450 Prof. Harkness's Address to Section G. 



of not less than 1,700 feet ; and south.- west from the Comeraglis, near 

 Dungarvon, they are upwards of 3,000 feet in thickness. In the 

 west of the county Cork we have 5,000 to 6,000 feet of Old Eed 

 Sandstone exposed ; and here the upper portion is denuded and the 

 base is not seen. In the Glengariff and Killarney country from 

 8,000 to 10,000 feet of these strata are exhibited, and here also their 

 base is not visible. 



On the south side of the Dingle Promontory the Old Eed Sand- 

 stones occur under different circumstances. They are here from 

 3,000 to 4,000 feet thick, and are seen resting unconformahly on 

 rocks which are of a reddish purple colour, and at least 10,000 

 feet in thickness. These reddish purple beds repose conformably 

 on the representatives of the Ludlow series. 



The strata of the south of Ireland, which represent the Old Bed 

 Sandstones, and which in the neighbourhood of Glengariff and Kil- 

 larney attain a greater thickness than 10,000 feet, are extremely 

 barren in organic remains. Several thousand feet of strata, con- 

 sisting of purple, red, and green beds, which, from being well 

 developed in the district of Glengariff, have received from the Irish 

 Geological Survey the name of " Glengariff Grits," have never yet 

 afforded a fossil. It is only in the upper portion of the series, 

 which is comparatively thin, and composed of Yellow Sandstones, 

 that organic remains occur ; these consist of remains of plants, 

 which, at Kiltorcan, in the county Kilkenny, are in a beautiful state 

 of preservation. Fish remains are also found referable to the genera 

 Coccosteus and Gyrolepis ; likewise a very characteristic shell, 

 Anodon JuTtesii, and Crustacean remains in the form of a species of 

 Eurypterus, etc. 



In Ireland the strata which succeed conformably the Yellow 

 Sandstones have been called by Sir E. Griffiths the Lower Lime- 

 stone and Shales. In the south of Ireland these strata have a great 

 thickness, and when they possess a slaty cleavage the term " Car- 

 boniferous Slate" has been applied to them. These strata, in the 

 eastern portion of the county Wexford, where the old Eed Sand- 

 stones are thin, have no distinct existence. In the western part of 

 the same coimty, at Hook Point, where the old Eed Sandstone de- 

 posits are thicker than in the eastern portion of Wexford, the Lower 

 Limestone shales make their appearance as a distinct group, sepa- 

 rating the Yellow Sandstones below from the Carboniferous Lime- 

 stones above ; and here their thickness is between 10 and 20 feet. 



We have already seen how the Old Eed Sandstones have increased 

 in thickness in the neighbourhood of Dungarvon. The Carboni- 

 ferous slates also attain a much greater development here than at 

 Hook Point, for the officers of the Geological Survey give their 

 thickness at 700 feet; and near Youghal, still further westward, 

 they have a thickness of about 900 feet. On the western side of 

 Cork Harbour we have examples of a still greater development of 

 the Carboniferous slates, for here they are at least 1,500 feet thick. 

 At the Old Head of Kinsale, 6,500 feet represent their thickness ; 

 and still further westward they attain to even a greater development. 



