One interesting form of natural phenomena is weathering. Weathering that occurs on the surface of the earth is identical to the process of formation of rocks and other landscapes. Weathering requires a very long time and is also influenced by various factors that occur around it.
Definition of Weathering
Weathering events are a process of destroying rock masses, whether they occur physically, chemically or biologically. Generally, rock weathering process requires a very long time.
The occurrence of each weathering process is also usually influenced by the weather. Weathering that occurs in rocks will change rocks that experience this weathering process turned into soil.
Factors Causing Weathering
Weathering that occurs in rocks is influenced by various factors. In general, there are four factors that influence rock weathering. Factors causing weathering include:
a. Rock Structure State
Rock structure is a physical and chemical characteristic that is already possessed by rocks. The physical properties of these rocks can be like the color of rocks, while the chemical properties of rocks such as chemical elements contained in these rocks.
These two properties can cause differences in rock resistance to weathering processes. There are rocks that are more weathered than other rocks because they have different physical and chemical properties.
Examples of weathered rocks for example, slab (sedimentary rocks). While examples of rocks that are difficult to weather are igneous rocks.
b. State of Topography
Topography is the condition of the earth’s surface. This topography also influences the weathering process of rocks. Rocks in steep slope areas tend to experience weathering, when compared to rocks in sloping areas.
On steep slopes, rocks can easily be eroded. These rocks will easily be weathered because they are directly in contact with the surrounding weather. However, on sloping or flat slopes, rocks tend to be covered by various deposits. This is what makes rocks in the sloping area experience slower weathering.
c. Weather and Climate
There are also elements of weather and climate that are very influential on the weathering process. Weather factors causing weathering include: air temperature, rainfall, sunlight, or wind. In areas with a humid and hot climate, the rocks will experience weathering more quickly compared to areas with cold climates.
In addition, if the weather changes frequently, such as the change in temperature between hot days and cold nights so felt, then this can further accelerate the weathering process.
d. Vegetation State
Vegetation or plants can be a factor in the weathering process. Plants have roots that can penetrate rock crevices. If the root is getting bigger, then the strength will also be greater so that it can break through the rocks and make the rocks become weathered.
In addition, litter of fallen leaves can also accelerate the weathering process of rocks. Rock litter contains carbonic acid and humus which can damage the rock’s strength.
Types of Weathering Types
Weathering can also be divided into several types. When viewed from the process, the weathering process can be grouped into three types, namely mechanical weathering, chemical weathering and organic weathering. Each has a different process and cause.
a. Mechanical weathering
Mechanical weathering is also referred to as physical weathering. This mechanical weathering is a process or event of the destruction and release of rock material, which occurs without changing the chemical structure of the rock. Mechanical weathering is the process of breaking down lumps of rock into much smaller pieces of rock.
There are several factors that can cause mechanical weathering. Factors causing mechanical weathering, namely:
a.1. Temperature difference . The difference in temperature can cause rocks to experience the process of expansion. This happens during hot weather. While rocks will experience shrinking at the same time when cold. If this process takes place continuously, then gradually the rock will peel, split, and break into small chunks.
a.2. Erosion. Due to erosion that occurs in mountainous areas, it can freeze water between the rocks. The freezing water between the rocks will increase in volume. Therefore, the water will be a suppressor that damages the surrounding rock structure. (Read full: Understanding and 10 kinds of erosion )
a.3. Influence of the activities of living things . The activity of living things such as animals and plants can cause rocks to experience weathering. For example, plant roots can damage rock structures, as can animals that always carry rock grains from the ground to the surface.
In addition, humans also participate in influencing the occurrence of mechanical (physical) weathering. Humans by using science and technology that are developed can easily destroy rocks even as large as ships until they are destroyed using dynamite.
a.4. The conversion of salt water into crystals. This usually occurs in groundwater that contains salt. Because, during the day the water will evaporate and the salt crystallizes. This salt crystal is very sharp so that it can damage the surrounding rock, especially the rocks in the coastal area.
b. Chemical weathering
Chemical weathering is the process of weathering rock masses accompanied by changes in the chemical composition of these weathered rocks. Chemical weathering can occur with the help of water and assisted with high temperatures. The process that occurs in chemical weathering is also called decomposition.
This chemical weathering process is known to have four processes. Four chemical weathering processes, including:
b.1. Hydration . Hydration is a process of rock formation that occurs by binding to rocks on its surface.
b.2. Hydrolysis . Hydrolysis is the process of decomposition of water (H 2 O) of its elements, so that it becomes positive and negative ions. The type of weathering process of hydrolysis is usually related to the formation of clay.
b.3. Oxidation . Oxidation is an iron rusting process. Rocks that undergo an oxidation process, generally have a brownish color because there is an iron content in the rock that has corrosion. The rusting process like this lasts very long, until the rocks experience weathering.
b.4. Carbonation . Carbonation is a rock weathering process that occurs due to carbon dioxide (CO 2 ). Carbon dioxide gas is contained in rainwater while it is still water vapor. Generally, the type of rock that is easily carbonated is the type of limestone.
The reaction that occurs between CO 2 and limestone causes the rocks to become damaged. Weathering is also influenced by the presence of water and high temperatures. Water that contains a lot of CO 2 (carbonic acid) can easily dissolve limestone (CaCO 2 ).
The carbonation event is also called the dissolution process. This dissolution can also cause karst symptoms. Chemical rock weathering process that occurs in karst areas is called kartification.
Natural symptoms or forms that occur in the karst region, for example are dolina (karst lake), caves and underground rivers, as well as stalactites and stalagmites.
c. Weathering (Biological)
Organic weathering is also referred to as biological weathering. This weathering is a process of rock weathering that occurs due to the influence of living things. Organic weathering can be chemical or mechanical. It’s just that the difference is the subject of the culprit, namely humans, animals, or plants.
Examples include weathering that occurs due to moss, fungi, or bacteria that damage rock surfaces.