374 ON VOLCANOES AND EARTHQUAKES. 



distinguish modern volcanoes may have been wasted 

 away; how the craters, the narrow and shallow cur- 

 rents, and the loose materials, may have vanished; 

 leaving nothing remaining but those solid rocks which 

 are no longer distinguishable from trap; or rather 

 which are real members of that family. 



If it is still a doubt among geologists whether the 

 Euganean hills are formed of trap, or whether they 

 are of volcanic origin, we must expect similar difficul- 

 ties elsewhere ; and till geologists shall think fit to 

 adopt more philosophical views, such difficulties must 

 ever remain ; as they will be always explained by the 

 particular prejudices of the observer. The very vol- 

 canoes of Auvergne might thus also equally claim to 

 be of the trap family, as they were once supposed : 

 while they form that intermediate link which is want- 

 ing to connect together two very distant periods of 

 eruption, or the two classes of phenomena, and thus 

 to prove the identity of both. Hence the Volcanic 

 Theory of the Earth, as it has been called, assumes a 

 form, which those who have taken a different view of 

 the effects of internal heat had neither the knowledge 

 nor the judgment to understand. The theories are 

 the same, under different names : but the self-imagined 

 improvers on Lazzaro Moro constructed a system out 

 of their own ignorance, disclaiming the teacher whose 

 facts they could not comprehend ; and willing, too, 

 perhaps, to pass for inventors. The volcanoes which 

 now elevate great tracts of land, whether from the 

 bottom of the sea or on the shore, have operated the 

 same effects in more antient times. I have shown 

 that these have been partial as well as general, and 

 that they have also been of different ages. By attri- 

 buting the greatest catastrophes of this nature to the 

 same causes as the smallest, an igneous system be^ 



