in The Wernerian Theory of Basalt 125 



where these are covered by sheets of basalt and wacke, and 

 that eruptions of lava take place when these overlying rocks 

 are melted by the combustion of the coal. He thus pro- 

 vided himself with a triumphant answer to any objector 

 who felt inclined to question his dictum as to the origin of 

 basalt. If the rock occurred on isolated hill tops, it was a 

 member of the Floetz-trap formation produced by universal 

 chemical precipitation. If it was found in the condition 

 of lava, the original precipitate had been fused by the 

 burning of underlying seams of coal. 



With so flexible a theory to defend and apply, it can 

 be understood how the pupils of the Freiberg school 

 scouted the idea that volcanoes were of any real geognosti- 

 cal importance, and how they had a ready answer to any 

 opponent, or a prompt explanation of any apparent diffi- 

 culty in the acceptance of their master's teaching. If any 

 one claimed that basalt was of volcanic origin, he was at 

 once confidently assured that this was an entire mistake, 

 for the great law-giver of Freiberg had pronounced it to 

 be a chemical precipitate from water. If he ventured to 

 quote the columnar structure as in favour of his view, he 

 was told that he ought to know that lava never assumed 

 this structure, 1 and that "rocks which have been formed 

 or altered by the action of heat are most distinctly different 

 from those that constitute the great mass of the crust of 

 the globe." 2 If he brought to the unabashed Wernerian 

 a piece of obsidian, and asked whether such a rock should 

 not be admitted to be a volcanic glass, " Nothing of the 

 kind," would have been, in effect, the immediate reply. 

 " It is true that the rock does resemble ' completely melted 



1 Jameson, op. cit. p. 58. 2 Op. tit. p. 74. 



