g90 T. G > BONN BY ON TIIB SERPENTINE AND 



We pass now along the edge of the cliffs northward ; these are 

 not seldom so precipitous as to make a close examination impossible. 

 The serpentine varies in character, being sometimes didl and com- 

 pact, sometimes redder in colour, and containing larger bronzito 

 crystals. The headland called the Horse is remarkable for the 

 boldness of the jagged rocks that form its crest, which in form, 

 colour, and even in aspect, recall memories of the gabbro of the 

 Cuchullin Hills ; the rock, however, is an ordinary serpentine. 



Nearly a mile in a direct line north-west from Kynance is a cove 

 called Gue Graze. A gully on the north side exhibits a granite 

 vein; it resembles that already seen*. On descending to the beach 

 we find the serpentine is in places much brecciated and cemented by 

 steatite, which is here abundant. Much of the serpentine on the 

 beach is rather peculiar in appearance (no. 5), being of a dull red 

 colour, with obscure dark greenish lines, a slightly rougher fracture, 

 and (under the lens) more granular texture than common ; it is 

 also remarkable for hardness and the absence of conspicuous bronzite. 

 In many places it is sand-polished. The joints are often coated, as 

 usual, with films of green steatite. 



Returning to the higher ground and passing Vellan Head, we con- 

 tinue to observe the apparently stratified structure in the serpentine, 

 which sometimes even seems to mimic current-bedding. Near the 

 Head its dip is fairly persistent, about 50° south ; but this does not 

 continue for long ; I observed, however, that it was often parallel 

 to one of the leading systems of joints ; and hereabouts fairly defined 

 tabular jointing is not unusual. The end of the serpentine is reached 

 at a spot called Ugethawr, on one side of George's Cove, to the south 

 of the place where a well-marked valley descends to the sea ; thus 

 the breadth of this practically uninterrupted tract of serpentine, 

 measured in a straight line from sea to sea, is about 2\ miles. I could 

 not find the actual junction of the hornblende schist and serpentine 

 on the rocky slope ; but it is possible to scramble down to the water's 

 edge, and there it can be discovered in a little sea-cave. It is in 

 many respects an interesting one. The hornblende schist is rather 

 compact and very dark ; so also is the serpentine, especially near the 

 junction — so compact, dark, and hardt, indeed, and with so con- 

 choidal a fracture, that at first sight it might readily be mistaken for 

 Lydian stone ; it overlies the hornblende schist, which here dips 

 rather evenly about 60° W.N.W., and seems to be closely welded to 

 it. One or two thin tongues of serpentine are thrust into the schist 

 within a foot or two of the junction. The serpentine is therefore 



* The granite of Gue Graze may be regarded as fairly typical of the veins on 

 the west coast ; so that it is the only one which I have examined microscopically. 

 It consists of quartz and felspar, both orthoclase and plagioclase. There is a 

 scale or two of magnesia mica, a good many small clusters of minute granules of 

 magnetite, with some fine needles and asbestiform fibres, some of which I think 

 are tourmaline. There ia an orthorhombic mineral of secondary origin here 

 and there in the felspar, probably prehnite. One rather abundant microlith 

 seems to be apatite ; but there is probably another mineral also present. Alto- 

 gether there are a good many included microliths and some minute cavities. 



t Its hardness varies slightly, but is about 5. 



