CHAP. III. BROUGHT UP BY WORMS. 133 



cinders had been strewed, only about half-a- 

 year before, and these either still lay on the 

 surface or were entangled among the roots of 

 the grasses ; and I here saw the commence- 

 ment of the burying process, for worm-cast- 

 ings had been heaped on several of the 

 smaller fragments. After an interval of 

 4f years this field was re-examined, and now 

 the two layers of lime and cinders were found 

 almost everywhere at a greater depth than 

 before by nearly 1 inch, we will say by f of 

 an inch. Therefore mould to an average 

 thickness of '22 of an inch had been annually 

 brought up by the worms, and had been 

 spread over the surface of this field. 



Coal-cinders had been strewed over another 

 field, at a date which could not be positively 

 ascertained, so thickly that they formed 

 (October, 1837) a layer, 1 inch in thickness 

 at a depth of about 3 inches from the surface. 

 The layer was so continuous that the over- 

 lying dark vegetable mould was connected 

 with the sub-soil of red clay only by the roots 

 of the grasses ; and when these were broken, 

 the mould and the red clay fell apart. In a 

 third field, on which coal-cinders and burnt 



L 2 



