What is Deposition?
Deposition is a natural geological process that transports sand, silt, and sediment from one place and deposits it in another. Agents like water, wind, gravity, and glaciers carry out this transportation.
The sediment is generated by erosion and weathering events. These agents are so powerful that they can transform boulders and mountains into the sediment. Sometimes chemical weathering (caused by acid rain) breaks down solid rocks and stones. The sediment is a raw material for new sedimentary rocks.
For example, ocean waves continuously hit rocks and erode them. The eroded particles are then carried to other places and usually end up at beaches and seashores.
Deposition Phases
The deposition process consists of two phases.
- Erosion
- Deposition
Agents Participating in Deposition
There are four agents that participate in the process of deposition. They are as below:
Frozen rivers/glaciers: These agents carry the eroded material or break large pieces from existing rocks and mountains when they melt or slide from one place to another.
Gravity: It interfere with the erosion when the rocks fall due to the earthquake.
Wind: The wind carries lighter sediment like sand, dust, and extremely small particles. You may have already seen how your porch gets all sandy after a windstorm. Imagine the places where windstorms occur regularly and how the wind will deposit sediment there.
Water: Water is the strongest of all the agents. It can carry large particles, boulders, small rocks, and lighter particles. The distance a particle will travel will depend on its size, water speed, and terrain. Water will only carry smaller particles if it’s moving uphill. However, it will carry larger particles if it’s moving downhill.
Similarly, the particle size will also impact how far sediment can travel. Larger particles and boulders travel less, and smaller particles travel larger.
Also Read: Transgression Geology: Definition, Animation, and Comparison with Regression
Elements Affecting Deposition
There are several elements that affect the process of deposition after the erosion of rocks. Here they are:
Speed of the Deposition Agents: The speed of natural agents plays a vital role in the process of deposition. A lower speed will deposit the sediment near to origin site. A faster speed will take sediment to faraway places from the origin site.
Sediments’ Size: The size of the sediments, their thickness and volume also play a vital role in this process. The heavier particle will be deposited near to the origin site and the lighter will travel more distance.
Sediment’s Shape: The shape of the eroded material plays an important role in the process of deposition. If the sediments are in round shape, they move quicker than the flat particles. In the same way, the sharpness of the eroded material takes them away from origin site.
Deposition Effects on Geographical Environment
Deposition affects the geographical environment in many ways. Following are them:
Gravity: It creates rock-sliding on the sides of the mountains and the rocks are deposited at the bottom.
Weight: The weight of the eroded material also creates rockslides.
Wind: Wind creates different sand dune patterns in deserts while taking the sand with it.
Rivers: When the rivers deposit sand and other eroded material with them, they create deltas. So, the water speed slows while reaching to deltas to be a part of the ocean.
Ocean Waves: The ocean waves with a forceful power create beaches and sand bars by continuously depositing sand to a particular location.
Positive Effects of Deposition
Deposition’s overall effect is positive on earth. For example, the Nile in ancient times bought silt from the nearby lands at its bank. The silt was fertile and increased the agricultural output.
Deposition often forms new islands. When the deposition process continues depositing sediment through wind and water, it forms new islands. This may take hundreds of years, but islands inside the sea are often created due to deposition.
Ocean waves carry sediment, silt, and sand particles to a particular location and may form new beaches. The Mar del Plata beach, Buenos Aires, Argentina, and Paradise Island Beach, Bahamas, are created from sediment deposition.
The deposition of alluvial sediment form river deltas. The common examples are the sedimentary delta in the river Nile and Mississippi Delta in the US.
