What is weathering?
weathering is a slow continuous process that breakdown the rock, minerals, and artificial structure into smaller particle. these broken-down particles can be rocks, soil, stone, etc. the weathering can happen in two ways: mechanical or physical disintegration of rocks and chemical decomposition of rocks. sometimes biological factors involved in the process of weathering.
Don’t confuse between weathering and erosion, erosion is a separate process involving the transport of weathered rock.
Types of weathering
the physical, chemical, and biological are the three major types of weathering.
1. physical weathering
In physical weathering, rocks breakdown into smaller fragments by entirely physical or mechanical ways. for example, friction between rocks and water or air continuously breakdown the surface of rocks.
now, let’s discuss which physical factors are involved in physical weathering.
when water strikes on the rock, it continuously removes the small particles from the rocks.
at some high latitude area, water goes into the pores of rocks. when temperature decreases, water becomes solid and occupies more space due to the volume increase. As a result, cracks appear in the rocks and the rocks break down into small parts. this process called freezing and thawing. this type of weathering mostly occurs at high in the mountains where the temperature fluctuates around 0 degrees C.
the wind is a weak force compared to water flow, so, wind can’t breakdown the rock directly. but dust particles present in the air are helpful to wind weathering.
When the wind blows rapidly, it takes the dust with it and forms a sandstorm. the friction between sandstorm and rock, breakdown the structure of the rock. As a result, dust removes the particles one by one from the rock. wind weathering mostly occurs in the desert where often sandstorm form.
Thermal or temperature weathering
The rocks expand when the temperature rises and the rocks contract when the temperature drops. As a result of the expansion and contraction, cracks appear in the rocks. These cracks fragment the rock into two or more parts.
the thermal weathering mostly occurs at the tropic of cancer and the tropic of Capricorn.
the rocks are slightly elastic. The deeply buried rocks are overlayed by a layer of sediment. When the sediment layer is removed by erosion, the pressure is removed from the rocks. in consequence, the rock responds to this pressure reduction by expanding. As a result, cracks appear in the rock and rocks breakdown into smaller rocks. this process of weathering called a pressure releasing or unloading.
2. Chemical weathering
In chemical weathering, decomposition or decay in rocks begin as a result of chemical changes in rocks. the precipitation increases the process of chemical weathering. let’s see some types of chemical weathering.
solution by water
when water contact in rock, water solvable substance dissolved in the water. As a result, the rock gets weak and breakdown into smaller rocks.
oxidation and reduction
oxidation is a chemical process by which oxygen combines with the compound present in the rocks. this process form oxides. due to oxidation the rock becomes weaker and easily weathered by water and air. for example, rusting of iron.
the reduction is the reverse process of oxidation where oxygen is removed from the compound present in the rock.
hydration is a process where minerals combine with water and expand. this expansion increases the size of the rock and it is easily decomposed.
carbonation is the reaction of carbonate and bicarbonate ions with minerals.
when carbon dioxide dissolved in the water, it forms carbonic acid. when carbonic acid reacts with water, it decomposes the minerals. this type of weathering important for the formation of sinkholes and caves.
hydrolysis is a process, in which mineral combines with water and make less stable minerals. the most common example of hydrolysis is clay that is formed by hydrolysis of feldspar.
3. Biological weathering
in biological weathering, living organisms and their action cause the breakdown of rock. plants, bacteria, and animals contribute the biological weathering.
for example, lichen is a fungus and algae that breakdown the rocks by releasing chemicals. The Burrowing animals help biological weathering by breaking the rock.
the physical, chemical and biological weathering interact with each other. For example, physical weathering breakdown the rock into smaller rocks and provide a better surface area to fasten the chemical weathering.