Deglaciation Dynamics Of The Scandinavian Ice Sheet In The Salpausselka Zone, Southern Finland

Deglaciation patterns of the Scandinavian Ice Sheet in the Salpausselka zone, southern Finland were studied. Digital elevation models (DEM/LiDAR-imageries) were used to map and categorize glacifluvial formations of the study area, and evidence for ice re-advance and retreat phases and their extent across the Younger Dryas Salpausselka zone was collected. The results suggest that the Finnish Lake District Ice Lobe, located in SE Finland, retreated a minimum of 60 km north of the proximal side of the present First Salpausselka ridge prior to the Younger Dryas, most probably during the Allerod interstadial (c. 13 900-12 700 years ago). This retreat phase was followed by a re-advance after which the First Salpausselka was formed (maximum age 13 300 +/- 900 years ago) in front of the Finnish Lake District Ice Lobe's ice margin. Subsequently, ice retreated further north and the Second Salpausselka in front of the Finnish Lake District Ice Lobe margin was formed, according to OSL-age determinations between 11 500 and 12 000 years ago. Previous research indicates that a similar retreat and re-advance event to that of the Finnish Lake District Ice Lobe did not take place in the area covered by the Baltic Sea Ice Lobe to the southwest. Overall, the results suggest that the ice retreat of the Finnish Lake District Ice Lobe was of the same magnitude as the contemporary Allerod interstadial ice retreat event along the western flank of the Scandinavian Ice Sheet in Norway and minor ice-sheet oscillations in central Sweden.