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This paper represents one output of the extensive seismo-acoustic profiling performed by the Estonian Geological Survey in the Väinameri, the shallow sea in the West Estonian Archipelago, during the geological mapping conducted in 2019â2022. Based on recordings from boomer-type sound transmitters, this study describes and analyses the bedrock relief to assess a prior suggestion that there exists a NEâSW trending pre-Quaternary river valley traversing the Väinameri, extending across the central Baltic Sea. The bedrock relief map and 3D model reveal a valley-like structure with distinctive cuesta elements crossing the central Väinameri. The cuesta plateau, along with the cuesta escarpment (Silurian Klint) that emerges faintly in the Bay of Matsalu, has been substantially reshaped by Pleistocene glaciers around the Muhu depression in the very centre of the Väinameri and is best preserved between Saaremaa and Hiiumaa islands. The general drainage pattern also points towards a fluvial erosion component in shaping the bedrock depression below the Väinameri. Despite that, the age and genesis of this valley-like feature with the Silurian Klint below the Väinameri remain open. The hypothesis that a pre-Quaternary Eridanos River System might have eroded these bedrock structures contradicts the altitude of the klint base below the Baltic Sea, which remains far below the presently estimated reach of the Eridanos fluvial erosion. Further studies are needed to specify the possible genesis and age of the klints and buried bedrock valleys in Estonia, which, in many aspects, reveal the characteristics of pre-Quaternary fluvial denudation rather than Pleistocene glacial erosion.

This paper represents one output of the extensive seismo-acoustic profiling performed by the Estonian Geological Survey in the Väinameri, the shallow sea in the West Estonian Archipelago, during the geological mapping conducted in 2019-2022. Based on recordings from boomertype sound transmitters, this study describes and analyses the bedrock relief to assess a prior suggestion that there exists a NE-SW trending pre-Quaternary river valley traversing the Väinameri, extending across the central Baltic Sea. The bedrock relief map and 3D model reveal a valley-like structure with distinctive cuesta elements crossing the central Väinameri. The cuesta plateau, along with the cuesta escarpment (Silurian Klint) that emerges faintly in the Bay of Matsalu, has been substantially reshaped by Pleistocene glaciers around the Muhu depression in the very centre of the Väinameri and is best preserved between Saaremaa and Hiiumaa islands. The general drainage pattern also points towards a fluvial erosion component in shaping the bedrock depression below the Väinameri. Despite that, the age and genesis of this valley-like feature with the Silurian Klint below the Väinameri remain open. The hypothesis that a pre-Quaternary Eridanos River System might have eroded these bedrock structures contradicts the altitude of the klint base below the Baltic Sea, which remains far below the presently estimated reach of the Eridanos fluvial erosion. Further studies are needed to specify the possible genesis and age of the klints and buried bedrock valleys in Estonia, which, in many aspects, reveal the characteristics of pre-Quaternary fluvial denudation rather than Pleistocene glacial erosion. [ABSTRACT FROM AUTHOR]

Bedrock relief with the basics (subdivision and thickness) of the overlying Quaternary sequence was studied by means of seismo-acoustic profiling beneath the Suur Strait in the West Estonian Archipelago. Reaching ca 15â20 m below sea level (b.s.l.) in the watershed area in the NE corner of the Gulf of Riga, the bedrock surface beneath the strait drops along two channels, divided by the islet of Kesselaid rising ca 15 m above sea level (a.s.l.), into a large depression more than 60 m b.s.l. in the interior of the Väinameri. A similar setting indicates that the low-lying bedrock surface between the Estonian mainland and the islands of Muhu and Saaremaa was formed by combining erosions of preglacial river(s) and Pleistocene glaciers. The large depression NW of the islet of Kesselaid possibly represents a section of an east-west running preglacial river, heavily reworked by Pleistocene glaciers. Although supported by preliminary data from the Soela Strait, the latter opinion still needs additional profiling between the islands of Hiiumaa and Saaremaa. The thickness of the Quaternary sequence around the strait follows the general height and ruggedness of the bedrock surface; it is occasionally missing in the nearshore bedrock plateaus (submarine alvars) and reaches ca 50 m in the depression NW of Kesselaid.

Bedrock relief with the basics (subdivision and thickness) of the overlying Quaternary sequence was studied by means of seismo-acoustic profiling beneath the Suur Strait in the West Estonian Archipelago. Reaching ca 15–20 m below sea level (b.s.l.) in the watershed area in the NE corner of the Gulf of Riga, the bedrock surface beneath the strait drops along two channels, divided by the islet of Kesselaid rising ca 15 m above sea level (a.s.l.), into a large depression more than 60 m b.s.l. in the interior of the Väinameri. A similar setting indicates that the low-lying bedrock surface between the Estonian mainland and the islands of Muhu and Saaremaa was formed by combining erosions of preglacial river(s) and Pleistocene glaciers. The large depression NW of the islet of Kesselaid possibly represents a section of an east-west running preglacial river, heavily reworked by Pleistocene glac iers. Although supported by preliminary data from the Soela Strait, the latter opinion still needs additional profiling between the i slands of Hiiumaa and Saaremaa. The thickness of the Quaternary sequence around the strait follows the general height and ruggedness of the bedrock surface; it is occasionally missing in the nearshore bedrock plateaus (submarine alvars) and reaches ca 50 m in the depression NW of Kesselaid. [ABSTRACT FROM AUTHOR]