Submerged ice marginal forms in the Celtic Sea off Waterford Harbour, Ireland implications for understanding regional glaciation and sea level changes following the last glacial maximum in Ireland

This paper presents the results of acoustic surveys and video imaging of the seabed off Waterford Harbour, beyond a previously identified submerged palaeochannel. This system extends south-west into waters at c. -56 m OD and terminates in an area of possible glacigenic sediments. The aim of the new surveys was to obtain multibeam sonar imagery and to correlate it with seismic profiles in order to understand the genetic relationships between the morpho-sedimentological elements of the seabed in this area. The multibeam sonar imagery revealed four arcuate, morphologically complex features that on-lap the regional bedrock and confine the previously identified palaeochannel. Both the morphology of these forms and their sedimentology, as revealed by video imaging, imply formation in an ice-marginal environment. These forms are hypothesised to reflect several stages of sedimentation at the margins of ice progressively retreating from the nearshore shelf of the Celtic Sea during the Last Glacial Maximum.