Ne7V Observations on Volcanoes and their Lavas. 225 



tains of the coiuitrv. In common with other travellers, he 

 has remarked that, the mountains of Giiancavelica being ma- 

 rine productions, there were sea fossils in them 5 but he has 

 not remarked that, the Cordeliers of the Andes being com- 

 posed of volcanoes, several of which are still burning, there 

 could not be any marine deposit there. It would be very 

 interesting to know the limits of these two classes of moun- 

 tains, so difl'erent from each other; in what place the one 

 finishes and the other begins, and in what manner they join. 

 We may conjecture, with good reason, that the volcanic 

 theory will maintain itself against the Neptunian. 



An opinion which I constantlv maintained with M. Do- 

 lomieu, and some other naturalists, viz. that basaltes are of 

 volcanic production, is confirmed, in the most distinct man- 

 ner, by the observations made by M. Daubuisson in Aii- 

 vergne. Thus, what I said at the conclusion of my Ob- 

 servations upon Basaltes is completely verified : *' The time 

 will come when naturalists belonging to the Neptunian 

 theory will no longer dispute the volcanic origin of basaltes j 

 for, the more inquirers there are, the more observations are 

 multiplied, and in different places, the more shall we acquire 

 a demonstration that, basaltes are a production of fire." — 

 Journal dc Physique, cahier de Fructidor, an. 9. 



Mr. Kirwan, as a proof that basaltes are of sea origin, has 

 instanced some basaltes which contain marine shells. I was 

 persuaded that this was a mistake, and I said so in the ob- 

 servations I made on the subject : since that time my con- 

 jecture has been completely verified. 



I have seen some pieces of this stone, said to be basaltes, 

 containing shells, brought from Ireland by professor Pictet. 

 This stone is not basaltic. It is disposed in horizontal layers 

 on the sea coast in the county of Antrim ; and the true ba- 

 saltes have nothing in common with it except the colour, 

 which is nearly similar. The shells it contains are those of 

 ammons ; a kind of shell unknown in animated nature, and 

 which is found only in the argillaceous ,or calcareous depo- 

 sits of the anlient sea. 



There is this important geological fact shown by volcanic 



mountain?, — that they have been much more numerous i'or- 



P 2 merly 



