Exogenic Processes - Geomorphic Processes - Geography Notes
Exogenic processes refer to external processes that occur on the Earth's surface primarily due to the Sun's energy, leading to weathering, erosion, and deposition. While endogenic processes emerge from internal Earth dynamics like tectonic movements, exogenic ones are driven by external atmospheric conditions. The two major climatic components that influence diverse exogenic processes are precipitation and temperature. Denudation, which literally means "to uncover," is a term that encompasses all exogenic geomorphic processes. This article will explain the concepts of exogenic processes which is an integral part of the geography syllabus. The exogenic process is an important concept for the UPSC exam.
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What is an Exogenic Process?
- The processes which occur on the earth’s surface due to the influence of exogenic forces are known as exogenic processes.
- It occurs at or near the earth's surface that makes the surface wear away.
- Exogenic processes are destructive in nature and are responsible for the degradation and sculpting of the earth's surface.
- Exogenic processes take their energy from the atmosphere, which is determined by the sun's ultimate energy as well as gradients caused by tectonic causes.
- Because the earth's surface has varied climatic zones, the exogenic geomorphic processes differ from one another.
- Temperature and precipitation are two essential climatic elements that influence a variety of processes.
- Denudation is a broad term that encompasses all exogenic geomorphic processes. The word 'denude' means to remove or reveal.
- Denudation includes weathering, mass wasting/movements, erosion, and transportation.
| Other Relevant Links | |
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| Denudational Processes | Chemical Weathering |
| Physical Weathering | Biological Weathering |
| Mass Movements | Soil Formation Processes |
Types of Exogenic Processes
Weathering
- It can occur physically by disintegrating the rocks physically due to factors like pressure release, abrasion, animals, growth of plants as well as chemically through chemical changes such as water, carbon dioxide, living organisms, and acid rain breaking them eventually.
- As very little or no motion of materials takes place in weathering, it is an in-situ or on-site process.
- The weathered material is carried farther away by erosion.
- Weathering is further classified into:
- Physical weathering - Mechanical disintegration of rocks occurs as a result of temperature variations, freeze-thaw cycles, wet-dry cycles, salt crystallization, animal and plant activities, and other factors.
- Chemical weathering - Chemical weathering is the process of rocks and soil decomposing chemically.
- Biological weathering - Biological weathering is caused by a variety of biological processes such as organism development and movement. They also bring with them the possibility of physical or chemical deterioration.
Erosion
- The earthen materials are carried away by natural forces such as wind, water, ice, and gravity.
- Erosion begins with the process called weathering.
- Flowing surface water Erosion - The terrain formed by the surface flow is called river terrain.
- Wind Erosion - These terrains are formed in dry and semi-arid areas where the effects of wind dominate. These terrains are called aeolian.
- Glacier Erosion - These terrains were carved by alpine glaciers.
- Wave Erosion - They are formed by the action of waves at the edges of the continent.
- Karst Erosion - These terrains are formed by the action of groundwater in karst or limestone areas.
Sedimentation
- It is a natural process where sediments are deposited at the bottom and undergo changes and form into solid structures.
- Sediments are particles that have been broken down.
- The size of the sediments is categorized, ranging from silts and muds to gravels and boulders.
- The main factors that control the breakdown of rocks into sediments are:
- Climate
- Topography
- Vegetation
- Properties (physical and chemical) of the rock
Mass Movements
- The slow and fast mass movements, also known as slope movement or mass wasting, affect the shallow to deep columns of material and works creep, flow, slide, and fall.
- The bedrock, as well as the results of weathering, are subjected to gravitational attraction. Weathering isn't a prerequisite for mass movement, but it certainly helps.
- Erosion does not apply to mass wasting because it is led solely by gravity and has no impact from geomorphic agents such as waves, currents, glaciers, water, or wind.
- Over steepened slopes, water, earthquake, and vegetation removal are the factors that trigger it.
- Mass Movements can be classified into:
- Slow movements - Such as solifluction, creep
- Fast movements - Such as earthflow, mudflow, avalanches
Conclusion
The formation and deformation of landforms on the earth's surface is a constant process that is influenced by both external and internal forces. Exogenic geomorphic movements, or simply exogenic movements, such as weathering and erosion, are the result of exogenic geomorphic processes. The effects of most exogenic geomorphic processes are minor and sluggish, but they will have a significant long-term impact on the rocks due to ongoing exhaustion.
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| Geography Notes | Physical Geography |
| Geomorphic Processes | Geomorphology |
| Endogenic Processes | Minerals and Rocks |
FAQs
Question: What are exogenic processes in geography?
Answer: Exogenic processes refer to the external forces that shape the Earth’s surface, primarily through weathering, erosion, transportation, and deposition. These processes are driven by forces such as wind, water, ice, and gravity, and they work to break down rocks, transport sediment, and alter landforms.
Question: How does weathering differ from erosion in exogenic processes?
Answer: Weathering refers to the breakdown of rocks into smaller particles through mechanical, chemical, or biological processes without the transportation of these particles. Erosion, on the other hand, involves the removal and transportation of rock particles by agents such as wind, water, and ice.
Question: What role does water play in exogenic processes?
Answer: Water plays a crucial role in exogenic processes through weathering, erosion, and deposition. It acts as a powerful agent in the breakdown of rocks (through processes like freeze-thaw weathering and chemical weathering), transports sediments in rivers and streams, and deposits these materials to form new landforms such as deltas and alluvial plains.
Question: What are the key agents involved in exogenic processes?
Answer: The key agents involved in exogenic processes include wind, water, ice, and gravity. These agents contribute to the weathering, erosion, transportation, and deposition of materials, which continuously shape and modify the Earth's surface.
Question: How do exogenic processes contribute to landform development?
Answer: Exogenic processes play a vital role in landform development by breaking down rocks, transporting sediments, and depositing them in new locations. For example, rivers erode valleys, glaciers carve out U-shaped valleys, and wind forms dunes in desert regions. These processes are essential for the creation of diverse landforms across the Earth.
MCQs
1. Which of the following is NOT an agent of exogenic processes?
A) Wind
B) Water
C) Ice
D) Tectonic activity
Answer: D See the Explanation
Explanation: Tectonic activity is an endogenic process that originates from forces within the Earth, while exogenic processes are driven by external forces like wind, water, ice, and gravity.
2. Which of the following processes involves the transportation of weathered material?
A) Weathering
B) Erosion
C) Deposition
D) Tectonic uplift
Answer: B See the Explanation
Explanation: Erosion involves the transportation of weathered material by agents like water, wind, or ice. Weathering refers to the breakdown of rocks, and deposition is the laying down of sediments.
3. Which landform is commonly formed by the deposition of river sediments?
A) Delta
B) Moraine
C) Cirque
D) Plateau
Answer: A See the Explanation
Explanation: A delta is a landform formed by the deposition of sediments carried by a river as the flow velocity decreases, usually where the river enters a standing body of water like a sea or lake.
4. Freeze-thaw weathering is an example of which type of process?
A) Chemical weathering
B) Biological weathering
C) Physical weathering
D) Erosion
Answer: C See the Explanation
Explanation: Freeze-thaw weathering is a type of physical weathering where water enters cracks in rocks, freezes, and expands, causing the rock to break apart.
5. Which of the following is a result of wind erosion?
A) Alluvial plain
B) Desert dune
C) Glacial moraine
D) Delta
Answer: B See the Explanation
Explanation: Desert dunes are formed by the deposition of sand particles transported by wind, making them a typical feature of wind erosion.
GS Mains Questions and Answers
Q1: Discuss the various exogenic processes and their role in shaping the Earth’s surface.
Answer: Exogenic processes refer to the external forces that shape the Earth's surface through weathering, erosion, transportation, and deposition. These processes are driven by agents such as wind, water, ice, and gravity. Weathering breaks down rocks into smaller particles through physical, chemical, or biological means, while erosion transports these materials from one location to another. Transportation occurs through rivers, glaciers, wind, and ocean currents, and deposition occurs when the transported material settles in a new location, creating landforms such as deltas, dunes, and floodplains.
These processes continuously shape and reshape the Earth's surface by breaking down landforms and creating new ones. For example, river erosion carves valleys and transports sediments, while glacial erosion creates U-shaped valleys and moraines. Wind erosion forms features like dunes, and gravity contributes to processes like landslides. Overall, exogenic processes play a critical role in the dynamic development of the Earth’s surface.
Q2: Analyze the impact of water as an agent of exogenic processes in landform development.
Answer: Water is one of the most powerful agents of exogenic processes and plays a key role in the development of various landforms. Through processes like weathering, erosion, and deposition, water shapes the Earth's surface in significant ways. Rivers erode valleys, transport sediments, and deposit them in low-lying areas to form features like floodplains and deltas. Coastal processes, driven by wave action, lead to the formation of cliffs, beaches, and sandbars.
In addition to surface water, groundwater contributes to the formation of karst landscapes through the dissolution of soluble rocks such as limestone. Water also acts as a catalyst in chemical weathering, breaking down minerals and altering the composition of rocks. Overall, water plays a vital role in shaping landscapes and creating diverse landforms across the Earth.
Q3: Evaluate the role of glaciers as agents of erosion and deposition in exogenic processes.
Answer: Glaciers are powerful agents of erosion and deposition in exogenic processes. As they move, glaciers erode the land beneath them through abrasion and plucking, creating U-shaped valleys, fjords, and cirques. The immense weight of glaciers allows them to carve out deep valleys and transport large amounts of rock and debris over long distances.
When glaciers melt, they deposit the materials they have transported, forming features like moraines, drumlins, and outwash plains. Glacial deposits contribute to the formation of fertile soils in many regions. The impact of glaciers as agents of erosion and deposition is particularly evident in high-altitude and polar regions, where glaciers have shaped dramatic landscapes. The movement and deposition of glaciers are significant contributors to the ongoing reshaping of the Earth's surface.
Previous Year Questions on Exogenic Processes
1. UPSC CSE Prelims 2019:
Question: Which of the following landforms is a result of river deposition?
A) Cirque
B) Delta
C) Arête
D) Fjord
Answer: B
Explanation: A delta is a landform created by the deposition of sediments carried by a river as it slows down upon entering a standing body of water such as an ocean or lake. It is a typical feature of river deposition.
2. UPSC CSE Mains 2020 (GS Paper 1):
Question: "Exogenic processes play a key role in the continuous reshaping of the Earth ’s surface." Discuss with examples of landforms created by these processes.
Answer: Exogenic processes, driven by external forces such as wind, water, ice, and gravity, are fundamental in the continuous reshaping of the Earth’s surface. Weathering breaks down rocks into smaller particles, while erosion transports these materials through rivers, glaciers, and wind. Landforms created by exogenic processes include river valleys, deltas, floodplains, sand dunes, and glacial moraines. For example, rivers erode valleys and deposit sediments to form deltas, while glaciers create U-shaped valleys and leave behind moraines as they melt.
These processes are responsible for the dynamic and ever-changing nature of the Earth's surface, as they break down existing landforms and create new ones. Understanding exogenic processes is essential to studying geography and the evolution of landscapes.
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