62 SOILS AND FERTILIZERS 



63. Wind. Wind also has been an important factor 

 in the production and modification of soils. The denud- 

 ing effects of heavy wind storms are well known. 

 Large areas of wind-formed soils are found in some 

 countries. Sand dunes are transported by winds, and 

 often their subjugation by soil-binding plants is neces- 

 sary in order to prevent encroachment upon valuable 

 farm lands and inundation of villages. Soils formed by 

 the action of winds are called aeolian soils. 



64. Combined Action of the Various Agents. In the 

 decay of rocks the various agents named water act- 

 ing mechanically and/ chemically, heat and cold, air, 

 micro-organisms, vegetation, earthworms, and wind 

 have acted jointly, and have produced more rapid disin- 

 tegration than if each agent had acted separately. 



DISTRIBUTION OF SOILS 



65. Sedentary and Transported Soils. The place 

 which a soil occupies is not necessarily where it was 

 formed ; that is, a soil may be produced in one locality 

 and transported to another. Soils are either sedentary 

 or transported. Sedentary soils are those which occupy 

 the original position where they were formed. They 

 usually have but little depth before rock surface is 

 reached. The stones in such soils, except where modi- 

 fied by weathering, have sharp angles because they 

 have not been ground by transportation. In the south- 



