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Catherine Breheny, National University of Ireland, Galway (Ireland)
Kathryn Moore, National University of Ireland, Galway (Ireland)
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The Copper Coast of County Waterford has been an official European Geopark since 2002: it has a rich and varied geological heritage including a long history of mining, as well as spectacular scenery. Remnants of Ordovician arc volcanism on the ancient continental margin of the shrinking Iapetus Ocean comprise widespread volcaniclastic sediments and contemporaneous lavas that have been interpreted by previous authors as two submarine volcanic centres: the Kilfarassy Volcano and the Bunmahon Volcano. The Kilfarassy volcanism was characterised by explosive eruptions of volatile-rich and rhyolitic magmas, producing lapilli tuffs with abundant compressed pumice (fiammé), vitric shards and accretionary lapilli. The Bunmahon volcanism is characterised by spillitized hyaloclastite, pillow lavas and peperite that, along with lapilli- and crystal-tuffs, have been interpreted as an underwater composite volcano. An interpretation of Bunmahon volcano magmatism on the locality scale has been devised for the coastal geology at Trawnamoe (near Bunmahon) and Stradbally Cove in order to communicate to the public the active ocean floor processes that produced the igneous lithologies. The main geological objective of the self-guided field excursions that have been designed is to demonstrate, in a simple manner, the effect on peperite morphology of varying physical conditions within the ocean floor, and of varying chemical composition of the magma.
Moreover, the nature of the contacts between igneous and sedimentary lithologies (from peperite, to bulbous intrusions to sharp contact intrusions) is used to convey a sense of repeated intrusions over time into sediment that is becoming increasingly lithified. Dissemination of the basic field-guides through amateur national Earth Science awareness magazines has begun and it is hoped that, with the inclusion of results from further ongoing research into the formation of the peperites, a final version of the field-guides will be distributed from the Geopark Office and local Tourist Information Centres.
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