*^ is I 



le 



^Mt 



^ 



ussBit; 



w 





er 



;rat3, 

 llto 



?i3- 



•t!i^ 

 ted ^^^ 



(1 



r 



HUTTONIAN THEORY. 267 ' 



^%; yet foft, againft the abrupt fides of the ft 



V, I The rocks which formed thofe moulds have 



Jies«' many cafes, entirely difappeared ; in others, a 



,aii(i' P^^^ ^^^^ remains, furrounding, or even covering, 

 ultv J the bafaltes, as in the Euganean Hills, in thofe 

 Dryijj of the Val di Noto in Sicily, the rocks near 



Lifbon *, and in different parts of Great B 



IP V ' Above ail, the veins of whinftone which in- 



^ ' terfed the ftrata, are the completeft proofs of 



the theory here given of thefe rocks, and the 

 moft inconfiftent, in all refpeds, with the hypo- 



thefis of their volcanic origin. 



240. If thefe criteria are applied to what arc 

 called extinguifh'ed volcanoes, I have no doubt 

 W^^ that many which have been reckoned of that 



number, will be found to derive their origin 

 more diredly from the fire of the mineral re- 



■ n 



otkrt gions. The bafaltic rocks of the Vivarais, I am 

 weree well perfuaded, belong to this clafs ; and I con- 

 oid;! elude that they do fo, not only from the account 

 oft'i of them given by Mr Strange, but from the de- 



}JE} fcription of Faujas himfelf, who, though under 

 ■X ji: the influence of the oppofite theory, feems very 



fair and accurate in his defcription of pheno- 

 mena. The moft unequivocal mark of real 

 whinftone rock, and of a formation in the ftrid- 



eft 



* Recherches fur les Volcains Eteints du Vivarais 5 

 Lettre de Dolomieu, p. 443, ' 





