'208 Proceedings of the Royal Irish Acadennj. 



these, a little south, of the Blackwater, was floated in, during a spring 

 tide, against the cliff, where it was fastened by a chain and left for 

 over six months. During the time it was allowed to remain the 

 land driftage collected against it a mass of .^JEolian sand, which has 

 since become permanent, and has stopped the denudation of the cliff- 

 line. Slips of the cliffs also form groynes, but only temporarily, as 

 they are gradually cut away by the sea. Poulduff, Courtown, and 

 Arklow piers have also acted as groynes, and to the southward of 

 each of these are now considerable permanent accumulations. 



On the coast of Wicklow, between the Kilcoole railway station 

 and The Breaches, very effective groynes were constructed. These 

 were erected under peculiar circumstances. The ''flow-tide " current 

 was rapidly cutting away the beach and endangering the railway ; 

 while the Company were restricted from making any works outside 

 their boundary, a width of less than six yards, and any groynes 

 placed inside such limits would extend only a short distance below 

 high water-mark. They were, however, erected, the principal ones 

 being over six feet high ; and, although the circumstances seemed to 

 be unfavourable, they filled rapidly, and formed a rampart that has 

 stopped the encroachment of the sea. 



At the north end of the Esplanade at Bray there is a system of 

 groynes ; but various circumstances have combined to make them 

 ineffective. Their site was only a short distance south of the channel 

 out of Bray Harbour ; and the water from the river and estuary cut 

 off the southward driftage of the beach to them, carrying it seaward, 

 while the detritus that was beached on the south of the harbour 

 channel was immediately carted away ; thus much of the materials 

 that should have filled the groyn-es never reached them. In addition 

 to this, the groynes do not seem to have been judiciously planned or 

 erected. They were constructed of round timber, driven down verti- 

 cally ; and in no place in Ireland have I found that round timber, 

 driven down vertically, forms effective groynes. Furthermore, mid- 

 way between the groynes extending from the coast-line, other short 

 ones were placed, a little above low water-mark, and these generated 

 currents which licked out all the shingle from between the land- 

 groynes. The boundary pilings at the new baths on Bray Esplanade 

 have acted as groynes, and have collected a considerable mass of 

 shingle alongside of them. 



