Flow‐pattern evolution of the Scandinavian Ice Sheet indicated by the subglacial lineation record over Norway, Sweden and Finland

Streamlined subglacial bedforms, including drumlins, mega‐scale glacial lineations, crag‐and‐tails and roche moutonnées, provide evidence for the past flow of large mid‐latitude ice sheets during the late Quaternary. Empirical reconstructions of palaeo‐ice sheet flow, based on such landforms, provide valuable insights into how ice sheets evolve over time and adjust their internal dynamics in response to climate change. We present a new 25‐stage reconstruction of changing flow directions of the Scandinavian Ice Sheet (SIS) based on systematic mapping of ~240 000 subglacial bedforms across Norway, Sweden, Finland and parts of NW Russia. Of these, 23 stages depict the ice flow evolution during advance and retreat of the SIS through Marine Isotope Stage (MIS) 2. Two additional stages likely represent flow patterns of an earlier ice sheet (potentially MIS 4 or older). Our reconstruction was enabled by the recent revolution in the availability of high‐resolution (1–2 m) digital terrain models. It is based on 611 flowsets, which summarise discrete ice‐flow patterns recorded by subglacial lineations and are individually categorised by their glaciodynamic contexts. The reconstruction honours the relative‐age chronology of flowsets indicated by cross‐cutting relationships of the subglacial lineations. We reconstruct, and provide maps of, changing ice‐sheet flow patterns and the migration of ice divides starting with ice‐sheet inception, through advance and subsequent deglaciation, and ultimately the fragmentation into independent ice masses. The primary ice divide migrated up to 500 km and developed a branched configuration during deglaciation. The reconstruction of SIS flow patterns we present is the most detailed and comprehensive to date, and the fact that we independently verify many properties of the ice sheet invoked by earlier workers is testament to the quality, rigour and enduring legacies of those studies. We release flowsets, relative chronology and flow‐pattern data along with a dataset of ~58 000 lineation linkages which summarise our detailed landform mapping and were invaluable for reconstructing ice‐flow patterns at the ice‐sheet‐scale. In releasing these data, we intend for them to serve as useful inputs or comparative data for future studies in palaeoglaciology. This includes, for example, approaches combining flow pattern information with numerical ice sheet modelling to improve representations of ice sheet behaviour. Such improvements should yield increased robustness of information on time‐varying glacio‐isostatic loading by the ice sheet, relevant for sea‐level forecasting. Our datasets also have wide utility for applications beyond palaeoglaciology, such as for mineral exploration.