CONICET | Buscador de Institutos y Recursos Humanos

This study takes a closer look at raised beaches adjacent to the Bellingshausen Dome on Fildes Peninsula, King George Island. One result of the overall retreating ice cap since the LGM is a shrinking weight on the island, causing an isostatic rebound and therefore a local falling relative sea level (RSL). Thus, raised beaches have slowly been revealed and partly been reworked by glacial readvances and/or overlaid by periglacial products and glaciofluvial sediments. The purpose of this study is to investigate whether characteristic marine, glacial and periglacial deposits could be recognised in the composition of these beach sediments. The information could then serve to narrow down the local maximum ice extent since the raised beaches were formed about 8,000 years ago.The sediments were examined due to their grain size, shape, composition and degree of sorting. Striated rocks and ice rafted boulders were also taken into account. The observations were then coded and digitalised on ARC GIS. Results suggest that the Collins Glacier has not advanced further than 400 metres from its current location in the past 8,000 years, as rounded and well sorted, clast-supported cobbles between 20 and 60 mm speak against any perturbation since they were formed and deposited by marine processes in this distance. However, towards the glacier the deposits become increasingly supported by sand and fine gravels that have been transported from frost weathered outcrops adjacent to the beach. Lastly, direct glacial perturbation close to the present ice margin becomes apparent, where a wide range of shapes, sizes and therefore a poor degree of sorting characterises the reworked raised beaches. In conclusion, this study could show that all criteria combined can be a useful tool for tracking glacial footprints