Glacial geomorphological map of the western margin of the British Irish Ice Sheet on the Irish continental shelf: Quaternary International 279-280 (2012) 121–232

This poster presents the results of the first systematic mapping programme of the submerged glacial geomorphological record of the former British Irish Ice Sheet on the Irish Atlantic continental shelf. The mapping is based on interpretations of high resolution (20 m) multibeam swath bathymetry and backscatter data from the Irish National Seabed Survey (INSS), supplemented by medium resolution Olex data of the shelf west of Mayo, Clare and Galway which was not surveyed as part of the INSS. Both data sets provide evidence of glacial and glacially related landforms which reveals the pattern of shelf extensive glaciation and subsequent ice retreat along this part of the Atlantic margin. Streamlined subglacial bedforms on the mid to outer shelf and the Barra/Donegal Fan-Malin Deep glacial trough system in the northwest sector record former offshore-directed ice flow and former ice stream activity in the Malin Shelf region. However, the most striking geomorphological features along the entire margin are sequences of well developed kilometre scale arcuate moraine ridges that arch across the shelf to the northwest and west of Ireland. Distal to all of these moraines on the outermost shelf prominent zones of iceberg scours are evident and give way into a well developed system of gullies and canyons which incise the continental slope. The large-scale, arcuate moraines record the episodic retreat, probably punctuated by minor readvances or oscillations, of grounded ice sheet lobes along the entire western margin. The data indicates that a major reorganisation of the British Irish Ice Sheet occurred in this region during deglaciation from an initial elongate ice sheet configuration extending to the shelf edge to pronounced lobate forms during ice retreat.