Chapter - 6
Geometric Processes
️ Tectonic Forces :-
The surface of the earth is uneven. The internal forces of the earth are responsible behind this inequality . These forces move the lithospheric plates . Due to which various landforms are created on the surface and the surface of the earth becomes uneven. These forces are called tectonic forces .
As soon as the surface of the earth is uneven, the exogenous forces generated by the power of the sun try to level it by sabotaging and eroding it.
❇️ Geomorphological processes: -
This game of endogenic forces and exogenic forces means that the landforms on the earth are formed.
Both these processes are continuously active on the surface of the earth. These are called geomorphic processes . As a result of these processes on the ground, man gets his livelihood and diverse resource base.
All the landforms visible on the surface are made of two types of forces.
- Extrinsic force
- intrinsic force
Intrinsic forces keep lifting the surface and external forces keep leveling them continuously.
Note: - In this chapter we will specifically study the external processes like denudation, erosion, mass movement etc.
Cover: -
Due to various exogenous geomorphic processes like weathering, erosion, movement, erosion, transport etc., the upper cover of rocks on the surface is removed, this is called denudation.
️ Weathering :-
Weathering is the mechanical, chemical and biological process due to which rocks keep breaking and breaking down at the same place .
️ Understand weathering by the following processes :-
- exfoliation
- contraction and expansion
- Snow and frost wedding
Exfoliation :- In this process of weathering, the layers of rocks come off like onion peel. This happens in dome shaped landforms. The layer above them is removed due to erosion and flaky bands develop.
Shrink and Expansion: - The minerals present in the rocks expand due to increase in temperature and shrink due to decrease in temperature, due to this process the rocks weaken and break.
Freezing and Frost Wedding :- The water gets filled in the cracks of the rocks and due to the fall in temperature, the water gets converted into snow. The formation of ice increases the volume which exerts pressure on the rocks. Repetition of this process breaks the shale.
️ Types of Weathering :-
There are two types of weathering :-
- chemical weathering
- physical weathering
️ Chemical Weathering :-
Chemical weathering can be understood with the help of the following examples. By keeping a nugget of salt in a moist place, it melts and ends. If iron is kept in a humid place in the open, it gets rusted. And gradually it gets destroyed in the soil, melting of salt and rusting of iron are chemical reactions, this process happens with rocks, then it is called chemical weathering.
️ Types of Chemical Weathering :-
Chemical weathering can be of the following types :-
Solution: - Many types of minerals present in rocks dissolve such as nitrate, sulfate and potassium. In this way, in areas of high rainfall and in humid climate, rocks containing such minerals get weathered.
Carbonation : - Carbonic acid is formed from carbon dioxide dissolved in rain water, this acid dissolves limestone rocks.
Hydration :- Some rocks like calcium sulphate absorb water and spread and become weak and later break.
Oxidation & Reduction :- Rusting of iron is a good example of oxidation. This process occurs when rocks come in contact with oxygen gas. This process takes place due to the mixing of the atmosphere and oxygen-rich water.
️ Physical Weathering :-
Due to physical weathering, rocks break into small pieces, for which factors like gravitational force, change in temperature, change of dry and wet conditions are responsible .
️ Types of physical weathering :-
Physical weathering takes place in the following ways:-
- Unloading
- Change in Temperature
- Freezing and Frost Wending
- Salt Weathering
- Biological Weathering
️ Biological Weathering :-
Weathering and physical changes resulting from the growth or movement of organisms lead to the transfer of minerals and human activities also help in biological weathering. New surfaces are formed by burrowing by organisms like earthworms, termites, rats etc. The roots of plants exert a tremendous influence on the substances of the surface and break them mechanically and separate them.
️ Carbonation Process :-
It is a process in which the byproduct of the reaction of carbonates and bicarbonates with minerals is called carbonation. Carbon dioxide is absorbed from the atmosphere and soil by water. This forms carbonic acid, which dissolves as a less active acid and leaves no residue. As a result, underground caves are formed in selected stone areas.
️ Importance of weathering process :-
Rocks help in the formation of soil by breaking it into small pieces. Weathering helps in the concentration of valuable minerals like iron, manganese, copper etc. in rocks because, due to weathering, other substances are leached and they get transferred and minerals get collected in one place.
Mass circulation: -
If the debris of rocks move slowly or rapidly along the slope due to the force of gravity in small or large form, then it is called mass movement.
️ Factors working behind the activation of mass movement :-
Many factors work behind the activation of mass movement. Which are as follows:-
- Removal of the base of the material above by natural and artificial means.
- Increase in slope and height.
- Overload caused by natural or artificial filling of substances.
- Overload caused by excessive rainfall, saturation and lubrication of materials by slope.
- Removal of matter or weight on the surface of the original slope.
- earthquake,
- Explosion or vibration of machines.
- Indiscriminate cutting of natural vegetation.
️ Rapid circulation process :-
The rapid movement of waterlogged soil or silt on slopes without steep or fast vegetation in a humid climate is called rapid movement.
This process is of many ways :-
Soil-flow: - When the movement of saturated clay and silt down hill slopes is called soil flow. While making a ladder, when this substance slides down like a snake, then it is called opportunity.
Mud Flow :- Due to excessive amount of weathering, the material becomes mud due to heavy rain. And in the form of a river of mud, the slopes start flowing towards the valleys, this phenomenon proves to be very disastrous.
Avalanche : - This process takes place on steep slopes, due to which the debris (pieces of rocks) comes down at a faster rate than the mud flow.
️ Depositing :-
The deposition is the result of erosion, when the slope decreases, the deposition of the erosive material starts.
️ What is soil?
Soil is a set of natural elements on the surface, which have the capacity to nourish animals and plants.
Factors affecting soil formation :-
Climate :- Climate affects the weathering of parent rock. Excess rainfall increases the amount of humus in the soil. But due to heavy rains, the fertile elements of the soil are also damaged.
Basic material: The type of soil is the same as the weathering of rocks, for example, the soil of South India is black due to the base rocks there.
Relief :- The layer of soil is thin in the hilly parts while the thickness of the soil layer is more in the plains.
Biological Activities: - The presence of vegetation cover and micro-organisms makes the soil more fertile.
Time : The soil formed over a long period of time is more rich and fertile.
How does weathering affect soil formation?
The material obtained from the weathering of rocks serves as the basis for soil formation. In this there are rotten parts of trees, plants and animals. who are called yumas. In this mixture, essential gases for life and nutrients dissolved in water are also found in the stomata. In this way a good mix of soil gets prepared over a long period of time.
️ Soil forming active and passive factors :-
Active Factors
- Climate and biological activities are active components.
- These components keep changing action in the soil.
- These components continue to decompose and disintegrate.
- Soil formation by these components takes less time.
Passive Factors
- Basic matter, surface and time are inactive components.
- These components do not bring any change by themselves.
- These components do not perform any action.
- Soil formation by these components takes a lot of time.
️ Erosion :-
Erosion is the cutting of rocks by flowing water, ground water, glaciers, wind, waves and currents, eroding and carrying the debris obtained from one place to another.
️ Floor Balance :-
Nature has created high mountains and deep valleys somewhere on the surface. The reduction of this difference in relief through various factors of erosion is called floor balancing.
