Geoscience Reference
In-Depth Information
have been correlated basin-wide. Thickness maps of the freshwater and the brackish
sediments ascribe the general change in the hydrographic circulation from a coast-
to-basin to a basin-to-basin system along with the Littorina transgression. Variations
in the salinity of the brackish (Littorina Baltic basin) are attributed to changes in the
North Atlantic oscillation (NAO), ascribing the wind forces and driving the inflow of
marine water into the Baltic basin. Time series analysis of facies variations reveals
distinct periodicities of 900 and 1,500 years. These periods identify global climate
change effects in Baltic basin sediments.
A main prerequisite for palaeo-environmental reconstructions based on sediment
proxies is the establishment of correct-age models. For dating Holocene sediments
the radiocarbon method is the most common one, but problems emerge for glacial
and coastal sediments poor in organic matter. In these cases, optical-stimulated lumi-
nescence (OSL) dating has become more common. Bitinas et al. used this method
to date lacustrine inter-till sandy sediments of the Klaipeda strait. The dating and
detailed geological investigations imply that the sediments are allochthonous, hav-
ing formed during marine isotope stages (MIS) 4. This conclusion sheds new light
on the genesis of the till beds beneath the bottom of the Klaipeda strait.
Controlled by climate change, but also by the glacial isostatic adjustment (GIA),
the relative sea level changes serve as the most important steering factor for long-
termed
coastline change
(Part IV) in the Baltic Sea. Harff and Meyer describe a
model that is applied to reconstruct the palaeogeographic development of a coastal
area and that generates future projections as coastline scenarios. For the hind-cast,
relative sea level, curves are compared with recent digital elevation models. For
future projections, data of vertical crustal displacement, measured from gauge mea-
surements, are superimposed with eustatic changes based on climate scenarios. The
authors classify the Baltic coasts in those influenced by crustal uplifting and another
type determined by subsidence and eustatically controlled sea level rise. For the
first type, Rosentau et al. combined geological, geodetic, and archaeological shore
displacement evidences to create a temporal and spatial water-level change model
for the SW Estonian coast of the Baltic Sea since 13.3 ka BP. A water-level change
model was applied together with a digital terrain model in order to reconstruct coast-
line change in the region and to examine the relationships between coastline change
and displacement of the Stone Age human settlements that moved in connection
with transgressions and regressions on the shifting coastline of the Baltic Sea.
Vassiljev et al. show in a GIS-based palaeogeographic reconstruction the devel-
opment of the Baltic ice lake (BIL) in the eastern Baltic during the deglaciation
of the Scandinavian ice sheet. The study shows that at about 13.3 ka BP the BIL
extended to the ice-free areas of Latvia, Estonia, and NW Russia, represented by the
highest shoreline in this region. Reconstructions demonstrate a detailed palaeogeo-
graphic history of BIL and glacial lakes Peipsi and Võrtsjärv, which is determined
by the glacio-isostatic uplift.
At the transition to sea level rise controlled coasts along the Sambian Peninsula,
erosional processes outweigh sediment accumulation. Sivkov et al. investigated the
bottom relief along the coast. The authors derived digital bathymetric and slope
angle maps from the modern 1:25,000, 1:50,000, and 1:100,000 nautical charts. A
