Difference Between Davis And Penck Cycle Of Erosion

Davis’ Cycle of Erosion Theory

 William Morris Davis was an American geographer who proposed the theory of landscape evolution known as the “Cycle of Erosion”. He came up with the theory in 1899 based on the erosion pattern of American mountainous Valleys. Davis is often considered the father of modern geomorphology.

As per Davis’ theory, landscapes undergo a cyclic evolution through the interplay of three main stages:

• Youthful Stage: This stage is characterized by active uplift, rapid erosion, and the formation of V-shaped valleys and steep slopes.
• Mature Stage: As erosion continues, valleys widen, slopes become less steep, and the landscape achieves a more mature and subdued appearance.
• Old Stage: In this stage, the landscape becomes relatively flat and large river valleys, wide floodplains, and low relief features are common.

Davis’ cycle of erosion theory emphasizes the dominance of erosional processes and suggests that landscapes tend to evolve towards an equilibrium state. However, this theory has faced criticism over the years, as many landscapes do not fit perfectly into the cyclic model, and external factors such as climate change and tectonics can significantly influence landscape evolution.

Penck’s Erosion Cycle Theory

Walther Penck was born in Vienna as the son of German geographer Albrecht Penck and he is the one who further developed and refined the concept of erosion cycles. He studied the Davis erosional cycle model and agreed with many thought about it, but disagreed on the process and stages components (i.e trio of Davis are the structure, process and stages) of Davis erosional model. Penck rejected that stage is not sequential and there may be interrupted by rejuvenation. 

Walter Penck gave a morphological system model in 1924 also referred also known as cycle of erosion. As per Walter Penck, the Endogenic force also interferes with the cycle of erosion through rejuvenation. Hence, the erosion cycle is a never-ending process. The erosional cycle is not time-dependent as Davis has proposed.

Penck’s erosion cycle comprises the following stages:

• Youthful Stage: Which is often associated with active tectonic uplift and intense erosion. During this stage, rivers and glaciers are efficient at eroding the landscape, resulting in the formation of V-shaped valleys, steep slopes and rugged terrain. The topography is relatively high-relief, and landforms are sharp and jagged.
• Mature Stage: As the landscape continues to evolve, erosion rates decrease, and the landforms begin to change. Valleys widen and deepen, and the slopes become less steep. The landscape takes on a more subdued appearance, and the relief decreases compared to the youthful stage.
• Old Stage: In this stage, the landscape experiences further erosion and denudation, leading to a smoother, rolling topography with meandering rivers.
• Rejuvenation Stage: If tectonic uplift occurs again after the old stage, the landscape enters a rejuvenation stage, where rivers begin to down-cut and deepen their valleys, creating an “entrenched meandering” pattern. 

Also Read: Difference Between Chemical And Physical Weathering

Davis And Penck Cycle Of Erosion In Tabular Form

What You Need To Know About Davis Cycle

• Davis suggested landform evolution as a function of structure process and stage (trip of Davis). It can be said that Davis limited his idea upto exogenic forces and almost ignored endogenic forces.
• Davis Cycle of erosion has three stages that is, youth, mature, and old stage.
• According to Davis, upliftment finished before degradation starts.
• According to Davis, the period of upliftment is small.
• The rate of upliftment is very rapid, according to davis.
• Davis didn’t back his theory by a concrete slope development idea.
• The end product of the Davis Cycle of erosion was flat extensive featureless plain which he referred to as Peneplain.
• Davis Geographical Cycle of Erosion is a monocycle that means cycle complete after the old stage of landforms.
• In Davis cycle, landforms are the result of Davis trios which include: structure, process,  and Time.
• Davis’s cycle of landform development is time-dependent.
• Davis limited his idea upto the humid and subhumid areas (evident from his fluvial cycle of erosion later extended to other regions).
• Landform development is a form of “slope decline”; for example “V” shaped valley get converted to “U” shaped valley and then featureless peneplain in Davisian cycle of erosion.

What You Need To Know About Penck Cycle

• Penck suggested that landform was resultant of competition between endogenic and exogenic forces. Penck paid equal attention to both the forces.  
• Penck completely rejected the stages. He mentioned five conditions i.e Primarumpf, Aufsteigende, Gleichforminge, Absteigende, and Endrumpf.
• According to Penck, upliftment and degradation starts together as soon as the landmass comes above the sea level.
• According to Penck, the period of upliftment is a long process.
• The rate of upliftment is sometimes slower and sometimes higher.
• Penck’s cycle of erosion contained the idea regarding slope replacement.
• The end product of the Penck cycle was endrumpf or peneplains (not entirely featureless).
• The Penck erosion cycle is polycyclic that means a never-ending process; the cycle starts again by the rejuvenation of landforms.
• Penck’s landforms are the result of the ratio between the intensity of endogenic and exogenic forces.
• The Penck cycle of erosion is not time-dependent.
• Penck original idea of cycle of erosion was applicable to arid, semi-arid and tropical regions.
• Landform development in the Penck cycle of erosion is in form of “slope replacement” where a free face slope and concave slopes get replaced to rectilinear slopes.