466 OBSERVATIONS ON TRAP ROCKS. 



who require that a theory should explain and reconcile all 

 the phenomena connected with its subject, it may be an- 

 swered, that it is conceded by many advocates of the Hut- 

 tonian system, that some basaltic rocl<s may have been 

 formed in the humid way from eruptions of mud such as 

 issue from some volcanoes in South America : not those that 

 are properly called mud volcanoes, which are destitute of 

 heat, and whose eruptions are produced by a fermentation 

 in which common salt is supposed to be concerned ; but ac- 

 tual fire volcanoes Into which water has found its way. In 

 this manner a different origin may consistently be attributed 

 to the rocks of both places. But I do not say that tlie trap 

 of the Connewago Hills is not a volcanic product, but only 

 that it exhibits no peculiar indicia of igneous origin. 



In conclusion, however, it must be acknowledged that the 

 footsteps of the agent employed to work those grand changes 

 of which we every where see such convincing proofs, are so 

 intricate and confused, that we never can expect with abso- 

 lute certainty to trace them home. The Huttonian system, 

 though open in some of its parts to strong objection, affords 

 the most rational solution of the most important phenomena 

 of the earth, and must eventually gain ground. Connected 

 with this subject there are few facts so devoid of interest as 

 to be unworthy of being communicated ; and the author of 

 these observations therefore trusts he will not be considered 

 a trespasser on public attention, by 'having given them pub- 

 licity. 



