Geomorphic Processes| Class 11 Geography Notes

The geomorphic process means bringing about changes in the configuration of the Earth’s surface. It happens due to the physical stresses and chemical actions on materials present on Earth. The physical and chemical actions happen due to different endogenic and exogenic forces.

In this article, we are going to discuss Geomorphic Processes in detail.

Geomorphic Processes| Class 11 Geography Notes

Geomorphic Processes

Geomorphic processes are the result of factors such as internal (endogenic) and external (exogenic) forces acting on the Earth’s surface, causing physical and chemical changes.

Here are some major facts about the Geomorphic Process as mentioned below.

• Geomorphic agents like wind, water, and ice move Earth’s materials because of slopes or pressure differences.
• Gradients are slopes from high to low areas or pressure variations that drive these movements.
• Gravity is a crucial force in these processes, as it moves surface materials.
• Without gravity and gradients, there would be no movement, which means no erosion, transportation, or deposition.

What are Geomorphic Agents?

Geomorphic agents are natural forces that shape the Earth’s surface through processes like erosion, transportation, and deposition. They create various landforms and continuously alter the Earth’s topography.

Examples of geomorphic agents include running water, groundwater, glaciers, wind, waves, and currents. Each agent operates uniquely, influenced by factors such as climate, terrain, geology, and vegetation.

Diastrophism

Diastrophism encompasses various geological processes that involve the movement, elevation, or alteration of portions of the Earth’s crust. These processes include:

1. Orogenic processes, which lead to mountain building through intense folding along elongated belts of the Earth’s crust.
2. Epeirogenic processes, which result in the uplift or warping of large regions of the Earth’s crust.
3. Earthquakes, which involve localized and relatively minor movements of the Earth’s crust.
4. Plate tectonics, which entail horizontal movements of crustal plates.

During orogeny, the crust undergoes significant deformation, often forming folds. In contrast, epeirogeny may involve simpler deformations without the intense folding seen in orogeny. Orogeny primarily contributes to mountain building, while epeirogeny is associated with the formation or alteration of continents.

These processes, including orogeny, epeirogeny, earthquakes, and plate tectonics, can lead to faulting and fracturing of the Earth’s crust. As a result of these movements, changes in pressure, volume, and temperature occur, inducing metamorphism in rocks.

Volcanism

Volcanism includes the movement of molten rock (magma) onto or toward the earth’s surface and also formation of many intrusive and extrusive volcanic forms.

Exogenic Forces and its Classification

Exogenic processes happen on the Earth’s surface and often smooth out the land. They involve weathering, erosion, transportation, and deposition of soil and rocks. Water, ice, and wind are the main forces behind these processes.

Process	Definition
Weathering	Weathering is the process of breaking down and wearing away rocks on the Earth’s surface due to weather conditions like rain, temperature changes, and frost.
Erosion	Erosion is the removal and displacement of soil and rock from the Earth’s surface by agents like wind and water.
Transportation	Transportation involves the movement of eroded material to different locations. Deposition, on the other hand, is the process of adding these materials to landforms.
Deposition	Deposition occurs when the energy of erosional agents decreases, causing them to drop the materials they carry. This leads to the accumulation of sediments.

Weathering

Weathering refers to the breakdown and alteration of earth materials by the elements of weather and climate. It encompasses various processes that act individually or in combination to transform earth materials into fragmented states. Weathering occurs in-situ, meaning it takes place on-site with minimal or no material movement.

Different Weathering Processes

1. Chemical Weathering Processes: Chemical weathering involves processes such as solution, carbonation, hydration, oxidation, and reduction. These processes decompose, dissolve, or reduce rocks through chemical reactions facilitated by oxygen, water, and other acids. Presence of water, air, and heat accelerates these reactions.
2. Physical Weathering Processes: Physical or mechanical weathering depends on applied forces such as gravitational forces, expansion forces due to temperature changes or crystal growth, and water pressures from wetting and drying cycles. These forces cause rock fracture, with thermal expansion and pressure release being common causes. Despite being slow, these processes can cause significant damage to rocks over time.
3. Biological Activity and Weathering: Biological weathering involves the contribution or removal of minerals and ions by organisms, as well as physical changes due to organism growth or movement. Activities such as burrowing and wedging by organisms, human disturbance of vegetation, and decay of plant and animal matter contribute to weathering. Plant roots also exert pressure on earth materials, mechanically breaking them apart.

Special Effects of Weathering

• Exfoliation: Exfoliation refers to the flaking off of curved sheets of rock from the surface due to processes like unloading, thermal contraction and expansion, and salt weathering. Exfoliation can result in smooth and rounded surfaces, with features like exfoliation domes and tors forming due to specific weathering mechanisms.

Significance of Weathering

• Weathering processes are crucial for breaking down rocks into smaller fragments, leading to the formation of regolith, soils, erosion, and mass movements. The depth of weathering mantles influences biomes and biodiversity, as forests depend on weathering for their development.
• Erosion and changes in landforms are outcomes of weathering, with weathering contributing to the enrichment and concentration of valuable ore deposits. Weathering also plays a vital role in soil formation and is essential for the national economy.

Mass Movements

Mass movements involve the transfer of rock debris down slopes solely under the influence of gravity. Unlike other geomorphic agents like air, water, or ice, which transport debris, in mass movements, the debris itself carries air, water, or ice. These movements can vary from slow to rapid and affect shallow to deep columns of materials. Types of mass movements include creep, flow, slide, and fall. While gravity acts on all matter, weathering is not a prerequisite for mass movement but aids in the process.

Characteristics of Mass Movements

Mass movements are solely aided by gravity, and other geomorphic agents like water, glaciers, wind, or waves do not participate in the process. Mass movements do not fall under erosion, although there is a shift of materials from one place to another facilitated by gravity. The resistance of materials on slopes determines their susceptibility to mass movements, with weak, unconsolidated materials and steep slopes favoring such movements.

Causes and Activating Factors

Several activating causes precede mass movements, including the removal of support from below, increase in slope gradient, overloading, heavy rainfall, earthquakes, excessive seepage, and removal of natural vegetation. These factors can destabilize slopes and lead to mass movements.

Types of Mass Movements

1. Heave: Heaving up of soils due to frost growth and other causes.
2. Flow: Relatively rapid and perceptible movements involving relatively dry materials.
3. Slide: Slipping of rock debris with backward rotation, rapid rolling or sliding of earth debris, free fall of earth debris from vertical faces, sliding of individual rock masses down bedding, joint, or fault surfaces.

Characteristics of Landslides

Landslides are a type of mass movement characterized by rapid movement of relatively dry materials. Different types of landslides include slump, debris slide, debris fall, rockslide, and rock fall. These movements vary in their mechanisms and can occur along discontinuities like bedding planes or faults. Landslide scars over steep slopes are evidence of these dynamic processes.

Erosion and Deposition

Erosion involves the acquisition and transportation of rock debris by various geomorphic agents such as running water, groundwater, glaciers, wind, and waves. These agents remove and transport rock fragments depending on their dynamics. Abrasion caused by rock debris carried by these agents further aids erosion. Erosion leads to the degradation of relief, wearing down the landscape. While weathering assists erosion, it is not a prerequisite for erosion to occur. Weathering, mass wasting, and erosion are degradational processes, with erosion primarily responsible for the continuous changes in the Earth’s surface.

Controlled by Kinetic Energy

Denudational processes like erosion and transportation are controlled by kinetic energy, as depicted in Figure 6.1. Wind, running water, glaciers, waves, and groundwater contribute to the erosion and transportation of earth materials. Among these, wind, running water, and glaciers are influenced by climatic conditions, representing gaseous, liquid, and solid states of matter, respectively.

Comparison of Climatically Controlled Agents

Wind, running water, and glaciers are influenced by climate conditions. Each agent operates differently based on the prevailing climatic factors. However, the work of waves and groundwater is not directly controlled by climate. Waves’ actions are determined by the coastal region’s location along the litho-hydrosphere interface, while groundwater’s activity depends more on the lithological characteristics of the region.

Deposition

Deposition is a consequence of erosion, occurring when erosional agents lose velocity and energy on gentler slopes, causing the carried materials to settle. Deposition fills depressions, with coarser materials deposited first followed by finer ones. The same agents responsible for erosion, such as running water, glaciers, wind, waves, and groundwater, also act as aggradational or depositional agents.

Soil Formation

Soil formation is influenced by five primary factors: parent material, topography, climate, biological activity, and time. These factors interact with each other to shape the process of soil formation.

Parent Material

The parent material serves as a passive control factor in soil formation, comprising in-situ weathered rock debris (residual soils) or transported deposits (transported soils). Soil formation depends on the texture, structure, mineral composition, and chemical makeup of the parent material. The rate and nature of weathering, as well as the depth of the weathering mantle, are crucial considerations.

Topography

Topography, similar to parent materials, acts as another passive control factor. It influences soil formation through factors like sunlight exposure and drainage patterns. Soil thickness varies based on slope steepness, with thin soils on steep slopes and thicker soils on flat upland areas.

Climate

Climate is a significant active factor in soil formation, influencing soil development through elements like moisture and temperature. Moisture affects chemical and biological activities, while temperature influences chemical reactions and biological processes. Precipitation, temperature variations, and humidity levels play crucial roles in soil formation.

Biological Activity

Biological activity, including vegetation cover and soil organisms, contributes to soil formation by adding organic matter, aiding in moisture retention, and facilitating nitrogen fixation. Bacteria, plants, and soil organisms play vital roles in decomposing organic matter, enhancing soil fertility, and altering soil texture and chemistry.

Time

Time is the third important factor controlling soil formation. The duration of soil-forming processes determines the maturation of soils and the development of soil profiles. Soils become mature through prolonged exposure to soil-forming processes, resulting in well-developed soil horizons. The length of time required for soil development varies, with recently deposited materials considered young soils.

Overall, soil formation is a dynamic process influenced by the interaction of these factors, leading to the creation of diverse soil types and profiles.

Types of Geomorphic Process And Differences

There are two major types of the Geomorphic Process including Endogenic Process and Exogenic Process. Lets discuss in details.

Aspect	Endogenic Process	Exogenic Process
Energy Source	Energy from within the Earth’s interior.	Energy from the atmosphere.
Geological Effects	Causes deformation of the Earth’s crust and volcanic activity.	Various effects influenced by climatic conditions and geographical factors.
Uniformity	The effects are not uniform. They are influenced by changes in geothermal gradients, crustal thickness, and strength.	Processes vary depending on climate and geographical features.
Denudation	Although not a direct aspect, endogenic processes contribute to long-term landform creation.	Denudation, including weathering, mass wasting, erosion, and transportation, shapes landforms.

Significance of Geomorphic Processes

Here is the Significance of Geomorphic Processes as mentioned below.

• Geomorphic processes shape Earth’s surface, forming features like mountains, valleys, plains, and plateaus.
• Natural resources such as soil, minerals, and groundwater are influenced by geomorphic activities. Sediment deposition in river valleys and floodplains enriches soil, benefiting agriculture.
• Understanding geomorphic processes aids in forecasting and minimizing the impact of natural disasters.
• Geomorphic processes provide clues about past climates, helping researchers understand environmental conditions over time.
• Knowledge of geomorphic processes guides the construction of infrastructure like roads and bridges, ensuring their resilience and safety.
• Geomorphic activities influence the water cycle by affecting groundwater recharge and surface runoff.
• Certain geomorphic processes contribute to the carbon cycle, impacting atmospheric carbon dioxide levels through the formation and breakdown of rocks.

FAQs on Geomorphic Processes Class 11 Notes

What are the 5 geomorphic processes?

A geomorphic process is something that changes the shape of the land. Examples include: erosion, weathering, mass movement, deposition and transportation.

What do you mean by geomorphological process?

Geo-morphological processes are a fancy word for the modification of land forms on the Earth’s surface through weathering. They are natural processes that shape the Earth.

What are the four main geomorphic processes?

Weathering, mass wasting, erosion and deposition are exogenic geomorphic processes. These exogenic processes are dealt with in detail in this chapter.

How many types of geomorphic process are there?

Exogenic and endogenic forces are responsible for the physical and chemical action. There are two main geomorphic processes. Endogenic Forces and Exogenic Forces.

What is the geomorphic cycle process?

Geomorphic cycle, theory of the evolution of landforms. In this theory, first set forth by William M. Davis between 1884 and 1934, landforms were assumed to change through time from “youth” to “maturity” to “old age,” each stage having specific characteristics.

What is a geomorphic factor?

In a much broader sense, geomorphic factors include the sculpturing of the landforms of a region by processes of erosion, transportation, and deposition of streams, waves, winds, and ice and by forces of volcanism and mountain building.

Is erosion a geomorphic process?

Erosion is a geomorphic process that detaches and removes material (soil, rock debris, and associated organic matter) from its primary location by some natural erosive agents or through human or animal activity.