What is physical weathering ?
The physical or mechanical weathering breaks rocks without altering its composition and chemical weathering decomposes slowly altering rocks minerals within them. Both processes develop together and produce wastes that are transported mechanically or in solution (erosion). Weathering processes also help soil formation.
Physical weathering results, first of all, from changes in temperature, such as intense heat or the action of water when frozen in the cracks of rocks. Changes in temperature expand and contract the rocks alternately, causing granulation, flaking, and lamination of the outer layers. The action of ice and spreading expose deeper layers to chemical weathering.
Mechanical or physical weathering. (Change of rocks by mechanical processes that accelerate chemical processes).
- Thermal weathering, produced by sudden changes in temperature.
- Gelifracción (cryoclastism), produced by the increase of the volume of the frozen water in cracks and fissures of the rocks.
- Saline weathering, produced by the desquamation of the rocks by increasing the volume due to the crystallization of the dissolved salt.
- Organic weathering, product of the growth of the plants in the cracks and fissures of the rocks.
What is chemical weathering ?
chemical weathering alters the original mineral composition of the rock in different ways: dissolving minerals in contact with water; Weakening soil acids by oxidation; Producing a chemical reaction with carbon dioxide (carbonation); And by hydrolysis, a process by which water combines and reacts chemically with the minerals. Plants, like lichens, also break down certain rocks by extracting soluble nutrients and iron from their original minerals.
Chemical weathering. (Change of rocks by solvent action of water that can be accelerated by mechanical weathering).
- By dissolution, product of the action of water: solvent, catalyst, dolomitization and cementation.
- Hydrolytic, produced by the destruction of the silicates of the clays as their molecular structure weakens.
- By oxidation, produced by the atmospheric oxygen contained in the water acting on the upper layer of the earth.
- Hydration, produced as a consequence of the increase of volume of the water of crystallization.
- Chemical – biological, produced by the action of the acids that form the organisms when decomposed.
Both in the physical, chemical and biological weathering, the climate is considered as variable factors, whose elements that make up are determinant and have a decisive influence in these processes as they are:
- The winds.
- Solar radiation
The main difference between physical and chemical weathering .
Differentiation and complementarity between physical, chemical and biological weathering.
The weathering not only affects the surface but also to a certain depth, where most of the processes of weathering by oxidation and hydration occur.
Although physical and chemical weathering act separately, both processes combine to carry out weathering of terrestrial materials.
In physical or mechanical weathering whose degradation process consists in the gradual fragmentation of the material into small particles without experiencing the chemical alteration, it can occur by: breakage or degradation, by granular disintegration.
The chemical weathering, although slower than the physical one, is of great importance as far as the alteration of the material for its transformations and modifications that the mineral components undergo.
Physical weathering breakdown rock into smaller pieces with no changes while chemical weathering breakdown rocks into new material with the use of weak acid and reaction to air .