UPSC MainsGEOLOGY-PAPER-I202015 Marks
Q7.

Discuss the difference in geomorphology of the Eastern Coast and Western Coast of India. What is the main reason of the difference?

How to Approach

This question requires a comparative analysis of the geomorphological features of India’s eastern and western coasts. The answer should begin by outlining the key features of each coast, then delve into the reasons behind their differences, focusing on the role of tectonic movements, river systems, and geological structures. A structured approach, comparing and contrasting features like coastal plains, estuaries, lagoons, and landforms, will be effective. Mentioning specific examples of landforms and coastal features will enhance the answer.

Model Answer

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Introduction

India’s coastline, spanning over 7,500 km, exhibits significant variations in its geomorphological characteristics. The eastern and western coasts, while both bordering the Indian Ocean, display distinct features shaped by differing geological histories and influencing factors. The western coast is characterized by steep, rocky terrain, while the eastern coast is known for its broad, sandy beaches and deltas. Understanding these differences is crucial for comprehending coastal processes, resource management, and vulnerability to natural hazards. This answer will discuss these differences and the underlying reasons for their divergence.

Geomorphology of the Western Coast

The western coast, stretching from Gujarat to Kerala, is generally narrow and characterized by:

  • Steep Slopes: The Western Ghats run parallel to the coast, creating a steep gradient and limiting the formation of extensive plains.
  • Rocky Coastline: Dominated by rocky outcrops, cliffs, and headlands.
  • Estuaries & Backwaters: Numerous estuaries (e.g., Narmada, Tapi) and backwaters (e.g., Kerala backwaters) are present, formed by the drowned river mouths.
  • Limited Delta Formation: Rivers flowing from the Western Ghats are relatively short and fast-flowing, lacking the capacity to form large deltas. The Narmada and Tapi rivers form estuaries rather than deltas.
  • Coastal Landforms: Features like sea caves, cliffs, and beaches are common.

Geomorphology of the Eastern Coast

The eastern coast, extending from West Bengal to Tamil Nadu, is broader and exhibits different characteristics:

  • Broad Coastal Plains: The Eastern Ghats are discontinuous and further away from the coast, allowing for the development of wider coastal plains.
  • Sandy Beaches: Predominantly sandy beaches, often with dunes.
  • Delta Formation: Major rivers like the Mahanadi, Godavari, Krishna, and Kaveri have formed extensive deltas.
  • Lagoons & Mudflats: Chilka Lake (Odisha), Pulicat Lake (Tamil Nadu & Andhra Pradesh) are prominent lagoons. Mudflats are also common.
  • Less Indented Coastline: The coastline is relatively straight and less indented compared to the western coast.

Comparative Table

Feature Western Coast Eastern Coast
Coastal Plains Narrow Broad
Slope Steep Gentle
River Systems Short, fast-flowing rivers Longer, slower-flowing rivers
Delta Formation Limited (Estuaries) Extensive
Coastline Indented, rocky Straight, sandy
Lagoons Less common Common

Reasons for the Difference

The primary reason for the difference in geomorphology lies in the tectonic history of the two coasts.

  • Western Coast – Submergence: The western coast is believed to have been formed due to the submergence of the Deccan Trap basalt flows during the Cretaceous period. This submergence created the narrow coastal plains and the characteristic estuaries. The submergence also resulted in the formation of sea caves and cliffs.
  • Eastern Coast – Emergence: The eastern coast, on the other hand, is considered to be an emerged coastline. This means that the land gradually rose from the sea, resulting in the formation of broad coastal plains and deltas. The upliftment allowed for the deposition of sediments by the major rivers.
  • River Systems: The eastern coast is drained by larger, more perennial rivers originating from the Deccan Plateau, which carry substantial sediment loads and contribute to delta formation. The western coast rivers are shorter and originate in the Western Ghats, lacking the same sediment-carrying capacity.
  • Geological Structures: The presence of the Western Ghats, a continuous mountain range, significantly influences the western coast’s geomorphology, while the Eastern Ghats are fragmented and less impactful.

Furthermore, the differential rates of erosion and deposition, influenced by wave action and currents, have also contributed to the distinct characteristics of each coast.

Conclusion

In conclusion, the contrasting geomorphological features of the eastern and western coasts of India are primarily attributed to their differing tectonic histories – submergence for the west and emergence for the east. This fundamental difference, coupled with variations in river systems, geological structures, and erosional processes, has shaped the unique coastal landscapes observed today. Understanding these differences is vital for effective coastal zone management, disaster preparedness, and sustainable development along India’s extensive coastline.

Answer Length

This is a comprehensive model answer for learning purposes and may exceed the word limit. In the exam, always adhere to the prescribed word count.

Additional Resources

Key Definitions

Estuary
A partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea.
Delta
A landform created by deposition of sediment where a river enters a body of water, typically a sea, ocean, lake, or another river.

Key Statistics

India’s coastline is approximately 7,516.6 km long, including the mainland and islands (Source: National Hydrographic Office, as of 2023).

Source: National Hydrographic Office

Approximately 20% of India’s population lives in coastal areas (as of 2011 Census).

Source: Census of India, 2011

Examples

Chilka Lake

Chilka Lake in Odisha is Asia’s largest brackish water lagoon, formed due to the sediment deposition by the Mahanadi River. It’s a significant habitat for migratory birds.

Frequently Asked Questions

Why are the rivers on the western coast not suitable for navigation?

The rivers of the western coast are generally short, fast-flowing, and have numerous rapids and waterfalls, making them unsuitable for large-scale navigation. They also lack the consistent depth required for sustained navigation.