No abstract

The paper contains results of new investigations in Lithuania of the first occurrences of terrestrial molluscs in calcareous tufa (travertine), carbonate content and radiocarbon dating. Terrestrial fossil molluscs (35 taxa) prevail in the mollusc fauna, while fresh water species are much more rare (6 taxa). The Dūkšta terrestrial mollusc fauna embraces a complex of thermophiles including such forest species as Acicula polita (Hartmann), Acanthinula aculeatа (Müller), Aegopinella cf. pura (Alder), Bulgaria сапа (Held) and Discus cf. rotundatus (Müller), as well as mainly South European Carychium tridentatum (Risso) and mainly West European Vertigo moulinsiana (Dupuy). The radiocarbon age of the sediments was found to correspond to the end of the Atlantic climatic period and the beginning of the Subboreal.

The fauna and flora of each Quaternary interglacial epoch of the middle latitudes possesses general and specific connections with climate. The presence of the Atlantic and West European mollusc Belgrandia marginata (Michaud) is distinctive in the freshwater malacofauna of the Eemian (Muravian, Merkine) interglacial in Belarus, Lithuania, and Poland. This species is present in eight malacofaunas of the region, with exclusively Eemian age. Paleontologic researches show that the species occupied reservoirs in this territory only during an optimum Eemian interglacial, giving it stratigraphical value in the region. The 1000 km sublatitudinal extent of the species through the Central European plain and Russian plain to the Dnieper River reflects, most likely, the direction of circulation of Atlantic air masses deep into the continent. The Eemian extent of B. marginata in the upstream Dnieper basin is imposed on the range of the Ponto-Caspian mollusc Dreissena polymorpha, which also occupied the upstream Dnieper basin only in the Eemian Interglacial. Both species are characteristic representatives of the Eemian (Muravian) freshwater malacofauna of Belarus.

Th e paper contains results of new investigations of interstadial deposits at Zervynos on the Ūla River in southeastern Lithuania regarding sapropelite occurence, radiocarbon dating and malacological analysis. Organic deposits belong to a lake formation. Th e age of lake deposits is the Alleröd time. Th e Zervynos malacofauna consists of seven ecological groups, eurytopic water molluscs playing the main role (41%). Lake species and those of overgrowing and silting water make only 18%. Lake fauna is characterised by Gyraulus laevis (Alder) and Armiger crista (Linnaeus). Evolution of the Ūla River valley is related to the development of glaciokarst depressions.

No abstract