Geological Structure of India

India’s landforms and geological structure are influenced by the movement of tectonic plates over millions of years. This has resulted in three main geological divisions:

The Peninsular Block

• The Peninsular Block is the oldest part of India, primarily made of igneous and metamorphic rocks such as granite and gneiss.
• Aravalli Range: One of the oldest mountain ranges, running southwest to northeast. It’s rich in minerals like lead, zinc, and marble.
• Narmada Rift Valley and Satpura Range: This region has undergone block faulting, where land blocks have moved vertically, creating valleys and hills.

The Himalayan and Other Peninsular Mountains

• The Himalayas are a young and tectonically active mountain range formed by the collision of the Indian Plate with the Eurasian Plate.
• The region contains various geological features like faults, folds, and thrust zones.
• The Purvanchal Hills in the northeast are an extension of the Himalayas, made up of tightly folded hills with dense vegetation.

The Indo-Ganga-Brahmaputra Plain

• This extensive plain was created by the deposition of alluvium from the Ganga, Brahmaputra, and Indus rivers.
• Previously a geosynclinal depression, it filled with sediment over time, creating the fertile plains.
• This region is highly productive for agriculture and is one of the most densely populated areas in India.

Physiographic Divisions of India

India’s landforms can be grouped into six major physiographic regions, each with unique features:

The Northern and Northeastern Mountains

1. Himalayas:
   • These mountains extend over 2,400 km from west to east.
   • The Himalayas have three major parallel ranges.
   • Greater Himalayas (Himadri): Home to India’s highest peaks, such as Kanchenjunga and Nanda Devi. The region is covered with permanent snow and glaciers.
   • Lesser Himalayas (Himachal): Includes well-known ranges like the Pir Panjal and Dhauladhar. It has scenic valleys like Kashmir and Kullu, and is rich in forests.
   • Shiwaliks: These are the foothills, formed from sediments brought down by rivers. The Bhabar belt at the base is rocky, while the Tarai region is marshy and fertile.
2. Purvanchal Hills:
   • Located in the northeastern states, these hills are heavily forested and consist of ranges like the Patkai, Naga, and Mizo Hills.
   • These hills are rich in biodiversity and have traditional tribal cultures.

The Northern Plains

Created by the deposition of sediments from the Ganga, Brahmaputra, and Indus rivers.

• Bhabar: A narrow belt of coarse pebbles and stones deposited by rivers at the foothills of the Shiwaliks. Water flows through the cracks and disappears underground here.
• Tarai: A marshy, waterlogged area with dense forests, where water re-emerges.
• Alluvial Plains:
  • Bhangar: Older, slightly elevated alluvium with calcareous deposits called kankar.
  • Khadar: Newer alluvium, renewed annually by floods, making it extremely fertile for crops like wheat and rice.

The Peninsular Plateau

One of the oldest landmasses, formed by volcanic activities and weathering.

• Deccan Plateau: Bordered by the Western Ghats and Eastern Ghats, and rich in minerals like iron ore, coal, and bauxite. Rivers like the Godavari and Krishna flow across it.
• Central Highlands: Includes the Malwa Plateau, Vindhyan Range, and Bundelkhand Plateau. These regions have rocky landscapes and are also rich in minerals.
• Northeastern Plateau: Includes the Meghalaya Plateau, known for coal reserves and unique biodiversity.

The Indian Desert (Thar Desert)

Location: in Rajasthan, with extensions into Gujarat and Punjab.

Characteristics:

• Consists of sand dunes and barchans (crescent-shaped dunes), with sparse vegetation.
• The climate is arid, with extreme temperatures and very little rainfall.
• Rivers are mostly seasonal, with the Luni being the most significant.

The Coastal Plains

• Western Coastal Plains:

  • Extends from Gujarat to Kerala. Divided into three parts: Konkan Coast (Mumbai-Goa), Kannada Coast (Karnataka), and Malabar Coast (Kerala).
  • Known for backwaters (Kayals) in Kerala and natural harbors like Mumbai and Kochi.

• Eastern Coastal Plains:

  • Extends from West Bengal to Tamil Nadu, comprising the Northern Circar and Coromandel Coast.
  • Features deltas from rivers like the Mahanadi, Godavari, Krishna, and Kaveri. These deltas are fertile and suitable for rice cultivation.

The Islands

• Andaman and Nicobar Islands:

  • Located in the Bay of Bengal, these islands are an extension of submarine mountains.
  • Andaman is volcanic, with the Barren Island being an active volcano.
  • The Nicobar Islands are closer to the Equator, making them rich in tropical rainforests.

• Lakshadweep Islands:

  • Located in the Arabian Sea, these are coral islands with 36 small islands.
  • Only a few islands are inhabited, and they are known for their unique coral reefs and marine biodiversity.

Formation and Evolution of Landforms

India’s landforms are shaped by both internal and external forces:

1. Plate Tectonics:
   • India’s drift from Gondwana to its collision with the Eurasian Plate resulted in the formation of the Himalayas.
   • Deccan Traps: Formed by volcanic eruptions when India passed over a hotspot during its drift northward.
2. Erosion and Deposition:
   • Rivers like the Ganga and Brahmaputra carry sediment that forms the fertile Northern Plains.
   • Coastal areas are shaped by wave action, forming features like sand dunes, spits, and bars.
3. Weathering:
   • The Peninsular Plateau has been worn down over millions of years, resulting in rolling hills and fertile soil suitable for forests and agriculture.

Influence on Climate, Economy, and Culture

India’s physical features greatly influence its climate and cultural diversity:

Himalayas:

• Act as a barrier to cold winds, contributing to India’s relatively warm climate.
• Source of major rivers that support agriculture in the plains.

Western Ghats:

• Trap moisture-laden winds, leading to high rainfall on the west coast, supporting biodiversity and agriculture.

Desert and Coastal Areas:

• The Thar Desert influences the lifestyle with practices adapted to the arid environment.
• Coastal plains are hubs for fishing, tourism, and maritime trade.

These physical features shape the livelihoods, agriculture, and settlement patterns across the country, contributing to India’s rich cultural heritage.

Conclusion

India’s physiography encompasses diverse regions, each with distinct features, climates, and resources. From the towering Himalayas to the fertile plains and vast coastlines, these features have shaped the nation’s economy, culture, and way of life. Understanding India’s physical geography helps us appreciate its natural beauty and the challenges of sustainable development in this varied landscape.