Activity: Talk or presentation › Oral presentation
Reconstructing the configuration and behaviour of palaeo-ice sheets is important as it provides new insights into how ice sheets respond to 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 PhD, currently in its first year, 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. This poster presents the workflow, which will be followed for this project, some initial results and future work. Preliminary analysis of multi-beam bathymetric data from both sites show a series of linear to lobate and arcuate submarine ridges. Based on their geomorphology, these bedforms are provisionally interpreted as end moraines and 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. To date, only the cores from the south of Ireland have been processed and interpreted in terms of depositional processes. They include a diamicton facies assumed to be a subglacial till based on lithology, fabric and shear vane measurements. Analysis of the cores from Newfoundland is underway. To better characterize the cause of the retreat, the new gathered data will be subject to a radiocarbon dating (14C), stratigraphic correlation together with seabed mapping and seismic correlation. Ultimately, using all records above, this project will test the (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.