STRUCTURE OF COUNTRY. 33? 



but its upper part was one crystalline mass of stems 

 of encrinites, some small, some of half an inch in 

 diameter, broken and disjointed. I searched in vain 

 for any head of an cncrinite, but the stems are pre- 

 cisely like those of the mountain limestone. I did 

 not succeed in find in g the bed from which this 

 block was detached, nor any similar bed, the bank 

 having a gentle slope, and being much covered with 

 debris from above ; but from the aspect of its lower 

 laminated portion, I have no doubt it belonged to 

 the red shale formation. About a quarter of a mile 

 farther up the brook, the valley contracts into a 

 narrow ravine with precipitous sides, but here the 

 only rocks exposed were cliffs of coral-limestone, 

 with a large, talus of debris at their foot. In this 

 debris were many recent shells, among which T 

 found one terebratula. 



I must confess the facts stated above are sufficiently 

 slender to prevent any decided inferences being 

 drawn, and it was a source of great regret to me 

 that time and opportunity did not allow of extending 

 my observations ; but I have little doubt that this 

 red shale and limestone, with associated trap rocks, 

 belongs to an old secondary formation, the substra- 

 tum of the country, and it is possible its age is not 

 greatly remote from that of the carboniferous forma- 

 tion of Western Europe. The trap rock may possibly 

 be the cause of its appearance at this spot, but it 

 would probably be found again at the surface in the 

 neighbouring valleys or ravines, or wherever the 



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