344 Dr BoLie oil the Formation of Tertiary Rocks. 



These obvious facts M. Brongniart seems to forget, when he 

 remarks, " Qu'il ne pent admettre des bassins entoures de ma- 

 niere a en faire autant de Caspiennes, dans lesquelles les pheno- 

 menes et les productions auront ete differens, qui se seront 

 trouvee a differentes hauteurs, dans lesquelles les phenomenes 

 geologiques auront eu des durees tres-diverses,''' (p. 202). The 

 structure and form of the tertiary deposits do not, according to 

 this geologist, support that idea, yet what a difference does not 

 M. Brongniart point out between the basins of Paris and of 

 Switzerland, those of London and of Auvergne, &c. As he 

 does me the honour of quoting my geological map of Europe 

 as a proof of the extent of tertiary deposits^ I use the liberty of 

 requesting him to compare their geographical distribution with 

 our idea, and to see the conformity of both. The actual state 

 of things, far from being unfavourable to our opinion, is, on the 

 contrary, much in favour of it, as we observe seas, as the Medi- 

 terranean and Red Sea, the Caspian and Black Sea, the Pacific 

 and Atlantic, near each other differing but little in their levels. 

 Now, supposing these seas to be dried up, we would have in each 

 of them peculiar deposits of limited basins. The differences of 

 level have been formerly greater, while the actual upraising 

 of continents are trifling in proportion to what formerly took 

 place. We must beheve that M. Brongniart starts from the 

 principle of Von Buch, that the chains have been produced du- 

 ring the alluvial period, and that Europe has been thus unequally 

 elevated; at least M. Brongniart tells us positively that, during 

 the saturnian or old alluvial period, " les plupart des mon- 

 tagnes on ete elevees, et les couches ont ete soulevees, inclinees, 

 courbees et brisees,"'"' (p. 64). The works of Steno, of Heim, 

 of Jobert, of E. Beaumont, and our own, contain proofs enough 

 that, on the contrary, the number of hills elevated has been less 

 in the alluvial period than in the preceding one. 



On this supposition of M. Brongniart, it is evident that the 

 basins would have had every where the same level, but then the 

 tertiary soil, in place of being distributed in basins, would have 

 covered the whole of Europe. M. Brongniart does not go so far 

 as Mr Martin *, who forms the tertiary basins after the deposi- 

 tion of the tertiary deposits^ M. Brongniart admits the existence 



*^ Qn the Denudation of Sussex, 1828-. 



