Lower Palceozoic Rocks of the South- East of Ireland. 569 



veiled from the more deeply seated portions towards the surface. This view, 

 however, is opposed by the fact that in no case can any direct connexion be 

 now traced between the granitic masses and the felstones, and that, although 

 the elvans are certainly most numerous in what we believe to be the lower beds, 

 yet they never traverse those beds directly across for any great distance, but 

 always run in lines parallel to the main strike of the rocks. They would seem, 

 therefi.-ie, either to have been injected as horizontal sheets in among the beds 

 before they were disturbed, or else as vertical or highly inclined dykes during 

 or after the action of those forces which tilted the beds into their present highly 

 inclined positions. 



With regard to the main mass of granite, it would appear that subsequently 

 to the deposition of the whole of the Carabro-Silurian rocks, some force acting 

 from below caused this to swell upwards and intrude to some extent into the 

 body of the rocks above. This upward intrusion of the granite would doubt- 

 less be accompanied by an elevation and an arching of the rocks above it, and 

 indications are not wanting to make it probable that there was a simultaneous 

 depression and sinking in of the rocks on each side of the elevated district. 



It appears also probable that the surface of contact of the granite and the 

 rocks over it was a very uneven and irregular one ; that not merely were there 

 dykes and veins of molten granite injected into the adjacent rocks, but that its 

 general outline was very irregular, large ridges, domes or mounds of granite, 

 protruding upwards into the rocks above, with corresponding hollows, furrows, 

 or basins, into which portions of the superincumbent rocks would necessarily 

 settle down. Hence arise the present rather irregular outlines of the surface 

 boundary of the granite and altered slate, and the detached patches of mica slate 

 to be seen in the granite, and, as it were, dipping down into it. Sometimes this 

 relation of position is carried so far as to produce the appearance of interstra- 

 tified beds of granite and mica schist, alternating with each other, as described 

 by Mr. Weaver.* 



Metamorphic Action of the Granite. — One result of this intrusion of the gra- 

 nite has been already alluded to, namely, the metamorphism produced on the 

 rocks in the immediate neighbourhood of the granite. Our district affords ad- 

 mirable opportunities of studying this action to any one who has time to examine 

 some large portion of it closely. Micaceous schists are always found in contact 



* " Transactions of the Geological Society," vol. t., first series. 



