Weathering is the breaking down of rocks, soil and minerals through contact with the Earth’s atmosphere, water and biological organisms. It can thus be defined as the process where rocks or soils are dissolved or worn away into smaller and smaller pieces due to particular environmental factors. 

Types of weathering: 

(a) Physical or mechanical weathering: Mechanical weathering is the physical breakdown of rocks into smaller and smaller pieces. One of the most common mechanical actions is frost shattering. It happens when water enters the pores and cracks of rocks, then freezes. Another type of mechanical weathering is called salt wedging. Winds, water waves and rain also have an effect on rocks as they are physical forces that wear away rock particles, particularly over long periods of time. 

(b) Biological weathering: It is the disintegration of rocks as a result of the action by living organisms. Trees and other plants can wear away rocks since they penetrate into the soil and as their roots get bigger, they exert pressure on rocks and makes the crack wider and deeper. Eventually, the plants break the rocks apart. Some plants also grow within the fissures in the rocks which lead to widening of the fissures and then eventually disintegration. 

(c) Chemical weathering: It happens when rocks are worn away by chemical changes. The natural chemical reactions within the rocks change the composition of the rocks over time. Because the chemical processes are gradual and ongoing, the mineralogy of rocks changes over time thus making them wear away, dissolve and disintegrate.