i 



; 







' 















n# 



alT. 





Ch. IV.] 



VULCANISTS AND NEPTUNISTS. 



71 



several geologists in Italy and elsewhere ; and his leading 

 divisions of the secondary strata were at the same time, and 

 independently, made the basis of an arrangement of the 



mith 



work I shall refer in the sequel. 



In re- 



The basalts 



,ists and Neptun 



gard to basalt and other igneous rocks, Werner' 



original, but it was also extremely erroneous. 



of Saxony and Hesse, to which his observations were cnieny 



confined, consisted of tabular masses capping the hills, and 



not connected with the levels of existing valleys, like many 



in Auvergne and the Yivarais. These basalts, and all other 



rocks of the same family in other countries, were, according 



to him, chemical precipitates from water. He denied that 



they were the products of submarine volcanos; and even 



taught that, in the primeval ages of the world, there were no 



was opposed, in a twofold sense, to 



volcanos . His 



same 



many 



imaginary causes supposed to have once effected great revo- 



become extinct 



& 



come 



instrument 



the agency of subterranean heat. 



So 



early as 1768, before Werner 



commen 



mineralogical studies, Easpe had truly characterised the 

 basalts of Hesse as of igneous origin. Arduino, we have 

 seen, had pointed out numerous varieties of trap-rock in the 

 Vicentin as analogous to volcanic products, and as distinctly 

 referable to ancient submarine eruptions. 



Desmarest 



company with Fortis, examined 



confirmed 



In 



compar 



1772, Banks, Solander, and Troil 

 basalt of Hecla with that of the Hebrides. Collini, in 1774, 

 recognised the true nature of the igneous rocks on the 

 Rhine, between Andernach and Bonn. In 1775, Guettard 

 visited the Vivarais, and established the relation of basaltic 

 currents to lavas. Lastly, in 1779, Faujas published his 

 description of the volcanos of the Yivarais and Velay, and 



