POMEL ON THE PALEONTOLOGY OF xiUVERGNE. 67 



It follows that the alluvia and conglomerates of all these last- 

 mentioned places form a system of deposits posterior to those of 

 Perrier, from which they are also separated on zoological considera- 

 tions. 



It appears then that during the Diluvial period the centre of France 

 has not only been deluged by lavas, but has been even still more 

 violently convulsed by the later basaltic eruptions. It was therefore 

 during that basaltic period that the extraordinary and complete change 

 of animal life took place ; a change respecting which we have suf- 

 ficient data for asserting, that it did not result from the state of local 

 disturbance to which central France was then subject. The phse- 

 nomenon is oi a, general character, and connected most remarkably with 

 the most curious physical fact that geological research has of late 

 years brought to light. 



From the Arctic countries to the most southern parts of Europe, 

 diluvial beds frequently exhibit the singular phsenomenon of the en- 

 tombment of animals, identical with living species which now dwell 

 only in the colder regions of our hemisphere. First of all the Reindeer, 

 then the Lagomys, the Spermophilus, and less frequently the Glutton, 

 and, what is not less remarkable, the Marmot, and a prodigious num- 

 ber of Bears, are found in the very lowest and most southern plams, 

 where they could not exist at present, or only in very small numbers, 

 from their habits and constitution being so opposed to the conditions 

 of the climate. The MoUusca present the same remarkable fact of 

 being found distant from their present habitats. But it is still more 

 remarkable that, associated with these species now existing only in 

 polar regions, we find other animals whose congeners at the present 

 day belong exclusively to tropical countries. These last however, be 

 it observed, are distinct from existing species, and the wonderful pre- 

 servation of the soft parts of some shows them to have been orga- 

 nized so as to endure a rigorous climate. Besides, whenever species 

 are not identical, it is impossible from a knowledge of those which 

 exist, to predicate the habits and the conditions of climate necessary 

 for the existence of those which are lost. This at least is undoubted, 

 that species living at present only in snowy regions extended themselves 

 during the diluvial period over all western Europe, in countries where 

 it would be impossible for them now to exist. Is not this fact inti- 

 mately connected with the greater extension of glaciers during that 

 same diluvial period, and the consequent diminution of temperature 

 in this hemisphere ? Mr. Smith of Jordan Hill has made the same 

 observation for the MoUusca contained in diluvial beds, which he looks 

 upon as the results of ancient glaciers. M. Pictet had been struck 

 vrith the same relations, when he considered that the Reindeer was the 

 analogue of the living species ; an important question which M. Pomel 

 was the first to demonstrate rigorously. Independently of the support 

 which these facts give to the theory of the greater extension of the 

 ancient glaciers, we see in this diminished temperature the probable 

 cause of the disappearance of the previous fauna which is of an emi- 

 nently tropical character. It may be considered as established by 

 these facts, that the same causes operated over a great part of Europe : 

 and consequently the extension of the glaciers (which can be demon- 



