Palaeoreconstruction of the Baltic Ice Lake in the Eastern Baltic - The Baltic Sea Basin - page 199

50-60 m below the Baltic Ice Lake water table (Kalm and Kadastik 2001 ) suggests
a higher water level during deposition of the ice-marginal plains.
Our results match well with the reconstructions published by Jakobsson et al.
( 2007 ) for the last stage of the BIL (BIII). However, in the southern part of
the Latvian coast, our data show about 4-6 m lower water level as compared to
Jakobsson et al. ( 2007 ) . Further in the south, their inferred shoreline elevations
(Jakobsson et al. 2007 ) indicate higher water levels than the observed shore dis-
placement data from the Lithuanian (Gelumbauskaite and Seckus 2005 ) and the
Polish coasts (Uscinowicz 2006 ) . Our reconstructions indicate that there are prob-
lems to model water levels in the southern part of the Baltic Sea, where the water
level was below present sea level, because of the lack of data.
Our reconstructions show that the so-called Estonian local ice lakes A 1 and A 2
were connected with BIL. Kvasov and Raukas ( 1970 ) proposed that the beginning
of the BIL in eastern Baltic was earlier than Ss I (BIL stage BI). They found that
when the proglacial lakes east and west of the Pandivere Upland joined up about
13,000 cal. years BP, proglacial lake A 2 formed as a first BIL stage. It was assumed
that Glacial Lake Peipsi and proglacial lakes in NW Russia had a higher water
level before that event. Our reconstructions indicate that water levels were simi-
lar and Glacial Lake Peipsi and BIL were already connected during stage A 1 about
13,300 cal. years BP (Vassiljev et al. 2005 ) . Moreover, reconstructions suggest that
A 2 proglacial lake emerged later, about 12,700 cal. years BP during the Palivere
stade (Rosentau et al. 2007 ) .
Reconstruction indicates that Lakes Võrtsjärv and Peipsi isolated from the BIL
clearly before Billingen drainage. Earlier it has remained unclear whether the iso-
lation was caused by the Billingen drainage or by uplift. Lake Võrtsjärv isolated
from BIL about 12,400-12,000 cal. years BP and it is also supported by the low
water level data from the southern part of the lake: buried peat layer in the bottom
of the recent Lake Võrtsjärv (Moora et al. 2002 ) and the water level reconstructions
(Pirrus et al. 1993 , Hang et al. 1995 ) . Isolation of Lake Peipsi from the BIL was
about 12,400-11,700 cal. years BP and it is in good agreement with low water level
indicators from the southern part of the lake (Sarv and Ilves 1975 , Poska and Saarse
2006 , Hang et al. 2008 ) . Our modelling results show that Lake Peipsi isolated from
BIL before the Billingen drainage at about 12,400-11,700 cal. years BP. However,
the Billingen drainage probably enhanced the threshold erosion and the water level
lowering in Lake Peipsi continued according to the amount of erosion estimation
which needs further investigation.
9.5 Conclusions
BIL in the eastern Baltic was reconstructed at five levels between 13,300 and
11,600 cal. years BP.
Around 13,300 cal. years BP, the BIL extended to the ice-free areas of Latvia,
Estonia and NW Russia, represented by the well-developed shoreline in this region.