^ XIII. 0« the Junction of Trap and Sandstone^ 



at Stirling Castle, 



i3y J. Mac Cullocii, M.D. Chemist to the Ordnance, and Lecturer on 



Chemistry at the Royal Military Academy at Woolwich. 



V, Pr. Geo. Soc. 



I 



HAVE herewith transmitted a sketch of one of those circum- 

 stances in the mutual relation of greenstone and sandstone, from 

 which the Huttonian theory is presumed by its advocates to derive 

 so material a support. The particular instance, of which this sketch 

 is intended to give a general notion, has been lately brought to 

 light, and has not, as far as I know, been observed by the geolo- 

 gists of Edinburgh. It does not indeed differ so greatly from the 

 same class of facts in the neighbourhood of that city, as to require 

 very particular attention ; but I have been induced to preserve this 

 notice, and drawings of it, (PI. 12, 13) partly on account of its 

 decided and clear disposition, and partly, lest the same operations by 

 which it was first exposed, may, at no distant period, again remove 

 or overwhelm it. Nevertheless, it may have its use in extending 

 the analogy between those classes of rocks in which this appearance 

 is found, and in rendering it probable that the same cause, whatever 

 it was, presided at the formation of all similar phenomena. 



The rock on which Stirling Castle is built, and on which the town 

 also is founded, resembles so strongly that on which Edinburgh 

 stands, that it would be superfluous to describe it very particularly. 



Vol. II. 2 q^ 



