THE SECONDARY STRATA. 265 



of animals. Nor need the present elevated nature of 

 any lands, now bounding or connected with, the chalk, 

 be used as an objection ; since this condition is poste- 

 rior, being the cause of the elevation of the chalk 

 itself. 



I have but this to add. If I have hitherto followed 

 geologists in considering the chalk as the uppermost 

 of the " secondary" and marine strata, as the most 

 recent of those disclosed at the last great revolution of 

 the Earth, it is not that I am satisfied with this re- 

 ceived opinion, but that I am not possessed of facts 

 sufficient to controvert it, and to propose a reform of 

 our classifications on this point. Yet is it more than 

 a merely suspicious hypothesis. If there be a stratum, 

 rocky or otherwise, among the marine ones ranked as 

 tertiary, which is parallel to the chalk, it may have 

 been elevated at the same time, and be thus a still 

 higher member of the same series ; nor will its par- 

 tial or limited extent affect that conclusion, since the 

 chalk itself is, like all else, a partial deposit. The 

 case would be parallel to that of the Italian alluvia 

 under other circumstances; and until the "tertiary" 

 strata have been more carefully studied, we cannot be 

 sure that it does not exist. But this is not all. Our 

 gravel beds have, with no small probability, been 

 thought to be derived from a decomposed rock ; and 

 if this should be the fact, then is this a stratum above 

 the chalk, to be ranked in the same series, though 

 now an alluvium in situ. If the obscure sand of cen- 

 tral England is to be considered a marine alluvium 

 when unconsolidated, it is still a rocky stratum in the 

 same series, when consolidated : unless any one can 

 prove that it has been consolidated in recent times. 

 Let us not, at any rate, decide till we are better in- 

 formed; lest in this case also, we, as usual, substitute 

 hypothesis for fact. 



