Lower Palceozoic Rocks of the South-Easi of Ireland. 581 



It may however, be objected to this view, that while the granites of the west- 

 ern side are surrounded by a belt of slate metamorphosed into mica schist, the 

 greenstones of the eastern are not so surrounded, and seem to have produced 

 little or no alteration on the beds adjacent to them. 



Secondly, we may suppose that the beds of the two parts of the district 

 are not the same, but that the north and south line mentioned before as 

 running through Rathdrum is a great line of dislocation, separating the one 

 set from the other. In support of this view it might be mentioned, that if 

 this line be continued to the north, it cuts the very abrupt S. W. termination 

 of the Cambrian rocks of Carrick Mountain, and meets the great fault which 

 is believed to run along the S. E. boundary of the Cambrian area B, that 

 of North Wicklow. If continued still further north, moreover, it would 

 appear to coincide for several miles N. and S. of Roundwood, with the boun- 

 dary line between the Cambrian and Cambro- Silurian rocks, which might also 

 be a fault. 



Still, even this hypothesis does not relieve us from tlie difficulty, since, if 

 this N. and S. line were merely a dislocation, we should expect to find the 

 bedded traps somewhere on the western side of it, striking to the S. W. up to the 

 granite; whereas, we not only do not find them in the band of country where 

 we should expect them, but we do not find them at all either to the north or 

 to the south of that band. We should still be left without any trappean set 

 of beds anywhere on the margin of the main granite area, to mark the sepa- 

 ration between the upper Cambro- Silurian beds in the centre of Wexford, and 

 those which we must believe to be the lowest part of the Cambro-Silurian 

 series, which rests on the Cambrian rocks on one hand, and the granite on the 

 other, in the country running by Roundwood and Douce Mountain, from the 

 Seven Churches up to Killiney. 



We must, for the present at all events, be content to leave this puzzle, with 

 others, still unsolved, and perhaps, from deficiency of data, for ever insoluble. 



There is yet a part of this area, of which we must say a few words. 



The band of bedded traps that stretch through Wexford into Waterford, 

 receive in the latter county large accessions to their mass, and spread over a 

 much greater width than they have in Wexford. So far as can be determined 

 by the few scattered observations that can be made on their position, the whole 



VOL. xxin. 4 G 



