Question.
Elaborate on the statement given by W. M Davis that " Landscape is a function of the structure, process, and time". ( UPPSC 2019)
"Landscape is a function of structure, process, and stage."- Explain and give suitable examples. ( UPPSC 2008)
Answer.
To understand the formation and evolution of various landforms that occur in the landscape, it is very important to understand its erosion cycle. Although there are many theories of the cycle of erosion that explain the formation of landforms, WM Davis was the first to explain the erosion cycle of landforms in 1889. Davis's erosion cycle is based on the study of the wetlands of the Appalachian Mountains in the northeastern United States.
According to Davis, the evolution of a landscape is a product of its structure, process, and time. He emphasized that there are three major controlling factors in the development of landscape – structure, process, and time.
Structure:
The process of erosion of a landscape depends on the structure of the terrain. The structure of land includes composition, folding, and faulting of the rocks. If the terrain is made of hard rock, then there is a slow erosion process. If the structure of the terrain is folded and cracked, then geomorphic factors such as running water erode the relief of the terrain very quickly. The intensity of the erosion process is determined by the composition of the terrain. Therefore, the structure of the topography is one of the deciding factors.
Process:
The process includes weathering, erosion, and transportation. What type of geomorphic agents are present in the erosion process, contribute a lot to the formation of landforms there.
For example,
- Running water is active in humid climates.
- Winds are active in dry climates.
- Glaciers are active in the glacial zone.
- Each landscape has different types of landform forming.
Time :
- The development of landscape is time-dependent, it develops in three phases - young, mature, and old age.
Youth stage:
- In areas with a humid climate, running water erodes more vertically in the young stage.
- In this stage, the landscape forms a narrow V-shaped valley and waterfall.
- This stage lacks a delta and a floodplain.
Mature stage:
- In this stage, the lateral erosion is more than the vertical erosion, resulting in the formation of a wide V-shaped valley.
- The river forms a narrow delta at its mouth.
Old stage:
- At this stage, the river forms the meander, the Oxbow Lake, the broad plains, and the well-developed delta.
- The river generally reaches the base level of its erosion.
- In this phase, featureless plains such as peneplain are formed.
Therefore, Davis asserted that structure, process, and time jointly determine the evolution of landforms.
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