62 NATURE AND PEOPERTIES OF SOILS 



Indiana, besides a wide band, as already noted, extending 

 soutbward along the eastern border of tlie Mississippi River. 

 Due to its mode of origin, its depth is always greatest near 

 the streams and gradually becomes less farther inland. In 

 places, notably along the Missouri and Mississippi rivers, its 

 accumulation has given rise to great bluffs, which bestow a 

 characteristic topography to the region. 



Not only is loess found over thousands of square miles in 

 the central part of the United States but it occurs else- 

 where in large areas. It is greatly developed in northern 

 France and Belgium, and along the Rhine in Germany, where 

 it is an important soil in all the valleys that are tributary 

 to that river. Silesia, Poland, southern Russia, Bohemia, 

 Hungary and Roumania have deposits of this highly fertile 

 material. Some of the most important moves of the World 

 War had as their aim the possession of these fertile areas. 

 In China loess is found over a very large part of the valley 

 of the Hwangho, a region probably larger in area than France 

 and Germany combined. The thickness of the deposit is 

 variable, ranging from a few feet to several thousand in 

 places. The depth is practically always sufficient for any 

 form of agricultural operations. 



Loess is usually a fine calcareous silt or clay loam, of a 

 yellowish or yellowishy buff color. While it may be readily 

 pulverized when subjected to cultivation, it possesses remark- 

 able tenacity in resisting ordinary weathering. The vertical 

 walls and escarpments formed by this soil show one of its 

 striking physical characteristics. In China caves that house 

 thousands of persons are dug in the defiles and canons ex- 

 isting in this deposit. Another feature of loess is the pres- 

 ence, especially in the subsoil, of minute vertical canals lined 

 with a deposit of calcium carbonate. These canals are sup- 

 posed to give the soil its vertical cleavage and its tenacity. 

 The particles of loess are usually unweathered and angular. 

 Quartz seems to predominate, but large quantities of feld- 



