Lake Zeribar sediments covering the time period of the last 25,000 years were examined for the contents of seeds, fruits, Characeae, diatoms, and molluscs. Reconstructions of the variations in the lake water level, salinity, and trophy suggest a sequence of climatic changes. Three pronounced stages of low and varying lake-water level occurred ca. 17,700–15,400, 12,600–12,000, and 10,000–6000 cal yr BP. Some water-level changes were correlated with variations in salinity. The most pronounced increase of salinity occurred 17,700–15,700 and 12,600–12,000 cal yr BP, and less distinct ones occurred about 6400–5900 and 2500 cal yr BP. Diatom assemblages indicated a strong increase of lake trophy ca. 20,200 cal yr BP. Between 6000 and 5000 cal yr BP diatoms characteristic of eutrophy increased in core 63J, and at about 3200 cal yr BP a distinct increase in mesotrophic forms occurred in core 70B. The changes in the occurrence of various organisms indicate increased temperatures about 21,000 cal yr BP, between 15,400 and 12,600, about 12,000, and about 11,700 cal yr BP. The reduced occurrence or disappearance of some of them suggest temperature decreases about 17,700–15,400 and 12,600–12,000 cal yr BP.

Situated in the southern part of the Polish Outer Carpathians, the development of the Krynica lanslide is presented in detail. Head scarps, slide shoulders and colluvial ridges connected with particular episodes of sliding occur on the western slope of the Parkowa Góra Mountain. Peaty silts and calcareous tufa suitable for the radiocarbon dating fill depressions within colluvial masses. Calcareous deposits contain rich assemblages of molluscs characterizing changes of the climate and the environment during the Late Vistulian and the Holocene. Four stages in the evolution of the landslide correspond with phases of increased mass movements distinguished elsewhere in the Carpathians according to radiocarbon dating as well as palynological and malacological analyses. The phases of enhanced mass movement correlate in turn with climatic changes.

Shells and opercula of an aquatic snail Bithynia tentaculata (L.) occur commonly in Quaternary deposits as a substantial component of subfossil malacocenoses. They have been noted mainly in lacustrine chalk and calcareous gyttja, as well as in silts and muds accumulated in fluviatile environments. The contemporary geographical range of this taxon is very wide, comprising the whole Palaearctic except areas extending north of the Arctic Circle. In subfossil assemblages of molluscs B. tentaculata (L.) has been described almost exclusively from Holocene and Interglacial deposits, apart from a few localities of sediments accumulated during the cold periods of Pleistocene, particularly in Late Glacial phases. As the range of the mentioned species is limited to the zones of the temperate, boreal and Mediterranean climate, it can be pointed out as a climatic-stratigraphic indicator, useful in malacological analysis of Quaternary deposits. Only a few taxa of aquatic molluscs have such a value. The proportion of shells and opercula characterizes sedimentary environments.

Two subfossil mollusc assemblages have been found near Sromowce, occurring in sediments of the Late Holocene. The older assemblage occurs in sediments dated to the V-XII centuries AD, and the younger one is connected with the sediments created in the two most recent centuries. The former comprises numerous species of forest and mesophilous snails and mass agglomerations of Bythinella austriaca shells.The presence of such a fauna indicates that in the Early Middle Ages, the southward slopes of the main range of the Pieniny Mountains were almost completely afforested. The dominants in the latter assemblage are typical snails of open habitats. The alteration of the malacofauna, being due to the deforestation of a considerable area, reflects a transformation of the natural environment under human impact. ABSTRACT Two subfossil mollusc assemblages have been found near Sromowce, occurring in sediments of the Late Holocene. The older assemblage occurs in sediments dated to the V -XII centuries AD, and the younger one is connected with the sediments created in the two most recent centuries. The former comprises numerous species of forest and mesophilous snails and mass agglomerations of Bji#'JinH!I.IVSITI~~ shells. The presence of such a fauna indicates that in the Early Middle Ages, the southward slopes of the main range of the Pieniny Mountains were almost completely afforested. The dominants in the latter assemblage are typical snails of open habitats. The alteration of the malacofauna, being due to the deforestation of a considerable area, reflects a transformation of the natural environment under human impact

A rich population of Planorbella duryi (Wetherby) has been found in Lake Albano near Rome. It is a pulmonate aquatic snail inhabiting the zone of tropical climate, and heated artificial reservoirs outside this zone. It has migrated from its area of origin-Florida-to Africa, South America and some islands, has been introduced in a few botanical gardens in Europe, and also found a favourable habitat in a small crater-lake Albano in Italy where it is now abundant.