Kinahan — Lisbellaio Conglomerate, Co. Fermanagh, 8fc. 505 



On the coast of south-east Ireland (Co. Wexford), as the normal 

 drift of the county for a large part is fine sand, the drift due to 

 the " flow-tide " current is in general of a similar character ; and 

 the big accumulations on the up-stream side of the groyne are in 

 general sand. This, however, is not the case in the beach to the 

 north of the Blackwater. Here, to the north-east, Cahore Point 

 acts as a groyne, and south-west of it, at the head of the current 

 from the Blackwater, there is a shingle beach. This is some- 

 what like the " Lisbellaw Conglomerate," gradually down-stream 

 becoming coarser and larger, but dying out before the extremity 

 or point of groyne is reached. The reason for the ending of a 

 shingle beach before it quite reaches the natural groynes is due 

 to the " on-shore, or half counter-tide currents." As this has 

 been previously explained in different Papers already published, 

 it is unnecessary to again repeat it. 



There is, however, a much more parallel accumulation in that 

 of the Chesil Bank, Dorsetshire ; although what is now taking 

 place at the latter is on a much larger scale than the work done 

 in Silurian times at Lisbellaw. 



The Chesil Bank travels eastward along the shore of Lyme 

 Bay, with the " flow-tide " current accelerated by the prevailing 

 winds from the westward, to be stopped by the natural groyne — 

 Portland Bill. If this beach is followed from the west eastward, 

 the accumulation gradually increases in size, and also in the di- 

 mensions of the materials, till eventually it forms a mass of more 

 or less coarse material to the westward of the Bill. But, on the 

 other hand, in "Weymouth Bay, eastward of The Bill, the accumu- 

 lation is at a minimum, and of fine materials. 



As may be seen in the accompanying diagrammatic plan (Plate 

 XII.), the relation between the adjuncts of the Chesil Bank and, on 

 a smaller scale, those in connexion with the " Lisbellaw Conglo- 

 merate," is very similar, except that while the "flow-tide" cur- 

 rent in the first set from the west eastward, that in the Silurian 

 sea must have ran south-westward. 



To the north-eastward of Lisbellaw, in Silurian times, there 

 was a shore-line trending north-eastward, and immediately west 

 of the village a spit of Ordovician land, somewhat like the Port- 

 land Bill, while westward of this spit was a bay that may be 

 compared with Weymouth Bay. 



