Model Answer
0 min readIntroduction
The Deccan Plateau, a large igneous province of India, constitutes a significant portion of the Indian subcontinent. Formed primarily during the Cretaceous-Early Paleogene period (66-62 million years ago) through massive volcanic eruptions, it covers an area of roughly 500,000 square kilometers. Its structural characteristics are a result of this volcanic activity, subsequent faulting, weathering, and erosion, shaping the landscape and influencing the region’s hydrology and resource distribution. Understanding these characteristics is crucial for comprehending the geomorphological evolution and resource potential of peninsular India.
Formation and Geological Composition
The Deccan Plateau’s formation is linked to the Reunion hotspot, a volcanic hotspot currently located near Réunion Island in the Indian Ocean. Massive flood basalt eruptions poured out over a prolonged period, creating thick layers of basaltic lava flows. These flows, known as the Deccan Traps, are the dominant geological feature. The composition is primarily basalt, a dark, fine-grained igneous rock rich in iron and magnesium. Intertrappean formations, sedimentary layers deposited between successive lava flows, contain fossils and provide insights into the paleoenvironment during the Deccan volcanism.
Structural Characteristics
1. Trap Formations & Layered Structure
The most prominent structural feature is the layered structure of the Deccan Traps. These layers, varying in thickness from a few meters to over 30 meters, are horizontally or gently inclined. The repeated layering is a direct consequence of successive lava flows. These layers are often separated by weathered zones or intertrappean beds.
2. Faulting and Jointing
The Deccan Plateau is extensively fractured by faults and joints. These features developed due to various stresses, including those related to the Indian plate’s collision with the Eurasian plate and subsequent uplift. Major fault lines include the Narmada-Son lineament and the Godavari graben. These faults have played a crucial role in shaping the drainage patterns and controlling groundwater movement. Jointing, the presence of regular fractures, further weakens the rock mass and facilitates weathering.
3. River Drainage Pattern
The structural features significantly influence the drainage pattern of the Deccan Plateau. The plateau exhibits a dendritic drainage pattern in areas with less fracturing, while a radial drainage pattern is observed around volcanic domes and hills. The major rivers – Godavari, Krishna, Cauvery, and Narmada – have carved deep valleys and gorges, often following pre-existing fault lines and zones of weakness. The presence of basaltic lava flows also contributes to the formation of terraced landscapes along the river courses.
4. Volcanic Landforms
Besides the extensive lava flows, the Deccan Plateau also exhibits other volcanic landforms. These include:
- Cinder Cones: Small, conical hills formed from accumulated volcanic cinders and ash.
- Basaltic Plateaus: Extensive flat areas formed by the accumulation of lava flows.
- Dykes and Sills: Vertical and horizontal intrusions of magma into pre-existing rock formations.
5. Residual Hills and Plateaus
Differential erosion of the basaltic layers has resulted in the formation of residual hills and plateaus. Harder, more resistant layers form plateaus, while softer layers are eroded, creating valleys and depressions. Examples include the Kaimur Plateau and the Chota Nagpur Plateau (though the latter has Gondwana formations as well).
Regional Variations
The structural characteristics vary across the Deccan Plateau. The western margin, bordering the Arabian Sea, is characterized by steep escarpments and terraced landscapes due to intense erosion. The eastern margin is gentler, with broader valleys and more extensive alluvial plains. The northern part, influenced by the Narmada rift valley, exhibits a more complex structural pattern with prominent faulting and grabens.
| Region | Dominant Structural Features |
|---|---|
| Western Margin | Steep escarpments, terraced landscapes, basaltic cliffs |
| Eastern Margin | Broad valleys, alluvial plains, gentler slopes |
| Northern Part | Rift valleys, grabens, prominent fault lines (Narmada-Son) |
Conclusion
The Deccan Plateau’s structural characteristics, shaped by its volcanic origins and subsequent geological processes, are fundamental to understanding the region’s geomorphology, hydrology, and resource distribution. The layered basaltic formations, faulting, and river systems have created a unique landscape with significant economic and ecological implications. Further research into the Deccan Traps and their impact on the Indian climate and biodiversity remains crucial for sustainable development and resource management in this vital region.
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.