Evolution of the Bug River Valley during the Holocene in the environs of Janow Podlaski (Eastern Poland) in the light of malacological analysis of oxbow lake deposits

The malacofauna of two profiles of deposits filling palaeomeanders of the Bug River Valley was studied. The first one (Zaczopki) represents an older phase of the valley development corresponding with the Early Holocene or even with the Late Glacial. Its assemblage contains numerous shells of cold-tolerant species. The second profile is situated near the village Woroblin. It represents a younger stage of the valley evolution (uppermost part of the Middle Holocene and Late Holocene). The mollusc fauna is typical of shallow and overgrown, stagnant water bodies. The sequences of mollusc aasemblages from both profiles characterise the development of these reservoirs, corresponding with climatic changes and differences in fluvial activity of the Bug River during the Holocene