150 MEETINGS. 



syenitie, and the relation of these two rocks to each other is 

 a point requiring further investigation. To the east of the 

 junction a small fissure cave has been produced by the erosion 

 of a diorite dyke. This cave is about 65 feet in depth, 25 

 feet high at the entrance and 5 feet average width. Still 

 further east is a picturesque natural arch formed along lines 

 of weakness caused by intruding dykes of felsite and diorite. 

 To the west of the junction a mica trap dyke occurs. Its 

 strike is apparently north and south, and being at least 

 twenty feet wide, it ranks among the most important in this 

 Island. 



SARK. 



A portion of the north-east coast of Sark was examined 

 on the 21st August, 1897, in most unfavourable weather. At 

 l'Eperquerie landing the rock is syenitie gneiss resembling 

 that of Richmond, and, like it, containing inclusions of diorite 

 drawn out into lenticular masses and bands. As the coast is 

 followed to the south-east, and the junction between the 

 syenitie gneiss and the hornblende schist so largely developed 

 in Sark is approached, the appearance of some of these 

 inclusions seems to indicate that they are portions of the 

 schist caught up and modified by the gneiss which was 

 originally an igneous rock. 



Large dykes of amorphous diorite resembling our talvane 

 cut both the syenitie gneiss and the schist, and are evidently 

 posterior in date. The junction between the gneiss and the 

 schist is obscured by the intrusion of several of these dykes, 

 and also by faults. This junction may be seen repeated on 

 both sides of a small cove to the south of the Eperquerie. 

 In the section on the north side of this cove, a strip of schist 

 about a yard wide runs vertically up the cliff bounded by 

 syenitie gneiss on one side and by diorite on the other. The 

 boundary between the gneiss and the schist is very distinct, 

 and is evidently a fault, while the diorite on the other side is 

 intrusive. On the south side of the cove veins of syenitie 

 gneiss may be seen intruding in the schist, but owing to a 

 fault (along which a natural arch has been formed by erosion) 

 the connection of these veins with the main body of the 

 gneiss cannot be traced. These veins cut across and disturb 

 the f elspathic and granitoid bands in the schist, which bands 

 are therefore anterior to the intrusion of the gneiss. That 

 the schist itself with its bands is also of igneous origin 

 appears probable from the fact that the bands may be seen 

 occasionally to pass into veins cutting the foliation at all 



