1 44 The Founders of Geology LECT. 



" Here," he says/' we find a veritable model of the form 

 and degradation of a volcano, such as cannot be found so 

 clearly either at Etna or Vesuvius. Here at a glance we 

 see how the lava has opened a way for itself at the foot of 

 the volcano, how with its rough surface it has rushed down 

 to the lower grounds, how the cone has been built above it 

 out of loose slags which the volcano has ejected from its large 

 central crater. We infer all this also at Vesuvius, but we 

 do not always see it there as we do at the Puy de Pariou." * 



Perhaps the most interesting passages in Von Buch's 

 brightly-written letters are to be found at the end. The 

 obviously volcanic origin of the rocks in Auvergne, and 

 their position immediately above a mass of granite through 

 which the craters had been opened, had evidently power- 

 fully impressed his mind. With all these recent vivid 

 experiences he reflects upon his earlier wanderings among 

 the basalt hills of Germany, and, as if taking his readers 

 into his inner confidence, he declares that " it is impossible 

 to believe in a particular or local formation of basalt, or in 

 its flowing out as lava, when we know what the relations 

 of this rock are in Germany, and when we remember how 

 many different kinds of rocks are there associated with 

 basalt as essential accompaniments, how these rocks form 

 with basalt a connected whole which is absolutely incon- 

 sistent with any notion of volcanic action a peculiar coal- 

 formation, entirely distinct from any other, only found 

 with basalt and entirely enclosed among basaltic rocks, 

 often even a peculiar formation of limestone." 2 



This was the one side of the picture. He could not yet 

 break entirely the Wernerian bonds that held him to the 



1 Op. cit. p. 240. 2 Op. cit. p. 309. 



