Question

Discuss the different steps of normal cycle of erosion with diagram after William Morris Davies.

Hint:

{Three Stages:}

• {Youth:} Deep V-shaped valleys, waterfalls (rapid down-cutting)
• {Maturity:} Wider valleys, meanders (lateral erosion)
• {Old Age:} Peneplain, monadnocks (low relief)

Answer 1

William Morris Davis' Geomorphic Cycle of Erosion

William Morris Davis (1899), an American geographer, proposed the concept of the Geomorphic Cycle or Cycle of Erosion. According to Davis, landforms evolve through three sequential stages — Youth, Maturity, and Old Age — similar to the human life cycle.

Basic Assumptions of Davis’ Model:

• Rapid uplift of land.
• Long period of tectonic stability after uplift.
• Erosion mainly carried out by running water.
• Landscape development follows a time-dependent sequence.

Conceptually:

\( Landform \, Development = f(Time + Structure + Process) \)

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Stages of the Geomorphic Cycle

1. Youth Stage

• Dominant Process: Vertical erosion (down-cutting)
• Valley Shape: Deep, narrow V-shaped valleys
• River Gradient: Very steep
• Relief: Increasing relief
• Drainage: Poorly developed tributaries
• Interfluves: Broad and flat

Common Landforms:

• Gorges
• Canyons
• Waterfalls
• Rapids

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2. Maturity Stage

• Dominant Process: Lateral erosion increases
• Valley Shape: Wider valleys with gentler slopes
• Relief: Maximum relief attained
• Drainage: Well-developed drainage system
• River Condition: Approaches base level
• Interfluves: Narrow and sharp

Common Landforms:

• Meanders
• Floodplains begin forming
• Valley widening

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3. Old Age Stage

• Dominant Process: Deposition and lateral erosion
• Valley Shape: Very wide valleys
• Relief: Very low relief
• River: Sluggish flow with large meanders

Common Landforms:

• Peneplain (almost plain-like surface)
• Oxbow lakes
• Swamps
• Residual hills called Monadnocks

Final stage representation:

\( Relief \rightarrow Minimum \quad \Rightarrow \quad Formation \, of \, Peneplain \)

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Important Concepts in Davis’ Model

• Uplift: The cycle begins with rapid tectonic uplift.
• Base Level: The lowest level to which a river can erode (usually sea level).
• Peneplain: Nearly level surface formed in old age stage.
• Monadnock: Resistant residual hill standing above peneplain.
• Rejuvenation: Renewed uplift restarts erosion cycle.

Mathematically:

\( Erosion \propto Time \)

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Criticisms of Davis' Model

• Assumes rapid uplift followed by long stability (rare in reality).
• Ignores climatic variations.
• Too deterministic and time-dependent.
• Over-simplifies complex geomorphic processes.
• Later modified by Walther Penck and modern geomorphologists.

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Conclusion

Davis’ Geomorphic Cycle was a pioneering model in geomorphology. Although later modified and criticized, it provided the first systematic explanation of landscape evolution based on time, erosion, and structural control.