Chemical Erosion Examples

Chemical erosion, also called chemical weathering, causes the breakdown and decay or rocks or other geological features through a chemical process. This process can be the result of manmade activity, or the chemical composition of soil or water as it moves across the rock's surface. Just as in other forms of erosion, such as wind, water, or tectonic activity, chemical erosion changes the surface structure of the rock over time.

Chemical erosion causes an alteration to the actual composition of the rock, primarily in its surface minerals. This process seeks out the minerals that are already fairly unstable in the rock's surface, and can often result in the formation of clay.

Water plays a very effective role in chemical erosion, as it introduces active agents that react with the minerals in the rock. This is especially true when combined with natural water erosion when the water seeps into existing fractures and causes the rock to break apart. It can also occur when water that contains key chemical agents dislodges thin pieces of shale material. Finally,chemical erosion can also include changes that occur only at the surface level and under low-temperatures, depending on the chemical agents present in the water or soil.

Smaller rocks are more susceptible to chemical weathering than larger rock masses, as they have more surface area to be affected by the reactions.

1. Carbonation - When carbon dioxide is present and carried by water, carbonation weathering can occur. The carbon dioxide reacts with the water, which forms a weak acid and eats away at the affected rock.

2. Hydration - This type of weathering occurs when rocks absorb water, and the resulting hydrogen and hydrate ions form new bonds with minerals present within the rock. This type of chemical erosion can actually result in a change to a new form of rock, such as the process by which gypsum is formed.

3. Hydrolysis - This erosion takes place when minerals in the rock form a new solution, usually due to the presence of water. An example of this would be the formation of salt water when natural minerals in the rock form a salt solution once water is introduced.

4. Oxidation - Much like carbonation-which occurs in the presence of carbon dioxide-oxidation takes place when rocks react with the presence of oxygen. Oxidation also requires the presence of water, but this can even be in such small amounts as the presence of moisture in the air. Oxidation is more commonly known as rust.