Weathering -Types and Effects

  • Our earth is a dynamic body. It is continuously changing. The changes on earth’s surface are a result of geomorphic processes.
  • Geomorphological processes are natural mechanisms of weathering, erosion and deposition that result in the modification of surficial materials and landforms on earth's surface.
  • Geomorphic processes include internal processes, and external processes. Internal processes mainly involve tectonic movements, which result into earthquake, volcanic eruption, and mountain building. Tectonic movements are the forces within earth, which are built up gradually and result into sudden movements of earth’s crust. External processes sculpt the surface of earth. They wear down the elevated areas and deposit materials in the lowlands. External processes include gradation, and weathering.
  • The levelling of land surface, resulting from the concerted action of erosion, transportation and deposition is known as gradation. The two types of gradation are degradation and aggradation.
  • Degradation can be defined as the wearing down of the land by the erosive action of water, wind, or ice.
  • Aggradation is the process that increases the elevation of land due to deposition of sediments. The process of gradation involves erosion, transportation, and deposition. Erosion happens when rocks and sediments are picked up and moved to another place by wind, water or ice. Transportation of sediments can be done by water, wind and, glaciers.
  • Deposition is done when rivers or winds do not have enough capacity to carry the sediments. Weathering is the disintegration and alteration of rocks due to exposure to the atmosphere.
  • The three main types of weathering are mechanical weathering, chemical weathering, and biological weathering. Mechanical weathering is a process in which rocks are broken into smaller pieces by force. Chemical Weathering is the disintegration of rocks caused by chemical reactions chiefly with water and substances dissolved in it. Chemical weathering includes the processes of carbonation, oxidation, hydration, and hydrolysis.
  • The decomposition and decaying of rocks that takes place due to organic matters such as flora and fauna is known as biological weathering. The different agents of biological weathering are vegetation, animals and insects, and human beings.
  • On the basis of rock type and presence of joint, four basic types of rock disintegration are recognised. These are granular disintegration, exfoliation, block separation, and shattering.
  • Effects of weathering can result into movement of weathered material, and soil formation. Weathered material can slide down the slope as it is detached from soil. It includes soil creep, landslide, and mudflow. Slow movement of soil and debris is called soil creep movement. A sudden collapse of a large mass of hillside or debris is called landslide. Mudflow is the flow of weathered material, sodden with water, down a hillside.
  • Soil is the most important layer of earth’s crust as it is capable of supporting life. Soil formation begins with the weathering of rocks into small fragments.

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