• There are three types of Weathering:

1. Biological Weathering.

2. Chemical Weathering.

3. Physical Weathering.

• Surface weathering of rocks makes smaller pieces. There are two main types: mechanical and chemical. Biological weathering isn't really a process, but living organisms can cause both mechanical and chemical weathering to occur.

• For example: tree roots can grow into fractures in a rock and pry the rock apart, causing mechanical fracturing. Moss and fungus can also grow onto a rock. In this case, the roots will produce a weak acid that dissolves the rock and does two important things (at least as far as the plant is concerned): gain nutrients (food), and make little holes for the rootlets to grow into. Either way, the rock is weathered (and the plant lives).

• Chemical weathering is caused by rain water reacting with the mineral grains in rocks to form new minerals (clays) and soluble salts. These reactions occur particularly when the water is slightly acidic. These chemical processes need water, and occur more rapidly at higher temperature, so warm, damp climates are best. Chemical weathering (especially hydrolysis and oxidation) is the first stage in the production of soils.

• Physical weathering is caused by the effects of changing temperature on rocks, causing the rock to break apart. The process is sometimes assisted by water. Physical weathering happens especially in places where there is little soil and few plants grow, such as in mountain regions and hot deserts.It happens through repeated melting and freezing of water or through expansion and contraction of the surface layer of rocks that are baked by the sun (hot deserts).

1. www.geolsoc.org.uk

2. education-portal.com

3. https://www.google.com.pk/search?q=biological+weathering

4. http://www.geolsoc.org.uk/ks3/gsl/education/resources/rockcycle/page3561.html

• education-portal.com