Submarine evidence of ice-streaming and ice-sheet re-advance of the British Ice Sheet

A number of major ice streams have been identified within the Pleistocene British–Irish Ice Sheet (BIIS), primarily based on onshore mapping and single beam bathymetric datasets offshore (e.g. Bradwell et al., 2008). The identification of these ice streams is crucial to better understand the flow pattern and demise of the last BIIS, although evidence is currently lacking for key marine sectors such as the North Sea Basin. An improved understanding of the past cycles of glaciation, timing and extent, has far reaching implications for better understanding global climate change and ice-sheet behaviour. This work focuses on the offshore geomorphological signature of the ice sheet sector referred to as the North Sea Lobe. New interpretations derived from high-resolution multibeam echosounder data and single-beam echosounder bathymetry data have been viewed in conjunction with onshore topographic digital surface models (NEXTMap). Derived layers of rugosity, slope, bathymetric positioning index and aspect were utilised during geomorphological mapping. Where available, multibeam backscatter intensity data have also been utilised as part of a semi-automated approach to identify areas of glacigenic deposits. Mega-scale glacial lineations and drumlin fields indicate the North Sea Lobe was fed by an ice stream emanating from the Forth–Tay catchment in central Scotland. Large arcuate moraine ridges, smaller-scale moraine ridges and grounding-zone wedges indicate a complex advance, recession and re-advance of the North Sea Lobe during the Last Glacial Maximum