60 



SOILS: PROPERTIES AND MANAGEMENT 



Si0 2 



A1 2 3 



Fe 2 3 



MgO 



CaO 



Na 2 



K 2 



P 2 5 



C0 2 



H 2 



67.10 

 10.26 

 2.52 

 1.24 

 5.88 

 1.42 

 2.68 

 .11 

 3.67 

 5.09 



It is immediately noticeable that the lime content of 

 these soils is high, as is also the phosphoric acid. In 

 fact, all the more soluble constituents are present in 

 relatively large quantities, as would naturally be ex- 

 pected from the mode of origin of such soils — they having 

 been subjected to aridity and then deposited by the wind 

 at a relatively recent period. It is maintained by some 

 geologists * that the deposition of loess is still going on 

 in certain parts of the world, but that the rate of accumu- 

 lation is so exceedingly slow that it escapes the notice 

 of all but trained observers. The lack of fossils, par- 

 ticularly those of plants, is accounted for by this slow 

 rate of formation, which allows sufficient time for all 

 organic matter to become fully oxidized before being 

 covered by the drifting material. Snail shells are often 

 found, but as they are of land species they argue against 

 a water origin of loess. 



1 Merzbacher, G. The Question of the Origin of Loess. Mitt. 

 Justus Perthes' Geogr. Anst., 59, pp. 16-18, 69-74, and 126-130. 

 1913. 



