SUB-PROVINCES, CLASSES, TYPES AND SURVEYS 113 



different strata. (6) The structure or granulation. (7) The 

 color of the strata. (8) The natural drainage. (9) The amount 

 of organic matter present. (10) The agricultural value, based 

 upon its natural productiveness. (11) The ultimate chemical com- 

 position and reaction, whether acid, neutral or alkaline. 



Naming of Soil Types. At first thought it might seem a very 

 easy and simple matter to name soil types. It is on a single farm, 

 but the difficulty increases with the size of the area, the number of 

 different soils, and the detail desired. From the standpoint of 

 everyone concerned, but more especially from that of the farmer, 

 the simpler and more expressive the name the better, and the easier 

 it will be to associate it with the soil. To a certain extent the name 

 should be descriptive of the type. According to the nomenclature in 

 use by the Bureau of Soils, names of soil types usually consist of 

 two parts, the series name and the class name, with sometimes a 

 modifying word included. The series name is that of some locality 

 where the soil in question was first found or where it is well de- 

 veloped. This gives names as follows: Cecil silt loam, Marshall 

 fine sand, Marshall black clay loam, etc. 



The above system of naming is applicable to extensive areas, 

 but for a limited area, such as a single state, a more expressive 

 system may be devised. After the texture, one of the most striking 

 characteristics of soils is the color. In the naming of soils in 

 Illinois, a combination of color and texture together with other 

 descriptive terms, when necessary, has been adopted as convoying 

 the most meaning to those who use the name. Without ever having 

 seen it, the name, so constructed, gives a very good idea of the 

 character of the soil. As illustrations, gray silt, loam on tight clay, 

 yellow silt loam, brown silt loam on gravel, and medium peat on 

 rock may be given. 



There are such great variations in color that these color dis- 

 tinctions do not always strictly apply. The soil on rolling and hilly 

 land is usually of a yellow color either on the surface or immediately 

 beneath the surface- soil, so that those aro called yellow silt loams, 

 yellow fine sandy loams, etc. The undulating timber soils are yellow 

 or grayish and the term or name yellow-gray is applied to them. 

 Prairies are either dark gray, brown, or black. The use of the 

 term "on" as part of a soil typo name indicates the presence of cer- 

 tain substrata within 30 inches of the surface. If the term " over " 

 is used, the material, such as sand, gravel, or rock, is more than 30 

 inches below the surface. 

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