Kinahan — On Granite and Metamorphic Rocks. 175 



between the granites and the associated schists are different from 

 those in Galway and Kilmacrenan. 



In north-east Mayo, Lough Conn district, the foliated granite, 

 or granitic gneiss, sends dykes and courses into the associated 

 schists. It is therefore evident that these granites were originally 

 newer than the associated rocks ; while subsequently all were 

 simultaneously foliated, the granite, as a mass, being newer than 

 the schists, but the last foliation in all being developed by one and 

 the same force. In the barony of Boylagh, Co. Donegal, the 

 greater part of the foliated granites occurs similarly to those of 

 Kilmacrenan. But at the extreme south of that barony, in the 

 Grlenties district, there are other foliated granites which seem to be 

 of the same class, and to occur more or less similarly to the granitic 

 gneiss of north-east Mayo. 



In the Co. Down the Slieve Croob granite was intruded into 

 the associated sedimentary rocks, while subsequently the margin of 

 the intrude, and a belt around it, were invaded by metamorphic 

 action, and foliation developed simultaneous in both ; the strikes 

 and dips of the foliation in both being similar. 



In the oldest granites (Post Ordovicians) of the Leinster range 

 there are two distinct structures allied to foliation. The first of 

 these is locally known as the " grain " of the granite, it consisting 

 of systems of parallel planes along which the rock splits easily. 

 This structure is often more or less obscure, and only to be recog- 

 nised by the eye of a practised quarryman ; but in some places, 

 especially in the counties Carlo w and Wexford, it is very con- 

 spicuous, giving the rocks a gneissose aspect. This structure, when 

 traced to the margin of the granite, is found to be quite distinct 

 from the foliation of the schists, the first striking more or less 

 obliquely at the latter. 



The second foliation found in the oldest Leinster granite is 

 confined nearly solely to the S.E. margin between Aughavannao-h 

 (south of Lugnaquillia), Co. Wicklow, and Killiney, Co. Dublin. 

 This structure, as in the Slieve Croob granite, seems to be parallel 

 to the margin of the intrude, and in places it strikes parallel to the 

 foliation of the associated schists. The latter, however, is not 

 always the case, as in some places the foliation of the schists strikes 

 at the margin of the intrude. In this area there were at least two 

 newer granites after the intrusion of the oldest of the Leinster range. 



