Palaeoreconstruction of the Baltic Ice Lake in the Eastern Baltic - The Baltic Sea Basin - page 192

BIL stages BI, BII and BIII are contemporaneous with the Salpausselkä I (SsI)
and Salpausselkä II (SsII) endmoraines (Donner 1969 , 1978 , Glückert 1995 ) , dated,
respectively, 12,250-12,030 and 11,770-11,590 corrected varve years BP (Saarnisto
and Saarinen 2001 , Rinterknecht et al. 2004 ) . BIL stage BI correlates with Ss I,
stage BII corresponds to the time when the ice retreated from Ss I to Ss II and
stage BIII corresponds to Ss II (Donner 1978 ) . Accordingly, the age of stage BI is
about 12,200, BII 12,000 and BIII 11,600 corrected varve years BP. Stage BIII cor-
responds to the BIL water level just before the Billingen drainage, which occurred
11,560 corrected varve years BP (Andrén et al. 2002 ) .
Modern DTM with a grid size of 200

×

200 m was generated using the linear
solution of the Natural Neighbour interpolation using different sources of eleva-
tion data. Estonian elevation data were derived from Digital Base Map of Estonia
on a scale of 1:50,000 (Estonian Land Board 1996 ) and complemented with more
detailed elevation data at critical threshold areas using Soviet military topographic
maps on a scale of 1:10,000 and 1:25,000. Elevation data for Latvia and NW
Russia were derived from Shuttle Radar Topography Mission (International Centre
for Tropical Agriculture 2004 ) and for southern Finland from GTOPO30 data (US
Geological Survey 1996 ) . Baltic Sea topography data were derived from Seifert
et al. ( 2001 ) .
DTM-based palaeoreconstructions have some limitations pointed out by
Leverington et al. ( 2002 ) due to the impact of deposition subsequent to the time
being modelled. The deposition influence on our modelling relates in critical thresh-
old areas mostly to the Holocene peat deposits, which were removed from DTM
according to the digital soil maps in scale 1:10,000 and different peat investigations
(Orru 1995 ) . After the removal of the Holocene peat and the interpolated surfaces
of water level from DTM, the shorelines and bathymetry were reconstructed for five
different stages.

9.3 Results

9.3.1 BIL 13,300 cal. years BP (A 1 )

Reconstruction shows that during Pandivere-Neva stade in front of the ice margin
the BIL extended to ice-free areas of Estonia, Latvia, Lithuania and NW Russia
(Fig. 9.2 ) . Several ice-contact slopes, flat-topped glaciolacustrine and glaciofluvial
landforms mark the ice-proximal coast of the lake up to 90 m above present sea level
in northern Estonia. Accumulative and abrasional coastal landforms developed in
more ice-distal areas. Water level near SW Lithuanian coast and further south was
below present sea level.
The Glacial Lake Peipsi was connected via strait system through the Lake
Võrtsjärv basin with BIL in the Baltic Sea basin (Fig. 9.2 ) . The water level in
Glacial Lake Peipsi was similar to BIL water level. A narrow strait could also exist in
northern Estonia and NWRussia directly in front of the Pandivere-Neva ice margin.