•3-Z 



LOCALITY AND FOREST VEGETATION. 



because the importance of the four substances, sand, clay, 

 Hme and humus, outweighs that of all other substances so 

 much, that the latter need not be taken into account in this 

 place. 



The subjoined table gives the composition of the ten principal 

 classes of soils (according to Church) : — 



Soils of sul)ordinate importance are : — 



Dolomite, a chalky loam with much magnesium carl)onate. 



Gypsum, a soil which is rich in calcium sulphate. 



Salt soil, which contains an excessive percentage of salts, 

 especially sodium chloride. 



Farmginous soil, which contains an excessive proportion of 

 ferric oxide. 



According to the preponderance of one or other of the 

 principal ingredients, numerous subdivisions have been made, 

 such as sandy, or marly clays ; loamy sand, sandy loam, 

 marly sand, sandy marl, etc. 



Clay, loam and calcareous soil are, as a rule, minerally 

 strong soils, while sandy soils are less strong, liuiuus soil 

 may be mild, dry, or sour humus soil ; the lirst acts very 

 favourably upon tree growth, the two latter unfavourably. 



