Weathering is a static process. The process of disintegration and decomposition of rocks in situ is generally called weathering.
Weathering refers to the breakdown or disintegration and decomposition of rocks in situ through mechanical and chemical changes in the rocks and their minerals effected by water, temperature, wind, different atmospheric gases and organisms provided that there is no large-scale transport of weathered products by denudational processes except massmovement of rockwastes down the slope under the impact of gravity.
According to C.D. Ollier (1969), “weathering is the breakdown and alteration of minerals near the earth’s surface to products that are more in equilibrium with newly imposed physico-chemical conditions”
According to P. Reiche (1950), “weathering is the response of minerals which were in equilibrium within the lithosphere to conditions at or near its contact with the atmosphere, the hydrosphere, and perhaps still more importantly ,the biosphere.”
B. B. Polynov(1937), has very precisely defined weathering as ‘the change of rocks from the massive to the clastic state.’
According to B. W. Sparks, “weathering may be defined as the mechanical fracturing or chemical decomposition of rocks by natural agents at the surface of the earth”
Arthur Holmes has presented more elaborate definition of weathering which also includes the processes of weathering.According to him “ weathering is the total effect of all the various subaerial processes that cooperate in bringing about the decay and disintegration of rocks, provided that no large-scale transport of the loosened products is involved. the work of rainwash and wind, which is essentially erosional, is thus excluded”
-A. Homes (1952)
It appears from the above definitions that weathering is essentially the breakdown of rocks due to chemical and mechanical processes at their places.