48 



GEOLOGY OF THE SECOND DISTRICT. 



are some inferences which will be drawn from the establishment of the doctrine, I have 

 deemed it essential that every variety of illustration should be brought to bear upon the 

 subject. 



a. Limestone. 



6. Granite. 



Tlie wood cut No. 8 exhibits another instance, or example of veins of limestone projecting 

 upwards through a mass of coarse crystalline granite. The veins of limestone widen as they 

 descend. The weathered surface of both rocks is traversed by irregular lines, but totally 

 unlike lines indicating a jointed structure. The limestone is more readily acted upon by 

 atmospheric agents, and hence its surface is below the granite ; and it is not only upon the 

 surface that decomposition is going on, but in the interior ; and the removal of calcareous 

 matter has proceeded to such an extent as to form quite large cavities, communicating with 

 the exterior. 



a. Limestone. 



6. Granite. 



The annexed diagram No. 9 exhibits four thin veins nearly parallel with each other. Phe- 

 nomena of the character represented in the cut preclude all suspicion that the granite could 

 ever have been ejected in a melted state, and have flowed over a mass of transition limestone ; 

 and were the phenomena reversed, that is, if the granite was the rock beneath, from which 

 veins shot up into the overlying mass, no doubt would have existed as to the theoretical views 

 which it would have supported. 



