Ill 



D'Aubuisson 139 



caution in their use, and in a field which the two parties 

 dispute foot by foot, every step should be justified by an 

 observation and marked by a fact. Citizen D'Aubuisson 

 has never seen either active or extinct volcanoes. Living 

 till now in the midst of aqueous formations, we should 

 like him to visit places where fire has manifested its 

 empire. We would especially desire that he should see 

 the basalts of Auvergne, which another disciple of Werner 

 [Leopold von Buch] has just visited. That the citizen 

 D'Aubuisson knows how to observe, is shown by his 

 published works, even if the memoir we have now been 

 considering were not ample enough proof, and the interest 

 of his observations cannot be recognized in a manner more 

 useful to science than by encouraging him to continue 

 them." 



D'Aubuisson lost no time in following the advice thus 

 given to him. He went to Auvergne and found the 

 basaltic rocks there lying on granite, which in some 

 valleys could be seen to be more than 1200 feet thick. 

 If these rocks were lavas, they must, according to the 

 Wernerian doctrine, have resulted from the combustion of 

 beds of coal. But how could coal be supposed to exist 

 under granite, which was the first chemical precipitate of a 

 primeval ocean ? Such an infra-position was inconceivable, 

 and thus an apparent confirmation of the Freiberg view of 

 the aqueous origin of basalt was at first obtained. But a 

 very short time sufficed to stagger the young geologist. 

 He saw the perfect craters with their rugged lava-streams, 

 which he followed along their branches into the valleys. 

 It was impossible to resist this evidence. "The facts 

 which I saw," he says, " spoke too plainly to be mistaken ; 



