Erosion may be defined as the wearing down of Earth’s surface through weathering and the transportation of the particles to distant places. For example, the boulder is first loosened in a mass movement and then its pieces are carried by the stream. Similarly, moving angular pieces of rocks produce etching which cuts the surface of the earth. Erosion agents include wind, moving ice, running water, underground water, and ocean waves.
The process of erosion is completed in many stages. These stages of erosion and aggravation complete the erosion cycle. The three stages of erosion are as given:
(1). Start of deformation of land masses
(2). Prime of the erosion process
(3). End of erosion followed by aggradation work (deposition)
According to H.J de Blij, the cycle is; ”The upland slope gradually attains lower angles until the upland transformed into mountainous terrain. Now the mountains are lowered until they are little more than convex hilly interfluves. Finally, even these hills are eroded away leaving a nearly flat and plain with a few remnants on it.”
Normal Cycle of Erosion:
The normal cycle of erosion is completed in the following three stages:
- Youth Stage
- Mature Stage
- Old Stage
(1). Youth Stage:
It is the first and initial stage of erosion. In this stage, the river takes shape and starts its downslope journey with great force. The flowing water makes its way by cutting the rocks. A full drainage system gets operational and rapid, waterfalls, cascades, gorges, canyons and V-shaped valleys emerge on the landscape. Thus, the process of the deformation of the landmass gets in full swing.
(2). Mature Stage:
It is the second stage of the normal cycle of erosion. The river water enters the valley and thus its speed slows down considerably. The process of lateral erosion starts. The river forms flood plains, natural levees, and OX-Bow lakes. Thus, the erosional process enters a mature stage.
(3). Old Stage:
It is the third and last stage of the normal cycle of erosion and is termed old stage erosion. At this stage, the process of leveling the ground is accompanied by the process of deposition (aggradation). Moreover, the flood plain becomes wider, the interfluves become narrow, and meanders form large loops. Thus the region is worn down and takes the shape of a plain. This stage completes the normal cycle of erosion.