NOMOS. 181 



roots, and because some of them are found to ter- 

 minate, not in the coal-seams, but in clay or shale- 

 seams. Indeed, the whole appearance of these trees 

 is suggestive of the idea that they had been floated 

 into their present position, and that it was the 

 merest accident which determined the kind of de- 

 posit in which their lower extremities would have 

 to rest. Still it is quite possible, nay probable, that 

 some few of the coal-seams were formed from forests 

 which grew on the spot, for the history of many 

 peat-mosses supports such a conclusion; but as a 

 rule there appears to be no other alternative than 

 to suppose that these strata, like the sedimentary 

 rocks, are the product of drifts. 



Nor is there any sufficient reason for supposing 

 that the limestone-strata are the work of zoophytes 

 or other calciferous creatures which lived 



, i , . The lime- 



On the spot, except in some very occa- St0 ne-strata, 



sional instances. "It requires," says Dr. 

 Young, the creative powers of fancy to 

 discover in these strata anything like 



' . . cent period, 



groves or beds of coral, such as exist in because they 

 recent coral-reefs. The corals of the fmS^U 

 oolite are generally laid flat, like the ^toS from 

 shells with which they are mixed, and " p v ^ gonthe 

 those which are found in an upright po- 

 sition might acquire that position in the same way 

 as the vertical plants and trees in the carboniferous 

 strata."* Moreover, some of these calcareous strata 

 are evidently formed from drifts. " In the marl- 

 stone bands occurring in the lias of Yorkshire," conr 



* Op. cit. p. 16. 

 N 3 



