Geoscience Reference
In-Depth Information
the Baltic Ice Lake, Ancylus Lake, and Littorina Sea stages. The linear struc-
tures described are overlain by post-glacial coast formations (the second-order
morphostructure).
10.6 Discussion
When interpreting the results, we relied on the current knowledge of the southern
foremost the 314 radiocarbon datings of terrestrial and marine sediments, backed
up by numerous pollen, diatom, micro- and macro-faunal analyses as well as by the
struct the history of relative sea-level changes as well as vertical crustal movements
and changes in the shoreline location during the Late Pleistocene and Holocene in
the southern Baltic. Every relative sea-level curve showed the joint effect of eustatic
change and vertical crustal movement. The two processes controlled the appear-
ance and disappearance of thresholds and played a prominent role in the relative
coast-level history. The contributions of eustasy and isostasy were determined by
comparing each relative sea-level curve with the eustatic curve.
The coast evolved at three stages: the Late Pleistocene-Early Holocene, a stage of
several rapid and extensive shoreline displacements; the Middle Holocene, initially
characterized by a rapid shoreline migration and the coast becoming stabilized
between 5 and 6 ka BP; and the Late Holocene, with a narrow range of shoreline
displacement and domination of coast levelling processes, resulting in the present
location of the shoreline.
By comparing the southern Baltic relative sea-level curves and the eustatic ocean-
The restrained rebound phase began c
.
17.5 ka BP and lasted until c. 14.0 ka BP.
Over that time, the sea level in the southern Baltic rose about 20 m. The basic
post-glacial rise proceeded from c. 14.0 to c. 11.0 ka BP, with the southern Baltic
area being raised by about 85 m. The rise proceeded at a maximum rate of about
45 mm/year around 12.2-12.4 ka BP. The residual rise began c. 11.0 ka BP and
terminated c. 9.0-9.2 ka BP, the crust rising about 15 m. The southern Baltic rate of
rising c. 10.0 ka BP slowed down to c. 5.5 mm/year and the uplift stopped c. 9.2-
9.0 ka BP. The rapid termination of post-glacial uplift within c. 11.0-9.0 ka BP was
probably caused by the restraining effect of hydro- and sediment isostasy. Around
c. 4.0 ka BP, the Earth's crust regained its equilibrium.
However, the actual history of Holocene sea-level changes, particularly in the
Atlantic, Subboreal, and Subatlantic, was undoubtedly more complex than that
emerging from a smoothed-out relative sea-level curve. In the Late Holocene in
particular, against the background of a slight and slow rise of the mean sea level,
regional eustatic fluctuations associated with climatic changes could have sub-
another factor not associated with glacio-isostasy that produced regional differences
