Model Answer
0 min readIntroduction
William Morris Davis proposed the ‘Geomorphic Cycle’ theory, explaining landscape evolution through stages of youth, maturity, and old age. He identified different cycles based on climatic conditions. The Normal cycle, prevalent in humid temperate regions, contrasts significantly with the Arid cycle, found in arid and semi-arid environments. Understanding these differences is fundamental to comprehending regional variations in landform development and the influence of climate on geomorphological processes.
Differences between Normal and Arid Cycles of Davis
The Normal cycle is characterized by a balanced interplay between erosion and deposition, leading to broad, gently sloping plains. It’s dominated by fluvial processes – vertical erosion in youth, lateral erosion in maturity, and peneplanation in old age. Conversely, the Arid cycle is marked by limited rainfall and significant temperature fluctuations.
Key Differences:
| Feature | Normal Cycle | Arid Cycle |
|---|---|---|
| Climate | Humid, temperate | Arid, semi-arid |
| Dominant Process | Fluvial erosion & transport | Wind erosion, flash floods, limited fluvial action |
| Landforms | V-shaped valleys, meanders, floodplains, peneplains | V-shaped canyons, mesas, buttes, playas, alluvial fans |
| Erosion Rate | Relatively slow and continuous | Episodic and rapid (due to infrequent but intense rainfall) |
| Vegetation Cover | Dense | Sparse or absent |
In the Arid cycle, vertical erosion is dominant due to infrequent but intense rainfall events, resulting in steep-sided canyons and angular landforms. Wind action plays a crucial role in shaping the landscape, creating features like yardangs and dunes. The lack of vegetation exacerbates erosion rates. The cycle often terminates in a bajada or playa rather than a peneplain.
Conclusion
In essence, the Normal cycle represents a landscape sculpted by gradual fluvial erosion in humid conditions, while the Arid cycle showcases a landscape carved by episodic, intense erosion and wind action in dry environments. These cycles highlight Davis’s attempt to link climate and landform development, though his model has been critiqued for its uniformitarian assumptions and rigid stages.
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.