34 



NATURE AND PROPERTIES OF SOILS 



The analyses indicate that the soil from the granite does 

 not differ greatly from the original rock, except in the loss of 

 bases, assumption of water, and increase of organic matter. 

 The soil from the limestone presents greater diflerences, due 



Vo 



■60.6C 



SiOg 



F2205+ 



.1 *mj* J I 



CaO+f ^•5'" 

 M<30 I 4 , 



/4.2 



KgO - 



I 1.1 



Na^Oi 



<0 Q mmmmim 



.6D 



HeO 



x:::; 



s. 



CZr3GHAMIT£ 



[RESIDUAL SOIL 



Pig. 6. — Diagram showing the composition of fresh granite and its 

 residual soil. Note the marked hydration of the soil. 



to the disappearance of the calcium carbonate. The analyses 

 of the two soils resemble each other rather closely in spite of 

 their widely different sources. Since weathering, especially 

 residual weathering, causes a loss of basic materials and 



