Erosion vs Deposition
It is not hard to understand the difference between erosion and deposition, if you understand the sequence of the geological processes that form relief features on the earth. The physical features of the surface of the earth keep on changing all the time on geological time scale. This is how we see mountains, valleys, plains, rivers, and other relief features. These topographical features are a result of natural geological processes called erosion and deposition. These are closely related concepts though totally opposite to each other. This is why there is confusion in the minds of many students of physical geography. This article attempts to clarify the doubts regarding natural processes called erosion and deposition. Let us take a closer look.
What is Erosion?
The movement of rock pieces from one place to another, once they have been loosened by the action of physical or chemical weathering, is known as erosion. It is the erosion that is responsible for many of the relief features that we see on the surface of the earth. Small pieces of rocks, sediment, and even soil are moved away by the action of natural geological agents such as flowing water, blowing winds, and melting ice of glaciers under the influence of gravity. Most of the relief features such as hills and valleys are a result of erosion that is a constant, continuous process that goes on unabated in nature. Thus, in simplest of words, erosion is the removal of loosened rock pieces from a higher elevation to a lowly point with the action of natural agents.
Erosion is considered a threat as it can cause landslides. There are different measures that are taken to prevent erosion such as planting trees on hill surfaces to stop water washing off the soil and dragging the top layer with it during the rainy season. Also, to stop rivers and the oceans from eroding banks or the beach, huge rock barriers are made.
What is Deposition?
The process of erosion is complete when the journey of all particles falling and flowing under gravity is done with and all the sedimentation gets deposited and settles on the surface. The final process is the process of deposition. Technically speaking, deposition is a part of the process of erosion. If erosion can be thought of as a sequence, it includes detachment, entrainment, transport, and finally deposition. Detachment is the end process of weathering that finally results in loosening of rock particles. Entrainment refers to the actual transport of these particles through a natural agent such as water, wind, or melting ice that slides down at some speed because of the action of gravity.
Deposition of sediments along the surface of the earth creates relief features such as hills, plateaus, valleys, plains, slopes, and so on. One can see the effect of continuous deposition at a place in the way colors of layers of rocks change one over the other. It is through carbon dating that one can get to know about the ages of various rock layers that are deposited at a place over thousands of years.
What is the difference between Erosion and Deposition?
• Erosion and deposition are continuous geological processes that are natural and result in relief features seen over the surface of the earth.
• If erosion is seen as a sequence of events, deposition takes place at last when the rock particles finally settle down on the surface of earth. So, erosion is the beginning of a process while deposition is the end of the same long process.
• Erosion is the movement of rock particles once they have been loosened by the action of natural agents of weather and others like roots of plants. Or, in other words, erosion is removal of loosened rock pieces from a higher elevation to a lowly point with the action of natural agents.
• When all particles falling and flowing under gravity is done with and all the sedimentation gets deposited and settles on the surface, we call it deposition. Now the particles that came a long way do not move anymore.
• Erosion can happen because of natural agents such as water, ice, and wind. However, when somehow these agents are disturbed and they cannot keep on dragging the particles, deposition takes place.
• Without erosion, deposition cannot take place.
- Lavaka (erosion gully) in Madagascar by Frank Vassen (CC BY 2.0)
- River deposition by Colin Inverarity (CC BY-SA 2.0)