KINDS OF SOILS 371 



(4) The Weight of Soils. — This is dependent upon (1) the 

 character of the particles composing the soil and (2) their 

 degrees of compactness. The figures given below are those of 

 Schubler/ 



Weight per Cubic Foot in Pounds, of Various Soils 



Dry siliceous or calcareous sand 110 



Halt sand and half clay 96 



Common arable soil 80-90 



Heavy clay 75 



Garden mould, ricli in vegetable matter 70 



Peat soil 30-50 



(5) Kinds and Classification of Soils. — Being derived from 

 rocks of all kinds and under greatly; ^varying conditions; in 

 almost infinitely variable conditions of comminution, decay, and 

 proportional amounts of their various constituents, no hard and 

 fast lines for soil classification can be laid down. All things 

 considered, they are best classed with the regolith of which they 

 form a part^ the general divisions of which are given in tabular 

 form on p. 288. "We thus have the primary divisions of seden- 

 tary and transported soils, accordingly as they have been formed 

 in place, or transported. Each of these is again subdivided ac- 

 cording to the agencies involved in its transportation or original 

 formation. 



Many varietal names have been applied to soils, but as a rule 

 in so loose and ill-defined a manner as to give them only a very 

 general significance. A common practice is to name one of 

 sedentary origin according to the rock from which it was de- 

 rived, as granite soil, limestone soil, etc. Transported soils, on 

 the other hand, are often designated either by the agencies in- 

 volved in transportation, as glacial, or molian soils, their position, 

 as terrace soils, or their physical or chemical characteristics, as 

 sandy or clayey soils. A loam is usually defined as an admixture 

 of sand and clay with more or less organic matter, a clayey 

 loam being one in which clay predominates and a sandy loam 

 one in which sand prevails. The terms peat, muck, loess, marl, 

 etc., have been already sufiiciently defined. Local names indica- 

 tive of suitability for particular crops, or sometimes of doubt- 

 ful or obscure meaning, are frequently met with. The iluegrass 

 soils of central Kentucky are limestone residuals celebrated for 



5 Handbook of Experiment Station Work, XJ. S. Dept. of Agriculture, 

 1893, p. 315. 



