324 ON THE DEPOSITS CALLED TERTIARY 



under imagined resemblances or identities. Unclassed 

 as they have remained, the futility of such attempts is 

 obvious ; but even where the geological facts corre- 

 spond, there is no philosophy in such endeavours. If 

 there are any strata on the face of the earth which are 

 truly independent, it must be these. General reason- 

 ing, and analogies drawn from the older strata, parti- 

 cularly from the coal series, must conclude, that such 

 deposits will differ in different places ; and thus the 

 fact proves. Not only do the number and the succes- 

 sion of strata differ in each, but the natures of the 

 substances themselves. Hence also the impropriety 

 as well as the inconvenience of using a positive term, 

 such as that of Plastic clay, or Calcaire grossier, to 

 designate what, in another place, may be neither of 

 those particular substances. It is plain that the nature 

 of any such deposit must have been regulated, like 

 every anterior stratum, by the matters which were 

 present : and to suppose that the organic remains 

 could correspond in remote places, is even to coli- 

 found all zoological history. 



If this remark applies to those which are of marine 

 origin, still more is it true where they have been 

 formed under fresh water ; since a want of coinci- 

 dence or similarity must still more occur in such cases, 

 and especially, as far as plants and animals are con- 

 cerned. It is this practice of generalizing from a 

 particular tract or country, which has constantly ob- 

 structed the progress of Geology, obstructing it still, 

 more than ever, in the case of the secondary strata ; 

 as the evil effects increase, the higher we ascend in 

 the series, from the increasing independence of the 

 deposits. There is no chance of our becoming truly 

 acquainted with the deposits under review, till Geo- 

 logists shall substitute real observation and descrip- 



