Physical Geography of India

Syllabus Unit: Geography of India & World

Why it matters

Chapter overview

India's physical geography is built from units laid down by the collision of the Indian and Eurasian plates roughly 50 million years ago: the young, still-rising Himalayan arc in the north, the ancient and stable Peninsular plateau to the south, and the fertile alluvial plains the great rivers built in between. This topic traces how relief, drainage and the monsoon interlock — the backbone of GS-I questions on Indian physiography.

General Studies Paper I Geography of India & World 12%–15% weightage

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HimadriGreat Himalaya, avg. 6,000 m, Kanchenjunga

HimachalLesser Himalaya, 3,700-4,500 m

ShiwalikOuter Himalaya, 900-1,100 m

Northern PlainsAlluvial apron: Bhabar-Tarai-Bhangar-Khadar

1Himalayas & the Northern Plains

The Himalayas are young fold mountains still rising a few millimetres a year; the plains at their feet are the alluvial apron those very mountains keep feeding.

Learning Objectives

Name and order the three parallel ranges of the Himalayas from north to south with approximate elevations.
Explain the plate-tectonic origin of the Himalayas via the closure of the Tethys Sea.
Distinguish Bhabar, Tarai, Bhangar and Khadar zones of the Northern Plains.
Locate key Himalayan passes (Nathu La, Shipki La, Zoji La) and their strategic significance.

Key Terms

HimadriThe Great/Inner Himalaya — the northernmost, continuous range averaging 6,000 m, containing Kanchenjunga (8,586 m), India's highest peak.

BhangarThe older, terraced alluvium of the Northern Plains lying above flood level, marked by calcareous concretions called kankar.

KhadarThe newer, younger floodplain alluvium, renewed by silt deposition every flood season and the most fertile soil in the plains.

DunsLongitudinal valleys between the Shiwaliks and the Lesser Himalaya, e.g. Dehradun, formed by structural depression.

The **Himalayas** are the world's youngest fold mountains, thrown up when the northward-drifting Indian Plate collided with the Eurasian Plate around 50 million years ago, closing the Tethys Sea. Collision is still active, so the range keeps rising roughly 5 mm a year and remains one of the most seismically active belts on earth (Seismic Zones IV-V).

Three parallel ranges, north to south

Himadri (Great Himalaya) — continuous, average 6,000 m, granite-gneiss core, permanently snow-covered; contains Kanchenjunga (8,586 m), the highest peak entirely in India.
Himachal (Lesser Himalaya) — 3,700-4,500 m; includes the Pir Panjal and Dhauladhar ranges; hosts hill stations such as Shimla, Mussoorie and Dharamshala.
Shiwalik (Outer Himalaya) — outermost and youngest, only 900-1,100 m, made of unconsolidated river-borne sediment; separated from the Lesser Himalaya by longitudinal valleys called duns.

Key PointRegionally the Himalayas are also divided west to east: Punjab Himalaya (Indus-Satluj), Kumaon Himalaya (Satluj-Kali), Nepal Himalaya (Kali-Tista) and Assam Himalaya (Tista-Dihang) — a favourite Prelims matching set.

The Northern Plains: an alluvial apron

Bhabar — 8-16 km porous, pebbly belt at the Shiwalik foothills where streams sink underground.
Tarai — marshy, damp belt south of the Bhabar where the sunk streams reemerge.
Bhangar — older alluvium forming a terrace above flood level, with kankar (calcium carbonate) nodules.
Khadar — newer floodplain alluvium, renewed annually, most fertile; called diaras in the Bihar stretch of the Ganga.

Common MistakeClassic trap: Bhangar (older, elevated terrace) is often confused with Khadar (newer, low-lying floodplain) — remember 'Khadar is Kal ka' (khadar is recent).