Chapter – 5
Geomorphic Processes
In this post we have given the detailed notes of class 11 Geography Book 1 Chapter 5 (Geomorphic Processes) in English. These notes are useful for the students who are going to appear in class 11 board exams.
Board | CBSE Board, UP Board, JAC Board, Bihar Board, HBSE Board, UBSE Board, PSEB Board, RBSE Board |
Textbook | NCERT |
Class | Class 11 |
Subject | Geography Book 1 |
Chapter no. | Chapter 5 |
Chapter Name | (Geomorphic Processes) |
Category | Class 11 Geography Book 1 Notes in English |
Medium | English |
Class 11 Geography Book 1 Chapter 5 Geomorphic Processes in English
Chapter 5: Geomorphic Processes
Introduction
- The Earth’s surface is constantly changing due to various processes.
- These processes can be categorized into endogenic (internal) and exogenic (external) forces.
- Geomorphic processes are the physical and chemical actions that shape the Earth’s surface.
- Geomorphic agents are the elements of nature (water, ice, wind) that cause these processes.
Endogenic Processes
- Endogenic processes originate within the Earth and are driven by its internal heat.
- This energy is generated by radioactivity, rotational and tidal friction, and primordial heat.
- These processes include diastrophism and volcanism.
- Diastrophism refers to the movements and deformation of the Earth’s crust, leading to the formation of mountains, continents, and other large-scale features.
- Volcanism involves the movement of molten rock (magma) onto or toward the Earth’s surface, creating various volcanic landforms.
Exogenic Processes
- Exogenic processes are driven by external forces, primarily solar energy and gravity.
- These processes include weathering, mass wasting, erosion, and deposition.
- Weathering is the breakdown of rocks, soil, and minerals through contact with the Earth’s atmosphere, water, and biological organisms.
- Mass wasting is the movement of rock and soil down slopes under the force of gravity.
- Erosion is the process of moving weathered material from one location to another by agents like wind, water, or ice.
- Deposition is the laying down of eroded material.
Weathering
- Weathering can be categorized into three types: chemical, physical, and biological.
- Chemical weathering involves the decomposition of rocks through chemical reactions.
- Solution: Dissolving of minerals in water.
- Carbonation: Reaction of minerals with carbonic acid.
- Hydration: Absorption of water by minerals.
- Oxidation: Reaction of minerals with oxygen.
- Reduction: Removal of oxygen from minerals.
- Physical weathering is the breakdown of rocks into smaller pieces without changing their chemical composition.
- Thermal expansion and contraction: Repeated heating and cooling causing rocks to break.
- Frost wedging: Water freezing in cracks and expanding, breaking the rock.
- Salt weathering: Salt crystals growing in cracks and pores, causing stress.
- Unloading: Removal of overlying pressure causing expansion and fracturing.
- Biological weathering is the weakening and disintegration of rocks by plants, animals, and microbes.
- Root wedging: Plant roots growing into cracks and breaking the rock.
- Burrowing animals: Animals digging and exposing new surfaces to weathering.
- Organic acids: Acids produced by decaying organisms aiding in decomposition.
Mass Movements
- Mass movements are classified based on the speed and type of movement.
- Slow movements:
- Creep: Gradual downhill movement of soil and regolith.
- Solifluction: Slow flow of saturated soil over impermeable material.
- Rapid movements:
- Landslides: Rapid downslope movement of rock and debris.
- Slump: Sliding of rock debris with backward rotation.
- Debris slide: Rapid rolling or sliding of earth debris.
- Debris fall: Free fall of earth debris from a vertical face.
- Rockslide: Sliding of rock masses down bedding planes or faults.
- Rockfall: Free falling of rock blocks over a steep slope.
- Debris avalanche: Extremely rapid flow of rock and debris.
- Landslides: Rapid downslope movement of rock and debris.
- Factors influencing mass movements include slope angle, water content, and vegetation cover.
Erosion and Deposition
- Erosion is the process of transporting weathered material by geomorphic agents.
- Deposition occurs when the transporting agent loses energy and the material settles.
- Erosional agents:
- Running water: Rivers and streams carve valleys and transport sediment.
- Glaciers: Erode and transport vast amounts of rock and debris.
- Wind: Picks up and carries loose particles, creating sand dunes and other features.
- Waves: Shape coastlines through erosion and deposition.
- Groundwater: Dissolves soluble rocks, creating caves and sinkholes.
- These processes lead to the formation of various landforms, such as valleys, deltas, and beaches.
Soil Formation
- Soil formation (pedogenesis) is the process of weathering and transporting materials to form soil.
- Soil-forming factors include parent material, topography, climate, biological activity, and time.
- Parent material refers to the original material from which the soil is formed.
- Topography influences soil formation by affecting drainage and exposure to sunlight.
- Climate plays a crucial role in soil formation through temperature and precipitation.
- Biological activity contributes to soil formation by adding organic matter and nutrients.
- Time is essential for soil development and profile formation.
Conclusion
- Geomorphic processes are essential in shaping the Earth’s surface.
- Understanding these processes is crucial for managing natural resources and mitigating natural hazards.
- By studying geomorphic processes, we can better appreciate the dynamic nature of our planet and its diverse landscapes.
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Category: Class 11 Geography Notes in English