Structure and Physiography of India 

Introduction

India’s physical features are the result of geological processes that have shaped its landscape over millions of years. The Indian subcontinent was once a part of the Gondwana landmass, which drifted and collided with the Eurasian plate, leading to the formation of the Himalayas and other significant physiographic divisions.

Geological Evolution of India

India’s landmass has undergone significant geological changes over time.

1. Tectonic History

• Gondwana Land (part of the supercontinent Pangaea) included India, Australia, South America, Africa, and Antarctica.
• Breakup of Gondwana Land (around 200 million years ago) led to the drifting of the Indian Plate towards the north.
• Around 50 million years ago, the Indian Plate collided with the Eurasian Plate, giving rise to the Himalayas.
• This collision is still ongoing, making the Himalayan region seismically active (frequent earthquakes).

2. Major Geological Divisions

India has three major geological regions:

1. The Peninsular Block – An ancient landmass that remained stable through geological time.
2. The Himalayas and other Plate Boundaries – Young, unstable mountains formed due to tectonic activity.
3. The Indo-Ganga-Brahmaputra Plain – Formed by sediment deposition from rivers.

Major Physiographic Divisions of India

India’s landforms can be broadly classified into five physiographic divisions:

1. The Northern and Northeastern Mountains (Himalayas)

The Himalayan mountain system extends from Jammu & Kashmir to Arunachal Pradesh and acts as a natural barrier between the Indian subcontinent and Central Asia.

  Characteristics of the Himalayas

• Young fold mountains formed by tectonic collision.
• Stretch over 2,500 km from west to east.
• Width varies from 400 km (in Kashmir) to 150 km (in Arunachal Pradesh).
• Geologically active region with frequent earthquakes and landslides.
• Source of major rivers such as the Indus, Ganga, and Brahmaputra.

ii. Division of the Himalayas

The Himalayas are divided into four parallel ranges:

1. Trans-Himalayas (Karakoram, Ladakh, Zaskar, Kailash ranges)
   • Composed mainly of Tibetan plateau-type rocks.
   • Home to Siachen Glacier (largest in India).
   • Cold desert conditions prevail in Ladakh and adjoining areas.
2. Greater Himalayas (Himadri)
   • Contains the highest peaks (Mount Everest – 8,848 m, Kanchenjunga – 8,586 m).
   • Perennial glaciers like Gangotri, Yamunotri, and Siachen.
   • Youngest and most unstable mountain range.
3. Lesser Himalayas (Himachal)
   • Includes ranges like Pir Panjal, Dhauladhar, Mahabharat.
   • Hill stations such as Shimla, Mussoorie, Nainital.
   • Composed of highly compressed and altered rocks.
4. Shiwalik Hills (Outer Himalayas)
   • Lowest range (900-1100 m altitude).
   • Composed of unconsolidated sediments, prone to landslides.
   • Has Duns (valleys) such as Dehradun, Kotli Dun, Patli Dun.

iii. Purvanchal Hills (Northeastern Hills)

• Located in Arunachal Pradesh, Nagaland, Manipur, Mizoram, Tripura.
• Composed of folded hills (extension of Himalayas).
• Examples: Naga Hills, Patkai Bum, Lushai Hills, Mizo Hills.

2. The Northern Plains (Indo-Ganga-Brahmaputra Plain)

• Formed by deposition of alluvium from the Indus, Ganga, and Brahmaputra rivers.
• One of the most fertile regions in the world, supporting dense population and agriculture.

Division of the Northern Plains

1. Bhabar Region
   • Narrow belt of pebbles and gravels at the foothills of the Himalayas.
   • No permanent rivers as water percolates underground.
2. Terai Region
   • Lies south of the Bhabar region.
   • Characterized by swampy and marshy lands.
   • Rich in biodiversity (e.g., Jim Corbett National Park).
3. Bhangar and Khadar
   • Bhangar: Older alluvium, found at a slightly higher level.
   • Khadar: Newer alluvium, very fertile, good for agriculture.

3. The Peninsular Plateau

• The oldest landmass in India (part of the Gondwana land).
• Composed of igneous and metamorphic rocks.
• Rich in minerals like iron, manganese, bauxite, and coal.

i. Division of the Peninsular Plateau

1. Central Highlands (Malwa Plateau, Bundelkhand, Baghelkhand)
2. Deccan Plateau (Maharashtra, Karnataka, Telangana)
3. Chotanagpur Plateau (rich in minerals).
4. Western and Eastern Ghats (hill ranges on the plateau’s edges).

4. The Coastal Plains

• Located between the Western and Eastern Ghats and the coastlines.
• Western Coastal Plain – Narrow and steep, includes Konkan Coast, Malabar Coast.
• Eastern Coastal Plain – Wider and flat, includes Coromandel Coast, Northern Circar.
• Deltas of major rivers (Ganga, Mahanadi, Godavari, Krishna, Kaveri).

5. The Indian Desert (Thar Desert)

• Located in Rajasthan and parts of Gujarat.
• Low rainfall (<150 mm annually), extreme temperatures.
• Sand dunes (Barchans, longitudinal dunes).

6. The Islands

1. Andaman & Nicobar Islands
   • Volcanic origin (Barren Island is the only active volcano in India).
   • Strategic importance (close to Malacca Strait).
2. Lakshadweep Islands
   • Coral atolls and reefs.
   • Smallest Union Territory of India.

Conclusion

India’s physiography is diverse, ranging from the towering Himalayas to the fertile Indo-Gangetic plains, rugged plateaus, vast deserts, coastal plains, and islands. These physical features shape the climate, agriculture, biodiversity, and human settlement patterns in India. Understanding these aspects is crucial for UPSC CSE aspirants, as they influence economic, environmental, and geopolitical dynamics.

MCQ PRACTICE

1. Consider the following statements regarding the geological history of India:

1. The Indian subcontinent was once a part of the Laurasia landmass.
2. The Himalayas were formed due to the collision between the Indian Plate and the Eurasian Plate.
3. The Peninsular Plateau is the oldest landmass of India and is tectonically stable.

Which of the statements given above is/are correct?
(a) 1 and 2 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2, and 3

Answer: (b) 2 and 3 only
Explanation: The Indian subcontinent was part of Gondwana Land, not Laurasia. The Himalayas formed due to the collision between the Indian Plate and the Eurasian Plate. The Peninsular Plateau is the oldest and most tectonically stable landmass in India.

2. Consider the following statements regarding the Himalayas:

1. The Greater Himalayas are also known as the Himadri range.
2. The Lesser Himalayas are composed of highly compressed and altered rocks.
3. The Shiwalik range is the youngest and most unstable part of the Himalayas.

Which of the statements given above is/are correct?
(a) 1 and 2 only
(b) 2 and 3 only
(c) 1, 2, and 3
(d) 1 and 3 only

Answer: (c) 1, 2, and 3
Explanation: The Greater Himalayas (Himadri) contain the highest peaks. The Lesser Himalayas (Himachal) are composed of compressed and altered rocks. The Shiwalik range is the youngest and most unstable, composed of unconsolidated sediments, making it prone to landslides.

3. Consider the following statements regarding the Northern Plains of India:

1. The Bhabar region is characterized by swampy and marshy lands.
2. The Terai region lies to the north of the Bhabar region.
3. The Khadar region is composed of newer alluvial deposits and is highly fertile.

Which of the statements given above is/are correct?
(a) 1 and 2 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2, and 3

Answer: (b) 2 and 3 only
Explanation: The Bhabar region consists of pebbles and gravels, where river water disappears. The Terai region, lying south of the Bhabar, is swampy and marshy. The Khadar region contains newer alluvium deposits and is extremely fertile for agriculture.

4. Which of the following rivers contribute to the formation of the Indo-Gangetic-Brahmaputra Plain?

1. Indus
2. Ganga
3. Brahmaputra
4. Narmada

Select the correct answer using the code below:
(a) 1, 2, and 3 only
(b) 2 and 3 only
(c) 1 and 4 only
(d) 1, 2, 3, and 4

Answer: (a) 1, 2, and 3 only
Explanation: The Indo-Gangetic-Brahmaputra Plain is formed by depositional activities of the Indus, Ganga, and Brahmaputra rivers. The Narmada River does not contribute to this plain; it flows through the rift valley in central India.

5. Consider the following statements regarding the Peninsular Plateau:

1. It is composed primarily of igneous and metamorphic rocks.
2. It is younger than the Himalayas and geologically unstable.
3. The Deccan Plateau is an extension of the Peninsular Plateau.

Which of the statements given above is/are correct?
(a)  1 only
(b) 2 and 3 only
(c) 1, 2, and 3
(d)1 and 3 only

Answer: (d) 1 and 3 only
Explanation: The Peninsular Plateau is one of the oldest landmasses, making it geologically stable. It is composed of igneous and metamorphic rocks and includes the Deccan Plateau as its extension.

6. Consider the following statements regarding the Indian Desert (Thar Desert):

1. It receives annual rainfall of less than 150 mm.
2. The presence of Barchans and longitudinal dunes indicates strong wind action.
3. It is formed due to the rain shadow effect of the Western Ghats.

Which of the statements given above is/are correct?
(a) 1 and 2 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2, and 3

Answer: (a) 1 and 2 only
Explanation: The Thar Desert receives less than 150 mm of rainfall annually and is dominated by Barchans and longitudinal dunes, indicating strong wind action. However, it is not formed due to the Western Ghats but due to continentality (distance from the sea).

7. Consider the following statements regarding India’s coastal plains:

1. The Western Coastal Plains are broader than the Eastern Coastal Plains.
2. The Eastern Coastal Plains contain the deltas of major rivers like the Godavari and Krishna.
3. The Malabar Coast is a part of the Eastern Coastal Plains.

Which of the statements given above is/are correct?
(a) 1 and 3 only
(b)2 only
(c) 1 and 2 only
(d) 2 and 3 only

Answer: (b) 2 only
Explanation: The Western Coastal Plains are narrow and steep, while the Eastern Coastal Plains are broader and more extensive. The Malabar Coast is part of the Western Coastal Plains. The Eastern Coastal Plains contain river deltas such as those of the Godavari, Krishna, and Mahanadi.

8. Consider the following islands of India:

1. Andaman & Nicobar Islands
2. Lakshadweep Islands
3. Majuli Island

Which of the above islands are of volcanic origin?
(a) 1 only
(b) 1 and 3 only
(c) 2 and 3 only
(d) 1, 2, and 3

Answer: (a) 1 only
Explanation: The Andaman & Nicobar Islands have volcanic origin, with Barren Island being India’s only active volcano. The Lakshadweep Islands are coral atolls, and Majuli is a riverine island in the Brahmaputra River.

9. Consider the following statements regarding the Purvanchal Hills:

1. They are part of the Himalayas.
2. They include Naga Hills, Patkai Bum, and Lushai Hills.
3. They are located in Jammu & Kashmir and Himachal Pradesh.

Which of the statements given above is/are correct?
(a) 1 and 2 only
(b) 2 only
(c) 1 and 3 only
(d) 1, 2, and 3

Answer: (a) 1 and 2 only
Explanation: The Purvanchal Hills are an extension of the Himalayas, including Naga Hills, Patkai Bum, and Lushai Hills. However, they are located in Northeastern states, not in Jammu & Kashmir or Himachal Pradesh.