CHAP. III. BROUGHT UP BY WORMS. 149 



of dark-coloured vegetable mould, and the 

 next 18 inches of sandy loam, containing in 

 the lower part many rolled pieces of sand- 

 stone, with some bits of brick and tile, probably 

 of Roman origin, as remains of this period 

 have been found close by. The sandy loam 

 rested on an indurated ferruginous pan of 

 yellow clay, on the surface of which two 

 perfect celts were found. If, as seems pro- 

 bable, the celts were originally left on the 

 surface of the land, they have since been 

 covered up with earth 3 feet in thickness, all 

 of which has probably passed through the 

 bodies of worms, excepting the stones which 

 may have been scattered on the surface at 

 different times, together with manure or by 

 other means. It is difficult otherwise to 

 understand the source of the 18 inches of 

 sandy loam, which differed from the overlying 

 dark vegetable mould, after both had been 

 burnt, only in being of a brighter red colour, 

 and in not being quite so fine-grained. But 

 on this view we must suppose that the carbon 

 in vegetable mould, when it lies at some little 

 depth beneath the surface and does not con- 

 tinually receive decaying vegetable matter 



M 2 



