Ch. VIII.] THE GRANITIC AND SCHISTOSE ROCKS. 151 



are vertical, others are inclined at different angles, and some 

 are perfectly horizontal. In one part of the Cove, where one 

 of the veins inclines at an angle of full 45, the slate is fallen 

 from the upper side, and has left a part of the vein exposed 

 to view. Near the same spot is an apparent intersection of 

 one granite vein by another, each of which is about a foot 

 wide. One of them appears to be heaved five feet to the left.* 



" In a great majority of instances," observes Professor 

 Sedgwick, "we are unable to trace the veins to the point 

 where they terminate in the granite: the nature of such 

 termination can only be made out by analogy. Fortunately, 

 some parts of the coast expose the base of the veins in such a 

 way as to leave no doubt respecting their origin. The best 

 example of this fact may be seen at the last junction near 

 Wicka Pool. Three large veins rise out from the granite 

 into the slate : the first soon disappears ; but the other two, 

 after being cut off by the retreat of the coast, re-appear in two 

 or three successive projections of the cliff. The largest of 

 them, at its insertion into the slate, is not less than fifteen 

 feet wide : at their lower termination, they are all distinct 

 prolongations of the granite itself, and in composition differ 

 from it in no respect whatever. They also contain imbedded 

 fragments resembling clay-slate; and, at a short distance 

 from their base, have the ordinary appearance of the granite 

 veins." f 



" A little south of the Pier, at the village of Mousehole, 

 near Penzance," says Mr. Majendie, " the clay-slate ceases, 

 and the granite commences, forming a promontory which 

 runs out in a southern direction from the central ridge. 

 The grey-coloured slate is in strata nearly horizontal, but 

 having a slight dip to the east ; it increases in hardness near 

 the junction. The granite, which is generally coarse and 

 porphyritic from the large imbedded crystals of felspar, 



* Geol. Trans, of Cornwall, vol. ii. p. 68. 



f Cambridge Philos. Trans. On Devon and Cornwall. 



L 4 







