286 DENUDATION OF THE LAND. Chap. VI. 



weeks, during which time the weather had 

 been alternately dry and rainy. Some, which 

 were of a yellowish colour had been washed 

 almost completely away, as could be seen 

 by the colour of the surrounding ground. 

 Others had completely disappeared, and these 

 no doubt had been blown away. Lastly, 

 others still remained and would long remain, 

 as blades of grass had grown through them. 

 On poor pasture land, which has never been 

 rolled and has not been much trampled on 

 by animals, the whole surface is sometimes 

 dotted with little pimples, through and on 

 which grass grows; and these pimples con- 

 sist of old worm-castings. 



In all the many observed cases of soft cast- 

 ings blown to leeward, this had been effected 

 by strong winds accompanied by rain. As 

 such winds in England generally blow from 

 the south and south-west, earth must on the 

 whole tend to travel over our fields in a 

 north and north-east direction. This fact is 

 interesting, because it might be thought that 

 none could be removed from a level, grass- 

 covered surface by any means. In thick and 

 level woods, protected from the wind, castings 



