Geomorphology is the systematic study of land-forms and the interpretation of them as records of past-history. Certain agents function to bring about gradation and result changes in land- forms. These may be called geomorphic agents, such as river, wind, glacier and sea-waves. This geomorphic agent basically serves three functions:
(i) Erosion,
(ii) Transportation, and
(i) Deposition.
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(i) Erosion:
The breaking-down or disintegration of rocks due to the physical forces associated with the natural agencies, followed by temoval of the dislodged rock-fragments and particles, and the sum total of the process is defined as erosion.
(ii) Transportation:
It is the process by which the weathered materials are removed from the site of their formation by various geomorphic agents.
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(iii) Deposition:
It is the process, whereby accumulation of the transported materials, which results from the loss of the transporting capacity of the geomorphic agents. This happens when the velocity is reduced or the material being transported exceeds the capacity for transporting. It may also happen because of chemical precipitation of the materials transported in solution.
Each geomorphic agent functions in a way peculiar to it and as a result produces erosional and depositional land-forms which arc characteristic of that agent.
It is therefore possible to recognize the origin of land-forms although the processes by which they were formed may have ceased to operate; it is because ‘geomorphic processes leave their imprint upon land-forms’.
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The structure of the crust acts as a control in the formation o’ land-forms. Folds, faults, unconformities, differences in the hardness and susceptibility of rock units to decomposition and disintegration provide a frame-work within which the geomorphic agents function.
The resulting physiographic features are always influenced by the structure of the underlying rock. Thus the combination of a particular structure being eroded primarily by one geomorphic agent will result in a predictable land-form.