] TYPICAL SOILS 65 



the soil consists almost wholly of the finer fractions, 

 nearly one-half being "clay" ; nor is there any difference 

 between soil and subsoil, except in the humus, which 

 improves the texture of the surface. 



The farmer's definition of land as heavy or light 

 is largely conditioned by the prevailing rainfall. A soil 

 that would be regarded as no more than a stiff loam in 

 the South of England would be called a heavy clay 

 in Scotland, with the greater rainfall and smaller 

 evaporation. Again, a soil texture that would be too 

 light and open for wheat or pasture in the east or 

 south of England is well fitted to carry these crops 

 in regions of greater rainfall. Soil is, as it were, a part 

 of the climate, or rather the two together determine the 

 environment to which the crop responds. 



Actually in the British Isles the really heavy clays 

 are to be found in the south: on the Oxford, Kimeridge 

 and London Clays the heaviest soils occur. In the 

 districts of higher rainfall not only have the soils been 

 lightened by the washing out of the finest clay particles, 

 but they have been more formed from the primitive 

 crystalline rocks. Colloidal particles are less abundant, 

 and the soils are in consequence more permeable. 



