Geomorphology By Kerala PSC: Biological weathering

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Kerala PSC

Geomorphology By Kerala PSC: Biological weathering

  • Biological weathering is the removal of minerals and ions and physical changes due to growth or movement of organisms.
  • Burrowing and wedging by organisms like earthworms, termites, rodents etc., help in exposing the new surfaces to chemical attack and assists in the penetration of moisture and air.
  • Human beings by disturbing vegetation, ploughing and cultivating soils, also help in mixing and creating new contacts between air, water and minerals in the earth materials.
  • Decaying plant and animal matter help in the production of humus, carbonic and other acids which enhance decay and solubility of some elements.
  • Plant roots exert a tremendous pressure on the earth materials mechanically breaking them apart.

Exfoliation

  • Exfoliation is the flaking off of more or less curved sheets of shells from over rocks or bedrock results in smooth and rounded surfaces
  • Exfoliation can occur due to expansion and contraction induced by temperature changes. Exfoliation domes and tors result due to unloading and thermal expansion respectively.

Erosion 

  • Erosion is the process of removal of rock debris from one place to another.
  • 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.
  • The process of abrasion by rock debris carried by these geomorphic agents aids greatly in erosion.
  • The landscape is worn down by the erosion, relief degrades. Weathering, mass-wasting and erosion are degradational processes.
  • Erosion is largely responsible for continuous changes that the earth’s surface.
  • The denudational processes like erosion and transportation are controlled by kinetic energy.
  • The erosion and transportation of earth materials is brought about by wind, running water, glaciers are controlled by climatic conditions
  • The work of the other two agents of erosion-waves and ground water is not controlled by climate.

Deposition

  • The erosional agents lose 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.
  • By deposition depressions get filled up.
  • The same erosional agents viz., running water, glaciers, wind, waves and groundwater act as aggradational or depositional agents also

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