1 78 On the Mineral Structure of the South of Ireland. 



It should be observed, that the red conglomerates and red 

 slates of the district of Killarney are situated on the south side 

 of the carboniferous limestone valley of Castlemaine, while 

 those of Cahirconree are on the north side ; that the upper 

 beds of both graduate into the carboniferous limestone series, 

 at Currens on the north side, and at Brickeen island in the 

 Lower Lake of Killarney on the south side of the valley. The 

 unconformability of the conglomerate beds with the transition 

 series on Cahirconree, and their conformability on McGilla- 

 cuddy's Reeks, the Purple Mountain, &c., is no proof that 

 the rocks are not identical, as, in England, the old red sand- 

 stone graduates both into the Silurian and mountain limestone 

 series. 



In respect to the fault described by me, the occurrence of 

 which is doubted by Mr. Weaver, I shall observe, that it is 

 clearly visible at the Gap of Dunloe and at Brickeen island ; 

 and I will assert, that the positions of the old red sandstone 

 strata on one side, and the chloritic rocks on the other, in 

 both those places, are as clearly indicative of a fault as any I 

 have ever seen. On the west side of the Gap of Dunloe, we 

 have a perpendicular cliff upwards of 200 feet in height, 

 which is traversed by a nearly upright cut or crack about 20 

 feet in breadth. On the south side of this cut we find strata 

 of dark-green chloritic quartz-rock dipping to the south at 

 an angle of 30, while the strata on the north side dip to the 

 west at an angle of 10, and are composed of rather fine- 

 grained conglomerate and a red quartzose-rock or compact 

 sandstone identical with that which lies beneath the red con- 

 glomerate of Cahirconree. I am of opinion that these ap- 

 pearances do prove that there has been a fault. 



Figure No. 4 in the plate is an accurate representation of 

 the fault as above described. 



Similar observations are applicable to the appearances at 

 Brickeen island. There also, the strata on the south side 

 of the fault consist of green chloritic rock, having rather a 

 slaty structure, which dip to the south ; while on the north 

 side, we have in succession, red quartzose-sandstone and red 

 slate, red limestone, and yellowish-green slate containing 

 calamites, abutting obliquely against the chloritic rock on 

 the north side. 



Towards the conclusion of his paper, Mr. Weaver observes, 

 " Proceeding now to the Dingle peninsula, the succession 

 given also by Mr. Griffith from north to south, namely, from 

 Brandon bay to Foylaturrive, is as follows: 1st, dark gray 

 clayslate," &c. The above sentence is a misquotation from 

 my paper. My words are, " If we make a section across the 



