Palaeoreconstruction of the Baltic Ice Lake in the Eastern Baltic - The Baltic Sea Basin - page 198

Reconstructions of BIL stages A 1 ,A 2 and BIII are comparable with
those given earlier by Björck ( 1995 ) ; however, there are differences concern-
ing revised (calibrated) ages given in an unpublished Baltic history summary
( http://www.geol.lu.se/personal/seb ). The deglaciation chronology on these maps
was related to conventional 14 C years BP (Björck et al. 1988 , Lundqvist 1986 )
so that the ages of the BIL stages were originally 12,000, 11,000 and 10,300
14 C years BP (Björck 1995 ) . The revised ages suggested by Björck are 14,000,
13,000 and 11,700-11,600 cal. years BP, respectively. However, the first age is not
supported by new datings. According to Björck ( 1995 ) , during BIL stage 12,000
uncal./14,000 cal. years BP, the ice margin was located in Sweden at Levene and in
Estonia at Palivere line (Fig. 9.1 ) , although the water level in Estonia in that map
corresponds to BIL stage A 1 , developed during Pandivere-Neva stade (Kessel and
Raukas 1982 , Rosentau et al. 2007 ) . Levene moraine formed around 13,400 cal.
years BP (Lundqvist and Wohlfarth 2001 ) , which is approximately the same age
as Pandivere-Neva ice margin: 13,300 corrected varve years BP (Saarnisto and
Saarinen 2001 , Hang 2003 , Kalm 2006 ) .
BIL stage at 11,000 uncal./13,000 cal. years BP has approximately the same
age as reconstructed BIL stage A 2 ; however, ice-marginal positions are different:
ice margin in Estonia was at Palivere during that time, but in Björck's ( 1995 )
map ice margin was in Sweden at Younger Dryas (YD, Skövde) moraines and in
Finland at Ss I (Fig. 9.1 ) . Lundqvist and Wohlfarth ( 2001 ) have shown that the
YD moraines in Sweden formed around 12,475-11,615 cal. years BP, which corre-
sponds to the Salpausselkä age (Ss I-Ss II) around 12,250-11,590 corrected varve
years BP (Saarnisto and Saarinen 2001 ) . Moreover, during Ss I (12,250-12,030 cor-
rected varve years BP (Saarnisto and Saarinen 2001 , Rinterknecht et al. 2004 ) ) BIL
stage BI developed (Donner 1978 ) . Thus, Björck's ( 1995 ) reconstruction around
13,000 cal. years BP represents the BIL at the supposedly first drainage, but the ice
margin position seems to be questionable. In previous studies, the age of BIL stage
A 2 was unclear: it was considered to be in between Pandivere and Palivere stades
(Kessel and Raukas 1982 ) . Rosentau et al. ( 2007 ) compared the water levels of
BIL stage A 2 in Estonia with shore displacement curve data from eastern Småland
(Svensson 1991 ) and Blekinge (Björck 1995 ) in Sweden and concluded that forma-
tion of the coastal landforms of BIL stage A 2 occurred before the first drainage of
the BIL (Björck 1995 ) at about 12,800 cal. years BP, which is equivalent to the age
of the Palivere ice-marginal zone (12,700 corrected varve years BP; Kalm 2006 ) .
Earlier studies in Estonia (cf. Kessel and Raukas 1982 ) have shown that dur-
ing Palivere stade, proglacial lake with ca. 30 m lower water level than A 2 existed.
However, there is no clear evidence of the low water level in eastern Baltic between
BIL stages A 2 and BI as has been suggested on the basis of low-lying glacioflu-
vial plateau-like plains in front of the Palivere (Kessel and Raukas 1982 ) and
Salpausselkä (Sauramo 1958 , Donner, 1982 ) ice margins (Fig. 9.1 ) . Fyfe ( 1990 )
showed that these plains in Finland are overlapping fans formed under the water.
Most likely, the above-mentioned plateau-like marginal formations in Estonia have
also been deposited below the water surface. The wide distribution of subaquatic
waterlain glacial diamictons formed during the Palivere stade at the depth of