140 The Rev. Maxwell H. Close, 



within, what may be called, comparatively narrow limits. The 

 facts that the granite has been intruded into the Lower Silurian 

 rocks, and that the slates of that formation have been meta- 

 morphosed all along the border of the granite into mica schist, 

 evidently by the action of the granite, show that the intrusion of 

 the granite was later than the formation of those rocks. On the 

 other hand, the facts that, in the Co. Kilkenny, the Old Red 

 Sandstone reposes undisturbedly on the granite and has not been 

 altered thereby, and that its beds sometimes contain a quantity 

 of granitic pebbles and detritus, show that the protrusion of the 

 granite took place before the deposition of those rocks. 

 - The main granite exposure includes the principal mass, with 

 the highest summits, of the S. Dublin, Wicklow, and Wexford 

 hills ; while the Silurian rocks form lower ground on each side, 

 with some subordinate hills. This, in connexion with the fact 

 that the general strike of the Low r er Silurian rocks is very nearly 

 parallel with the length of the granite exposure, on each side, 

 might, at first sight, give rise to the idea that the granite, while 

 being forced into the Silurian strata, had broken through them, 

 upheaving them and throwing them off on either side, so as to 

 make them dip away in both directions. But what evidence 

 there is on the point bears against this supposition. The granite 

 has nowhere brought up the underlying Cambrian rocks on its 

 flanks ; nor has it thus brought up the lower of the Silurian 

 rocks. It is true that the metamorphosed Silurian slates, close 

 along the sides of the granite, usually dip away therefrom, on 

 each side; but notwithstanding this, the Silurian strata on the 

 western side of the granite, though evidently much folded and 

 contorted, seem nevertheless to dip, as a whole, towards the 

 granite ; so that the higher beds come against it ; and it would 

 appear that in the Co. Wexford, also, on the eastern side, they 

 are the upper beds which border the granite (although it is not 

 bo, northward of that, in the Co. Wicklow.) Again there are 

 patches of altered Silurian slates lying on some of the highest 

 parts of the granite hills, including the very summit of Lugna- 

 culliagh itself, 3,0o9 feet, the highest point of all. It is just at 

 the highest part of the granite, where it has escaped denudation, 

 that we find the schist still lying upon it ; while on the other 

 hand, it is just where the valley of the Slaney cuts across the 

 range of the granite hills, and the denudation has been greatest. 



