GEOLOGY OF THE CAMPSIE HILLS. S9 



gating, that, in the district above described, he 

 could perceive no effects either as to matter or 

 form, that might not have been produced by at^ 

 mospheric action alone ; nor could he perceive 

 any appearances in the various strata that occur 

 under the trap, that indicated in any degree, in- 

 terior heat having ever acted upon them. It is 

 well known, that with regard to geology, there 

 are two systems very different from each other, 

 and by the tenets of these systems, they are 

 widely separated. The adopters of these systems 

 are in general keenly bent towards their support, 

 and fiercely argue upon the propriety of their dif- 

 ferent creeds. 



One class of those philosophers, hold, that the 

 polygonal forms which have been here described 

 as belonging to the Campsie Hills district, are of 

 aqueous origin ; and some of this class, even go 

 so far as to say, that the columnar forms found so 

 frequently in the vicinity of volcanic regions, 

 have not assumed that form in consequence of 

 volcanic fire, but that such columns have been on- 

 ly detached from their interior native rocks by 

 the violence of volcanic shocks, and have been 

 ejected in their native state unchanged by vol- 

 capic fire. 



The other class of philosophers, hold these 

 forms to have been produced by the agency of 

 volcanic fire, or from internal heat proceeding 



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