Chemical Weathering Vs Mechanical Weathering

4 Types and Examples of Chemical Weathering

ThoughtCo / Hilary Allison

Updated on Oct 29, 2019

In that location are three types of weathering: mechanical, biological, and chemical. Mechanical weathering is caused by wind, sand, pelting, freezing, thawing, and other natural forces that can physically alter stone. Biological weathering is acquired past the actions of plants and animals as they grow, nest, and burrow. Chemical weathering occurs when rocks undergo chemic reactions to form new minerals. Water, acids, and oxygen are just a few of the chemicals that pb to geological alter. Over time, chemical weathering can produce dramatic results.

Chemical Weathering From Water

Stalagmites and stalactites grade as dissolved minerals in h2o deposit on surfaces. — Alija/Getty Images

Water causes both mechanical weathering and chemical weathering. Mechanical weathering occurs when water drips or flows over stone for prolonged periods; the Grand Canyon, for example, was formed to a large degree past the mechanical weathering activity of the Colorado River.

Chemical weathering occurs when water dissolves minerals in a rock, producing new compounds. This reaction is called hydrolysis. Hydrolysis occurs, for example, when water comes in contact with granite. Feldspar crystals within the granite react chemically, forming dirt minerals. The dirt weakens the rock, making it more likely to break.

Water also interacts with calcites in caves, causing them to dissolve. Calcite in dripping water builds up over many years to create stalagmites and stalactites.

In addition to irresolute the shapes of rocks, chemical weathering from h2o changes the composition of water. For example, weathering over billions of years is a big factor in why the ocean is salty.

Chemical Weathering From Oxygen

Vermilion Cliffs National Monument — Philippe Bourseiller/Getty Images

Oxygen is a reactive element. It reacts with rocks through a process called oxidation. Ane case of this type of weathering is rust formation, which occurs when oxygen reacts with atomic number 26 to form iron oxide (rust). Rust changes the colour of the rocks, plus iron oxide is much more than frail than iron, so the weathered region becomes more than susceptible to breakage.

Chemical Weathering From Acids

The effect of acid rain on a copper mural in a mausoleum. — Ray Pfortner/Getty Images

When rocks and minerals are altered by hydrolysis, acids may be produced. Acids may as well be produced when h2o reacts with the atmosphere, so acidic water tin react with rocks. The effect of acids on minerals is an example of solution weathering. Solution weathering also covers other types of chemical solutions, such as basic rather than acidic ones.

One common acid is carbonic acrid, a weak acid that is produced when carbon dioxide reacts with h2o. Carbonation is an of import process in the formation of many caves and sinkholes. Calcite in limestone dissolves nether acidic conditions, leaving open spaces.

Chemical Weathering From Living Organisms

Barnacles and other aquatic organisms can lead to weathering of structures. — Phil Copp/Getty Images

Living organisms perform chemical reactions to obtain minerals from soil and rocks. Many chemical changes are possible.

Lichens can take a profound effect on rock. Lichens, a combination of algae and fungi, produce a weak acid that tin dissolve rock.

Plant roots are as well an of import source of chemical weathering. Equally roots aggrandize into rock, acids tin can alter the minerals in the rock. Establish roots also use carbon dioxide, thus changing the chemistry of the soil.

New, weaker minerals are often more than brittle; this makes information technology easier for institute roots to break up the stone. Once the rock is broken up, h2o tin get into the cracks and oxidize or freeze. Frozen water expands, making the cracks wider and farther weathering the rock.

Animals can also effect geochemistry. For example, bat guano and other animal remains incorporate reactive chemicals that can affect minerals.

Human activities also accept a major impact on rock. Mining, of course, changes the location and status of rocks and soil. Acid rain caused by pollution can eat away at rocks and minerals. Farming changes the chemical composition of soil, mud, and stone.