EXOGENETIC FORCE

The exogenetic force or process is also called a Denudational Process. These forces are also called destructive forces as these are engaged in removing surface irregularities in highlands and lowlands produced by endogenetic forms. This is also called the process of gradation. This process by removing highlands and depositing sediments in low lands removes altitude and slope and brings equilibrium to the surface. on the direction of processes, it is broadly classified into two categories:

(a) Processes of Denudation/ Degradation
(b) Aggregation
(a) Process of Denudation- This process transforms highlands into lowlands over some time. Processes of weathering, erosion, and transportation are included in the process of degradation.

Weathering-In situ/ no perceptible movements or decomposition of rocks which transform hard and massive rocks into finer/smaller rock fragments and parts is known as weathering. based on the dominance of processes weathering it is broadly classified into two categories.

PHYSICAL WEATHERING

It is dominant in cold and dry regions. Chemical weathering is dominant in humid regions. A temperate humid climate dominates with the most intense chemical weathering, as water is retained in rocks for a longer period of duration due to low evaporation. Weathering is faster as sedimentary rocks are soft and absorb and retain water compared to igneous rocks which are hard and non-porous.

Physical Weathering– Physical atmospheric processes combined with gravity are involved in the disintegration of rocks. This is the process involved in physical weathering.

Thermal heating and cooling of rocks– It is a periodic phenomenon during daytime and summer seasons heating of the outer layers of rocks is faster compared to the inner layer of rocks. Thus rate of expansion of the outer layer/surface layer is faster compared to the inner layer.

During the height time of the winter season rate of cooling and contraction between the outer and inner developmental of a lateral space and rocks are removed by the outer layer. This process is called onion peeling or exfoliation. This process produces a landform known as Tor which is a spherical rock outcrop on the surface.

Freeze-Thaw– It is prominent in high latitudes and altitudes where seasonal thermal/ contracting is high during the winter season as the temperature is extremely low. Water is transformed into ice in the joints, fractures and fractures and cracks of the rocks as water is transformed into ice, there is an increase in the volume of rocks. This increase in the rocks. this periodic change is responsible for the splitting of rocks and rock fragments.

Deloading of the process– As the weathering of rocks occurs rocks are removed from the inner layers and there is subsequent expansion. This expansion in inner layers of decoding of rocks or pressure is responsible for the disintegration of rocks.

Biological– As plants evolve and develop on the rocks, rocks disintegrate on the influence of these two combined processes: (a) There is the growth of roots of the plants which puts pressure on the rocks. (b) As plants grow their weight on the rocks increases which further causes disintegration.

CHEMICAL WEATHERING

The presence of water is responsible for the decomposing of rocks. Chemical weathering is classified into the following categories: Carbonation, Oxidation, Hydration, Dehydration, and Humification.

Carbonation– This decomposition is associated with the presence of carbonic acid in the rain because of the presence of acid in the rain. This acidic nature of the rain is the most prominent factor for the weathering of rocks made up of limestone. In the presence of carbonic acid cracks, fracture joints are large due to the process of dissolution.

Oxidation– This process is prominent in rocks containing iron, iron is present in water and is oxidized to form ferric acid which is the rusting of rocks and their decomposition.

Hydration and Dehydration of rocks– It is a combination of physical as well as chemical composition processes that occurs in porous rocks. During the process of hydration, there is expansion in the rocks as well as in the presence of water. Ions are formed in the presence of chemical reactions and related decomposing is enhanced. This process is prominent in the rocks containing carbonate iron, and aluminum during the dehydration of rocks as water evaporates there is a contraction of rocks.

Humification– as the biomass of dead plants and animals is bio-decomposed to formed humus and acid is formed which is called Humic acid. This humic acid is responsible for the decomposition of rocks.

EROSION

It is the process that is carried by mechanical agents that flow on the surface of the earth under the influence of gravity and kinetic energy. Based on mechanical force erosion is classified into the following categories:
Fluvial erosion– It is carried by rivers and streams that flow from highlands to lowlands under the influence of gravity. These are the processes involved in fluvial erosion: corrasion, corrosion, attrition, and hydraulic action.

Aeolian Erosion– It is prominent in arid and semi-arid regions where actions are dominant over barren land surfaces. Deflection, corrosion, or abrasion are the most important factors.

Glacial Erosion– It is dominant in highlands which are above snowlines and prominently covered with glaciers and ice caps. These are two erosional forms in glaciated regions.

Oceanic waves/currents– Their actions are similar to fluvial action, as these are also related to the flow of water.

TRANSPORTATION
Mechanical agents have kinetic energy which is determined by their mass and flow. This kinetic energy is the source of the downward flow of sediments from the highlands to the lowlands.

DEPOSITION
It is the process of deposition of sediments on lowlands like river valleys, plains, and coasts. Deposition starts kinetic energy of mechanical agents declines below sediments present in their flow.

DENUDATION
Denudation or aggradation combine to produce landforms of gradation. This process of highlands changing into lowlands and lowlands into highlands through denudation and deposition is known as Relief.