5.3.3. Erosion and Deposition
The erosion can be defined as “application of the kinetic energy associated with the agent to the surface of the land along which it moves”. Erosion is a term referring to those processes of Denudation which wear away the land surface by the mechanical action of the debris which is being acquired and transported by various agents of erosion. The agents by themselves are also capable of erosion. Abrasion by rock debris carried by these geomorphic agents also aid greatly in erosion. For erosion to occur the agent must be capable of exerting a force on the surface greater than its shear strength.
When massive rocks break into smaller fragments through weathering and any other process, erosional geomorphic agents like running water, groundwater, glaciers, wind and waves remove and transport it to other places depending upon the dynamics of each of these agents. Weathering aids erosion but it is not a pre-condition for erosion to take place.
Deposition is a consequence of erosion. The erosional agents loose their velocity and hence energy on gentler slopes and the materials carried by them start to settle themselves. The coarser materials get deposited first and finer ones later. Alluvial fans at the foothills, alluvial plains, delta etc. are few examples of deposition landforms.
UPSC Questions
1. What do you understand by the theory of continental drift? Discuss the prominent evidences in its support.(UPSC 2013/5 Marks)
2. Sea-floor spreading. (UPSC 2010/5 Marks).
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CONTINENT DRIFT, SEAFLOOR SPREADING, ENDOGENIC AND EXOGENIC FORCES AND BASICS OF PLATE TECTONICS, SOME IDEAS ABOUT SUPERCONTINENTS ETC.
Contents
1. Earthquakes 49
1.1. Types of Earthquakes 49
1.2. Seismic Waves 50
1.3. Depth of Earthquakes 50
1.4. Measurement of Earthquakes 50
1.4.1. Magnitude Scale 50
1.4.2. Intensity Scale 50
1.4.3. Classification of Earthquakes 51
1.5. Distribution of Earthquakes 51
1.5.1. Seismic Belts of the world 51
1.5.2. Seismic Zones of India 52
1.6. Effects of Earthquakes 53
2. Tsunami 53
2.1. Causes 54
2.2. Propagation 54
2.3. Consequences 55
2.4. Early Warning and Mitigation 55
3. Volcanoes 56
3.1. Vulcanicity 56
3.1.1. Causes of Vulcanism 56
3.2. Components of a Volcano 56
3.2.1. Types of lavas 57
3.3. Types of volcanoes 57
3.4. Volcanic Landforms 58
3.4.1. Extrusive Landforms 58
3.4.2. Intrusive Landforms 59
3.5. Distribution of Volcanoes 60
3.6. Effects of volcanic eruptions 61
3.7. Geysers 61
3.8. Hot Springs 62
3.9. Fumaroles 62