Physiography of India
Physiographic Divisions of India
India has a total area of 3,287,263 sq km (including Pakistan-Occupied Kashmir and Aksai Chin) and displays remarkable physiographic diversity — from the towering Himalayas in the north to the coastal plains and island groups. India is divided into six major physiographic divisions.
Key Dates
India covers 3,287,263 sq km — 7th largest country in the world by area
8 degrees 4 minutes N (Indira Point, Andaman & Nicobar) to 37 degrees 6 minutes N (Indira Col, Siachen, J&K)
68 degrees 7 minutes E (Gujarat, Ghuar Mota) to 97 degrees 25 minutes E (Arunachal Pradesh, Kibithu)
Passes through 8 states: Gujarat, Rajasthan, Madhya Pradesh, Chhattisgarh, Jharkhand, West Bengal, Tripura, Mizoram
82 degrees 30 minutes E passes through Mirzapur (UP) — IST is UTC+5:30
India has 7,516.6 km of coastline touching 9 states and 4 Union Territories
Kanchenjunga (8,586 m) is the highest peak entirely within India, in Sikkim
India's highest peak overall, located in Pakistan-Occupied Kashmir (Karakoram Range)
One of the oldest landmasses — part of the Gondwana supercontinent
India shares borders with 7 countries: Pakistan, China, Nepal, Bhutan, Bangladesh, Myanmar, Afghanistan (PoK)
India has 15,106.7 km of land border — longest with Bangladesh (4,096 km)
India shares a maritime border with Sri Lanka (Palk Strait, ~30 km) and Maldives (Eight Degree Channel)
Indian Plate collided with Eurasian Plate, beginning formation of Himalayas and Northern Plains
India's Location and Extent
India lies entirely in the Northern Hemisphere and almost entirely in the Eastern Hemisphere. It extends from 8 degrees 4 minutes N (Indira Point on Great Nicobar Island — India's southernmost point) to 37 degrees 6 minutes N (Indira Col near the Siachen Glacier in Ladakh — India's northernmost point). On the mainland, the southern tip is Cape Comorin/Kanyakumari (8 degrees 4 minutes N mainland). Longitudinal extent: 68 degrees 7 minutes E (Ghuar Mota, Gujarat — westernmost point on the mainland) to 97 degrees 25 minutes E (Kibithu, Arunachal Pradesh — easternmost point). The Tropic of Cancer (23 degrees 30 minutes N) passes through 8 states from west to east: Gujarat, Rajasthan, Madhya Pradesh, Chhattisgarh, Jharkhand, West Bengal, Tripura, and Mizoram. The Standard Meridian (82 degrees 30 minutes E) passes through Mirzapur (Uttar Pradesh), defining Indian Standard Time (IST = UTC + 5:30). India's longitudinal span of ~30 degrees means there is about a 2-hour difference in sunrise between Arunachal Pradesh and Gujarat. India shares land borders with 7 countries: Pakistan (3,323 km — west/northwest), China (3,488 km — north/northeast, including Aksai Chin which is Indian territory under Chinese occupation), Nepal (1,751 km — north), Bhutan (699 km — northeast), Bangladesh (4,096 km — east, India's longest border with any country), Myanmar (1,643 km — east), and Afghanistan (106 km — through PoK, via Wakhan Corridor). Maritime borders: with Sri Lanka (Palk Strait, about 30 km wide; Adam's Bridge/Ram Setu connects), Maldives (Eight Degree Channel), Indonesia (southeastern Andaman Sea), Thailand (eastern Andaman Sea).
The Himalayan Mountains — Overview and Formation
The Himalayas are young fold mountains formed by the collision of the Indian Plate and the Eurasian Plate during the Tertiary Period (about 50-55 million years ago). They stretch about 2,400 km in an arc from the Indus gorge (Nanga Parbat, 8,126 m) in the west to the Brahmaputra gorge (Namcha Barwa, 7,782 m) in the east, with a width varying from 400 km in Kashmir to 150 km in Arunachal Pradesh. The Himalayas are not a single range but a complex system of parallel and converging ranges. They are geologically young and still rising at about 1 cm/year due to the continued northward movement of the Indian Plate (~5 cm/year). The Himalayas are the source of three major river systems (Indus, Ganga, Brahmaputra), contain the third-largest reservoir of ice after Antarctica and the Arctic (sometimes called the "Third Pole"), and influence the climate of the entire Indian subcontinent by blocking cold Central Asian air in winter and intercepting the moisture-laden monsoon winds in summer. The Tethys Sea (the ancient ocean between the Indian and Eurasian plates) deposited marine sediments that were uplifted, folded, and metamorphosed during the collision — Tethys/Tibetan Himalayas contain marine fossils at elevations above 5,000 m, proving these mountains were once an ocean floor.
The Himalayan Ranges — Greater, Lesser, and Outer
The Himalayas consist of three parallel ranges from north to south: (1) Greater Himalayas or Himadri — the innermost, highest, and most continuous range with an average elevation of 6,000 m; contains all peaks above 8,000 m; major peaks in India: K2/Godwin-Austen (8,611 m, Karakoram Range, PoK — India's highest peak; world's 2nd highest), Kanchenjunga (8,586 m, Sikkim — India's highest peak entirely within its territory; world's 3rd highest), Nanda Devi (7,816 m, Uttarakhand — was considered India's highest before Sikkim's accession in 1975), Kamet (7,756 m, Uttarakhand), Namcha Barwa (7,782 m, near the Brahmaputra gorge); permanently snow-covered; composed of granite and gneiss; major glaciers: Siachen (76 km — world's longest non-polar glacier; India operates a military base here), Gangotri (30 km — source of Ganga), Zemu (Sikkim), Rathong (Sikkim). (2) Lesser Himalayas or Himachal — average elevation 3,700-4,500 m; includes the Pir Panjal Range (separating the Kashmir Valley from the Jammu plains — passes: Banihal Pass leads to Jawahar Tunnel on NH-44), Dhaula Dhar Range (HP), and Mahabharat Range (Nepal border); famous valleys: Kashmir Valley (between the Greater Himalayas and Pir Panjal), Kangra Valley, Kullu Valley; hill stations in this range: Shimla (2,205 m), Mussoorie (2,005 m), Nainital (2,084 m), Darjeeling (2,042 m), Srinagar (1,585 m), Manali (2,050 m). (3) Outer Himalayas or Shiwaliks — the youngest and southernmost range with elevation 900-1,100 m; composed of unconsolidated alluvial sediments (sand, gravel, conglomerate) easily eroded; extends from Jammu to Arunachal Pradesh; longitudinal valleys between the Shiwaliks and Lesser Himalayas are called Duns (e.g., Dehra Dun, Patli Dun, Kotli Dun).
Trans-Himalayas, Mountain Passes, and Eastern Extension
Beyond the three main ranges, the Himalayan system includes: Trans-Himalayas (Tibetan Himalayas) — north of the Greater Himalayas; includes the Karakoram Range (K2, Masherbrum; Siachen Glacier; Ladakh is in this zone), Ladakh Range (between the Indus and Shyok rivers), Zaskar Range, and the Kailash Range (Tibet — Mount Kailash, 6,638 m, is sacred to four religions); Aksai Chin (Indian territory occupied by China) lies in this region; extremely cold, arid, high-altitude desert; Ladakh's Nubra Valley, Pangong Tso, and Tso Moriri are in this zone. Important mountain passes: Karakoram Pass (5,359 m, Ladakh — historically on the trade route to Central Asia; near the Aksai Chin Line of Actual Control), Zoji La (3,528 m, connecting Srinagar to Leh via NH-1; Zojila Tunnel under construction), Banihal Pass (2,832 m, J&K — Jawahar Tunnel), Rohtang Pass (3,978 m, HP — connecting Manali to Lahaul-Spiti; Atal Tunnel underneath is the world's longest highway tunnel above 10,000 ft at 9.02 km), Shipki La (HP — border pass with Tibet), Nathu La (4,310 m, Sikkim — India-China border; reopened for trade in 2006), Bomdi La (2,217 m, Arunachal Pradesh — India-Tibet border), Lipulekh Pass (5,334 m, Uttarakhand — India-Tibet-Nepal tri-junction; disputed by Nepal), Jelep La (Sikkim), and Diphu Pass (Myanmar border). Eastern Extension (Purvanchal Hills): at the Dihang/Brahmaputra gorge, the Himalayas turn south into northeast India as the Purvanchal Hills — Patkai Hills, Naga Hills, Manipur Hills (Loktak Lake), Mizo Hills (Lushai Hills), and Barail Range; these hills run roughly north-south, separating India from Myanmar; predominantly composed of sandstone and shale; home to diverse tribal communities.
The Northern Plains (Indo-Gangetic-Brahmaputra Plains)
The Northern Plains stretch about 2,400 km from the Sutlej in the west to the Brahmaputra in the east, with a width of 150-300 km. Formed by the alluvial deposits of three major river systems — Indus, Ganga, and Brahmaputra — in the foredeep (trough) created between the rising Himalayas and the Peninsular Plateau. The alluvial deposits are up to 2,000 m deep near the Himalayas, making these among the deepest alluvial plains in the world. They are divided into four zones from north to south: (1) Bhabar — a narrow belt (8-16 km wide) of coarse pebbles, gravel, and boulders at the foothills where rivers emerge from the mountains; highly porous — streams disappear underground; unsuitable for agriculture. (2) Terai — a marshy, densely forested belt south of Bhabar (15-30 km wide) where underground streams re-emerge as springs and surface streams; once malarial and sparsely populated; largely cleared for agriculture and settlement after independence; remnant Terai forests in UP, Bihar, and West Bengal still harbour tiger, rhinoceros, and elephant populations. (3) Bhangar — older alluvium (Pleistocene age) forming elevated terraces above the floodplain; contains calcareous concretions called kankar; soil is less fertile than khadar but widely cultivated. (4) Khadar — newer alluvium (Holocene age) forming the active floodplain; renewed almost every year by floods; the most fertile soil zone in the plains; ideal for agriculture but flood-prone. The Northern Plains are divided regionally: Punjab Plains (doabs between the five rivers: Bist Doab, Bari Doab, Rechna Doab, Chaj Doab, Sindh Sagar Doab — "doab" means land between two rivers), Ganga Plains (the largest, from Allahabad/Prayagraj to the delta; includes the most densely populated areas of India — UP, Bihar), and Brahmaputra/Assam Plains (characterized by riverine islands like Majuli — the world's largest river island, prone to devastating annual floods).
The Peninsular Plateau — Central Highlands and Deccan Plateau
The Peninsular Plateau is one of the oldest landmasses on Earth, part of the ancient Gondwana supercontinent. It is a triangular tableland composed of old crystalline, igneous, and metamorphic rocks (Archaean gneisses and schists, over 3 billion years old). Average elevation is 600-900 m. The Narmada River divides the Plateau into two parts: (1) Central Highlands — north of Narmada; includes: Aravalli Range (the oldest fold mountains in India and among the oldest in the world, Pre-Cambrian age, highly eroded; extends ~800 km from Gujarat to Delhi; Guru Shikhar at 1,722 m in Mount Abu, Rajasthan, is the highest peak; separates the Thar Desert from the fertile plains; mineral-rich: zinc, lead, copper in Zawar mines, marble in Makrana used for the Taj Mahal). Vindhya Range (separates northern India from the Deccan; average 300-650 m; runs approximately east-west; historically considered the boundary between Hindustan and Dakshinapatha). Satpura Range (between Narmada and Tapi rivers; runs east-west; includes Dhupgarh, 1,350 m, highest point in MP; Pachmarhi hill station, Satpura Tiger Reserve; Mahadeo Hills, Maikal Hills are extensions). Malwa Plateau (elevated tableland in western MP; formed by lava flows; rich black soil; major rivers: Chambal, Betwa, Ken). Chota Nagpur Plateau (Jharkhand — one of India's richest mineral regions: coal, iron ore, mica, bauxite, uranium; Rajmahal Hills, Parasnath Hill at 1,365 m is the highest peak; the Damodar Valley is called "the Ruhr of India" for its industrial concentration). Bundelkhand Plateau (UP-MP; granite and gneiss; chronically drought-prone).
The Deccan Plateau and Volcanic Landscape
The Deccan Plateau — south of Narmada — is a triangular tableland tilting from west to east (rivers like Godavari, Krishna, and Kaveri flow eastward to the Bay of Bengal). It is bounded by the Western Ghats on the west and the Eastern Ghats on the east. Sub-divisions: Maharashtra Plateau (covered by the Deccan Trap basalt — massive lava flows from ~66 million years ago that covered about 500,000 sq km; produces regur/black cotton soil, ideal for cotton cultivation; laterite soils on plateau edges), Karnataka Plateau/Mysore Plateau (predominantly granite and gneiss; Baba Budan Hills contain India's oldest known iron ore deposits), and Telangana Plateau (rich in minerals including Kolar Gold Fields — now exhausted — and diamond deposits). The Deccan Trap is one of the largest volcanic provinces on Earth — it is believed to have been caused by the Reunion hotspot as the Indian Plate moved over it about 66 million years ago, coinciding with the Cretaceous-Paleogene (K-Pg) mass extinction event that killed the dinosaurs. The lava flows are visible today as horizontal layers of basalt in road cuttings across Maharashtra. The Western Ghats are the faulted edge of the Deccan Plateau — the steep western escarpment (the plateau drops sharply to the narrow coastal plain) and gentle eastern slope explain why most peninsular rivers flow eastward. Coorgi Plateau (Karnataka), Anantapur-Bellary region (mineral-rich, driest part of South India), and the Deccan Plateau's mineral wealth (iron ore in Bellary, Hospet, Sandur; manganese in Dharwad; limestone in Gulbarga) make it industrially significant.
The Western Ghats (Sahyadri)
The Western Ghats run continuously for about 1,600 km from the Tapi River (Gujarat-Maharashtra border) to Kanyakumari (Tamil Nadu), with an average elevation of 900-1,600 m. They are not true fold mountains but a faulted edge of the Deccan Plateau (a horst, or uplifted block). They are higher and more continuous than the Eastern Ghats. The Western Ghats are broken only by three significant passes (ghats): Thal Ghat (near Nashik — Mumbai-Nashik road and railway), Bhor Ghat (near Pune — Mumbai-Pune Expressway; historically the route between Deccan and Konkan), and Palghat/Palakkad Gap (about 30 km wide — the most significant break; connects Kerala and Tamil Nadu; allows the SW monsoon to pass through to the rain-shadow area of Tamil Nadu). The Western Ghats are a UNESCO World Heritage Site (2012) — the serial nomination covers 39 sites across Kerala, Karnataka, TN, and Maharashtra; recognized as one of the world's 8 hottest biodiversity hotspots. Highest peaks: Anai Mudi (2,695 m, Anaimalai Hills, Kerala — highest peak in South India), Dodda Betta (2,637 m, Nilgiri Hills, TN), Kudremukh (1,894 m, Karnataka — iron ore mining controversy), Kalsubai (1,646 m, Maharashtra — highest in Maharashtra), Mullayanagiri (1,930 m, Baba Budan Hills, Karnataka — highest in Karnataka). Major hill ranges within the Western Ghats from north to south: Sahyadri proper (Maharashtra), Nilgiri Hills (TN-Karnataka-Kerala junction — where Eastern and Western Ghats meet), Anaimalai Hills (Kerala-TN), Palani Hills (TN — Kodaikanal hill station), and Cardamom Hills (Kerala — cardamom cultivation; Periyar Tiger Reserve). The Western Ghats are the source of most peninsular east-flowing rivers: Godavari, Krishna, Kaveri, Tungabhadra, Bhima. West-flowing rivers (Narmada, Tapi — not from Western Ghats; Sharavati, Netravati) are shorter but have higher gradients, making them suitable for hydropower (Jog Falls on Sharavati — India's second-highest plunge waterfall at 253 m).
The Eastern Ghats
The Eastern Ghats are discontinuous hills running from Odisha in the north through Andhra Pradesh to Tamil Nadu in the south, with an average elevation of 600 m. They are broken by the river valleys of the Mahanadi, Godavari, Krishna, and Kaveri, which have carved through them on their way to the Bay of Bengal. Major peaks: Mahendragiri (1,501 m, Odisha — highest peak of the Eastern Ghats; sacred to the Saura tribe), Arma Konda (1,680 m, Andhra Pradesh — disputed as possibly the highest in the Eastern Ghats), Jindhagada (1,690 m, AP — Araku Valley), and Shevaroy Hills (1,623 m, TN — Salem district). The Eastern Ghats merge with the Western Ghats at the Nilgiri Hills in Tamil Nadu. Key features: Araku Valley (AP — coffee cultivation, tribal tourism, Borra Caves — one of India's largest caves with million-year-old stalactites), Simhachalam Hills (Visakhapatnam), Nallamala Hills (AP — Nagarjunasagar-Srisailam Tiger Reserve, largest Tiger Reserve in India), Javadi Hills (TN), Shevaroy Hills (TN — Yercaud hill station), Palkonda Range (AP), and Velikonda Range (AP). The Eastern Ghats contain several significant mineral deposits: bauxite in the Visakhapatnam Agency (among the largest reserves in India; mining opposed by tribal Dongria Kondh community), manganese in Odisha (Joda-Barbil belt), and iron ore in AP. The Eastern Ghats are less biodiverse than the Western Ghats but still harbour unique species: the Jeypore Hill Gecko (discovered 1877, rediscovered 2010), several endemic plants in the Nallamala Hills, and tribal communities who maintain traditional knowledge of medicinal plants.
The Western Coastal Plain
The Western Coastal Plain stretches from Gujarat to Kerala along the Arabian Sea, between the Western Ghats and the sea. It is narrow (averaging 50-65 km) because the Western Ghats run close to the coast. It is divided regionally (north to south): (1) Gujarat Coast — includes the Rann of Kutch (a vast salt marsh that becomes a shallow wetland in the monsoon; Great Rann is about 7,500 sq km; Little Rann is about 5,000 sq km — home to the Wild Ass Sanctuary; the Rann of Kutch was a shallow arm of the Arabian Sea until it was uplifted by the 1819 earthquake), the Kathiawar/Saurashtra Peninsula (Gir Forest is here; Porbandar — birthplace of Mahatma Gandhi; Somnath Temple), and the Gulf of Khambhat (highest tidal range in India; Narmada and Tapi rivers enter here; major petroleum refining centre — Jamnagar has the world's largest oil refinery). (2) Konkan Coast (Maharashtra and Goa) — narrow, with laterite hills and estuaries; Mumbai is on Salsette Island in this zone; Goa's beaches, laterite architecture; the Konkan Railway (completed 1998) is an engineering marvel with 2,000 bridges and 92 tunnels. (3) Karnataka Coast (Kanara/Karavali) — rice paddies, coconut groves; Karwar, Mangalore (major port for cashew, coffee export), Udupi. (4) Malabar Coast (Kerala) — famous for backwaters (kayals) — a chain of lagoons and lakes fed by 44 rivers; Vembanad Lake (longest lake in India at 96.5 km; Ramsar site; Kumarakom Bird Sanctuary); Kerala's backwaters are unique globally; Alleppey is called the "Venice of the East"; the coast is intensively cultivated with coconut, rice, rubber, pepper, and cardamom.
The Eastern Coastal Plain
The Eastern Coastal Plain is broader (100-130 km average, up to 200 km near deltas) and stretches from Tamil Nadu to West Bengal along the Bay of Bengal. The broad plain is due to the Eastern Ghats being farther from the coast. Divided regionally (south to north): (1) Coromandel Coast (Tamil Nadu) — extensive sandy beaches; receives rainfall mainly from the Northeast Monsoon (October-December) via the Bay of Bengal; major cities: Chennai (4th largest city), Mahabalipuram (UNESCO WHS — shore temple); Buckingham Canal runs along this coast. (2) Northern Circars (Andhra Pradesh and Odisha) — named by British from the Mughal administrative unit "Sarkar"; fertile alluvial plain with deltas of the Godavari, Krishna, and Kaveri; Visakhapatnam (major naval base and port), Rajahmundry (Godavari delta). (3) Utkal Coast (Odisha) — Mahanadi delta, Chilika Lake (India's largest coastal lagoon, 1,100 sq km; Ramsar site), Puri (Jagannath Temple), Konark (Sun Temple, UNESCO WHS); cyclone-prone coast. The Eastern Coastal Plain features the deltas of major peninsular rivers — these are among the most fertile and densely populated areas in India: Mahanadi Delta, Godavari Delta (2nd largest in India — "Dakshina Ganga"), Krishna Delta, and Kaveri Delta (called "the granary of South India"). Pulicat Lake (TN-AP border — 2nd largest brackish water lagoon in India; Dutch settlement remains), and the Sundarbans Delta — shared by the Ganga and Brahmaputra, is the world's largest delta (~58,752 sq km). The eastern coast is more cyclone-prone than the western coast because the Bay of Bengal is warmer and more enclosed.
The Thar Desert (Great Indian Desert)
The Thar Desert, also called the Great Indian Desert, lies in western Rajasthan and extends into Gujarat, Haryana, Punjab, and Sindh (Pakistan). Area: approximately 200,000 sq km in India, making it the world's 17th-largest desert and the most densely populated desert in the world. The Thar is bounded by the Aravalli Range to the east (which blocks moisture-laden SE trade winds, creating the rain shadow), the Rann of Kutch to the south, and the Indus River valley to the west. Climate: arid, with rainfall below 25 cm in the western Thar and up to 50 cm on the eastern fringe; temperatures range from over 50 degrees C in summer to near-freezing in winter; hot, dry winds (Loo) blow in May-June. Landscape: sand dunes (barchans — crescent-shaped, and longitudinal dunes), rocky desert (hamada), gravel plains, and salt flats; the Luni River is the only significant river (drains into the Rann of Kutch; one of the few inland drainage rivers in India). The Thar is geologically young — formed during the Quaternary period due to the shift in the course of the river Saraswati (now considered dried up) and the reduction in monsoon rainfall. The Indira Gandhi Canal (Rajasthan Canal) — India's longest canal at 649 km, drawing water from the Sutlej-Beas confluence at Harike Barrage (Punjab) — has transformed parts of the western Thar, making the Jaisalmer and Barmer regions cultivable. The Desert National Park (3,162 sq km, Jaisalmer) protects the Great Indian Bustard (critically endangered, ~150 remaining), desert fox, chinkara, and 180-million-year-old fossils. The Thar is strategically significant as the India-Pakistan border runs through it (the Radcliffe Line); the Pokhran nuclear test site (1974 and 1998 tests) is in the Thar.
Andaman & Nicobar Islands
The Andaman & Nicobar (A&N) Islands are a group of 572 islands (of which 38 are permanently inhabited) in the Bay of Bengal. They form a Union Territory with Port Blair as the capital. Geologically, they are the emerged peaks of a submerged mountain chain — an extension of the Arakan Yoma range of Myanmar. They lie on the convergent boundary where the Indian Plate subducts beneath the Burma Plate, creating the Andaman Trench. The islands are divided into two groups separated by the Ten Degree Channel (10 degrees N latitude): Andaman group (North, Middle, and South Andaman — collectively called Great Andaman — plus Little Andaman and numerous smaller islands) and the Nicobar group (Car Nicobar, Katchal, Great Nicobar, and others). Key geographic features: Indira Point on Great Nicobar Island is India's southernmost point (submerged 4.25 m during the 2004 tsunami); Saddle Peak (732 m) on North Andaman is the highest point; Barren Island has India's only active volcano (last erupted 2017); Narcondam Island has a dormant volcano. The islands have dense tropical evergreen forests (86% forest cover — highest among Indian UTs); mangroves; coral reefs (some of the best preserved in India). Indigenous tribes: Great Andamanese (only ~50 remain), Onge (Little Andaman, ~100), Jarawa (about 400; hostile to outsiders until recently; Jarawa Tribal Reserve protects them), Sentinelese (North Sentinel Island — one of the world's last uncontacted peoples, estimated 50-200; protected by Indian law; a 2018 incident where an American missionary was killed highlighted the need for their isolation). Nicobar tribes: Nicobarese (largest, about 30,000; of Mongoloid origin) and Shompen (Great Nicobar, about 200; nomadic). The 2004 tsunami devastated the A&N Islands — about 3,500 people killed; entire islands shifted; Indira Point submerged; the Car Nicobar airbase was destroyed.
Lakshadweep and Other Island Groups
Lakshadweep — a group of 36 islands (12 atolls, 3 reefs, 5 submerged banks, 1 raised bank) in the Arabian Sea, about 200-440 km off the Kerala coast. Total area: only 32 sq km — the smallest Union Territory of India by area. Population: about 64,000 (2011). The islands are of coral origin — built on the Chagos-Laccadive submarine ridge; maximum elevation is only 5 m above sea level, making them extremely vulnerable to sea level rise. Only 10 islands are inhabited. Capital: Kavaratti. The Eight Degree Channel (8 degrees N) separates Lakshadweep from the Maldives; the Nine Degree Channel (9 degrees N) separates Amindivi Islands (northern group) from the Cannanore Islands (southern group) within Lakshadweep. Economy: fishing (tuna), coconut products, tourism (water sports, diving — some of the best coral reefs in India). Special protections: the islands are a Scheduled Area under the Fifth Schedule; the Lakshadweep (Protection of Scheduled Tribe) Regulation, 2023, restricts land ownership and settlement by non-islanders. Other notable islands of India: Majuli (Assam) — in the Brahmaputra River; the world's largest inhabited river island (about 352 sq km); a center of Vaishnavite culture (satras/monasteries); declared India's first island district in 2016; shrinking due to erosion (was 1,246 sq km in 1853). Sagar Island (West Bengal) — at the mouth of the Hooghly River; Gangasagar Mela pilgrimage site. Islands in the Gulf of Mannar — 21 islands between India and Sri Lanka; Gulf of Mannar Marine National Park; dugong (sea cow) habitat. Diu and Daman — islands/coastal territories (now part of the Dadra and Nagar Haveli and Daman and Diu UT); Portuguese colonial history.
Major Mountain Passes and Their Significance
India's mountain passes have historically been routes for trade, invasion, and cultural exchange: Northwestern passes (J&K/Ladakh): Karakoram Pass (5,359 m — one of the highest motorable passes; connects Ladakh to Xinjiang, China; near the Line of Actual Control), Khunjerab Pass (4,693 m — connects PoK with China; on the Karakoram Highway), Zoji La (3,528 m — connects Srinagar to Leh; NH-1; Zojila Tunnel under construction will be Asia's longest bi-directional road tunnel at 14.15 km), Banihal Pass (2,832 m — Jawahar Tunnel on NH-44 connecting Jammu to Srinagar). Himachal Pradesh: Rohtang Pass (3,978 m — connects Kullu Valley to Lahaul-Spiti; Atal Tunnel is 9.02 km, world's longest highway tunnel above 10,000 ft, completed 2020), Bara-lacha La (4,890 m — on the Manali-Leh highway), Shipki La (4,500 m — India-Tibet trade route; Sutlej River enters India here). Uttarakhand: Mana Pass (5,545 m — near Badrinath; last Indian village before Tibet), Lipulekh Pass (5,334 m — India-Tibet-Nepal tri-junction; disputed by Nepal; trade route to Kailash-Mansarovar), Niti Pass (5,068 m — near the Garhwal-Tibet border). Sikkim: Nathu La (4,310 m — India-China border; reopened for trade in 2006; was used during the 1967 India-China border skirmish), Jelep La (4,267 m — connects Sikkim to Chumbi Valley, Tibet). Arunachal Pradesh: Bomdi La (2,217 m — India-Tibet border; site of 1962 India-China war battles), Se La (4,170 m — road from Tawang to Bomdila; Tawang monastery is one of the largest Buddhist monasteries). Western Ghats: Thal Ghat, Bhor Ghat, Palghat Gap (discussed earlier). Southern passes connect NH routes between states across the Ghats.
Geological Framework of India
India's geological structure can be understood through its three main physiographic units: (1) The Peninsular Block — the oldest and most stable part; composed of Archaean rocks (over 3 billion years old) — gneisses, schists, and granites; the Dharwar System rocks (Karnataka — among the oldest in India, about 3.5 billion years) contain iron ore, manganese, and gold deposits; the Cuddapah System (AP) and Vindhyan System (central India) are Proterozoic sedimentary formations containing diamond deposits (Panna, MP; Golconda, Telangana), sandstone, and limestone; the Gondwana System rocks (Permian-Triassic, ~300-200 MYA) in river valleys of Damodar, Son, Mahanadi, and Godavari contain 98% of India's coal reserves and bear Glossopteris flora fossils proving India's Gondwana origin; the Deccan Trap basalt (~66 MYA) covers ~500,000 sq km in western-central India. (2) The Himalayan Zone — composed of marine sedimentary rocks of the Tethys Sea (now uplifted to great heights); metamorphosed into slate, schist, marble, and quartzite; geologically young and unstable; fossils of ammonites (marine cephalopods) are found at altitudes above 5,000 m in the Spiti region of HP. (3) The Indo-Gangetic Trough — filled with Quaternary alluvium up to 2,000 m deep; no bedrock is visible; alluvium deposited by Himalayan rivers over the last 2-3 million years. India is divided into 4 seismic zones (II-V): Zone V (very high risk) — J&K, Ladakh, HP, Uttarakhand, North Bihar, all of NE India, Kutch (Gujarat), and A&N Islands; Zone IV (high risk) — remaining parts of J&K, HP, Delhi, northern UP, parts of Maharashtra; Zone III (moderate) — most of peninsular India; Zone II (low) — remaining areas.
Relevant Exams
Physiographic divisions of India is one of the most fundamental and frequently tested topics in geography. UPSC Prelims regularly asks about mountain passes, peaks, ranges, and their locations. SSC and RRB exams focus on factual recall — highest/longest/largest features, states touched by the Tropic of Cancer, and island geography. Questions on Western vs Eastern Ghats comparisons and river-related landforms appear almost every year.