SOIL BUILDERS 19 



precious soil into huge heaps, preparatory to carry- 

 ing it away into the mountains, beyond the grasp of 

 the avaricious whites. But the white men came 

 before the soil could be carried away, took it for 

 their grain fields, and it has been in heaps ever 

 since. The more prosaic geologist, however, says 

 that these fertile hills were made almost entirely 

 by wind, assisted by erosion. In parts of Cali- 

 fornia, Oregon, Washington, and Wyoming, the 

 clay less "dust soil" becomes cracked and loosened 

 in dry weather and is carried away by the wind in 

 dense clouds, banking up like snow behind rocks 

 and bushes. Recall, also, the stories of caravans 

 in the desert being overwhelmed by sandstorms. 

 There are numerous records of large quantities 

 of soil being carried over a thousand miles by 

 wind. 



Even where the soil has been made mostly by 

 other agencies, wind contributes something to it. 

 Fine soil, leaves, chaff and dust are swept over the 

 hill crest and deposited on the leeward slope. The 

 amount of soil that is made and transported by 

 wind, in the form of dust, must amount to an 

 appreciable quantity in the course of a year. The 

 slope opposite to that of the prevailing wind is 

 usually less abrupt than the other, because so 

 much soil material has been deposited there by the 

 wind. 



Still another way in which wind assists in making 

 soil is by blowing fine particles of sharp sand and 

 dust against the rocks and so wearing them away. 

 At first thought it would seem that the result of 

 this would be very insignificant, but in reality it is 

 often quite important. In arid parts of the United 

 States and elsewhere, the millions and millions of 

 soil grains blown against cliffs and rocks leave a 



