Exogenic Forces: Classification

Exogenetic forces are those that operate from a location beyond the surface of the earth. Landforms (typically plains or minor landforms) were generated by forces from outside the earth that acted upon the surface of the earth and changed it.

What are Exogenic Forces?

The forces which get their strength from the earth’s exterior or originate within the earth’s atmosphere are described as exogenic forces or external forces.

The activity of exogenic forces results in wearing down and so they are known as land wearing forces.

External Processes, also Known as Denudation

Exogenic processes, also known as exogenic geomorphic processes, are those that take place on the surface of the earth as a result of the effect of factors that originate from beyond the planet.

The four most important exogenic processes are called weathering, mass wasting, erosion, and deposition.

Denudation, which literally means “to strip off” or “to uncover,” is the umbrella term that encompasses all of the exogenic processes.

The components of mother nature that are capable of causing these exogenic processes are referred to as geomorphic agents (or exogenic geomorphic agents). Such as the air, the sea, the waves, etc.

Weathering

The process of weathering refers to the action of the components of weather and climate on the material of the ground.

Rocks undergo both a mechanical and a chemical breakdown as a result of the combined effects of a variety of weather and climate conditions. This process is referred to as weathering.

The process of weathering rocks causes some minerals to be eliminated as a result of chemical or physical leaching by groundwater. As a result, the concentration of the minerals that are still present, which are precious, increases.

The process of weathering can be broken down into three categories: the physical, the chemical, and the biological.

Weathering is caused by physical and mechanical processes

The use of certain forces is required for several physical or mechanical weathering processes.

It’s possible that the applied forces include I gravitational forces including overburden pressure, load, and shearing stress; (ii) expansion force owing to temperature variations, crystal development, or animal activity; and (iii) water pressure controlled by wetting and drying cycles.

Causes: The majority of the deterioration that occurs due to weathering is brought on by thermal expansion and pressure.

Unloading and Expansion

The removal of an overlying rock load as a result of ongoing erosion provides relaxation of vertical pressure. This results in the formation of new space.

Therefore, the upper layers of the rock that is still there expand, which results in the dissolution of rock masses.

The direction that fractures grow is roughly parallel to the surface of the earth.

Arched cracks have a tendency to give rise to large sheets or exfoliated slabs in regions where the ground surfaces are curved.

The term “exfoliation” refers to a state rather than a process. The formation of smooth and rounded surfaces is accomplished by the flaking off of sheets of shells that are more or less curved from over rocks or bedrocks.

Therefore, unloading and expansion cause the formation of exfoliation domes, which are enormous, smooth, spherical mounds.

Changes in Temperature and Expansion 

Every mineral expands and pushes against its neighbor as the temperature rises, and as the temperature drops, a comparable contraction takes place in the mineral crystal structure.

The smooth, rounded surfaces of rocks are the consequence of differential heating, which causes the surface layers to expand and compress, followed by the layers’ exfoliation from the surface. This process occurs over time.

Because of this exfoliation process, rocks like granite can develop smooth-topped and rounded boulders of varying sizes that are referred to as tors.

Freezing, Thawing and Frost Weathering

Frost weathering is caused by repeated cycles of freezing and thawing, which occurs when the temperature rises above freezing and allows snow and ice to melt.

It is most effective at high elevations in the middle latitudes, where there is frequent cycling between freezing and melting of the snow.

The fast expansion and increased pressure of the water are caused by its rapid freezing. As a consequence of the expansion that takes place, joints, cracks, and even minor intergranular fractures grow progressively larger until the rock completely breaks apart.

Salt Weathering

The process by which salts in rocks expand as a result of heat action, hydration, and crystallization is known as salt weathering.

There are a variety of salts that have a tendency to expand, including calcium, sodium, magnesium, potassium, and barium.

The temperature, as well as the thermal characteristics both, have an effect on the expansion. This type of salt expansion is encouraged by the high temperatures that vary from 30 to 50 degrees Celsius at the surface of deserts.

The process of salt crystallization is the most efficient of all the ways that salt may be weathered. It thrives best in environments that have alternating periods of soaking and drying.

The process of chemical weathering

The processes of the solution, carbonation, hydration, and oxidation/reduction are all examples of chemical weathering.

Solution

The term “solution” refers to the state that results when something is dissolved in a liquid, such as water or an acid; the liquid or acid with the dissolved content.

The ability of a mineral to dissolve in water or mild acids is an important factor in this procedure, which requires the removal of particles that are already in solution.

Many substances are able to dissolve and become mixed together as a suspension in water upon coming into contact with water.

This process has an effect on soluble rock-forming minerals such as nitrates, sulfates, potassium, and other similar elements.

The most common conditions for this type of weathering are wet ones.

Limestone contains a variety of minerals, some of which are soluble in water containing carbonic acid (which is produced when carbon dioxide is added to water). These minerals, such as calcium carbonate and magnesium bicarbonate, are transported away in the water as a solution.

The mineral sodium chloride, which is more commonly known as table salt, is also capable of producing rocks and can be dissolved by this mechanism.

Carbonation

Carbonation is the reaction of carbonate and bicarbonate with minerals. It is a frequent process that helps break down feldspar and carbonate minerals. Carbonation is the reaction of carbonate and bicarbonate with minerals.

The absorption of carbon dioxide from the atmosphere and the air in the soil by water results in the formation of carbonic acid, which is a weak acid.

The creation of caves is the consequence of calcium carbonates and magnesium carbonates being dissolved in carbonic acid and then removed from the solution without leaving any trace behind.

Hydration

Hydration refers to the process of adding water to a chemical reaction.

Minerals are capable of absorbing water and expanding as a result; this expansion results in a rise in the volume of the substance or rock itself.

The process can be reversed, but it takes a long time. Repeating this process over and over again generates fatigue in the rocks, which can eventually lead to their collapse.

When calcium sulfate comes into contact with water, it transforms into gypsum, which is an unstable compound compared to calcium sulfate.

Conclusion 

Exogenic processes are those that take place on the earth as a result of factors that originate from beyond the planet. Exogenic processes include weathering, mass wasting, erosion, and deposition. The activity of exogenic forces results in wearing down and so they are known as land wearing forces. Arched cracks have a tendency to give rise to large sheets or exfoliated slabs in regions where the ground surfaces are curved. Frost weathering is caused by repeated cycles of freezing and thawing, which occurs when the temperature rises above freezing and allows snow and ice to melt.

Minerals are capable of absorbing water and expanding as a result. This expansion results in a rise in the volume of the substance or rock itself. Carbonation is the reaction of carbonate and bicarbonate with minerals. Hydration is the process of adding water to a chemical reaction.