14 MEETINGS. 



has been exposed by a landslip, on the north-east of the island. 

 This specimen contains good crystals of quartz, white or slightly 

 pink felspar, and hornblende well crystallised. I have carefully 

 examined the specimen for mica, but I cannot satisfy myself that it 

 is present. The stone weathers first whitish, owing to the formation 

 of kaolin, and then into green and red shades. 



No. 2 is a specimen taken from the out-crop overhanging the 

 beach opposite Crevichon. This specimen brings out the effects of 

 weathering fairly well, but gives us no new facts. 



No. 3, taken from the west side, is different in colour, owing to 

 its containing less quartz and more felspar. 



No. 4 is a piece of quartz from the only vein I saw ; this specimen 

 gives the width of the vein. The absence of mica in the adhering 

 decomposed rock, is, I think, sufficient proof of the syenitic nature of 

 the rock. 



No. 5, a close-grained variety, which gives some idea of the 

 changes due to weathering. In these the formation of kaolin is 

 plainly visible. Pink felspar has also been largely replaced in the 

 rock by a brick-red variety. 



No. 6. — This specimen I consider one of considerable interest. 

 In passing along the north-east face, I was struck by a band of red 

 rock some three feet wide, running from the beach into the sea, 

 having all the appearance of an intrusion. I spent some time here 

 endeavouring to obtain a good representative piece, but I had to 

 satisfy myself with a piece partially weathered owing to the impossi- 

 bility of removing specimens from the unweathered portions with 

 the means at my disposal. The matrix of the rock is red felspar ; 

 besides this there is a white variety, some quartz and a green 

 mineral. The latter I am inclined to look upon as a decomposition 

 product, probably viridite^ but I may be mistaken. The colour is too 

 light for chlorite, too dull for mica, as well as incorrect in shape. 

 This is probably a rock, the true nature of which can only be 

 determined by a petrographic examination. 



If I am correct in my idea of the constitution of this band, it is 

 a felstone and an intrusion. The red and green colours give to this 

 intrusion a peculiar appearance, and it strikes me as quite peculiar 

 to Jethou. At all events I do not remember seeing an equivalent 

 rock in Guernsey. 



I do not look upon this paper as exhaustive, and consider the 

 points I have raised to be mere indications of the work to be done. 

 I think, however, that we are justified in believing the rocks of 

 Jethou to be distinct modifications well worthy the study of an 

 expert. 



Mr. Roberts also exhibited two specimens of the rocks 

 of Crevichon. Votes of thanks to Mr. Austin Lee for 

 permission to visit Jethou, and also to his agent, Mr. J. 

 Torode ; to the readers of the papers, and to the Secretary 

 for organising the excursion, brought the meeting to a close. 



