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Penck model of the cycle of erosion Geography UPSC | Geomorphology | Physical Geography

Penck model of the cycle of erosion Geography UPSC | Geomorphology | Physical Geography

13:49
Walter Penck was a German geographer, he studied the Davis erosion cycle model which is based on the wet region. Penck agreed with most of Davis's views and disagreed on the components of the process and stages of erosion in Davis's trios—structure, process, and phase.

Walter Penck gave two concepts on landforms development:
  • Slope replacement model
  • Cycle of erosion

For the slope replacement concept of Penk, please refer to Penck Slope replacement

Walter Penck gave a geomorphological system model in 1924 also known as the cycle of erosion.
According to Penk, 
  • Erosion of landforms starts with the start of the upliftment process. Upliftment and erosion processes go simultaneously.
  • Landform development is the result of the ratio between the intensity of the rate of upliftment ( i.e endogenic forces) and the intensity of the rate of erosion ( i.e exogenetic forces).
  • The erosion process continues until it reaches the base level.
  • Penck rejected the sequential stage of Davis's erosional cycle. As per Penck, the erosional process is polycyclic as after reaching the base level erosion cycle again starts after the rejuvenation of the landform. Rejuvenation of landforms happens either by lowering the base level or upliftment of the landform.
  • Mainly endogenic forces interfere with the cycle of erosion through Rejuvenation.
  • According to Davis, the erosion cycle is time-dependent but Penck believes that it is not time-dependent, it is a never-ending process.
As per Walter Penck:
There are five stages in the erosional cycle, not three stages as Davis proposed.
  • Primarampf
  • Aufteingend
  • Gleichforminge
  • Absteigende
  • Endrufmpf


Penck cycle 

Primarumpf:

As per Penck, initially, there is a featureless surface that Penck called "Primarumpf" or "primary Pedeplain".
  • It is a prior stage of landform development.
  • In this stage, a landscape exists with no landforms development.
  • No mountain, no hills in this stage.
  • The upper curve and the lower curve of the landform are similar.

Aufteingend:

  • Landforms begin to develop.
  • The mountains are suddenly rising.
  • The valleys are getting deeper and form narrow valleys.
  • Relief increases and convex and free face slopes develop.
  • The gradient between the upper curve and the lower curve increases.
  • In this step, endogenous forces >> exogenous forces.

Gleichforminge:
There are three parts to this stage.
  • In the first stage, uplift is more than erosion.
  • The highest peaks are formed in the upper curve.
  • In the second stage, uplift and erosion are almost identical.
  • In the final stage, the process of regeneration slows down. Gradually the valley starts widening and the height of the mountain also starts decreasing.


Absteigende:
  • Summit or upper curve erodes faster.
  • The river becomes graded and convex and free face slopes are replaced with rectilinear slopes.
  • Conical-shaped Inselberg formed in this stage.

Endrumpf:
  • Landform development stops.
  • Pediplain formed at the end.
  • There is some erosion in the upper parts of the landforms and eroded material gets deposited in the lower part of the landform.



inselberg
inselberg
What are inselbergs?

In the fourth stage of Penck landform development, due to parallel retreating of the slopes, a steep conical hill formed is called inselbergs.


Penck 's Trippen Concept:
  • First: Erosional landforms
  • Second: Transportation
  • Third: Depositional landforms.
Rejuvenation:
Through rejuvenation, the cycle is returned back from the old stage to the young stages.
Rejuvenation can be through two processes:
  • Lowering the base level
  • Upliftment of landforms.
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