India: Physical Aspects

India, renowned for its diverse geographical features, extends from the Himalayas in the North to the sunlit coastal villages in the South, the humid forests of the South-West, the fertile Brahmaputra valley in the East, and the arid Thar Desert in the West. Situated in the Northern Hemisphere, it lies between 8°4’ N and 37°6’ N latitudes and 68°7’ E and 97°25’ E longitudes. The nation measures about 3,214 km from its Northern to Southern extremes and 2,933 km from East to West, with a land frontier spanning 15,200 km and a coastline totaling 7,516.6 km. India’s neighbors include Afghanistan and Pakistan in the North-West, China, Bhutan, and Nepal in the North, Myanmar in the far East, and Bangladesh to the East of West Bengal. Sri Lanka is separated from India by the Palk Strait and the Gulf of Mannar.

Learning Outcomes:

1. Understand India’s geographical profile, location, and neighboring countries.
2. Explore India’s geological structure and rock systems.
3. Examine the physiographic units and features of India.
4. Recognize the distribution and characteristics of soil and vegetation in India.

Geological Structure

The geological structure influences India’s land relief, soil nature, and mineral wealth. Indian rocks, categorized by formation periods on the Geological Time Scale (GTS), include:

1. The Archaean Rock System: Oldest rocks found beneath sedimentary deposits worldwide, forming ancient plateaus and mountain ranges like the Himalayas. In India, these rocks are in Peninsular regions (Odisha, Madhya Pradesh, Chhattisgarh, etc.) and the Himalayas (except Sikkim). These rocks are devoid of fossils.
2. The Dharwar System: Ancient metamorphosed sedimentary rocks rich in minerals like iron ore, manganese, and copper. Found in Karnataka (Dharwar, Bellary, Mysore) and other regions including Jharkhand, Odisha, and Rajasthan.
3. The Cuddapah System: Found in Andhra Pradesh (Cuddapah, Kurnool) and parts of Chhattisgarh, Jharkhand, Odisha, and the Aravallis. Rich in iron, copper, manganese, though not always economically viable for extraction.
4. The Vindhyan System: Spanning from Bihar to Rajasthan, these rocks are known for ornamental stones, limestone, and building materials. They lack metallic minerals.
5. The Dravidian Rock System: Includes various rocks like sandstone, shales, dolomite, and coal, predominantly found in the Himalayan region.
6. Gondwana System: Consisting of sandstones, shales, clay, and containing India’s richest coal deposits (98%). Found in Damodar, Mahanadi, and Godavari valleys.
7. The Deccan Trap: Basaltic lava deposits in Gujarat, Madhya Pradesh, Maharashtra, forming fertile regur soil, favorable for cotton cultivation.
8. Recent Formations (Pleistocene): Comprising alluvial deposits in the Indo-Gangetic plain, Kashmir, and Brahmaputra valley.

Physiography of India

India’s mainland features five physiographic units:

1. The Great Himalayas: Extending from Nanga Parbat in the West to Namcha Barwa in the East, the Himalayas are categorized as Trans-Himalayas, Greater Himalayas, Lesser Himalayas, and Shiwaliks. Formed from the collision of the Indian plate with the Eurasian plate about 70 million years ago, the ranges exhibit convex slopes toward the Peninsular Plateau and concave slopes toward the Tibetan Plateau.
2. The Great Plains of North India: Known as the Indus-Ganga Brahmaputra plain, stretching 3,200 km with varying widths (150–300 km). Divided into Bhabar, Terai, Khadar, and Bhangar regions, each characterized by distinct alluvial deposits, soil types, and topographical features.
3. The Peninsular Plateau: An ancient geological formation covering 16 lakh sq km, bounded by the Aravallis, Western and Eastern Ghats. Includes various subdivisions like Central Highlands, Deccan Plateau, and Eastern Plateau.
4. The Coastal Plains: Narrow stretches flanking the plateau. The Western Coastal Plains run parallel to the Western Ghats, featuring lagoons and backwaters, while the Eastern Coastal Plains stretch from Tamil Nadu to West Bengal.
5. The Islands: Includes Andaman and Nicobar in the Bay of Bengal and Lakshadweep in the Arabian Sea, with formations ranging from coral reefs to volcanic peaks.

Important Note: Mount K2 (8611 m) in the Karakoram range is the highest peak in India.

Geological Comparisons

Mountain Passes of India

The Great Plains of North India

1. Bhabar Region: Located along the Shiwaliks, characterized by porous soil, making rivers disappear underground.
2. Terai Region: South of the Bhabar, where underground streams re-emerge, creating marshy lands.
3. Khadar Region: Made of new alluvium, found in delta regions, replenished yearly by floods.
4. Bhangar Region: Elevated plains made of old alluvium, not reached by floodwaters.

Important Concept: Doab: A tract of land lying between two converging rivers, common in the Western region of seven rivers (Sindhu Sagar, Chhaj, Rechna, etc.).

Climate and Vegetation

India exhibits a monsoon climate with marked regional variations:

1. Temperature: Ranges from 55°C in Rajasthan to -45°C in Leh. Coastal areas have minimal seasonal contrasts.
2. Winds & Rainfall: Influenced by monsoon winds, Western disturbances, and cyclones. Rainfall is seasonal, with Meghalaya exceeding 1080 cm and Rajasthan receiving less than 10 cm annually.
3. Seasons:

• Winter: Cold, clear skies, influenced by high-pressure zones in the Northwest.
• Summer: High temperatures, cyclonic storms, onset of monsoons by June.
• Monsoon: South-West winds bring extensive rainfall.
• Retreating Monsoon: North-East winds withdraw, impacting the Tamil Nadu coast.

Important Note: India’s agriculture is heavily dependent on the monsoon rains.

Vegetation and Wildlife

India’s natural vegetation ranges from tropical rainforests in the Western Ghats and Andaman Islands to temperate forests in the Himalayas.

India is also home to diverse wildlife, including the elephant in Assam, **rhin

oceros** in West Bengal, and the tiger in the Himalayan foothills. Efforts to conserve fauna have led to the establishment of national parks and biosphere reserves.

Important Note: Mangroves in India constitute around 3% of the world’s total mangrove cover.

Indian Soils

India’s agricultural success hinges on its diverse soil types, including:

1. Alluvial Soils: Covering 40% of India’s soil area, found in Northern plains, rich in minerals, suitable for rice, wheat, and sugarcane cultivation.
2. Red Soils: Present in Tamil Nadu, Karnataka, Chhattisgarh, red due to iron content, less fertile.
3. Black Soils: Known as regur, found in Maharashtra, Gujarat, ideal for cotton due to high water-retaining capacity.
4. Laterite Soils: High in iron and aluminum, found in Odisha, West Bengal, poor in fertility but useful for plantations.
5. Desert Soils: Found in Rajasthan, sandy, rich in minerals, suitable for crops like bajra, pulses.

Drainage Systems

India’s drainage comprises:

1. Himalayan Drainage: Includes Indus, Ganga, and Brahmaputra systems, characterized by perennial rivers due to glacier-fed waters.
2. Peninsular Drainage: Encompasses Mahanadi, Godavari, Krishna, and Cauvery rivers, generally seasonal, with defined channels.

Important Concept: Inland Drainage: Rivers like the Ghaggar do not reach the sea, instead, they flow into inland regions like the Rajasthan desert.

MCQ (Multiple Choice Question)

Q: Which rock system in India is known for its rich coal deposits?

1. Archaean
2. Dharwar
3. Gondwana
4. Vindhyan

Answer: 3. Gondwana