Tilting of Lake Pielinen, eastern Finland – an example of extreme transgressions and regressions caused by differential post-glacial isostatic uplift

Abstract

Tilting of large lakes due to differential isostatic uplift in the glaciated regions of the Northern Hemisphere is a well-documented process. With the help of accurate digital elevation models and spatial GIS analysis techniques, the resulting hydro­logical changes, including shifts in the outlets and changes in the size and configuration of lakes, can now be mapped and calculated more precisely than before. As a case study to highlight the magnitude of such changes in Fennoscandia, we investigated and reinterpreted the Holocene palaeogeography and palaeohydrology of Lake Pielinen in eastern Finland. This lake is currently 99 km long and located parallel to the direction of land uplift, being thus particularly sensitive to the impacts of tilting. Our results show that the lake was formed at the end of the regional deglaciation, following drainage of a local ice-dammed lake. In its initial stage until 10 200 cal yr BP, the outlet of the newly-formed lake was located in its northwestern end, but the tilting led to a major water level transgression in the basin, eventually causing formation of a new outlet over the southeastern threshold. The lake area was 143 km long and its area was 1998 km2 at the time of formation of the southeastern outlet at 10 200 cal yr BP. The lake level has been regressive throughout the basin during the last 10 200 years. This regression will continue for approximately another 10 000 years until all the glacial isostatic adjustment has occurred, after which Lake Pielinen will be only 89 km long and 565 km2 in area

Development of an ancient shoreline database to reconstruct the Litorina Sea maximum extension and the highest shoreline of the Baltic Sea basin in Finland

“…for the highest shoreline formed during the Yoldia Sea and the Ancylus Lake stages in Finland. Areas covered by the Ilomantsi Ice Lake (A) (Vesajoki et al, 1986), the Saimaa-Sääminki Ice Lake (B) (Saarnisto, 1970;Eronen & Haila, 1992;Hakulinen, 2009), the Pielinen Ice Lake (C) (Miettinen, 2002;Seppä et al, 2012), the Sotkamo Ice Lake (D) (Saarelainen & Vanne, 1997), and various ice-dammed lakes in Northern Finland (E) (Johansson, 2005) are shaded with dark blue. Basemap © the National Land Survey of Finland.…”

“…Among these is the history of the BSB, as well as the evolution of the great lakes in Finland and their main palaeohydrological changes (e.g. Saarnisto, 1970;Eronen, 1992;Seppä et al, 2012). The relative altitude of the shoreline in the past also strikingly contributed to the genesis of the superficial deposits in Finland, which is why defining the boundary between subaquatic and supra-aquatic areas, as well as shoreline displacement over time, is important when mapping Quaternary deposits and searching for raw materials such as gravel, sand or clay for industry and construction (Ikävalko et al, 2011;Palmu, 2011;Vuori et al, 2011).…”