Chemical Weathering vs. Mechanical Weathering

Difference Between Chemical Weathering and Mechanical Weathering

Chemical and mechanical weatherings are a part of natural processes that nature imposes on its subjects. Weathering happens when there is a physical or chemical breakdown, to the surface mineral of rocks. This event is brought about by natural elements like water, gas, ice and plants.

Chemical Weathering

The rocks can break down or dissolve and change in the composition the same time by a chemical process to form the residual material. It’s called the chemical weathering. There are three very common chemical processes involved with the chemical weathering. First is the dissolution that occurs when the water e.g. rain reacts with the minerals and by the process of winding up the rock causes the chemical composition to change. Oxidation is a process where oxygen reacts with minerals in a rock, especially iron, to form rust. That’s why we see red-colored rocks at times. Hydrolysis happens when water reacts with Feldspar, which is the most common mineral in rocks and form another product, usually clay, which can be easily dissolved later.

Mechanical weathering

Mechanical weathering happens when rocks disintegrate or break down in smaller pieces by physical forces that could be any of the following: exfoliation, abrasion and freezing and thaw weathering. When rocks shed off sheets along its joints that form by applying pressure on the rock through natural causes such as tectonic activities exfoliation occurs. Abrasion occurs when the rock surface wears down and removes away layers by friction. The rocks get broken down and are reduced to size due to the wind that constantly keeps rubbing on it. In cold locations where temperatures reach the freezing point, the water that has accumulated and frozen in between the crevices of a rock grows in volume. When the water thaws, it gives more space for more water to sink inside the crack and freeze again. Till then the rock breaks along such crevice by reducing it into smaller fragments.

Difference between Chemical Weathering and Mechanical Weathering

Chemical and mechanical weathering are both natural processes that decompose rocks. Their goal may be the same but the processes are different. The chemical weathering needs chemical reactions with minerals within the rock and causes changes in the composition of rock. Sometimes this process will produce a different kind of product because of the reaction. Mechanical weathering involves only mechanical physics of rock to smaller pieces of fragments. Without changing the physical composition of the rocks, mechanical disintegrating erodes rock with natural physical pressure.

The climate is very important in the process of weathering. Cold temperatures are suited to mechanical weathering while warm temperatures support the chemical weathering. And while weathering is complete, the remaining material will be eroded and transported by wind or water.

 

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  • Jgillies12

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