8 Die Küste, 74 ICCE (2008), 1-17 
and/or early Neogene age (Sylt Island), which can be found on the North Frisian barrier 
islands. The typical elongated shape of the East Frisian barrier islands with sandy foreshores 
and beach and dune sediments on the coast exposed to high wave energy, and with fine 
grained organic-rich deposits on the sheltered lee indicate that their formation is very much 
related to the ongoing interaction of mobile sediments with currents and waves (Davis, 1994). 
However, the presence of erosional relicts of Pleistocene deposits in depths of only -5 to 
-10 m NN beneath almost all islands indicates that in a former stage of their geological evo 
lution they also had a core of older deposits. As can be seen on the island of Sylt today, these 
cores are directly exposed to the forces of the rising water level and at least are partly erode 
during periods of lower water levels. These cores were finally inundated, and - in their tem 
porarily last stage of island evolution -, they were buried under younger, now sea-born 
sediments. Under conditions of a presumably rising sea level, the development of these 
islands is characterised by an almost continuous landward shift of the shoreline. 
Likewise elongated accumulation bodies located in Dithmarschen (north of the Elbe 
estuary) and on the Eiderstedt peninsula, on the other hand, underwent a completely diffe 
rent depositional evolution. Doubtlessly, in a former stage of the Holocene coastal evolution, 
these gravel and coarse sand accumulations were formed under strong wave and current 
action (Hummel and Cordes, f 996). A subsequent and in some areas still ongoing intensive 
import of sea-born sediments into this region leads to a pronounced seaward shift of the 
shoreline. Today these f ormer wave exposed island-like structures are still visible as elongated 
low elevations in the flat marshlands some 10 kilometres inland. 
3. Baltic Sea 
The Baltic Sea is a non-tidal intra-continental shelf sea with a narrow connection to the 
North Sea through Kattegat and Skagerrak (Fig. 6). It is the second largest brackish water 
body in the world, covering an area of 412,560 km 2 , with a volume of 21,631 km 3 , extending 
1,300 km in S - N direction (54°-66°) and 1,000 km in E - W direction (10°-30°). The maxi 
mum width is approximately 300 km, the average depth is 52 m (Helcom, 1990) and the 
deepest part, Landsortdeep, is 460 m in depth. The bathymetry is controlled by the presence 
of sills and deep basins, which developed mainly during the last glacial period. These basins 
increase in size and depth from West to East (Mecklenburg Bight, 25 m deep; Arkona Basin, 
45 m deep; Bornholm Basin, 100 m deep; Gotland Basin, 250 m deep). 
3.1 Palaeozoic to Palaeogene Development 
The geological basement of the northern and central part of the Baltic Sea is dominated 
by Precambrian crystalline rocks belonging to the East-European-Craton. They have under 
gone a long term uplift until today forming the Scandinavian mountain ranges. Palaeozoic 
sediments (older than 251 million years) have been deposited on the southern rim of this 
craton, forming parts of the East European Platform (Fig. 1). Separated by the huge, more 
than 2,000 km long “Sorgenfrei - Tornquist - Teisseyre - Fracture Zone” (Katzung, 2001), 
the West- and Middle European Platform is dominated by sediments of Mesozoic age 
(251-65.5 million years old; Ehlers, 1990). Their basement is formed by deposits of Permian 
age (see Tab. 1), a period, when arid climate was dominating and the deposition of terrestrial 
sediments took place. At the end of the Perm period, marine conditions developed due to