62 The Founders of Geology LECT. 



are to be found among the ejections of old volcanoes, and 

 the inference would naturally suggest itself that the fires 

 kindled by the combustion of carbonaceous substances 

 underneath a volcano might fuse the surrounding and 

 overlying rocks, and expel streams of molten material. 

 We shall find that Werner adopted this view, and that 

 through him it became predominant over Europe even 

 after more enlightened conceptions of the subject had 

 been announced. 



Desmarest does not seem to have had at this time, if 

 ever, any very definite conception of the origin of the 

 high temperature within volcanic reservoirs. Nor had 

 chemistry yet afforded much assistance in ascertaining the 

 resemblances and differences among rocks and minerals. 

 His mistakes were thus a faithful reflex of the limited 

 knowledge of the period in which he wrote. 



In the second part of his Memoir, Desmarest gives a 

 historical narrative of all that had been written before 

 his time on the subject of basalt. The most interesting 

 and important passages in this retrospect are the comments 

 of the author on the writings he summarises, and the 

 additions which he is thereby enabled to make to the 

 observations already given by him. He confesses that, 

 had he begun his investigations among such isolated 

 patches of basalt as those capping the hills in Cassel and 

 Saxony, he would never have been able to affirm that 

 basalt is only a lava. But he had encountered such 

 perfect demonstration of the volcanic nature of the rock, 

 tracing it with its fresh scoriae up to the very craters 

 whence it flowed, that he could not allow this clear 

 evidence to be invalidated, or even weakened, by cases 



