536 Geological Society. 



Mr. Brodie infers, from the occurrence of oysters in some of the 

 layers, that the beds were accumulated in an estuary which afforded 

 considerable variations in the nature of the sediment accumulated, 

 and of the animals by which it was frequented. 



In conclusion, the author states, that he is indebted to Mr. Owen 

 for determining the characters of the fossil Isopod, 



A letter was afterwards read, addressed to the Rev. Dr. Buck- 

 land,_ President of the Society, by R. Griffith, Esq., P.G.S. of 

 Dublin, respecting the geological relations of the several rocks of 

 the South of Ireland. 



This communication was accompanied by a copy of Mr. Griffith's 

 Geological Map of Ireland ; and its principal object is to explain why 

 he has coloured, as old red sandstone and carboniferous limestone, 

 extensive districts of the counties of Kerry, Cork, and Waterford, 

 which had been previously considered to be transition. 



The geological base of these counties is clay slate passing into 

 quartzose slate, quartz rock, and occasionally conglomerates. This 

 is particularly the case in the peninsula of Corkaguinny or Dingle 

 in the county of Kerry ; and as the succession of rocks forming the 

 south of Ireland is well exposed in that district within a short dis- 

 tance, Mr. Griffith selected it for the purpose of explaining his views. 



The lowest formation on the sea-shore at Brandon Bay consists of 

 black and red clay slate, and gray quartz rock. The beds are nearly 

 vertical, but occasionally dip 70° or 80° to the south. In some lo- 

 calities near the Bay, the slates alternate with red and gray quartzose 

 conglomerates ; and on the western coast of the peninsula, at Doon- 

 guin, Ferriter's Cove, and Filaturrio, S.E. of Dingle, the slate con- 

 tains Orthis, Terebratulse, corals, &c. This series is succeeded, un- 

 conformably, by beds composed of rolled masses of quartz and mica 

 slate, in an arenaceous base, and it is assigned by Mr. Griffith to the 

 old red sandstone. On the summit of Cahirconree mountains, this 

 conglomerate, associated with beds of fine-grained red sandstone, dips 

 to the east at an angle of 10°. Proceeding eastward, in ascending 

 order, the conglomerate disappears, and the formation consists of red 

 and reddish-brown quartzose sandstone, alternating with coarse-red 

 slate, flagstone, and occasionally green slates. These strata are 

 succeeded, conformably, by a fine, yellowish-gray sandstone, forming 

 the commencement of the carboniferous series. The sandstone con- 

 tains Calamites, and at Gortaclay, 2 miles west of Curreen's Bridge, 

 indistinct bivalves. Its upper beds alternate with coarse and fine 

 dark-gray clay slate, abounding with Productae, Spiriferse, Tere- 

 bratulse, Encrinites, corals, and other fossils. Continuing to ascend 

 in the series, beds of carboniferous limestone, containing the same 

 organic remains, alternate with the fossiliferous slate ; then appear 

 strata of gray, fine-grained, indurated sandstone, alternating in the 

 upper partwith slate; next, a series of strata of limestone and greenish- 

 clay slate, containing the same fossils ; beyond which the slate gra- 

 dually disappears, and the whole mass is composed of limestone. In 

 the flat central space between Curreen's Bridge and Castle Island, are 

 probably shale and limestone. Near Castle Island occurs the upper 



