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. 
8 
The 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. 
9. 
a. Limestone. b. 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. 
