INTRODUCTION. 101 



Prudelle, near Clermont, basaltic pillars in close relationship 

 with a lava flow, and he spent many years in collecting facts 

 to prove the volcanic origin of the basalt. The work which 

 he published in the Memoires de r Academic royale des Sciences 

 (1774-75) established the igneous origin of basalt without a 

 shadow of doubt. 



Desmarest was himself so entirely convinced of the result 

 of his conclusions that he took no part in the strife between 

 Neptunists and Volcanists, but when questioned by .any .hesi- 

 tating adherents of either party he usec io , reply laconically, 

 "Go and see." 



It was remarkable how complete 1 )'. Werner, and, h]? school 

 ignored the incontestable results Of Desmarest. And the 

 later work by Desmarest, " On the Determination of different 

 Epochs of Volcanic Activity in Auvergne," was also neglected 

 in Germany (Mem. de rinst. Sc., Math, et Phys., 1806). His 

 own countrymen, however, fully realised the value of Desmarest's 

 achievements. Following the same lines as Desmarest, Faujas 

 de Saint-Fond and Abbe Soulavie made known the volcanoes 

 of Vivarais and Velay with their magnificent basaltic pillars and 

 lava streams ; so that when D'Aubisson, a student of Werner's, 

 returning to Paris from Freiberg, tried to spread Neptunian 

 doctrines, he had no success, and a visit to Auvergne con- 

 verted D'Aubisson himself to Volcanistic beliefs. 



The intellectual politician and scientific investigator, Count 

 Reynaud de Montlosier, published in 1789 an Essay on the 

 Volcanoes of Auvergne, in which he promulgated a new theory 

 about volcanoes. Like Desmarest, Montlosier recognised that 

 there were in Auvergne volcanoes of different ages. The 

 younger have preserved their typical conical form and their 

 craters uninjured. The older are for the most part situated 

 at higher levels, and these characteristic features are absent ; 

 they are connected ridges or isolated mountains composed of 

 pillared basalt, or trachytic rocks, frequently reposing on 

 granite. Whereas it is clear that the younger craters and 

 cones of loose ejected material and lava are of true volcanic 

 character, Montlosier claimed for the older and relatively 

 higher groups of igneous rocks that they represented a single 

 upheaval of an extensive viscous mass of rock-material that 

 had then cooled in the elevated position. 



The Pyrenees also attracted the attention of French geolo- 

 gists towards the close of the eighteenth century. Abbe 



