Submerged HoloceneWave-Cut Cliffs in the South-eastern Part of the Baltic Sea: Reinterpretation Based on Recent Bathymetrical Data - The Baltic Sea Basin - page 208

The spectrogram obtained by Gelumbauskaite ( 1982 ) revealed four levels:
Y (52-62 m), Anc2 (40 m), Lit1 (28 m), and Lit2 (18 m). These levels were defined
by mapping the axial lines of wave-cut platforms, platform edges, and rear seams,
and were marked on transverse profiles of the underwater slope. These so-called
distinctive lines are situated at similar depths and reflect the location of coastal for-
mations of a similar age. Unlike in the spectrogram by Gudelis et al. ( 1977 ) , all
the levels are horizontal, except Y. This exception, presented in the deeper part of
the lowest submerged ancient coastline, runs southward from 52 to 62 m, and -
according to Gelumbauskaite ( 1982 ) - was caused by late- and post-glacial glacio-
isostatic crust movements which virtually stopped at the Ancylus (Boreal) stage.
Deviations from the mean levels identified (i.e. deformations of the distinctive lines)
were interpreted as a result of relative vertical crust movements during the Holocene.
The resultant schematic map shows the vertical movements to have proceeded at a
rate of +1.4 to -0.8 mm/year, which is within the generally accepted, estimated
range of tectonic movements in the area during the Holocene. At the same time,
Gelumbauskaite ( 1982 ) listed some factors that affected the hypsometric level of
the fossil coast formations and rendered their identification and mapping difficult.
Those factors include various origins of the submerged erosion-exaration cliffs and
the adjacent erosion-accumulation surfaces, coastal orography, and the lithological
composition of bottom sediments (rocks), which influenced the intensity of litho-
dynamic processes. Besides, the wave-cut platform edges and their rear seams are
usually poorly visible on the cross section of the submerged slope; moreover, it is not
always possible to identify wave-cut platform levels on echograms and bathymetric
maps.
Blazhchishin et al. ( 1982 ) defined the Holocene coast levels by analysing wave-
cut platform surface depths. They identified a few underwater levels and one which
lies above modern sea level. Unfortunately, their bathymetry and age designations
often differ from the information in the text and in the schematic maps, casting
doubts on their reliability. The map published by Blazhchishin et al. ( 1982 ) fea-
tures five ancient coast lines: Y (55-62 m), Anc1 (35-42 m), Lit1 (27-32 m),
Lit2 (16-20 m), and Lit3 (3-0 m).
According to Blazhchishin et al. ( 1982 ) , it would be difficult to date the fossil
coast formations in the sediment cores with a higher precision because those coasts
were frequently shifting during the Holocene, with the transgression-subjected land
edge being cut and transformed by the oncoming sea. Two submerged levels were
also defined NW of Cape Taran at depths of 70-75 and 90-105 m: the first is visible
as an accumulation plain and the other as a well-defined wave-cut cliff, 10 m high,
buried by the sediment cover. Blazhchishin et al. ( 1982 ) suggest that the two levels
are associated with sea-level fluctuations during the Pleistocene, since the lowest
Holocene level of the southern Baltic is to be found at 60-65 m (Kvasov 1975 ) .
Kharin ( 1987 ) reported detecting further four wave-cut cliffs north of Cape Taran,
at the depths of 90-96, 16-24, 12-20, and 4-6 m; in addition, he noted the presence
of faintly expressed steps (at 68-69, 62-63, 57-58, 42-45, 37-39, 30-34, 26-27,
and 16-18 m depths) in the northern part of the area of study as well as wave-cut