The Peninsular Plateau

4.1 Geological Origin

The Peninsular Plateau is a remnant of the ancient Gondwana supercontinent that broke up ~140 million years ago. It is India's oldest, most rigid, and most stable geological region, composed of some of the world's oldest rocks (Archaean crystalline basement). The plateau covers roughly 16 lakh sq km — about half of India's total area.

Key geological features:

• Composed of Archaean gneisses and schists (basement rock, 2.5–4 billion years old)
• Overlaid by Gondwana sedimentary sequences (rich in coal deposits — Damodar Valley, Godavari Valley, Mahanadi Valley)
• Deccan Trap basalts cover a large portion — formed by massive volcanic eruptions 65–60 million years ago, creating the world's largest trap formation (~5 lakh sq km)
• Black cotton soil (Regur) — formed from weathered Deccan basalts; ideal for cotton cultivation in Maharashtra, Madhya Pradesh, Gujarat

4.2 Sub-Divisions of the Peninsular Plateau

1. Central Highlands

• North of Narmada River; slopes northward
• Includes Malwa Plateau (Madhya Pradesh), Bundelkhand Plateau (UP/MP border), Baghelkhand
• Malwa Plateau: 500–600 m; drained by Chambal, Betwa, Ken (northward-flowing)
• Chhota Nagpur Plateau (Jharkhand): Archaean rocks; rich in coal (Damodar Valley), iron ore (Singhbhum), copper, mica

2. Deccan Plateau

• South of Narmada; classic triangular-shaped Peninsular plateau
• Tilts east (higher in west, lower in east — rivers flow eastward)
• Includes Telangana Plateau, Karnataka Plateau, Maharashtra Plateau
• Highest point in Peninsular Plateau: Dodda Betta (2,637 m) in Nilgiris, Tamil Nadu

3. Western Ghats (Sahyadri)

• Continuous escarpment; western face steep, eastern face gentle
• Length: 1,600 km; width: 50–80 km; average elevation: 1,200 m
• Anamudi (2,695 m) in Kerala — highest peak south of Himalayas
• Three major passes: Thal Ghat, Bhor Ghat (rail passes to Deccan), Pal Ghat (lowest gap, 150 m)
• UNESCO World Heritage biodiversity hotspot (2012)

4. Eastern Ghats

• Discontinuous; cut by major rivers (Mahanadi, Godavari, Krishna, Kaveri)
• Average elevation 600 m; gentler than Western Ghats
• Highest peak: Jindhagada (1,690 m) in Andhra Pradesh
• Rich in bauxite (Visakhapatnam), iron ore, coal (Singareni fields)

5. Southern Plateau

• Includes Nilgiri Hills (where Western and Eastern Ghats meet — Dodda Betta 2,637 m)
• Anaimalai Hills, Cardamom Hills (Idukki) of Kerala
• Tamil Nadu's plateau (Madurai, Tirunelveli regions) is lower, semi-arid

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