the Tertiary Formations. 26S 



and that thus the differences of dimate beginning to be esta- 

 bhshed, or becoming more decided, different vegetables must 

 have grown in the different zones of the earth, and different ani- 

 mals have peopled a soil, whose vegetation was no longer the 

 same. 



But if at the time of the deposition of the lias the earth was 

 already divided, as it now is, into different zones, each of which 

 was characterized by animals and vegetables peculiar to itself, 

 ought it not equally to be concluded, that the geological times 

 were less remote from the present epoch than has hitherto been 

 supposed ? In fact, the crystalline deposites, which seem to have 

 been solidified anteriorly to the appearance of living beings up- 

 on the globe, and which alone are of any importance with refe- 

 rence to the solidity of our globe, are probably only the result 

 of the diminution of the earth's temperature ; or, in other 

 words, a pure thermometrical effect, while the deposites which 

 contain remains of organised bodies enter into the effects pro- 

 duced within the limits of causes at present in action. The ter- 

 restrial globe has undergone modifications in its formation, as 

 the other planetary bodies probably have ; but it has not under- 

 gone great and numerous revolutions, unless the name be given 

 to the last inundation, which has scattered the diluvium over a 

 considerable extent of the lower part of our planet. 



What at least appears certain, is, that the distinctly stratified 

 tertiary deposites have been produced by causes which had no- 

 thing violent or irregular in their action, and that all have taken 

 place in the bosom of the same fluid, whatever diversity there 

 may have been in the habitation of the animals and vegetables, 

 whose remains they contain *. It also appears certain, that the 



• This opinion is also that of M. Constant Prevost, who announced it lone 

 ago ; but it is not admitted by all geologists, and it can only as yet be consi- 

 dered as a theory possessed of more or less probability. We hope to be able 

 shortly to publish an article in which this opinion will be carefully exa- 

 mined, and in which the facts that are favourable or contradictory to it 

 will be comparatively discussed and weighed. For the present we shall 

 merely observe, that we are far from adopting the theoretical opinions con- 

 sidered as positive facts by the author of this memoir; and that, in general, 

 we are desirous of collecting in these annals the most discordant opinions, 

 and those most foreign to our own ideas, when they are deserving of being 

 submitted to the general examination of naturalists. — Editok. 



