Agents of erosion
The erosion is caused mainly by the three agents:-
The fourth agent which helps is gravity.
Water is the most important agent of erosion responsible for the maximum havoc it creates in the form of erosional damages to the land surface.
It may act in three forms i.e. as falling drops, running overland flow and as running rivers and streams. The erosion caused by water is generally quite devastating and may create various engineering problems, if not properly checked or accounted for, while planning the engineering projects.
The earth, as you know is surrounded by an environment of gases, called the atmosphere. The movement of the atmosphere in a direction parallel to the Earth’s surface, is wind, where as the vertical movements of the atmosphere are termed as air- currents. The cause of wind formation is the subject of a science called Meteorology, and is beyond the scope of this program. We under engineering Geology are mainly concerned with the geological work done by wind, in the form of erosion and consequent deposition of the eroded material.
Like water, wind is also an agent of erosion, transportation, as well as deposition. It is quite an effective agent of erosion in deserts and arid dry areas.
Erosion by moving ice
A glacier is a mass of moving ice, which causes erosional of the surface over which it moves. The third agent of erosion i.e. ice or glaciers may also cause a lot of erosional damages, although it becomes slightly less important in a tropical country like Uganda. The eroded material is carried in an embedded state by the glacier over some distance and then deposited at some place(s) as and when the sediment load gets separated out due to over-loading or sudden disturbance or melting of glacier itself. A glacier, like water and wind, thus act as an agent of erosion, transportation, as well as deposition. About 10% of our present land of the globe is covered by glaciers. They are slow erosive agents, much less effective than water, as far as the overall erosion is concerned. However, in areas of excessive snow falls, such as in mountain tops and solar regions, they become quite effective over a period of time and are thus believed to have developed many land forms (i.e. geological features) of the world