WORK OF THE WIND 



S3 



wind to the edge of the dry region, where it is precipitated by rain or falls slowly by 

 its own weight. Here some of it is held by the grasses of the high plains, whose roots 

 have left, upon their decay, the vertical columns characteristic of loess. " But if 



Fig. 31. — Loess deposits, Shan-si, China. The canyon-like depression 

 was excavated by the wind as the loess was loosened by traffic. The two 

 levels on the right are old roads. The ability of loess to stand in almost 

 vertical walls is shown. (Carnegie Institution.) 



the desert dust has ceased to be the plaything of the wind, it has not ended its jour- 

 ney. From now on rills take charge of it and continue the work of which the wind is 

 no longer capable." (De Martonne.) In this way loess is spread over a large terri- 

 tory. 



In China there are extensive areas which have been built up by the accumulation 



