CHAP, v.] Soil and Situation 97 



has taken place, and (3) some of the lighter products of 

 decomposition (clay) are more easily washed away than others 

 that are heavier (sand). Hence, for practical sylvicultural 

 purposes, no better classification of soils can be adopted than 

 that made by Grebe, which is now generally adopted at the 

 experimental stations on the continent : 



Sandy Soils, containing 75 % or more of disintegrated sand. They 

 occur as sand-drifts, or are the product of the decomposition of sand- 

 stones. 



Sand consists of about 90 % of sand, and not more than 10 % of 



clay and other constituents. 

 Loamy sand consists of about 75 to 85 % of sand, and from 15 to 



25 % of clay and other constituents. 



Loamy Soils, always tinged with iron, containing 60 to 70 % of fine 

 sand and silicious dust, the rest being chiefly made up of clay with less 

 than 5 % of lime, and an almost constant quantity (5 %) of hydrated 

 ferric oxide. 



Loam consists of about 60 % of sand and 40 % of clay. 

 Sandy loam consists of about 70 % of sand and 30 % of clay. 

 Clayey Soils, containing 50 % or more of clay. They are mostly 

 formed from rocks rich in feldspars, augite, and hornblende, of sand- 

 stones and conglomerates cemented with clayey cohesive substance, and 

 of the clayey layers and bands throughout sandstones and lime forma- 

 tions. 



Clay consists of about 60 to 70 % of clay, the rest being chiefly 



sand, and also other constituents. 



Loamy clay consists of about 50 % of clay, and 50 % of sand. 

 Limy Soils, containing not less than 10 % of carbonate of lime. 

 They are produced chiefly by limestones, but also by other rocks 

 containing lime felspar (labradorite). It often happens that limestone 

 rocks produce a loamy rather than a limy soil on decomposition. 



Lime consists of at least 50 % of carbonate of lime, the rest being 



chiefly clay. 



Clayey lime consists of about 40 % of lime and 60 % of clay. 

 Loamy lime consists of about 30 % of lime and 70 % of loam. When 

 rich in carbonate of magnesia it is called dolomitic lime or 

 dolomite. 



Marl consists of 10 to 20 % of carbonate of lime, with 80 to 90 % 

 of clayey and sandy ingredients. 



Sandy soils have a coarse gritty feeling when slightly mois- 

 tened. When there is any considerable admixture of loam, 



H 



