A comparative study on the last deglaciation of Ireland and Newfoundland using marine geophysical data and sediment cores

Reconstructing the configuration and behaviour of palaeo-ice sheets is an important scientific goal as it provides new insights into how ice sheets respond to both internal and external drivers over a range of time-scales. During the last glaciation, the British-Irish Ice Sheet (BIIS) and the Newfoundland Ice Sheet (NIS) were situated on opposite sides of the Atlantic Ocean but at similar latitudes. Their position on the edge of the continent and the fact that they terminated in a marine environment make them key sites for examining ice sheet-ocean-climate interactions. The glacial history of the southern marine sectors of both ice sheets is still poorly understood. This project will shed new light on the extension and retreat of these ice sheets during the last glacial period, using high-resolution marine geophysical and sedimentary data collected on the SW Irish and southern Newfoundland shelves. Preliminary analysis of multi-beam bathymetric data from both sites show a series of linear to lobate and arcuate submarine ridges in both regions. Based on their geomorphology, these bedforms are provisionally interpreted as moraines in Ireland and fjord-mouth moraines in Newfoundland. They provide clear evidence of grounded ice and an opportunity to date ice sheets retreat across the continental shelves. Thirty-four sediment cores were acquired on and around these features, in both regions. Initial analysis of the cores has been focused on the interpretation of depositional processes. They include a diamicton facies assumed to be a subglacial till based on lithology, fabric and shear vane measurements, and glacio-marine muds displaying laminations and IRD in the X-radiographs. This presentation will include all of the results to date with the aim of testing the character and (a)synchronicity of the (de)glacial history of two ice sheets across the Northern Atlantic Ocean in order to assess the main drivers for ice sheet decay in the Late Quaternary.