Investigation of an elevated sands unit at Tralispean Bay, South-West Ireland – potential high-energy marine event

Abstract

A sequence of high elevation sands containing both broken and whole marine shells, as well as many mega-sized, raft-shaped boulders (1-3m across) has been discovered at Tralispean Bay, West Cork, Ireland. Ground-Penetrating Radar (GPR), ground surveying and differential GPS (dGPS) show that the sediments cover an area of c.0.75ha, reaching a maximum height of c.+18.5m ODM, with interconnected pockets of sand varying in thickness of up to 1m. Coring, lithostratigraphic study, granulometry, organics loss-on-ignition and carbonate content analyses, together with examination of micro- and macrofossils, indicate that the shelly sands were deposited rapidly, under high energy conditions. Informal interviews with local residents, as well as the extent of the sands, suggest that the deposit is not the result of human actions. Elevations reached by the sediments, the presence of mega-boulders, and other indicators make it unlikely that these sediments arose from storm activity. It is possible that they have been deposited as the result of a tsunami. The radiocarbon (AMS) date obtained places the age of such an event at 1465 AD (Cal BP 485). At present, no clear historical record has been identified of any tsunami impacts affecting the south coast of Ireland other than the Lisbon earthquake of 1755.