India: Physiography

Flagship: what this is and why CAPF cares

Physiography is the study of the surface form of the land, and for India it is the single most map-heavy chapter the exam tests. CAPF Paper I treats it as a location-and-name quiz: which range is the highest, which State a pass lies in, which gap breaches the Western Ghats, where the only active volcano sits, which point is the southernmost. The security value is direct. The Himalayas are India's northern wall and the theatre where the Indo-Tibetan Border Police and the Army hold the Line of Actual Control; the open Shiwalik and Terai belt is the Sashastra Seema Bal's ground along Nepal and Bhutan; the Andaman and Nicobar Islands anchor surveillance over the eastern sea approaches. Everything in this note is, in the end, terrain that a border force has to hold. The standard reference is NCERT Class XI, India: Physical Environment (chapters on structure, physiography, and the drainage system).

Locational frame

India lies between about 8° 4 minutes N and 37° 6 minutes N latitude, and 68° 7 minutes E to 97° 25 minutes E longitude, with a mainland that spans roughly 3,214 km north to south and 2,933 km east to west. The Tropic of Cancer (23.5° N) cuts the country almost in half and passes through eight States. The standard meridian of India is 82° 30 minutes E, passing near Mirzapur in Uttar Pradesh, and Indian Standard Time is set 5 hours 30 minutes ahead of Greenwich Mean Time. India is the seventh-largest country by area, covering about 3.28 million square kilometres, roughly 2.4 percent of the world land area, and it stretches across nearly 30° of longitude, which is why the sun rises in Arunachal Pradesh about two hours before it does in the Rann of Kutch even though both keep the same clock.

The six physiographic divisions

NCERT divides India into six physical regions: the Northern and North-eastern Mountains (the Himalayas), the Northern Plains, the Peninsular Plateau, the Indian Desert, the Coastal Plains, and the Islands. Read them as a north-to-south traverse from the youngest fold mountains, across the alluvial trough they fed, onto the oldest stable shield, and out to the seas.

The Himalayas (Northern and North-eastern Mountains)

The Himalayas are young fold mountains formed by the collision of the Indian and Eurasian plates, a collision that is still in progress, so the range is still rising and is seismically active. They run about 2,400 km in an arc from the Indus gorge in the west (near Nanga Parbat) to the Brahmaputra gorge in the east (near Namcha Barwa), with a width that narrows from about 400 km in Kashmir to about 150 km in Arunachal.

Three roughly parallel ranges run lengthwise:

• Greater Himalayas or Himadri: the northernmost, highest and perpetually snow-clad range, holding the loftiest peaks; its core is granite and it is the source of the great Himalayan glaciers.
• Lesser Himalayas or Himachal: the middle range, home to the famous hill stations (Shimla, Mussoorie, Nainital, Darjeeling) and valleys (Kashmir, Kangra, Kullu); the Pir Panjal is its longest range and the Dhauladhar and Mahabharat are also part of it.
• Outer Himalayas or Shiwaliks: the youngest, lowest, southernmost foothills, made of unconsolidated sediment eroded off the rising ranges; their flat-floored longitudinal valleys are called Duns (Dehra Dun, Kotli Dun, Patli Dun).

Lengthwise, the Himalayas are also divided into the Punjab or Kashmir Himalayas (Indus to Sutlej), the Kumaon Himalayas (Sutlej to Kali), the Nepal Himalayas (Kali to Tista) and the Assam Himalayas (Tista to Dihang). Beyond the eastern bend, the range turns sharply south as the Purvanchal or Eastern Hills (Patkai, Naga, Manipur and Mizo or Lushai Hills), the low forested ranges that screen the Myanmar border. The Karakoram, with K2 (Mount Godwin-Austen), the second-highest peak on earth at 8,611 m and the highest entirely within Indian-claimed territory, lies to the north-west as a trans-Himalayan range along with the Ladakh and Zaskar ranges and the cold desert plateaus.

The Himalayan ranges and their key features, summarised:

The great Himalayan glaciers feed the perennial rivers: the Gangotri (source of the Bhagirathi-Ganga), the Yamunotri (Yamuna), the Siachen and Baltoro in the Karakoram (among the largest outside the poles), the Zemu (below Kangchenjunga in Sikkim) and the Pindari (Kumaon). High-altitude lakes the exam names include Pangong Tso and Tso Moriri (Ladakh, brackish endorheic lakes straddling or near the LAC), Chandra Tal and Suraj Tal (Himachal), and Gurudongmar and Tsomgo or Changu (Sikkim).

The Northern Plains

The Northern Plains are a vast aggradational lowland, the deepest alluvial trough on earth, built up over millions of years by the silt of the Indus, Ganga and Brahmaputra systems on top of a buried foredeep. They run about 2,400 km from the Punjab plains to the Assam valley and are agriculturally the heart of India. From the mountain foot southward they grade through four belts:

• Bhabar: a narrow porous boulder belt at the Shiwalik foot where the swift streams deposit pebbles and disappear underground.
• Terai: a re-emergent marshy, reedy belt below the Bhabar where the streams resurface; once malarial jungle, now reclaimed farmland.
• Bhangar: the older alluvium of the higher terraces, dark, often charged with calcareous kankar nodules.
• Khadar: the newer, lighter, more fertile floodplain alluvium renewed by fresh silt every flood season.

The plains are subdivided regionally into the Punjab plains (built by the Indus tributaries, with interfluves called doabs), the Ganga plains (the broadest, from Haryana to Bengal) and the Brahmaputra plains (the Assam valley).

The regional subdivisions of the Northern Plains:

The plains are the agricultural and demographic core of India: the most productive soils, the densest population, the Green Revolution heartland and the deepest groundwater development all sit here, which is why this division underpins indian agriculture and cropping and indian industries transport and population.

The Peninsular Plateau

The Peninsular Plateau is the oldest and most stable part of India, a fragment of the ancient Gondwana shield made of hard crystalline metamorphic and igneous rock, with old block mountains and rift valleys. It is broadly triangular and tilts gently to the east, which is why most peninsular rivers flow east to the Bay of Bengal. It splits into two:

• Central Highlands: north of the Narmada, including the Malwa Plateau, the Bundelkhand and Baghelkhand uplands, and the Chota Nagpur Plateau in the east (India's mineral heartland).
• Deccan Plateau: south of the Narmada, the larger southern block, bordered by the Western Ghats and the Eastern Ghats and crossed by the Maharashtra plateau and the Karnataka and Telangana uplands.

The bounding hills are the Vindhya and Satpura ranges in the north (separating the Central Highlands from the Deccan, with the Narmada in the rift between them), the Aravallis in the north-west (among the oldest fold mountains on earth, running from Gujarat to Delhi, with Guru Shikhar on Mount Abu the highest point), the Western Ghats or Sahyadri (continuous, high, rising eastward, the true edge of the plateau on the west), and the Eastern Ghats (lower, broken into hills, dissected by the great east-flowing rivers). The Deccan Trap of the north-west is a thick stack of basaltic lava flows from ancient fissure eruptions that weather into the black cotton soil.

The plateau hills and ranges, summarised:

The Western Ghats meet the Eastern Ghats at the Nilgiri Hills, and the only major break in the Western Ghats wall is the Palakkad (Pal Ghat) Gap, which carries the Tamil Nadu to Kerala road and rail.

The Indian Desert

The Indian or Thar Desert lies west of the Aravallis in Rajasthan, an arid sandy and rocky tract with longitudinal dunes (called dhrian when shifting), barchans (crescent dunes), and ephemeral salt lakes; the Luni is its only significant river, draining to the Rann of Kutch. It receives under 150 mm of rain a year and merges into the salt marshes of the Great and Little Rann of Kutch along the Pakistan border.

The Coastal Plains

The Coastal Plains flank the peninsula on both seaboards.

• Western Coastal Plain: narrow and submerged, divided from north to south into the Konkan (Maharashtra and Goa), the Kanara (Karnataka) and the Malabar (Kerala) coasts, fringed in Kerala by lagoons or backwaters (the kayals, of which Vembanad is the longest) and by laterite uplands.
• Eastern Coastal Plain: broad and emergent, divided into the Northern Circars (north) and the Coromandel Coast (south), built up by the wide deltas of the Mahanadi, Godavari, Krishna and Kaveri, and holding the largest brackish lagoon, Chilika, and Pulicat lake.

The Islands

• Andaman and Nicobar Islands: in the Bay of Bengal, the larger group, of continental and volcanic origin, separated by the Ten Degree Channel; Barren Island is India's only active volcano, Narcondam is a dormant volcano, Saddle Peak (North Andaman) is the highest point, and Indira Point on Great Nicobar is India's southernmost point.
• Lakshadweep Islands: in the Arabian Sea, small low coral atolls and reefs built on a submarine ridge, separated from the Maldives by the Eight Degree Channel; Minicoy is the largest and Kavaratti the capital.

The north-east and the Purvanchal

The north-east is physiographically distinct: the Brahmaputra and Barak valleys are flanked by the Meghalaya (Shillong) Plateau, an outlier of the Peninsular shield separated from it by the Garo-Rajmahal gap, and ringed by the Purvanchal hills (Patkai, Naga, Manipur, Mizo). The Khasi, Garo and Jaintia hills of the Meghalaya Plateau funnel the Bay of Bengal monsoon branch to give Mawsynram and Cherrapunji the world's heaviest rainfall, a fact that links this division to indian monsoon and climate.

How the divisions formed

The geological story underpins the physiography and occasionally appears in statement questions.

• The Peninsular block is part of the ancient Gondwanaland supershield, made of Archaean crystalline rocks, stable and rigid, which is why it has old block mountains and rift valleys rather than fresh folding.
• The Himalayas and the Northern Plains lie where the Indian plate, drifting north after Gondwana broke up, collided with the Eurasian plate, closing the Tethys Sea; the sediments of the Tethys were squeezed up into the fold mountains, and the trough in front filled with alluvium to make the plains.
• The collision is ongoing, so the Himalayas are still rising a few millimetres a year and the belt is seismically active (the Himalaya, the north-east and the Kutch are high-earthquake zones).
• The Deccan Trap formed from vast fissure eruptions of basaltic lava near the end of the Cretaceous, before the plate reached its present position.

Hill stations (matching)

Division summary (master table)

Rivers cross these divisions: the Himalayan rivers rise in the mountains, cut antecedent gorges, and build the plains; the peninsular rivers drain the tilted plateau east to the Bay of Bengal, except the Narmada and Tapi which exploit the rift valleys to flow west. The drainage detail is in indian drainage system and rivers.

Static facts to memorise

Coastal plains and the seas (reference)

The west coast is narrow and submerged with few good natural harbours but deep water close inshore (Mumbai, Mormugao); the east coast is broad, emergent and deltaic with shallow water and mostly artificial or river ports (Chennai, Paradip). The Gulf of Khambhat and the Gulf of Kutch indent the Gujarat coast; the Gulf of Mannar and the Palk Strait separate India from Sri Lanka.

Island groups (reference)

Other notable islands and offshore features: Majuli (the world's largest river island, in the Brahmaputra in Assam, technically riverine not marine), New Moore or South Talpatti (a former disputed sandbar in the Bay of Bengal), and Sriharikota (the spaceport island on the Andhra coast).

Peaks reference table

Himalayan passes (high-yield matching)

Security and strategic angle

The Himalayas are not just scenery; they are the defensive geometry of the northern border. The passes named above are precisely where the Line of Actual Control runs and where the Indo-Tibetan Border Police and the Army hold forward posts. Nathu La and Jelep La (Sikkim), Shipki La (Himachal), and Bum La and Se La (Arunachal) were focal in the 1962 war and in later standoffs; Se La in particular guards the road to Tawang. The high Shiwalik and Terai belt along the open Indo-Nepal and Indo-Bhutan border is the Sashastra Seema Bal's domain, where there is no fence and movement is free under treaty. The Purvanchal hills screen the porous Myanmar border held by the Assam Rifles. The Thar and the Rann of Kutch define the Border Security Force's desert and marsh posture against Pakistan. The Andaman and Nicobar Islands host India's only unified tri-service command and project surveillance toward the western mouth of the Malacca Strait. The 1962 reverses taught India that without roads to these heights the terrain favours the side already on the plateau, which is why the Border Roads Organisation now drives all-weather roads and tunnels (the Atal Tunnel under Rohtang, the road and tunnel work toward the LAC) up to the forward edge. See india borders neighbours and strategic geography and straits chokepoints and strategic waterways.

How CAPF asks it

• Single-correct location: "The only active volcano in India is located in" (Barren Island, Andaman); "India's southernmost point is" (Indira Point).
• Matching feature to location: pass to State, peak to range, Ghat gap to coast.
• Statement-based: judge two statements such as "The Tropic of Cancer passes through eight States" (correct) and "The Eastern Ghats are higher than the Western Ghats" (incorrect).
• Ordering / sequence: arrange the Himalayan ranges from south to north, or peaks by height.
• Pairing: trans-Himalayan range to its peak (Karakoram to K2).

Authored practice:

1. The widest gap in the Western Ghats, lying between the Nilgiris and the Anaimalai hills, is the (a) Thal Ghat (b) Bhor Ghat (c) Pal Ghat (d) Senkottai. Answer (c). The Palakkad Gap carries the road and rail link from Tamil Nadu into Kerala.
2. Which of the following is the highest peak lying entirely within Indian territory (excluding disputed areas)? (a) Kangchenjunga (b) Nanda Devi (c) Anamudi (d) K2. Answer (b). Kangchenjunga sits on the India-Nepal border and K2 is in India-claimed but contested Karakoram, so Nanda Devi is the highest wholly within undisputed Indian territory.
3. The Dun valleys are a feature of the (a) Greater Himalayas (b) Lesser Himalayas (c) Shiwaliks (d) Karakoram. Answer (c). Duns are flat longitudinal valleys within the youngest Shiwalik range.
4. Consider the statements: (1) The Aravallis are among the oldest fold mountains in India. (2) The Deccan Plateau lies north of the Narmada. Which is or are correct? Answer: only statement 1. The Deccan lies south of the Narmada; the Central Highlands lie north.
5. The Ten Degree Channel separates (a) India from Sri Lanka (b) the Andaman group from the Nicobar group (c) Lakshadweep from the Maldives (d) the Great and Little Andaman. Answer (b). The Eight Degree Channel separates Lakshadweep from the Maldives.
6. The Western Ghats meet the Eastern Ghats at the (a) Anaimalai hills (b) Nilgiri hills (c) Cardamom hills (d) Nallamala hills. Answer (b). The Nilgiris, with Dodabetta, are the junction of the two Ghats.
7. Match the belt of the Northern Plains nearest the mountains where streams vanish underground: (a) Khadar (b) Bhangar (c) Bhabar (d) Terai. Answer (c). Below the Bhabar the streams resurface in the marshy Terai.
8. The Siachen and Baltoro glaciers lie in the (a) Greater Himalayas (b) Karakoram (c) Pir Panjal (d) Shiwaliks. Answer (b). They are among the largest glaciers outside the polar regions, in the trans-Himalayan Karakoram.

Common confusion

• Greater Himalayas (Himadri, highest) versus Outer Himalayas (Shiwaliks, youngest and lowest); height and age move in opposite directions across the three ranges.
• Western Ghats (continuous, higher, true plateau edge) versus Eastern Ghats (broken, lower, dissected by rivers).
• Central Highlands (north of Narmada) versus Deccan Plateau (south of Narmada).
• Bhangar (old, kankar-rich, higher) versus Khadar (new, fertile, flood-renewed).
• Kangchenjunga (highest peak in India, on the Nepal border) versus Nanda Devi (highest wholly within India proper) versus K2 (highest in India-claimed Karakoram).
• Andaman and Nicobar (continental and volcanic, Bay of Bengal) versus Lakshadweep (coral, Arabian Sea).
• Barren Island (active volcano) versus Narcondam (dormant), both in the Andamans.
• Meghalaya Plateau (Shillong, an outlier of the peninsular shield) versus the surrounding Purvanchal fold hills.
• Greater Himalayas (Everest, Kangchenjunga) versus Karakoram (K2, Siachen); the Karakoram is trans-Himalayan, north of the main range.
• Ten Degree Channel (Andaman from Nicobar) versus Six Degree Channel (Great Nicobar from Indonesia) versus Eight Degree Channel (Lakshadweep from the Maldives).

Memory hook

• Ranges south to north: "Some Hardy Hikers" for Shiwalik, Himachal, Himadri.
• Western Coast belts north to south: "Ko-Ka-Ma" for Konkan, Kanara, Malabar.
• Northern Plains belts mountain-down: "Be The Best Kid" for Bhabar, Terai, Bhangar, Khadar.
• Three highest world peaks: Everest, K2, Kangchenjunga (E-K-K).
• Channels by number, south to north: Six (Great Nicobar from Indonesia), Eight (Lakshadweep from the Maldives), Ten (Andaman from Nicobar).
• The Meghalaya Plateau is an outlier of the peninsula stranded in the north-east, which is why it is so old and rocky.
• High-altitude lakes ladder: "Pangong, Tso Moriri, Gurudongmar" for Ladakh and Sikkim.

Extreme points and quick map facts

• Northernmost point: Indira Col (Siachen area, Ladakh). Southernmost: Indira Point (Great Nicobar); southernmost mainland point: Kanyakumari.
• Westernmost: Guhar Moti (Kutch, Gujarat). Easternmost: Kibithu (Arunachal Pradesh).
• The Tropic of Cancer States, west to east: Gujarat, Rajasthan, Madhya Pradesh, Chhattisgarh, Jharkhand, West Bengal, Tripura, Mizoram.
• The largest State by area is Rajasthan; the smallest is Goa; the highest plateau region is Ladakh.

Night before

• Six divisions; ranges south to north are Shiwalik, Himachal, Himadri.
• Kangchenjunga (Sikkim) highest in India; Anamudi highest in the peninsula; Guru Shikhar highest in the Aravallis.
• Tropic of Cancer through eight States; standard meridian 82° 30 minutes E.
• Pal Ghat is the widest Western Ghats gap; Barren Island is the only active volcano; Indira Point is the southernmost point.
• Ten Degree Channel splits Andaman from Nicobar; Eight Degree Channel splits Lakshadweep from the Maldives.
• LAC passes: Nathu La and Jelep La (Sikkim), Shipki La (HP), Bum La and Se La (Arunachal).
• Nilgiris join the two Ghats; the Aravalli is the oldest fold range; the Satpura-Narmada is a horst-and-rift pair.
• Siachen and Baltoro glaciers are in the Karakoram; Pangong Tso and Tso Moriri are the Ladakh high lakes.

Glossary

• Fold mountains: ranges raised by the buckling of crust under compression, like the young, still-rising Himalayas.
• Aggradational plain: a lowland built up by the deposition of sediment, like the alluvial Northern Plains.
• Bhabar: the porous boulder belt at the Shiwalik foot where streams sink underground.
• Terai: the re-emergent marshy belt below the Bhabar.
• Bhangar: older, higher alluvium with calcareous kankar.
• Khadar: newer, lower, flood-renewed and more fertile alluvium.
• Dun: a flat-floored longitudinal valley within the Shiwaliks (Dehra Dun).
• Doab: the interfluve land between two rivers, as in the Punjab plains.
• Deccan Trap: the thick basaltic lava sheet of the north-western Deccan that weathers into black soil.
• Ghat (gap): a low pass breaching the Western Ghats wall, such as the Palakkad Gap.
• Backwater (kayal): a coastal lagoon parallel to the shore, characteristic of the Malabar coast.
• Barchan: a crescent-shaped sand dune of the desert.
• Atoll: a ring-shaped coral reef enclosing a lagoon, the form of the Lakshadweep islands.
• Syntaxis: the sharp bend where the Himalayan arc turns (the western bend at Nanga Parbat, the eastern at Namcha Barwa).
• Shield: an ancient, stable, rigid block of crust, like the Peninsular plateau of Gondwana origin.
• Tethys: the former sea whose sediments were folded up to make the Himalayas when the plates collided.
• Endorheic lake: an inland lake with no outflow to the sea, like Pangong Tso and Sambhar.
• Block mountain (horst) and rift valley (graben): an uplifted block and a down-dropped trough, as with the Satpura and the Narmada.
• Trans-Himalaya: the ranges (Karakoram, Ladakh, Zaskar) lying north of the Greater Himalayas.
• Submerged versus emergent coast: a drowned coast (west) versus one raised above the sea (east).
• Outlier: a detached fragment of an old landmass, like the Meghalaya Plateau stranded in the north-east.
• Antecedent stream: a river older than the mountain it crosses, having cut its gorge as the land rose.
• Plateau: an elevated, relatively flat-topped upland, like the Deccan and the Malwa.
• Foredeep / foreland basin: the sediment-filled trough in front of a rising mountain belt, the base of the Northern Plains.
• Sahyadri: the local name for the Western Ghats, the continuous range forming the western edge of the Deccan.
• Purvanchal: the eastern hills (Patkai, Naga, Manipur, Mizo) that screen the Myanmar border.
• Rann of Kutch: the seasonally flooded salt marsh of western Gujarat, the Great and the Little Rann.

Related notes

• indian drainage system and rivers
• indian monsoon and climate
• soils and natural vegetation of india
• minerals and energy resources of india
• india borders neighbours and strategic geography
• straits chokepoints and strategic waterways
• syllabus index