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Tree stumps from the bottom of the Vistula Lagoon as indicators of water level changes in the Southern Baltic during the Late Holocene

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Łęczyński L. , Miotk-Szpiganowicz G. , Zachowicz J. , Uścinowicz S. , Krąpiec M.

tom No. 49 (2)

245-257

The Vistula Lagoon is situated along the south-eastern shore of the Gulf of Gdansk and is linked with the gulf through the Strait of Baltiysk. Separated from the open sea by the Vistula Spit, the Vistula Lagoon is a shallow body of water with a mean depth of 3 m; the bottom is covered with a layer of mud several metres thick. This article presents a unique, newly discovered locality of tree stumps occurring in situ at the bottom of the Vistula Lagoon. The radiocarbon age of the alder stumps and the top of the peat in which they are rooted is Subboreal. The alder wood was dated to 4770š35 and 3295š35 years BP. The top layers of peat were dated to 4670š40, 4410š35 and 3690š35 years BP. The considerable scatter of the dates indicates the significance of erosional processes during marine transgressions. Radiocarbon dates and pollen analyses indicate that in the late Atlantic - early Subboreal periods, the water level of the Vistula Lagoon was about 3 m lower than it is today. The -2 m level was passed no earlier than c. 3500 years ago; the -1 m level was reached around 2000 years ago.

Simulation of the shorelines of glacial Lake Peipsi in Eastern Estonia during the Late Weichselian

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Rosentau A. , Hang T. , Miidel A.

tom Vol. 48, No 4

299--307

Digital reconstruction of the evolution of glacial Lake Peipsi, Eastern Estonia, was based on a geographic information system (GIS) method that removed isostatically deformed palaeowater planes fromthe current digital terrain model. A reconstruction of the proglacial water levels was performed with respect to geomorphological correlation of river terraces, raised shorelines and eroded surfaces of various aqueoglacial landforms. The configuration of shorelines, main outlets and water depths of glacial Lake Peipsi, corresponding to the Otepää, Piirissaar, Kaiu and Pandivere–Neva stades during the deglaciation of the Lake Peipsi depression, was simulated. The two approaches used, reflecting the geomorphological correlation of Raukas and Rähni (1969) and Hang (2001), are discussed.

Recharge and drainage of lakes in the Powidzki Landscape Park in conditions of increased anthropogenic and environmental pressure (central-western Poland)

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Nowak B. M. , Przybyłek J.

tom Vol. 64, No. 1

205--219

The lakes of the Powidzki Landscape Park (Gniezno Lakeland) are known for their natural and recreational values. The majority of them are located within two large glacial tunnel valleys, that in many places cut through several levels of till and inter-till aquifers. Regional hydraulic linkage systems are developed where surface water and groundwater remain in direct contact. Smaller water bodies occur between the lakes, in other tunnel valleys, in isolated meltwater basins, or in river valleys. These water bodies constitute local drainage bases. The existence in the area of such morphologically diverse lakes with different flow rates, varied morphology, and heterogeneous geological structure permitted tracing of the hydrodynamic dependencies of lake catchments of various types. Hydrogeological cross-sections, comparative analyses of structural maps for successive aquifers, bathymetric plans of lakes, and piezometric contour maps were prepared. Surface and groundwater level fluctuations were investigated, as well as their response to changing atmospheric conditions. Water balances of lakes were also determined for selected lake catchments. The study showed that all the lakes analysed are closely related to groundwater, and that the deepest ones reach lower aquifers. The majority of the lakes drain the aquifers, but some of the lakes feed them. Such a situation was documented in coastal wetlands and in the eastern part of the Park, affected by a depression cone associated with a nearby lignite opencast mine. The study showed that the deepest of the lakes analysed have a very wide catchment area of groundwater recharge, expanding beyond the boundaries of their surface catchment areas. This is important for the development of their resources, especially in periods of hydrogeological low flow.

Paleolimnological study based on ostracods (crustacea) in late-glacial and holocene deposits of Lake Krakower See (Mecklenburg-Vorpommern, NE Germany)

86%

Finn A.

2004

tom Vol. 21

109-115

Two cores were taken from the southern lake basin to record the lake development from the Allerod until today. The Late Glacial and Holocene deposits of Lake Krakower See (Mecklenburg-Vorpommern, NE Germany) revealed changing water levels of the lake. Subfossil freshwater ostracods were used to interpret signals in terms of hydrological changes, eutrophication and temperature. A diverse ostracod fauna of 24 species was found in the examined sedyment samples. For the first time the development of Late-Glacial and Post-Glacial freshwater ostracod assemblage could be recorded in the study area.