Submerged HoloceneWave-Cut Cliffs in the South-eastern Part of the Baltic Sea: Reinterpretation Based on Recent Bathymetrical Data - The Baltic Sea Basin - page 214

in relative sea-level changes, and hence affected the shoreline evolution at that time
(Dodonov et al. 1976 , Sliaupa 2002 ) .
The present understanding of sea-level changes, as discussed above, allows the
fossil coast levels revealed to be assigned to the periods indicated below (see
Fig. 10.3 ) .
Fragments of the four deepest submerged wave-cut cliffs (62, 68, 76, and 88 m)
are probably correlated with post-glacial fluctuations of the water level in the near-
glacier lakes, or were caused by glacial exaration, or else their origin is structure
dependent. A special study is required to resolve this question. At some sites, sep-
aration of wave-cut cliff locations was not possible. These wave-cut cliffs are most
probably best described as polygenic.
The range of the first BIL regression (11.2-11.0 ka BP, Allerød-Younger Dryas)
was estimated from the River Vistula progradational deltaic structures as well as
from barrier structures on the western slopes of the Gdansk Basin (Uscinowicz
2003 ) . The two set of structures are found down to the depth of about 65 m, which
speaks of the sea level being located lower when the structures were being devel-
oped. Subsequently, the BIL southern coast experienced a rapid transgression with
the maximum occurring c. 10.3 ka BP.
Consequently, the breaks visible at the depths of 62 and 68 m may be inferred to
have been related to the maximum BIL regression. However, the absence of any
northward rise of the lines suggests that their origin is independent of the late-
and post-glacial sea-level fluctuations and isostatic effect. Thus, they are probably
structure-dependent breaks.
In our opinion, the next submerged coastline (at the average depth of 53 m),
which occurs at the depth range of 58-55 m near the Sambian Peninsula and at
50-45 m on the Curonian-Sambian Plateau, corresponds to the beginning of the
Yoldia-Ancylus transgression (Y1). Its depths correspond to the location of the low-
est relative sea level (Gudelis 1979 , Uscinowicz 2003 ) reached after the rapid BIL
regression and at the beginning of the Yoldia stage. The isostatic depth difference
matches Gudelis's ( 1979 , 1982 ) estimates of the maximum at 10-12 m during the
late- and post-glacial periods.
The next fossil coastline (at the average depth of 48 m), discovered near the
Sambian Peninsula at the depth of 52-50 m and at 45-40 m on the Curonian Rise,
corresponds to the Yoldia Sea stage (Y2) as well.
The 38-m-level coastline identified on the submerged slope of the Sambian
Peninsula corresponds to the first Ancylus shoreline (Anc1), with the 29-m level
corresponding to the initial stage of the Littorina transgression (Lit1). The wave-
cut cliffs at those depths had formed earlier during the BIL transgression (BIL1,
Allerød) and Anc2. The middle levels of 38 and 29 m probably merge on the
Curonian-Sambian Plateau because of the difference between isostatic rise rates.
Finally, the 21-m middle level corresponds to the initial stage of the Littorina
transgression.
Unfortunately, our reinterpretation has not eliminated the major discrepan-
cies between wave-cut cliff locations put forth by different authors. This can be
illustrated by comparing locations of the Y wave-cut cliff: while Gudelis et al.