i Guettarfs Volcanic Theory 41 



error, but the error was general in his time, and was shared 

 in by his most illustrious contemporaries. " For the pro- 

 duction of volcanoes," he remarks, " it is enough that there 

 should be within these mountains substances that can burn, 

 such as petroleum, coal or bitumen, and that from some 

 cause these materials should take fire. Thereupon the 

 mountain will become a furnace, and the fire, raging 

 furiously within, will be able to melt and vitrify the most 

 intractable substances." 1 He finds evidence in Auvergne 

 of this presumed connection between the combustion of 

 carbonaceous substances and volcanic eruptions, and he cites 

 in illustration the Puy de Crouel and Puy de la Poix, near 

 Clermont, where the black bituminous material can actually 

 be seen at the surface. Summing up his observations he 

 concludes thus : " I do not believe that the reality of our 

 volcanoes will now be called in question, save perhaps 

 from anxiety for the safety of the districts around them. 

 For myself, confident as to the first point, I confess that I 

 share in the anxiety regarding the second. Hot springs 

 have generally been regarded as due to some kind of 

 concealed volcanoes. Those of Mont Dore rise at the very 

 foot of the mountains ; those of Clermont are only some 

 two leagues from the chain of the Puys. It may very well 

 be that their high temperature is kept up by the same 

 internal fires which formerly had a communication with 

 these extinct volcanoes, or might now easily establish one 

 should they increase in activity." 2 



His fears for the safety of the Auvernois were by no 



1 Trans. Roy. Acad. Sciences for 1756, p. 52. This suggestion is 

 severely criticized by Desmarest, but it was subsequently adopted by 

 Werner, and became a prominent item in the Wernerian creed. 



2 Op. tit. p. 53. 



