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Geography Optional Paper II – Page 3

Peninsular Plateau of India: Evolution & Structure

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1. Introduction

The Peninsular Plateau is the oldest and most stable physiographic unit of India. It represents the ancient core of the Indian subcontinent and is composed mainly of igneous and metamorphic rocks. Its geological stability contrasts sharply with the young and dynamic Himalayan mountain system.

2. Geological Evolution of the Peninsular Plateau

• Precambrian Origin: The plateau evolved during the Precambrian era and forms part of the ancient Gondwana landmass.
• Shield Structure: It is a continental shield formed by crystallization and consolidation of magma deep within the Earth.
• Tectonic Stability: Since its formation, the region has largely remained free from major folding and mountain-building processes.
• Rifting & Drift: The Indian Plate separated from Gondwana and drifted northward, carrying the Peninsular block intact.

3. Structural Characteristics

• Hard Crystalline Rocks: Dominated by granite, gneiss, schist, and quartzite.
• Block Mountains: Faulting led to the formation of block mountains like the Vindhya and Satpura ranges.
• Absence of Folding: Unlike the Himalayas, folding is minimal, indicating ancient stability.
• Presence of Rift Valleys: Narmada and Tapi rivers flow through tectonic rift valleys.

4. Major Physiographic Divisions

• Central Highlands: Includes Malwa Plateau, Bundelkhand, Baghelkhand.
• Deccan Plateau: Lava-covered region formed by Deccan Traps.
• Eastern & Western Ghats: Fault scarps along the edges of the plateau.
• Chotanagpur Plateau: Mineral-rich region and storehouse of Indian resources.

5. Role of Volcanism – Deccan Traps

Massive volcanic eruptions during the late Cretaceous period resulted in the formation of Deccan Traps. These basaltic lava flows cover large parts of Maharashtra, Madhya Pradesh, and Gujarat, creating step-like topography.

6. Drainage Characteristics

• Most rivers are east-flowing (Godavari, Krishna, Kaveri).
• Rivers follow old fault lines and joints.
• Well-developed dendritic drainage pattern.

7. Significance for UPSC Mains

• Frequently asked in 10–15 mark questions.
• Ideal for diagram-based answers (plate structure, rift valleys).
• Useful linkage with climate, soils, minerals, and agriculture.

8. Model Mains Question (PYQ Type)

“Discuss the geological evolution and structural characteristics of the Peninsular Plateau of India.” (UPSC Geography Optional)

9. Answer Writing Hint

• Start with age and origin
• Add simple labelled diagram
• Link structure with drainage and resources
• Conclude with its significance

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