WEATHERING PROCESS-MASTERING PHYSICAL GEOGRAPHY

TYPES OF WEATHERING   #makephysicalgeographyeasy #MasterPhysicalGeography

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#WEATHERING: MEANING AND CONCEPT

The process of disintegration and decomposition of rocks, due to physical, chemical  or biological factors, in situ (at their own place) is known as weathering.

 As soon as the rocks are exposed on the surface and are affected by the climate factors, this process starts. 

Weathering as a process of denudation, comprises a number of processes by which  surface and subsurface rocks disintegrates into mineral particles or dissolve in water. 


Weathering includes various processes by which rocks are disintegrated or decomposed for their easy removal and transportation by various processes of denudation such as running  water, wind, waves, glaciers and underground water. According to the fact, weathering is the   most important step in erosion of land. 

But by the breakdown or decay or rocks a mantle of  waste (regolith) is created which will remain in situ until agents of erosion cause it to be  moved. So finally it can be conclude that weathering is the breakdown of rock materials in 

place, involving no movement. 


     #FACTORS CONTROLLING WEATHERING 

The rate at which weathering succeeds in the disintegration and decay of rocks 

depends upon a variety of conditions and factors, these can be summarized in some of which  are as under:

1. Rock Composition and Structure-

since weathering involves disintegration and decomposition of rocks and hence 

mineral composition, joint patterns, layering system, faulting, folding etc. largely affects the nature and intensity of weathering. For example, carbonate rocks (e.g. calcium carbonate,  magnesium carbonate etc.) having more soluble minerals are easily affected by chemical  weathering. 


Well jointed rocks are more subjected to mechanical disintegration. Rocks 

having vertical strata are easily loosened and broken down due to temperature changes, frost  action, water and wind action. On the other hand, rocks having horizontal beds are more compact and are less affected by the mechanism of disintegration and decomposition. 

2 Nature of Ground Slope-

ground slope controls mechanical disintegration of rocks and mass movement of 

weathered products down the slope. The rocks in the regions of steep hillslope are easily  disintegrated due to mechanical weathering and the weathering materials are instantaneously  moved down the hill slopes in the form of rock fall, debris fall and slide etc. 

3 Climatic Variations-

Important controls on weathering rates are climatic elements, such as the amount of precipitation, temperature, and freez-thaw cycles. Mechanical and chemical weathering  processes are closely related to climate conditions, specially temperature and annual  precipitation. For example, physical or mechanical weathering dominates in drier, cooler  climates, whereas chemical weathering dominates in wetter, warmer climates. In hot deserts 

marked by extreme dryness, weathering is reduced to a minimum. On the contrary, in hot and  humid climates (tropical and equatorial) most rocks weather rapidly, and the effect of  weathering is carried deep below the surface. 

In climates where the diurnal range of temperature is high, and freezing due to  nocturnal cooling is common, the freeze –thaw action expands the water in rock crevices  (freezing) and then contracts it (thawing). This succession of freeze-thaw action creates forces that are strong enough to mechanically split the rocks. 

4 Floral Effects-

The rate of weathering is also affected to a large extent by the vegetation cover. It may be pointed out that vegetation is partly a factor of weathering and partly a protector of  rocks. In fact, vegetations bind the rocks through their network of roots. These roots of  vegetation-cover protect rocks from weathering and erosion but the same time the penetration of roots weakens the rocks by breaking them into several blocks. 

The absence of vegetation cover in arid regions promotes erosion by wind and 

running water and exposes the bed rocks to the action by the agents of weathering.

All these factors work in close co-operation and influence weathering to a large 

extent. However, time is the crucial factor in weathering, for these processes require long  period of time to operate.

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Weathering can be divided into two major categories 

1. Mechanical/ physical Weathering

2. Chemical weathering 

To be continued......