This article is about weathering of rocks and minerals. Mechanical or physical weathering involves the breakdown of rocks and soils through direct contact with atmospheric conditions, such as heat, water, ice and pressure. The second classification, chemical weathering, involves the direct effect of atmospheric chemicals or biologically different types of weathering pdf chemicals also known as biological weathering in the breakdown of rocks, soils and minerals.
While physical weathering is accentuated in very cold or very dry environments, chemical reactions are most intense where the climate is wet and hot. However, both types of weathering occur together, and each tends to accelerate the other. In addition, many of Earth’s landforms and landscapes are the result of weathering processes combined with erosion and re-deposition. Physical weathering, also called mechanical weathering or disaggregation, is the class of processes that causes the disintegration of rocks without chemical change.
However, chemical and physical weathering often go hand in hand. Physical weathering can occur due to temperature, pressure, frost etc. For example, cracks exploited by physical weathering will increase the surface area exposed to chemical action, thus amplifying the rate of disintegration. Abrasion by water, ice, and wind processes loaded with sediment can have tremendous cutting power, as is amply demonstrated by the gorges, ravines, and valleys around the world. In glacial areas, huge moving ice masses embedded with soil and rock fragments grind down rocks in their path and carry away large volumes of material.
However, such biotic influences are usually of little importance in producing parent material when compared to the drastic physical effects of water, ice, wind, and temperature change. For example, heating of rocks by sunlight or fires can cause expansion of their constituent minerals. As some minerals expand more than others, temperature changes set up differential stresses that eventually cause the rock to crack apart. This process may be sharply accelerated if ice forms in the surface cracks. 2, disintegrating huge rock masses and dislodging mineral grains from smaller fragments. The process of peeling off is also called exfoliation.
Intense localized heat can rapidly expand a boulder. The thermal heat from wildfire can cause significant weathering of rocks and boulders, heat can rapidly expand a boulder and thermal shock can occur. At some point, this stress can exceed the strength of the material, causing a crack to form. If nothing stops this crack from propagating through the material, it will result in the object’s structure to fail. Frost weathering: recent advances and future directions”.