Physical Geography of India Questions for CDS

Physiographic Divisions of India

India is divided into six major physiographic units. Think of them as horizontal belts from north to south: the mountains, then plains, then plateau, then coasts, then islands. Each unit has distinct rock type, age, and economic importance. CDS often asks which state or river belongs to which division.

• The Himalayan Mountains in the north — youngest fold mountains, geologically active
• The Northern Plains — formed by alluvial deposits of Indus, Ganga, Brahmaputra systems
• The Peninsular Plateau — oldest landmass in India, made of hard igneous and metamorphic rock (Gondwanaland origin)
• The Indian Desert (Thar) — lies west of Aravalli range in Rajasthan
• The Coastal Plains — Eastern coast is wider and has deltas; Western coast is narrow with estuaries
• The Islands — Andaman and Nicobar (Bay of Bengal), Lakshadweep (Arabian Sea, coral origin)

The Himalayan System

The Himalayas run about 2400 km from Indus gorge in the west to Brahmaputra gorge in the east. They are arranged in three parallel ranges. The Himalayas are young fold mountains formed by collision of Indo-Australian plate with Eurasian plate. CDS frequently asks about passes, peaks, and range names.

• Three ranges: Greater Himalayas (Himadri) — highest, always snow-covered; Lesser Himalayas (Himachal) — hill stations like Shimla, Mussoorie; Outer Himalayas (Shiwaliks) — foothills, prone to earthquakes
• Highest peak in India: Kangchenjunga (8586 m) — located on India-Nepal border in Sikkim
• K2 (8611 m) is in Pakistan-occupied Kashmir — highest peak of the Karakoram range
• Important passes: Karakoram Pass (Ladakh), Rohtang (Himachal Pradesh), Nathu La (Sikkim), Banihal (J&K)
• Duns are longitudinal valleys between Himachal and Shiwalik ranges — Dehradun is the best example
• The Purvachal are Eastern hills running through Manipur, Nagaland, Mizoram

Northern Plains

The Great Northern Plains stretch from Punjab in the west to Assam in the east — about 3200 km long. They are formed by deposition from three river systems. The plains are agriculturally the most productive zone. CDS tests the sub-divisions and terminology like Bhabar, Terai, Khadar, Bhangar.

• Bhabar: porous gravel belt just below Shiwaliks — streams disappear underground here
• Terai: marshy, forested belt south of Bhabar — streams reappear here
• Bhangar: old alluvium, upland plains, less fertile — contains calcareous nodules called Kankars
• Khadar: new alluvium, flood plains, very fertile — renewed every flood season
• Doab means land between two rivers — Punjab means land of five rivers (Panj = five, Ab = water)

Peninsular Plateau and Drainage

The Peninsular Plateau is a tableland made of old crystalline, igneous and metamorphic rocks. It is divided by the Narmada river into the Central Highlands (north) and the Deccan Plateau (south). The Western Ghats and Eastern Ghats border it on west and east. Most peninsular rivers are rain-fed, flow east, and form deltas.

• Western Ghats: continuous range, act as water divide; highest peak is Anamudi (2695 m) in Kerala
• Eastern Ghats: discontinuous, lower, cut by rivers; highest peak is Jindhagada (Andhra Pradesh)
• Deccan Traps in Maharashtra — lava-covered plateau, black soil (regur) ideal for cotton
• Peninsular rivers flowing east and forming deltas: Mahanadi, Godavari, Krishna, Kaveri
• Rivers flowing west into Arabian Sea: Narmada, Tapi — they flow through rift valleys (faults), form estuaries not deltas
• Chilika Lake (Odisha) is the largest coastal lagoon in India — on Eastern coast

River Systems — Himalayan vs Peninsular

CDS repeatedly tests differences between Himalayan and Peninsular rivers. Himalayan rivers are perennial (fed by snow and rain), have long courses, form meanders and ox-bow lakes in plains. Peninsular rivers are mostly seasonal (rain-fed), have hard rock beds, shorter courses, and no meanders.

• Longest river entirely in India: Ganga — but Indus is longer overall (originates in Tibet)
• Ganga: originates at Gangotri glacier (Uttarakhand), meets Bay of Bengal at Sagar Island
• Brahmaputra: originates in Tibet as Tsangpo, enters India through Arunachal Pradesh, forms largest river island Majuli (Assam)
• Godavari: called Vridha Ganga (Old Ganga) — longest peninsular river
• Krishna originates at Mahabaleswar (Maharashtra); Kaveri at Talakaveri (Coorg, Karnataka)
• Narmada and Tapi flow west — they are rift valley rivers, a common CDS question trap

Coastal Plains and Islands

India has about 7516 km of coastline. The Western coast runs along the Arabian Sea and the Eastern coast (Coromandel coast) along the Bay of Bengal. CDS tests specific names of coastal sections and island features.

• Western coast sections (north to south): Konkan (Maharashtra-Goa), Kanara (Karnataka), Malabar (Kerala)
• Eastern coast sections: Northern Circars (Odisha-AP), Coromandel (Tamil Nadu)
• Eastern coast is broader, has lagoons and deltas; Western coast is narrow with backwaters (Kerala)
• Andaman and Nicobar: volcanic and sedimentary origin; Barren Island is only active volcano in India
• Lakshadweep: coral origin, smallest Union Territory by area, capital Kavaratti
• Palk Strait separates India from Sri Lanka; Gulf of Mannar lies between them

• Confusing K2 as India's highest peak — K2 is in Pakistan-occupied Kashmir; India's highest is Kangchenjunga
• Thinking Narmada and Tapi flow east like other peninsular rivers — they flow west through rift valleys and form estuaries
• Mixing up Bhangar and Khadar — Bhangar is old alluvium (less fertile, higher ground); Khadar is new alluvium (more fertile, near rivers)
• Assuming Brahmaputra originates in India — it originates in Tibet as Tsangpo and enters India via Arunachal Pradesh
• Calling Godavari the longest river in India — it is the longest peninsular river; overall longest is Ganga (entirely in India) or Indus (by total length)

• Physiographic belts top to bottom: HIM-NOP-CI = Himalayas, Northern plains, Old plateau (peninsular), Plains of coast, Islands
• Three Himalayan ranges: G-H-S = Greater, Himachal, Shiwalik — remember Going Higher Slowly
• West-flowing peninsular rivers: NT = Narmada, Tapi — both are Rift valley rivers, think NT = Naturally Turns (westward)
• Peninsular rivers forming deltas east: Make Good Kings Conquer = Mahanadi, Godavari, Krishna, Kaveri
• Lakshadweep = Coral (L sounds like Lagoon-Coral); Andaman = Volcanic and Sedimentary (A = Active volcano Barren Island)

• CDS consistently asks 1-2 questions on river origins and which rivers flow west vs east — memorize NT (Narmada-Tapi) as the only major west-flowing peninsular rivers
• Highest peaks and important passes appear almost every year — prepare a short list: Kangchenjunga, Anamudi, K2 (not in India), and passes Rohtang, Nathu La, Karakoram
• Questions on coastal features like lagoons, backwaters, and estuaries test whether you know Eastern vs Western coast differences — Eastern has deltas, Western has estuaries and backwaters
• Island facts are easy scoring — Barren Island active volcano, Majuli river island, Lakshadweep coral, smallest UT — these are direct one-liner questions
• Alluvial plain terminology (Bhabar, Terai, Khadar, Bhangar) appears in MCQs asking which is more fertile or which lies closer to the mountains — always answer in order: Bhabar closest to hills, then Terai, then Bhangar, then Khadar near river channels