Baltic Ice Lake levels and a LiDAR/DEM-based estimate of the glacio-isostatic uplift gradient of the Salpausselkä zone, SE Finland

Glaciofluvial ice-contact deltas were mapped and altitudes of the highest shorelines defined in the eastern arc of the Salpausselkä zone, southern Finland, using Light Detection and Ranging (LiDAR)-based digital elevation models and GIS tools. Mapping of deltas and the highest shorelines in the Salpausselkä zone were undertaken in order to calculate and define the glacio-isostatic uplift palaeo-isobases, uplift gradients and equidistant diagrams (distance diagrams) for the Salpausselkä zone. The results indicate that the glacio-isostatic uplift palaeo-isobases were orientated NE-SW (50°–230°) and the uplift gradients for both the First and the Second Salpausselkä in the eastern arc, are virtually the same, namely 0.6 mkm-1. This suggests that both Salpausselkä ridge complexes, which were originally laid down in front of the Finnish Lake District Ice Lobe (FLDIL) in relatively shallow water, were deposited within a short time period during the Late Weichselian Younger Dryas Stadial. The results also suggest that the Baltic Ice Lake water level regressed 7.5 metres from Baltic Ice Lake level B I to level B III as the ice retreated in its eastern arc from the First to the Second Salpausselkä.