🟦 Geography Optional – MAINS Level
Paper–I : Physical Geography
Page – 3 | Geomorphology
UPSC / UPPSC | Shaktimatha 369 Learning
Q3. Compare the theories of slope development proposed by Davis, Penck and King. Which theory provides a more realistic explanation of slope evolution?
Directive: Compare + Evaluate (Very High Difficulty)
Introduction
Slope development is a crucial aspect of geomorphology as it reflects the balance between uplift, erosion and denudation. Several geomorphologists have proposed models to explain slope evolution, notably Davis, Penck and King.
Main Body
1. Davis’ Theory of Slope Decline
- Based on the concept of the geographical cycle
- Slopes gradually decline in angle over time
- Associated with youth–maturity–old age stages
- Criticism: Overly time-dependent and ignores tectonic activity
2. Penck’s Theory of Slope Replacement
- Emphasised rate of uplift rather than time
- Convex slopes replace concave slopes during active uplift
- Introduced the concept of waxing, waning and uniform uplift
- Criticism: Empirical validation is limited and terminology is complex
3. King’s Theory of Parallel Slope Retreat
- Slopes retreat parallel to themselves while maintaining angle
- Common in arid and semi-arid regions
- Associated with pediplanation
- Criticism: Limited applicability to humid regions
4. Comparative Evaluation
- Davis explains temporal evolution but ignores tectonics
- Penck integrates uplift and erosion dynamically
- King explains arid landscapes more realistically
Conclusion
No single theory universally explains slope development. However, Penck’s dynamic approach is considered more realistic as it recognises the continuous interaction between uplift and erosion, making it closer to present-day geomorphic understanding.
Diagrams to draw in exam:
• Davis slope decline diagram
• Penck slope replacement model
• King’s parallel slope retreat
Examiner’s View:
✔ Comparison done systematically
✔ Evaluation included (mandatory for high marks)
✔ Thinkers named correctly
✔ Diagrams can push answer to 18+ marks
End of MAINS – Page 3
Shaktimatha 369 Learning
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