to the Mineral Structure of the South of Ireland. 1 73 



I shall now make a few remarks with regard to Mr. Wea- 

 ver's section as compared with my own, and particularly with 

 reference to the position of the limestone of the several troughs 

 in which it occurs. 



We agree with respect to the limestone of the valleys of the 

 Suire and the Blackwater, both considering it to be carboni- 

 ferous ; but what are the geological circumstances under 

 which these limestones occur? They both rest conformably 

 on the red slate and conglomerate series, whichin the valley 

 of the Suire Mr. Weaver calls old red sandstone, but in the 

 valley of the Blackwater transition slate. In respect to the 

 latter, I have shown that he is mistaken by means of my ori- 

 ginal section, and the sections from Ballyvoil Head and Gloun- 

 dolgan ; but Mr. Weaver in his section exhibits the carboni- 

 ferous limestone of the Blackwater at Lismore in the form of 

 a trough, the north side dipping to the south, and the south 

 side to the north, which is not the fact; as in that locality, as 

 already mentioned, the carboniferous strata dip to the south 

 on both sides of the valley, on the north side at an angle of 

 30°, and on the south at an angle of about 60°. 



If Mr. Weaver had carefully examined the dips of the 

 strata, he must have observed this fact; and, following the 

 principle he has adopted in other places, he should have in- 

 cluded this limestone in his transition suite ; but knowing 

 this was not the fact, from its connexion with the great lime- 

 stone field of Ireland, he has represented this rock at Lismore 

 as a trough having reverse dips on the opposite sides of the 

 valley. 



We next come to the limestone of the valley of the Bride 

 at Tallow, which Mr. Weaver in his section truly represents 

 as a trough having dips in opposite directions ; but this lime- 

 stone, though undoubtedly the same in geological position, in 

 lithological character, and in fossils, as the limestone of the 

 Blackwater, he makes transition, though from its position and 

 true trough shape, he must have considered it to rest on the 

 top of the red slate series which lie beneath it on the north 

 side of the valley dipping to the south, and on the south side 

 to the north. 



I shall now make a few observations respecting the exten- 

 sive district represented by me as carboniferous slate, which 

 occupies the greater portion of the south of the county of 

 Cork, and which Mr. Weaver has included in his transition 

 district. In geological position it rests upon the red slate and 

 conglomerate series; near its commencement it is usually in- 

 terstratified with gray or yellowish-gray sandstone and arena- 

 ceous slate, which frequently contain calamites, and in some 

 cases, as at the Old Head of Kinsale, where the strata are 



