Mr. Griffith on the Rocks of the Sotith of Ireland. 537 



limestone, abounding in nearly every known fossil of the carboni- 

 ferous limestone of Ireland ; and eastward of Castle Island is dis- 

 played, in conformable position, the millstone grit, the lower shales 

 of which contain, in considerable quantity, Encrinites, Posidonise, 

 Spiriferse, Productse, Ammonites, Orthocera, &c. 



The change effected by Mr. Griffith in this district, consists in 

 removing the dark-gray and greenish-gray fossiliferous slate at 

 Curreen's Bridge from the transition series to the lower part of the 

 carboniferous limestone system, in consequence of its resting con- 

 formably on the sandstone, and dipping regularly under the lime- 

 stone, as well as on account of its fossils. 



Mr. Griffith then describes a line of country between Mount 

 Leinster, in the county of Wexford, and the sea-coast south of Cork. 

 This district presents a succession of east and west valleys, in which 

 flow the Suire, Blackwater, Bride, and Lea, with intermediate 

 ridges, more or less elevated. The valleys are occupied by lime- 

 stone, beneath which, in each instance, are, in descending order, 

 the carboniferous slates, yellow sandstone, red slate, quartz rock, 

 the conglomerate and subjacent greywacke, thus presenting the 

 whole of the former section with the exception of the millstone grit. 

 Since the reading of his paper on this district at the Meeting of 

 the British Association at Newcastle, Mr. Griffith has revisited the 

 country, and found that his views of its structure, given in that 

 paper, are perfectly correct ; and during his examination he directed 

 his attention more particularly to the limestones in the neighbour- 

 hood of Cork. A detailed section from French Furze, south of Cur- 

 rigoline to Middleton and Broomfield, intersecting the limestones 

 of Cork Harbour, was exhibited and described in the paper. It 

 displays the same succession of formations, namely, carboniferous 

 limestone, carboniferous slate, yellow sandstone, red slate, and 

 quartz rock. 



To prove more particularly the correctness of his views, Mr. 

 Griffith gives a minute account of the structure of the Monavollagh 

 Mountains, in the county of Waterford. The base of these moun- 

 tains consists of greywacke, covered unconformably by alternations 

 of coarse- red or brownish conglomerates, coarse-red slate, and red 

 quartzose slate. From Crotty's Rock the conglomerates are suc- 

 ceeded southward by alternations of coarse-red slate and quartz 

 rock, the latter being interstratified, in descending towards the 

 Blackwater, with beds of roofing slate, which occur only in the 

 upper portions of the red slate series. On approaching the Black- 

 water, the clay slate is succeeded, conformably, by yellowish- white 

 sandstone, and sandstone slate, containing casts of Calamites. These 

 strata are again overlaid, conformably, by the greenish-gray im- 

 perfect clay slate, which alternates with the limestone of the valley 

 of the Blackwater. The limestone of this valley is connected with 

 that of the counties of Cork, Tippcrary, &c., allowed by other geo- 

 logists to belong to the carboniferous limestone of Ireland. The 

 dip of the limestone strata in tlie valley of the Blackwater varies 

 from 20° to 75°. Mr. Griffith then shows, that a similar though 



