Fig. 1: Predicted ice shelves in the North Sea confirmed by the presence of multi-keeled iceberg ploughmarks.

a Model reconstruction of the retreat of the last British-Irish (BIIS) and Fennoscandian (FIS) ice sheets between 22 ka and 17 ka from Clark et al. 40, showing the locations of predicted ice shelves (colored by reconstruction age), and the high-resolution 3D (HR3D) seismic datasets analysed in this study (turquoise circles). The orientations of the multi-keeled iceberg ploughmarks observed within the HR3D seismic datasets (if present) are indicated by arrows. Palaeo topography and water depths at 21 ka are from Bradley et al. 60. The inset map displays the modern coastline for reader orientation; green “+” symbols mark previously inferred locations of ice shelves surrounding the BIIS from seabed geomorphological evidence41,42,43,44,47,48. b Cross profile of the central North Sea showing the modeled retreat of the BIIS and FIS between 21 ka and 17 ka from Clark et al. 40. Palaeo topographies (rebounding as the ice retreats) from Bradley et al. 60 are displayed as dashed lines and are in reference to modern sea level. WGB—Witch Ground Basin. NC—Norwegian Channel.