1919] Pendleton: A Study of Soil Types ::< 



be a sample of the soil thoroughly typical of the class and type in 

 question. Sample no. 3 had a large lime content which I thought 

 might more or less obscure the texture. "Slightly heavy, and barely 

 enough sand for a sandj' loam" is the comment on sample 12, while 

 "a heavy sandy loam, approaching a loam" is found in the notes on 

 sample 13. The second column of the table shows the class sub- 

 divisions into which the soils were placed according to the mechanical 

 analysis. The words in parenthesis show modifying conditions but 

 do not indicate a change in the class. In considering the class groups 

 such as sandy loam, fine sandy loam, etc., it should be remembered 

 that though the groups are rather broad, the limits are arbitrary 

 and quite sharp. So the results of a mechanical analysis may place 

 a soil in the sandy loam class if 25% or more is fine gravel, coarse and 

 medium sand, while if less than 25% be present the soil belongs to the 

 fine sandy loam class, providing at the same time the amounts of silt, 

 clay, and fine sand are within the specified limits. The two soils may 

 be a great deal alike in texture though placed in different classes. 

 The failure of my judgment regarding the texture shows one of the 

 difficulties that the field man is continually facing. And his failure 

 to judge textures correctly is one of the causes of criticism of soil 

 survey work. 



Table 2 — Mechanical Analyses, Hilgard Elutriator Method 



Diablo Clay Adobe 

 Separates 



