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In the continental pattern of glacial geomorphology, Estonia represents a transition zone between strong erosion to the north and west, and an area of predominant deposition to the south and southeast. Therefore, Estonia is characterized by rather rugged bedrock topography and uneven distribution of the Pleistocene cover. Distinct ice lobe depressions and interlobate uplands alternate as consequence of repeated Quaternary glaciations. The onset of the Late Weichselian glaciation in Estonia begun ca. 20-22 ka ago and the deglaciation took place between 15.7 and 12.5 ka BP.
Estonia plays a significant role in the former meltwater drainage characteristics and pathways in the region of the Scandinavian Ice Sheet, between the Fennoscandian Shield and the Palaeozoic sedimentary rock basin. Estonia was affected by the Baltic Ice Stream, which has a largely stable bed with no evidence of regional pervasive subglacial deformation and a significant amount of meltwater at the ice bed. The distribution of eskers and bedrock/tunnel valleys is a reflection of the large pattern of time dependent organisation of the channelized subglacial hydraulic system. Drumlinisation and local soft sediment deformation features facilitated by high pore-water pressure caused by the insufficient drainage indicate the widespread presence of a thin water film at the ice/bed interface.
Current study focuses on subglacial conditions and meltwater discharge mechanisms beneath a local southeasterly flowing ice stream which overriding the interlobate bedrock upland (Pandivere) formed the drumlin field (Saadjärve) behind the upland. Along this track, the differences in subglacial bed/bedrock geology and topography influenced significantly ice flow conditions. The Pandivere Upland is prominent bedrock high with an area 2500 km2 (along 80 m isoline) and reaching 130 m a.s.l. The Quaternary strata are very thin (occasionally even lacking) and mostly consist of till deposited during the last ice advance or later. The bedrock consists of the Ordovician and Silurian carbonate complex with thickness of up to 100 m. Behind the upland the bedrock falls to ca. 20 m a.s.l. in the more distal part of the drumlin field. The drumlin field indicates an area of converging ice flow where the ice stream was funnelled into a narrow track at the most distal part of the drumlin field. Substratum geology of this area is more complicated because of heterogeneous and stratigrafically different Quaternary sediment strata with variable thickness.
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