Geomorphological changes on the Barrier Coasts of South Wexford

Abstract

Contrary to recent published accounts the coast of South Wexford does not comprise a series of westerly prograding spits, but a landward moving (transgressive) system of gravel-based barriers. Fringing, bar and spit barrier types are all represented. The periodic marine overwashing of the barrier crest creates washover facies in both coarse sediments at Carnsore and Lady's Island Lake and fine sediments at Tacumshin, where storm steepage structures also occur. The barriers are remnants of much larger transgressive features which arc now stranded against the Wexford terrestrial platform. At several points longshore brackish water lagoons exist, partially recharged by freshwater drainage systems. At Lady's Island Lake a discrete surface outlet is unnecessary as seepage through the barrier is capable of dealing with lagoonal discharge pressure. However at Ballyteige the barrier is breached by a major inlet, with a well-developed ebb-tide orientated delta, in order to effect drainage. At Tacumshin the lagoon outlet is a more ephemeral feature, seemingly subject to closure by longshore sediment drifting during low (lows. The dynamics of inlet processes, coupled to longshore wave and sediment transport potential, are the main factors causing change on the south coast of Wexford. It is suggested that the transverse gravel structures at Nemestown, including St Patrick's Bridge, may be the remnants of a now degraded barrier tombola inherited as a transgressive relic from earlier and lower shoreline positions.