NCERT Class 11 Physical Geography Chapter 6 – Geomorphic Processes

NCERT Class 11 Physical Geography Chapter 6 explains the natural forces that continuously shape the Earth’s surface. Students should refer to the official NCERT website at for authentic textbooks and syllabus updates. In NCERT Class 11 Physical Geography Chapter 6, students study internal forces (endogenic forces) such as earthquakes and volcanoes, and external forces (exogenic forces) like rivers, wind and glaciers that cause weathering, erosion and deposition.

NCERT Class 11 Physical Geography Chapter 6 is extremely important for CBSE board exams and competitive exams like UPSC and BPSC because questions related to landform formation, erosion processes and disaster-related topics are frequently asked. A strong understanding of NCERT Class 11 Physical Geography Chapter 6 builds the foundation for studying landforms and their evolution in the next chapter.

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1. Geomorphic processes

• Geomorphic processes are the natural processes that shape and modify the Earth’s surface.
• The Earth’s surface is continuously influenced by two types of forces: Endogenic forces (internal) and Exogenic forces (external).
• Endogenic processes originate from within the Earth and are mainly responsible for building up landforms.
• Exogenic processes operate on the Earth’s surface and are mainly responsible for wearing down and lowering relief.
• The interaction between endogenic and exogenic forces causes continuous changes in relief features.
• The Earth’s surface remains uneven because these opposing forces act simultaneously.

2. Endogenic processes

• Endogenic processes originate within the interior of the Earth and are mainly responsible for the upliftment and deformation of the Earth’s crust.
• These processes are driven by internal energy generated due to radioactive decay and residual heat inside the Earth.
• Endogenic forces create major relief features such as mountains, plateaus and basins.
• They include processes like Diastrophism and Volcanism, which cause structural changes in the crust.
• Endogenic processes act slowly over long geological periods, but their effects are large-scale and long-lasting.

2.1 Diastrophism

• Diastrophism refers to the large-scale deformation of the Earth’s crust due to internal forces.
• It includes processes that result in folding, faulting, uplift and subsidence of crustal rocks.
• Diastrophic movements are broadly classified into Orogenic movements and Epeirogenic movements.
• Orogenic movements are mountain-building movements associated with intense folding and faulting.
• Epeirogenic movements involve broad uplift or subsidence of large portions of the crust without significant deformation.
• These movements are responsible for the formation of major landforms such as fold mountains and plateaus.

2.2 Volcanism

• Volcanism refers to the movement of magma from the interior of the Earth towards or onto the surface.
• It includes all processes related to the eruption of lava, gases and pyroclastic materials.
• Volcanism may occur either on the surface through volcanic eruptions or beneath the surface through the intrusion of magma.
• When magma reaches the surface and solidifies, it forms various volcanic landforms.
• Volcanic activity plays a significant role in building new landforms and modifying the Earth’s surface.

3. Exogenic processes

• Exogenic processes operate on the Earth’s surface and are driven mainly by solar energy and gravity.
• These processes are responsible for the wearing down (degradation) and leveling of elevated landforms.
• The main exogenic processes include weathering, mass movements, erosion and deposition.
• Exogenic forces continuously act on landforms created by endogenic processes, reducing relief differences.
• Agents such as running water, wind, glaciers and sea waves play an important role in shaping the Earth’s surface.
• The balance between endogenic and exogenic processes maintains the dynamic nature of the Earth’s surface.

4. Weathering

• Weathering is the in-situ (on-site) disintegration and decomposition of rocks at or near the Earth’s surface.
• It occurs without the movement of material and differs from erosion, which involves transportation.
• Weathering is caused by atmospheric elements such as temperature changes, water, frost and biological activity.
• It weakens rocks and prepares them for further processes like erosion and mass movement.
• Weathering is broadly classified into Chemical Weathering, Physical (Mechanical) Weathering and Biological Weathering.
• It plays a crucial role in soil formation and landscape development.

4.1 Chemical Weathering Processes

• Chemical weathering involves the decomposition and alteration of rocks through chemical reactions between minerals and atmospheric elements.
• It is more active in regions with warm and humid climates, where moisture and temperature accelerate reactions.
• Important chemical weathering processes include Solution, Carbonation, Hydration, Oxidation and Hydrolysis.
• Solution occurs when soluble minerals dissolve in water.
• Carbonation happens when carbon dioxide (CO₂) combines with water to form carbonic acid, which reacts with minerals like limestone.
• Oxidation involves the reaction of oxygen with minerals, especially those containing iron.
• These processes change the chemical composition of rocks and often lead to the formation of new minerals.

4.2 Physical Weathering Processes

• Physical (Mechanical) weathering involves the disintegration of rocks into smaller fragments without any change in their chemical composition.
• It is mainly caused by temperature changes, which lead to expansion and contraction of rock minerals.
• The process of repeated heating and cooling causes exfoliation, where outer layers of rocks peel off.
• In cold regions, water entering cracks freezes and expands, leading to frost action, which breaks rocks apart.
• Pressure release due to the removal of overlying rocks can cause rocks to crack and break.
• Physical weathering is more effective in areas with extreme temperature variations and arid or cold climates.

4.3 Biological activity and weathering

• Biological weathering is caused by the action of plants, animals and microorganisms on rocks.
• The growth of plant roots into rock cracks exerts pressure, leading to the disintegration of rocks.
• Burrowing activities of animals expose rocks to weathering agents like air and water.
• Microorganisms produce organic acids that contribute to the chemical decomposition of minerals.
• Human activities such as mining and construction also accelerate the weathering process.
• Biological activity plays a significant role in the breakdown of rocks and contributes to soil formation.

4.4 Special effects of weathering

• Weathering results in the formation of a layer of loose material called regolith, which covers the solid bedrock.
• In regions composed of limestone, chemical weathering leads to the development of distinctive karst topography.
• Features such as caves, sinkholes and underground drainage systems are formed due to the solution of limestone.
• Differential weathering occurs when rocks of varying resistance are exposed, leading to uneven surface features.
• Weathering contributes to the development of characteristic landforms depending on the type of rock and climatic conditions.

4.5 Significance of weathering

• Weathering is the first step in the development of soil, as it breaks down rocks into finer materials.
• It prepares rock material for erosion and transportation by weakening and disintegrating it.
• Weathering contributes to the formation of various landforms by influencing surface relief.
• It plays a crucial role in the release of minerals and nutrients, which are essential for plant growth.
• The type and intensity of weathering influence the nature and depth of the soil profile.
• Weathering helps maintain the dynamic balance between endogenic and exogenic processes on the Earth’s surface.

5. Mass movements

• Mass movements refer to the movement of weathered material down a slope under the direct influence of gravity.
• These movements occur without the involvement of transporting agents like water, wind or ice.
• Mass movements are influenced by factors such as slope angle, water content and the nature of rock material.
• They may occur slowly over time or suddenly, depending on conditions.
• Mass movements play an important role in shaping slopes and modifying landforms.
• They are closely associated with weathering and erosion processes.

5.1 Landslides

• Landslides are a type of mass movement involving the rapid downward movement of rock, soil or debris along a slope.
• They commonly occur in mountainous regions where slopes are steep and unstable.
• Heavy rainfall, earthquakes and human activities such as deforestation and road construction increase the chances of landslides.
• Landslides may block rivers, damage infrastructure and cause loss of life and property.
• The occurrence of landslides is influenced by the nature of rock, slope gradient and water saturation.

6. Erosion and deposition

• Erosion is the process by which weathered material is removed and transported by agents such as running water, wind, glaciers and sea waves.
• Unlike weathering, erosion involves both the wearing away and movement of rock materials.
• The main agents of erosion are rivers, wind, glaciers and ocean waves, each forming distinct landforms.
• After transportation, materials are laid down through the process of deposition, forming new landforms.
• Deposition occurs when the transporting agent loses its energy and can no longer carry the material.
• Erosion and deposition together play a major role in shaping the Earth’s surface over geological time.

7. Soil formation

• Soil is a thin layer of loose material covering the Earth’s surface, formed from the weathering of rocks and organic matter.
• Soil formation begins with the breakdown of rocks through weathering processes.
• The accumulation of humus (decomposed plant and animal matter) contributes to soil development.
• Soil formation is a slow and continuous process that occurs over long periods.
• The characteristics of soil depend on the nature of the parent rock and environmental conditions.

7.1 Process of Soil Formation

• The process of soil formation is known as Pedogenesis, which begins with the weathering of the parent rock.
• Weathered material gradually mixes with organic matter, forming a layer of soil on the surface.
• Over time, vertical differentiation leads to the development of distinct soil horizons.
• The uppermost layer becomes rich in humus and nutrients, while lower layers accumulate minerals leached from above.
• Continuous interaction between climate, organisms and parent material influences the nature of the soil profile.

7.2 Soil-forming Factors

• Soil formation depends on five major factors: Parent Material, Climate, Relief, Organisms and Time.
• Parent Material determines the mineral composition and texture of the soil.
• Climate, especially temperature and rainfall, controls the rate of weathering and organic activity.
• Relief (topography) influences drainage, erosion and the depth of soil formation.
• Organisms, including plants, animals and microorganisms, contribute organic matter and aid in the breakdown of rocks.
• Time is essential, as soil formation is a slow process that develops over long geological periods.

NCERT Class 11 Physical Geography Chapter 6 provides a scientific understanding of how internal and external forces modify the Earth’s surface. Mastering NCERT Class 11 Physical Geography Chapter 6 helps students connect earthquakes, volcanic activity and erosion with landform development.

A detailed study of NCERT Class 11 Physical Geography Chapter 6 strengthens preparation for topics like landforms, environmental change and disaster management.

Continue reading NCERT Class 11 Physical Geography Chapter 7 – Landforms and their Evolution to understand river, glacier, desert and coastal landforms in a structured and exam-oriented manner.

Frequently Asked Questions (FAQs)

Q1. What is NCERT Class 11 Physical Geography Chapter 6 about?
NCERT Class 11 Physical Geography Chapter 6 explains the processes that shape the Earth’s surface through internal and external forces.

Q2. Why is NCERT Class 11 Physical Geography Chapter 6 important for exams?
NCERT Class 11 Physical Geography Chapter 6 is important because weathering, erosion and landform development are frequently asked in CBSE and UPSC examinations.

Q3. What are endogenic and exogenic forces in NCERT Class 11 Physical Geography Chapter 6?
In NCERT Class 11 Physical Geography Chapter 6, endogenic forces originate inside the Earth (like earthquakes), while exogenic forces act on the surface (like rivers and wind).

Q4. How does NCERT Class 11 Physical Geography Chapter 6 help in UPSC preparation?
NCERT Class 11 Physical Geography Chapter 6 strengthens conceptual clarity about Earth surface processes, which are important for Geography and Environment sections.

Q5. Is NCERT Class 11 Physical Geography Chapter 6 linked with later chapters?
Yes, NCERT Class 11 Physical Geography Chapter 6 forms the base for understanding landform evolution discussed in the next chapter.

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