Key Concepts from the Lecture on India's Physical Geography

Introduction

• Physical Features: Words like smart, beautiful, describe outer appearance; similarly, Earth has varied landforms.
• Landforms: Include mountains, plains, plateaus, deserts, coastal plains, islands. Formed in different geological periods.

Comparison: Himalayan Mountains and Peninsular Plateau

• Himalayas: Recent, young fold mountains with high peaks, deep valleys, fast-flowing rivers.
• Peninsular Plateau: Ancient landmass with gentle hills, wide valleys, small rivers.
• Composition: Himalayas are sedimentary; Plateau is igneous/metamorphic.

Himalayas

• Stretch over northern India from Indus to Brahmaputra.
• Longitudinal Extent: Great/Inner Himalayas (Himadri), Lesser Himalayas (Himachal), Shivalik Range.
• Himadri: Loftiest peaks (e.g., Everest), covered with snow, glaciers.
• Himachal: Compressed rocks, important valleys (Kashmir, Kangra).
• Shivaliks: Outermost range, composed of loose sediments.

Regional Divisions of Himalayas

• West to East Divisions: Punjab, Kumaon, Nepal, Assam Himalayas.
• Purvanchal Range: Eastern hills, composed of sandstones, dense forests.

Northern Plains

• Favorable for Settlement: Flat, fertile, adequate water, suitable climate.
• Formation: By Indus, Ganga, Brahmaputra and tributaries depositing alluvium.
• Spread: 7 lakh sq km; 2400 km long.
• Riverine Islands: Formed by deposition, Majuli is world's largest.
• Sections: Punjab, Ganga, Brahmaputra Plains.
• Relief Features: Bhabar, Terai, Bhangra, Khadar.

Peninsular Plateau

• Oldest Part: Composed of crystalline igneous/metamorphic rocks, formed from Gondwanaland.
• Divisions: Central Highlands, Deccan Plateau.
• Central Highlands: North of Narmada, surrounded by Vindhya, Aravali ranges.
• Deccan Plateau: South of Narmada, bordered by Western and Eastern Ghats.

Western and Eastern Ghats

• Western Ghats: Continuous, higher, cause orographic rainfall.
• Eastern Ghats: Discontinuous, lower, breached by rivers.

Indian Desert (Thar Desert)

• Features: Sandy plain, sand dunes (barchans, longitudinal), low rainfall, arid climate.
• Seasonal Rivers: Luni River flows only in rainy season.

Coastal Plains

• Western Coastal Plain: Between Western Ghats and Arabian Sea. Sections - Konkan, Kannad, Malabar.
• Eastern Coastal Plain: Between Eastern Ghats and Bay of Bengal. Sections - Northern Circars, Coromandel Coast.
• Chilka Lake: Largest saltwater lake, located in Odisha.

Islands of India

• Lakshadweep: Coral islands in Arabian Sea, example of atoll reef.
• Andaman and Nicobar Islands: In Bay of Bengal, divided by 10 degrees channel, strategic importance.
• Active Volcano: Found on Barren Island in Andaman group.

These notes provide a detailed overview of India's physical geography, focusing on the diversity and characteristics of its landforms, and serve as a reference for further study.