88 ME. GARDIXER AND PKOF. REYNOLDS ON THE [Feb. I9I2, 



eastern exposure on the small peninsula opposite Kilbride Rock the 

 dip of the exposed rocks is south erl}-. We regard this as a local 

 inversion. 



On Kilbride Eock the Calcareous Flags are seen, and we have 

 thought it best to map them to the south of the red-shale outcrop 

 on the mainland, despite the fact that they have not been detected 

 there, and although certain large blocks doubtfully in situ appear 

 to bear a greater resemblance to the Red Sandstone. 



The greater part of the area between Bird Hill and Kilbride 

 Rock is occupied by a fine development of the Annelid- Grits, 

 which show the characteristic tubes probably as well as anywhere 

 in the Kilbride Peninsula. The rocks betray signs of disturbance, 

 and discordant dips are noted. In the neighbourhood of Bird Hill 

 the Annelid-Grits are faulted against lime-bostonite and red 

 sandstone, which strike in a north-north-easterly direction. 



IV. Field-Relations of the Intrusive I&neous Rocks. 



{a) The Felsites. 



Felsite is intruded only in the Arenig rocks, for at Knocknamuck 

 (the only place where it is found in contact with the Silurian 

 sediments) the junction is almost certainly a faulted one ; and 

 west of Knocknamuck lime-bostonite has been intruded at the base 

 of the Llandovery strata, separating them from the felsite on which 

 they were doubtless originally deposited. Felsite occurs principally 

 in one enormous mass of very coarsely-quartzose rock, which stretches 

 along the southern shores of Derrypark Bay from Knocknamuck 

 to above Red Island. Although it does not form the summit of 

 Knock Kilbride, the highest point in the area, it gives rise to some 

 of the steepest and most rugged country. Two small masses of the 

 same type of felsite, each having a length of some 250 yards, lie 

 to the west of the main mass, the more westerly being bisected by 

 a band of grit and cut off on the west by the Oak Island Fault. 



Three very small intrusions of the somewhat coarsely-quartzose 

 felsite penetrate the spilites or breccias near the top of the water- 

 shed south-east of Lough Mweelaun; while two other small in- 

 trusions occur on the borders of the breccia and spilite a third of a 

 mile south-west of this Lough. 



Felsite of a type somewhat different from those just mentioned, 

 and devoid of conspicuous quartz-crystals, forms Red Island and a 

 narrow strip on the shore south and west of it. A mass of felsite, 

 about 300 yards long and 200 yards broad^ occurs north of Finny : 

 it is of a type similar to the felsite of Red Island. 



