262 DENUDATION OF THE LAND CHAP. VI. 



CHAPTER VI. 



THE DENUDATION OF THE LAND Continued, 



Denudation aided by recently ejected castings flowing down 

 inclined grass-covered surfaces The amount of earth which 

 annually flows downwards The effect of tropical rain on 

 worm castings The finest particles of earth washed com- 

 pletely away from castings The disintegration of dried cast- 

 ings into pellets, and their rolling down inclined surfaces 

 The formation of little ledges on hill-sides, in part due to the 

 accumulation of disintegrated castings Castings blown to 

 leeward over level land An attempt to estimate the amount 

 thus blown The degradation of ancient encampments and 

 tumuli The preservation of the crowns and furrows on land 

 anciently ploughed The formation and amount of mould 

 over the Chalk formation. 



WE are now prepared to consider the more 

 direct part which worms take in the denuda- 

 tion of the land. When reflecting on sub- 

 aerial denudation, it formerly appeared to 

 me, as it has to others, that a nearly level or 

 very gently inclined surface, covered with 

 turf, could suffer no loss during even a long 

 lapse of time. It may, however, be urged 

 that at long intervals, debacles of rain or 



