in India) and Pulicat are found here.

6. The Islands

• Andaman and Nicobar Islands in the Bay of Bengal – about 570+ islands, the tops of a submerged mountain chain continuous with the Arakan Yoma of Myanmar. Barren Island has India's only active volcano. The Ten Degree Channel separates the Andamans from the Nicobars; Indira Point on Great Nicobar is India's southernmost point.
• Lakshadweep in the Arabian Sea – 36 small coral islands and atolls; the Nine Degree Channel separates Minicoy from the main group, and the Eight Degree Channel separates Minicoy from the Maldives.

How physiography shapes life

The Himalayas act as a climatic barrier, blocking cold Central Asian winds and forcing the monsoon to shed its rain over India; they also feed perennial rivers and hold huge hydropower potential. The Northern Plains are the food bowl and the densest belt of population. The Peninsular Plateau is a storehouse of minerals – iron ore, coal, manganese and bauxite – and the base of heavy industry. The coasts support fisheries, ports and trade, and the islands give India a vast Exclusive Economic Zone and strategic reach in the Indian Ocean.

Mains practice question

"The physiography of India has shaped its economy and society." Discuss with examples from the Himalayas, the Northern Plains and the Peninsular Plateau. (250 words)

Answer framework

• Intro: six divisions and their geological origin.
• Himalayas: climate barrier, rivers, hydropower, tourism, but disasters and connectivity limits.
• Plains: alluvium, agriculture, population density, urbanisation, flood risk.
• Plateau: minerals, black soil and cotton, industry, tribal belts.
• Coasts and islands: ports, fisheries, EEZ, strategy.
• Conclusion: region-specific planning.