584 Mr. J. Beete Jukes and the Rev. Samuel Haughton on the 



quite so far, — all these detached patches of mica schist would have been joined 

 into a continuous mass, and a skin of mica schist would have spread completely 

 over the granite. 



Immediately south of this, on the other hand, where the ground is very 

 low and the granite area is traversed by the valley of the Slaney, we have the 

 widest exposure of granite at the surface, and find it to be most free from 

 included patches of mica schist. We see in these facts how directly the 

 appearance of granite at the surface is related to the occurrence and the extent 

 of denudation. 



It follows also from these and the preceding descriptions, that this main 

 granite mass, however extensive it may be, and Jiowever it may form the most 

 prominent and striking feature of our district, is yet not to be looked upon as 

 either its geological or geographical axis. 



North of Lugnaquillia, certainly, the granite hills form a watershed, between 

 the affluents of the Liffey on the one hand, and those of the brooks that flow 

 out on the coast at Arklow, Wicklow, and Bray, on the other. South of that 

 mountain, however, the more important rivers, Slaney, Barrow, and Nore, run 

 directly across the granite area from one side to the other, the whole drainage 

 of the south-east of Ireland coming right across its strike. 



Its geological relations are not more influential than its geographical. 

 We have already seen that the prevailing strike of the greater part of our 

 district is as nearly as possible N. E. and S. W. The direction of the main 

 granite band differs from this by an angle of 25°. 



If the granite area served as a geological axis, we should, of course, always 

 find the lowest rocks upon the flanks of the granite, and come upon higher and 

 higher beds as we receded from it. So far from this being the case, it is the 

 actual fact that the largest Cambrian area, that of Wexford, A, seems to stand 

 especially aloof, both from the granite of the main area, F, and from that of 

 Carnsore; while the Cambrian of North Wicklow (area B), although it is much 

 nearer the granite, and at its northern extremity is quite close to it, is yet never 

 brought up on the flanks of the granite, is not altered by it, has neither its beds 

 nor its boundaries parallel to the direction of the granite, and, in short, seems 

 in no way to be afiected by it. 



At the southern end of the area F, the granite is at a distance of twelve 



