Littorina Sea Research Articles

Radiocarbon age and gastropods of Littorina sediments from south-eastern Skåne, Sweden

Abstract An early phase of the Littorina transgression is 14C dated at 6800–7000 B.P. (plant material at 2–3 m above sea level). It corresponds to the first Atlantic transgression in Blekinge and western Skåne. The highest mean water level of the Littorina Sea was at ca. 5 m above sea-level. By analogy with western Skåne and Blekinge it is suggested that this level was attained in the time range 5500-4500 B.P. During this interval the highest Littorina beach ridges were formed at 6.5–7 m. A gastropod fauna found in a lime gyttja overlain by the highest Littorina beach ridge includes Discus ruderatus (but not D. rotundatus). The fauna is compared with a Recent to ‘sub-Recent’ fauna containing D. rotundatus but lacking D. ruderatus. D. ruderatus (a boreo-alpine species today) might have persisted into the Atlantic stage or longer as a relict from a cooler climatic stage.

Late- and Post-glacial sediments in the Randers fjord area. Geochemical, sedimentological, and geoelectric investigations

Thickness and distribution of Late- and Post-glacial sediments in an Eastern Jutland valley system have been mapped, and their sedimentogenetic and diagenetic relations have been studied. The chemical and sedimentological methods used are discussed in detail. Post-glacial marine sediments formed in a tidal fjord environment are the most important deposits in the area, and it is shown that river supplies of freshwater control the salinity of the environment and were responsible for the rather high content of allochthonous material in the sediment. The marine sediments rest on Late-glacial sand, whose surface topography indicates that the valleys were formed by subglacial erosion. Local occurrences of dead ice were present at least until the Littorina sea (Atlantic) transgression. Depth conditions for Early Post-glacial peat are used to estimate the groundwater level and the course of the river Gudenå in the Continental Period. Sedimentary facies in the Atlantic Littorina sea are discussed, including salinity, tidal activity, water depth, nutrient conditions, and exchange of stagnant bottom water from the deepest parts of the fjord area. The sequence seems to have been influenced only by minor syndiagenetic and weathering processes.With the intention of providing supplementary information to that obtained from mapping of the Post-glacial sediments of the region 161 electric soundings have been carried out in the Randers fjord area. The specific resistivity of the sediments has been determined and the principle limitations of the methods applied have been investigated. Interpretation of the electric soundings has been done using a new system of computer programs. Maps showing the thickness relationships and variations in specific resistivity in the uppermost, largely Post-glacial deposits in the area have been prepared, and a map showing the location of the surface of the Danian limestone and occurrence of Tertiary clay is also presented.

Fangstdyrene ved de danske strande

Fangstdyrene ved de danske strande

Early Postglacial in Aamosen. Geological and Pollen-Analytical Investigations of Maglemosian Settlements in the West-Zealand Bog Aamosen. Vol. I

This paper is a discussion and interpretation of the stratigraphical and pollenanalytical material presented by the author in Vol. II of this paper: "Description of sections and pollen-analyses - A presentation of the bog-geololical material".Eight pollen diagrams from the bog Aamosen are presented, covering Preboreal, Boreal, and early Atlantic periods.On the basis of the curves of the diagrams an attempt is made to elucidate the development of the vegetation in the area. The water-level in the basin is determined from the succession of sediments and from the pollen diagrams, and a possible alternation with the oscillations of the Littorina sea is pointed out.The climate development is discussed, and a climatic oscillation in the early Atlantic period is deduced from the courses of the curves for Hedera and Viscum.Finally the habitation at the Maglemose settlement Verup 5 in Aamosen is interpreted, and individual phases of it are pollen-analytically dated.

Das Rätsel des Ancylussees

The Baltic basin within the circular Fennoscandian region of deglaciation updoming has a lenght axis that lies radially between the inner and outer hinge lines of the upwarped shore levels. Its first postglacial connection with the ocean, the Yoldia Sea stage, came into existence across Central Sweden in Narke in the beginning of the pre-Boreal time, Zone IV in forest history. The connection still prevailed during the Boreal Echineis Sea stage (earlier named by the author Rhabdonema Sea), because of the eustatic rise of the sea level, until the Subzone Vb in the forest history was reached. Thereafter, during the Subzone Vc, the threshold in Central Sweden was rapidly uplifted above sea level, as it happened to lie inside the younger inner hinge line at the very moment of its formation. Thus the Baltic water body converted into a lake, called the Ancylus Lake, which drained westward through an outlet channel at the place of the previous sound. After some 300 or 400 years the height of the lake already was so much as 13 m bis 14 m. Then, at the transition from Zone V to Zone VI in the forest history, this short-lived stage ended in a sudden drainage down to the level of the sea through the Belts in Denmark because of a crustal sinking in the outer part of the southwestern sector of the updoming area. A new transitional stage in the history of the Baltic, the Mastogloia Sea, set in to be followed, during the warm-climate maximum, by the Littorina Sea.