- External processes are geomorphic activities that originate from forces outside the Earth's surface.
- These processes are also called exogenic processes.
- They include weathering, erosion, transportation, and deposition.
- External processes are driven by solar energy, gravity, and the hydrological cycle.
- Weathering is the breakdown of rocks into smaller particles through physical, chemical, or biological means.
- Physical weathering includes processes like frost action, thermal expansion, and exfoliation.
- Chemical weathering involves the alteration of rock composition through reactions like oxidation, hydrolysis, and carbonation.
- Biological weathering occurs due to the actions of plants, animals, and microorganisms.
- Weathering contributes to the formation of soil and other sediments.
- Erosion is the removal and transport of surface materials by agents like water, wind, ice, and gravity.
- Water erosion creates landforms such as river valleys, canyons, and gullies.
- Wind erosion leads to features like sand dunes and yardangs, common in arid regions.
- Glacial erosion forms U-shaped valleys, fjords, and other glacial features.
- Coastal erosion shapes sea cliffs, arches, and stacks through wave action.
- Mass wasting, or mass movement, is the downslope movement of materials under gravity, forming landslides, debris flows, and rockfalls.
- Transportation refers to the movement of eroded materials by natural agents like rivers, glaciers, and winds.
- Rivers transport sediments as bedload, suspended load, and dissolved load.
- Glaciers carry large boulders and fine debris, forming features like moraines and drumlins.
- Wind carries fine particles, leading to the formation of loess deposits.
- Deposition occurs when transported materials are dropped due to a decrease in energy.
- Depositional landforms include river deltas, alluvial fans, and sandbars.
- In deserts, deposition forms features like sand dunes and playas.
- Glacial deposition creates landforms like moraines, eskers, and outwash plains.
- Coastal deposition leads to features like beaches, spits, and barrier islands.
- External processes continuously reshape the Earth's surface, balancing the forces of uplift and erosion.
- Fluvial processes, driven by rivers, dominate in humid regions and shape floodplains, levees, and terraces.
- Aeolian processes, caused by wind, are significant in arid and semi-arid regions.
- Glacial processes are active in polar and high-altitude regions, carving landscapes and depositing sediments.
- Marine processes shape coastal landforms through wave action, tides, and ocean currents.
- Karst topography forms in regions with soluble rocks like limestone, leading to caves, sinkholes, and stalactites.
- Human activities like deforestation, mining, and construction accelerate erosion and alter natural processes.
- Understanding external processes helps in managing soil erosion, landslides, and other environmental challenges.
- Climatic factors, such as temperature and precipitation, influence the intensity and type of external processes.
- Topography affects the rate and pattern of weathering, erosion, and deposition.
- Vegetation helps stabilize soils, reducing erosion and enhancing deposition.
- External processes are essential for creating diverse landforms and maintaining ecological balance.
- They play a crucial role in the formation of natural resources like soil, sedimentary rocks, and fossil fuels.
- Weathering and erosion contribute to the geochemical cycle, recycling minerals and nutrients.
- External processes are interlinked with internal processes, shaping Earth's dynamic landscape.
- Long-term changes in external processes are influenced by factors like climate change and sea-level variations.
- Monitoring and managing these processes are vital for sustainable development and disaster mitigation.
- Natural landscapes owe their diverse forms to the combined effects of external processes over geological timescales.
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