520 Scientific Proceedings, Royal Dublin Society. 



larger down the current, till it comes to the groyne, when it accu- 

 mulates, while westward of the groyne the accumulations are fine 

 and small. On the map, for no perceptible reason, the " Lisbellaw 

 Conglomerate " is made to belong to one] geological group, and 

 the conglomerates of Lough Eyes to another. (Antea, p. 504.) 



In these groups there are in places sandstone: these, from the 

 ancient structures in which they were used, are proved to be du- 

 rable, and capable of producing good work ; now, however, they 

 are not much sought after, except for [local purposes, partly on 

 account of their hardness, but more generally on account of lime- 

 stone being found in their vicinity — the latter rock, in such lo- 

 calities, being now more generally preferred^ or cut-stone purposes. 

 Quite recently, however, in a few localities^they seem, in some- 

 measure, to be rising in public estimation. 



CARBONIFEROUS. 



The Carboniferous sea in the Irish area must have been of 

 different depths, besides having in it islands varying greatly in 

 dimensions. The rocks deposited in the greater depths seem, for 

 the most part, to have been arenaceous and argillaceous (Lower 

 Carboniferous Sandstone and Shale, or Yellow Sandstone — Griffith) ; 

 but similar rocks were also afterwards [deposited as littoral accu- 

 mulations on different geological horizons, even up into the Coal- 

 measures ; therefore rocks of this class^are formed not only under 

 all the limestones, but also at different higher levels ; they solely 

 indicating different localities near ancient land in the Carboni- 

 ferous sea. After a time, in some parts the bottom of this sea 

 seems to have grown up, or to have been moved up, causing the 

 water to become shallow, and the conditions more or less like those 

 at the first, so that sandstones and shale (Calp), somewhat like 

 those at the original bottom (Lower Carboniferous Sandstone), were 

 again deposited. 



In Munster, the adjoining portion of Leinster (King's and 

 Queen's Counties), and in north-western Connaught (Mayo), nearly 

 everywhere the Lower Carboniferous Sandstone occurs, margining 

 the older rocks, and separating them from the limestone. This, 

 however, in general, is not the case in the rest of Ireland. In the 

 Co. Wexford, to the north-west of the limestone, are such shore 



