4O The Founders of Geology LECT. 



As if no discovery was entitled to the name unless it had 

 been elaborated in the fullest detail and followed to its 

 remotest consequences. When one of Guettard's country- 

 men and contemporaries could write thus of his claims to 

 recognition, it is not surprising that for the best part of 

 a century his name should have almost entirely passed 

 out of mind. 



That Guettard preceded every one else in the recognition 

 of the old volcanoes of Auvergne, and that he thus became 

 the originator of the Vulcanist party in the famous warfare 

 of the end of last century, in no way diminishes the claim 

 of Desmarest to occupy the foremost place among the 

 Vulcanists and to be ranked as the real founder of volcanic 

 geology. I shall have occasion to dwell at some length 

 on Desmarest's work, which for accuracy and breadth has 

 never been surpassed. 



Guettard, having never seen a volcano, was guided in 

 his observations and inferences by what he had read of 

 volcanic countries, and what he had learnt about lavas by 

 familiarity with specimens of these rocks brought from 

 Vesuvius and other modern volcanoes. He noted the close 

 resemblance between the rocks of Auvergne and the Italian 

 lavas, not only in appearance, density and other characters, 

 but in their position on the ground, the specimens which 

 he had gathered from the bottom, sides and crests of the 

 puys having each their own distinctive peculiarities, as in 

 existing volcanoes. He compared the curved lines on some 

 of the rocks of Mont Dore and the Puy de Dome with the 

 ropy crusts of certain Vesuvian lavas. 



When this distinguished man stepped from the observa- 

 tion of fact into the region of theory, he at once fell into 



