94 Mr. Moyh on Granite Veins. [Au6i 



containing its iisual quantity of mica ; whereas what composes 

 the veins has always a slaty fracture, contains Uttle or no mica, 

 and has a white chalky appearance. ji^it dj^ ■ i 



" A protruding mass of granite from the base of the eastern 

 side of this recess to the height of 25 or 30 feet {/). It is of a 

 very singular outline, yet does not appear to have shown the 

 slaty laminae reposing on it out of their usual direction." This 

 I should also denominate a granitic vein, which soon becomes 

 hid and lost on the beach from the ruins of the chfF above. It 

 has in eveiy respect the same characters as the granite of the 

 other veins ; by careful examination the slate may be observed 

 beneath the vein, making it about 18 feet thick. Its other end 

 soon becomes lost behind the mound of rubbish in the recess, 

 and from its inclination, I should think the vein {g) on the west- 

 ern side its continuation. " The mound of rubbish in the 

 recess enabled us to ascend more than half way up the cliff, and 

 trace the two large veins before mentioned into an enormous 

 bunch of granite, which here reposes on the top of the cliff, and 

 is supported by undisturbed beds of slate ; the line of demarca- 

 tion being nearly horizontal, and at an elevation of 60 or 70 feet 

 above the level of the beach. The denuded face of this bunch 

 of granite is 30 or 40 feet thick. Two or three veins appear to 

 take their origin from this anomalous overlying mass. One 

 spreads out in minute ramifications towards the part of the cliffs 

 which abuts towards Trewavas Point, at the termination of the 

 killas in that direction. Two others descend obliquely, and are 

 lost behind the lar^e mound of rubbish before mentioned." 



The whole of the slate has an evident incHnation to the 

 east at an angle of about 15°; and in no part of it traversed 

 by the granitic veins, are its laminje, Sec. interrupted. There 

 are evident symptoms of these veins being formed subsequently 

 to the slate ; for in one part of the vein (c), there is a shght 

 fissure running perpendicular through the slate until it meets the 

 vein, which fissure may be again seen on the opposite side of 

 the vein holding its direct course. Several small quartz veins 

 traverse the slate in all directions, but observe the same law as 

 regards the granitic vein ; and in no part whatever could I find 

 either fissure or quartz vein of the slate to penetrate the granite 

 (except the one before mentioned, where the granitic vein is 

 heaved by it) ; but in every instance to present themselves as in 

 fig. 5. 'the slate does not make its appearance more than 200 

 feet west of this recess. 



I am, dear Sir, your humble servant, 



M. P. MOYLE. 



