Weathering is a complicated process, which alters the external features of stones, rocks and soils in a natural way. Weathering involves simultaneous occurrence of chemical, biological and physical reactions. Unlike erosion, weathering is a static process. It causes rocks and stones to disintegrate.

Types of Weathering

Depending upon the processes involved, weathering can be classified as mechanical or physical weathering and chemical weathering, Gradual decay of rocks and soils by natural atmospheric variations like rainfall, flood, heat, snow fall and air pressure is described as mechanical or physical weathering. Chemical weathering popularly known as biological weathering happens when naturally produced chemicals get involved in the process of decay.

Weathering Associated with Thermal Expansion

Weathering sometimes comes with thermal expansion. Exfoliation, onion-skin weathering and thermal shock are some of the thermal expansion related weathering commonly observed in arid and semi-arid regions of the world. In deserts, scorching heat during daytime causes expansion of rocks. At night, as the temperature starts falling rapidly, contractions occur on the rock surface resulting in flaking off of the rock layers.

Weathering Associated with Freeze Thaw

This is a special type of weathering widely observed in hilly regions. If temperature continues to remain close to the freezing point, ice crystals and freezing water create cracks on rock surface. Deposit of ice crystals weakens the porous exterior of rock causing it to decay over time.

Weathering Associated with Salt Crystallization

Salt crystallization causes severe type of weathering on rocks. It happens when saline solution enters into the inner layers of rocks through the pours and cracks. When rocks get heated due to high atmospheric temperature it causes expansion of the salty solutions inside the rocks. It results in weathering. Magnesium sulfate, sodium sulfate and calcium chloride are the chemical salts, which causes salt crystallization.