Geoscience Reference
In-Depth Information
over the last 8,000 years in the German part of the south-western Baltic coast
by close cooperation between geologists, geophysicists, geographers, geodesists,
botanists, zoologists, dendrochronologists and archaeologists (Harff et al.
2007
).
This chapter has to be considered against the background of this new approach
to research. It presents some general reflections on methodological preconditions
and several case studies from different time periods and regions of the Baltic rim
that show how the multidisciplinary approach has improved our knowledge of the
continuous displacement of the shoreline and the development of settlement in the
shadow of such coastal changes.
To avoid any misunderstanding as far as chronology is concerned, it must be
mentioned that all the dates discussed in this chapter should be understood as cal-
endar years (calibrated
14
C years BC/AD), calibrated using the Calpal program by
O. Jöris and B. Weninger (see Manual Calpal or
www.calpal.de
).
15.2 Methodology
Due to the melting of the ice masses in the glaciers of the Fennoscandian ice
sheet, the global sea level started to rise rapidly at the end of the Weichselian
period. During this process, the shape of the present Baltic Sea became subject
to constant change, with regional differences in the dynamics and extent of this
change. Today, the Baltic Sea basin is filled with brackish water but, in the past, its
salinity and the proportion of freshwater changed repeatedly. In post-glacial times,
the whole Baltic area experienced a period of regionally variable glacio-isostatic
land uplift with its centre in the northern part of the Gulf of Bothnia. Although
the rate of uplift has declined since the end of deglaciation, an on-going uplift of
9 cm/century is still being recorded today in this area (Rosentau et al.
2007
, Meyer
et al.
Chap. 14
, this topic). Even though the sea level rose more or less continuously,
the coastal landscape in this region was mainly shaped by a permanent regression.
As a result, the coastline in central Sweden has advanced by about 300 km since
7,000 cal. BC.
The land uplift in the eastern Baltic area is much smaller and has recently aver-
aged only 1-2 cm/century so that it is more or less balanced by the rise in sea level
of 1.8 mm/year. On the other hand, in the south-western Baltic area, the uplift of
about 1 cm/century is considerably less than the average rise in sea level so that,
relatively, the coast is sinking and land is gradually being lost. Consequently, the
coastline of the southern Baltic rim around 7,000 cal. BC was situated up to 70 km
north of its present location.
Despite these changes in coastline and landscape, the contact zone between land
and water around the Baltic Sea has always been an area of special importance for
human communities. Only this ecosystem provides access to marine resources such
as fish, mussels and oysters and an opportunity to hunt brants and ducks, walruses
and seals as well as other sea birds and mammals. Together with lakes and rivers,
the sea was the most important transportation system up until the Middle Ages,
