WEATHERING OF ROCKS 



TABLE 1 

 Composition of a Gray Forest Soil* (from Glinka) 



* Podsol. 



material has all originated from the compact rocks by slow proc- 

 esses of disintegration due to weathering, encouraged by the action 

 of waters, heat and cold, other atmospheric agencies, and biologi- 

 cal factors. Some of this material remains superimposed upon 

 the rocks from which it was formed; some becomes translocated 

 by waters and winds and finds its resting place at regions far 

 distant from the place where it originated. The disintegration 

 of rocks finally leads to an accumulation of granulated material 

 of the fineness of sands and clay. Soon after or even during rock 

 disintegration, and also greatly assisting this process, vegetation 

 springs up. The inorganic materials which are soluble in water 

 or dilute acids, such as carbonic, are then removed from the soil 

 by plants and percolating waters. Some of these materials again 

 enter the soil and become incorporated with it on the death of 

 the vegetation. Here also the plants undergo partial or complete 

 decomposition by microorganisms. 



The chemical processes involved in the weathering of rocks are 

 those of hydrolysis, oxidation, hydration, solution, and carbona- 

 tion, or carbonate formation. The following reactions illustrate 



