Final stage of loess accumulation in the glacial zone of the last glaciation (northwestern Russian Plain)

For the first time the article discusses the final stage of loess accumulation in the area of the last (Valdai, Ostashkov) glaciation in the northwest of the Russian Plain (Leningrad region). Based on data from large-scale soil mapping of the land-use area of the former Volna farm (Volosovsky district), located in the Devonian plain, three groups of soils have been identified, in the profile of which a thin (50—100 cm) mantle of subaerial sediments stands out. The granulometric groups of the soils are determined by the sedimentometric method, as well as by laser diffraction. As part of the lithomatrix of the soil profile, sub aerial al sediments form a part of the texturally differentiated profile of Holocene soils, which is light in terms of granulometric composition and enriched with a large silt fraction. The upper part of the soil profile is underlain by rocks of various genesis (tills, glaciofluvial and glaciolacustrine silty sediments, etc.). Loessoids were previously undetected in the soil profile structure. The landscape contiguity and areals of these deposits need further investigation. Aeolian sedimentation could be associated with "micro-periglacial" zones formed during the gradual retreat of the glacier. The presented factual material on the silty pebbleless sediments of the northwestern Russian Plain requires in-depth research with the involvement of specialists from related disciplines.