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Show 148 AMOUNT OF EARTII CHAP. III. frmn above, loses its dark colour jn the cour e of centuri s ; but whether this is probable I do not know. vVorms appear to act in the same manner in New Zealand atJ in Europe; for Professor J. von I-Iaast has described* a section near the coast, consisting of mica-schist., " covered by "5 or 6 feet of loess, above which about 12 "inches of vegetable soil had accumulated." Between the loess and the mould th re was a ]a yer from 3 to 6 inches in thickness, consisting of "cores, implements, flakes, a~d "chips, all manufactured from hard basaltic "rock." It is therefore probable that the aborigines, at sorne former period, had left these objects on the surface, aud that they had afterwards been slowly covered up by the castings of worms. Fanners in England are well aware that objects of all kinds, left on tho surface of pasture-land, after a time disappear, or, as they say, work themselves downwards. I-Iow powdered lime, cinders, and. heavy stones, can work down, and at the sa1ne rate, through the matted roots of a grass-covered * 'Trans. of theN cw Zealand Institute,' vol. xii., 1880, P· 152. CHAP. IlL BROUGIIT UP DY WORMS. 149 surface, is a question wl1ich has probably never occurred to them.* Tlte Sinlcin,r; of great Stones tltrouglt tile Action of TVorrn.'.-When a stone of largo size and of irregular shape is left on tho surface · of the ground, it rests, of cour ·e, on the more protuberant parts; but worms soon fill up with their castings all the hollow spaces on the lower siJe ; for, as lien ·en remarks, they like the shelter of stones. As soon as the hollows are filled up, the wontl, eject the earth which they have swallowecl beyond the circumference of the stones ; and thus the surface of tho ground is rajsed all round the stone. As the burrows excavated directly beneath the stone after a time collapse, the stone sinlcs a little.t Hence * Mr. Lindsay Oarnagie, in a letter (June 1838) to Sir C. Lyel l, remarks that occ,tch f~trmcrs arc afraid or putting lime oil ploughed land until just before it is laid tlown for }Jafiturc, from a belief tl1at it has some tendnncy to sink. He atl<ls: ", ome years smce, in autumn, !laid lime oo an oat-stubble and ploughed 1t down; tlms bringing it iuto immeuiatc coutact wiLh the de<td vegetable n.aLter, and securing its thorough mixture through the means of all the subseq ucu t operations of fallow. In conscq uence of tho above prejuclicc, I was considered to have committed a great fault; but the result was eminently successful, nnd the practice was partially followed. By means of Mr. Darwin's observations, 1 think tho prejudice will be removed." t This conclusion, which, as we shall immctliatcly sec, is fully |
