How Are Mechanical & Chemical Weathering Alike?
- At the most basic level of similarity, mechanical weathering and chemical weathering perform the same function: they break rock down into smaller and smaller pieces. Both types of weathering help to form soil, which is required for plant growth and acts as the basis for all terrestrial ecosystems.
- The rate of weathering, both mechanical and chemical, is determined by the climate of an area. For example, chemical weathering occurs more rapidly in warm climates. Forms of mechanical weathering such as insolation weathering (when rocks eventually break apart due to constant cycles of thermal expansion and contraction) and frost wedging (when rocks break apart due to the expansion of freezing water) also depend on climactic factors such as temperature and amount of precipitation.
- Both mechanical and chemical weathering can be carried out by living things. This is known as "biological weathering." An example of chemical weathering that can also be characterized as biological weathering is the action of lichens, which chemically break down rock in order to gain nutrients. An example of physical weathering that is also biological weathering is "root wedging."
- Physical and chemical weathering work together in complementary ways. When physical weathering breaks down a rock into several smaller pieces, it substantially increases the amount of surface area that is exposed to air and water, which are necessary for chemical weathering to occur. Similarly, the chemical actions of lichens create cracks where physical processes such as salt crystallization, frost wedging and root wedging can occur.
- Both chemical and mechanical weathering cause problems for human beings by destroying man-made architecture. The Statue of Liberty, for instance, is under attack by both types of weathering. Because the Statue of Liberty is constantly exposed to salt water, it is susceptible to physical weathering processes such as salt crystallization and frost wedging. It is also subjected to a form of chemical weathering known as galvanic corrosion. The damage caused by weathering culminated in a two-year series of repairs from 1984 to 1986. Both physical and chemical weathering necessitate that people occasionally repair and restore their monuments.
