The Indo-Gangetic Plain

3.1 Formation and Extent

The Indo-Gangetic Plain (also called the Great Northern Plain or Trans-Himalayan Plain) is a structural trough that developed between the Himalayas (to the north) and the Peninsular Plateau (to the south) as the Indian plate subducted beneath Eurasia. Over millions of years, rivers flowing from the Himalayas deposited enormous quantities of alluvium, creating the world's largest alluvial plain.

Key statistics:

• Total length: ~2,400 km (east–west), from Punjab to Assam
• Width: 150–300 km (narrower in east, wider in west)
• Area: Approximately 7.5 lakh sq km (about 23% of India's total area)
• Depth of alluvium: 1,000–2,000 metres (extraordinarily deep)
• Elevation: Almost flat — only a few metres decline per kilometre

3.2 Sub-Divisions

The plain is divided into distinct north-south zones based on the nature of alluvial deposits:

1. Bhabar Belt

• Narrow band (8–16 km wide) at the foothills of the Himalayas
• Highly porous, coarse gravel and pebble deposits from Himalayan streams
• Rivers disappear underground; re-emerge further south
• Unsuitable for agriculture; dense forests (sal, teak); used for limited cultivation

2. Terai Belt

• South of Bhabar; 15–30 km wide; rivers re-emerge from underground
• Swampy, humid, waterlogged conditions; dense forests
• Rich in wildlife — tiger reserves (Jim Corbett, Dudhwa), elephant habitats
• Agriculture possible after swamp drainage; major area for sugarcane cultivation

3. Bangar — Old Alluvial Uplands

• Higher terraces with old alluvium (deposited during Pleistocene era)
• Contains calcareous nodules called Kankar
• Slightly elevated; less fertile than Khadar; found in Uttar Pradesh, Punjab
• Examples: Doab areas between river systems

4. Khadar — New Alluvial Floodplains

• Active floodplains regularly inundated by rivers
• Fresh, fine-grained, highly fertile alluvium renewed annually
• Best agricultural land in India; intense cultivation of wheat, rice, sugarcane
• Examples: Ganga-Yamuna Doab Khadar, Brahmaputra floodplains

3.3 Regional Divisions of the Plain

Division	States	Major Rivers	Agricultural Feature
Punjab Plain	Punjab, Haryana	Ravi, Beas, Sutlej	Wheat capital; Canal irrigation
Ganga Plain	UP, Bihar, West Bengal	Ganga, Yamuna, Ghaghra	Rice-wheat belt; most populous
Brahmaputra Plain	Assam	Brahmaputra, Barak	Tea gardens; floodprone
Rajasthan Plain	W. Rajasthan	Luni (seasonal)	Arid; Thar Desert fringe

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