Rory Quinn

Identifying and characterising submerged archaeological deposits:Case Studies from Rathlin Island and Bantry Bay

Rathlin Island, off the north coast of Ireland, has a history of settlement and seafaring from the Late Mesolithic period to the present day. The maritime Sites and Monuments Record (SMR) for Rathlin indicates high wrecking incidences. In 1999, a reconnaissance side-scan sonar survey confirmed the presence of 46 targets of possible archaeological potential around Rathlin Island. Thirteen of these anomalies were positively identified as shipwrecks. Of the remaining 33 targets, nine were dived on in order to ground-truth the geophysical data. A successful and rapid methodology of ground-truthing side-scan sonar data for archaeological purposes was developed. The results from the side-scan survey and diver-truthing exercise enhanced the existing maritime SMR.
Between 1998 and 2000, a series of geophysical surveys were conducted over the site of La Surveillante, a French Frigate wrecked in 1797 in Bantry Bay, Co. Cork, Ireland. The objectives of the surveys were to accurately relocate the wreck-site, delineate the extent of site, map the seafloor and subsurface lithologies in the wreck-environs and provide basemaps for more detailed diver investigations. The integrated surveys employed a suite of equipment consisting of a digital echo-sounder, side-scan sonar, Chirp sub-bottom profiler and an Overhauser-effect magnetometer. Integration and interpretation of the geophysical data indicate La Surveillante was wrecked on a fine-grained substrate in a low energy environment, with site distribution limited to an area measuring 50 x 25m centred on the wreck. Integration of geophysical- and diver-survey data with tidal and sediment records indicates the La Surveillante was wrecked in a low energy environment, with site formation being dominated by biological and chemical processes.