Late Pleistocene iceberg scouring in the north-eastern Baltic Sea, west of Estonia

During the last glacial period, the western sea area of Estonia in the northern Baltic Sea was covered by the Fennoscandian continental ice sheet. High-resolution multibeam bathymetric images of the seafloor reveal widespread linear and curved depressions, interpreted as iceberg scours (ploughmarks) that were produced by ploughing and grounding icebergs during and soon after the final ice retreat from the area. Two main populations (A and B) of scours are identified, formed either on top of the acoustic substratum (bedrock or coarse-grained glacial deposits) or on top of the superimposed glaciolacustrine and post-glacial sediments that are exposed on the seafloor. Both populations have similar characteristics, being on average 780 m long, 54 m wide and 1.6 m deep. Most of the scours are linear, with an average NE-SW orientation for Population A, and an average ENE-WSW orientation for Population B. The scour patterns indicate a partially grounded ice sheet in the shallower parts of the study area. We suggest that the period of most intensive iceberg calving and scouring lasted for approximately 1100 years, from 13.2 to 12.3 kyr BP.