Stratigraphy of Quaternary deposits in the Skærumhede II boring: lithology, molluscs and foraminifera

The new Skærumhede II boring penetrated the upper glaciofluvial deposits and the upper part of the marine Skærumhede series. On the basis of the results of sedimentological and lithological investigations such as grain counting and determination of ignition residue and of grain size, it has been possible to subdivide the sequence into several sediment zones. The coarser material in part of the fine-grained marine sediment has presumably been conveyed by drift ice.

Studies of the molluscs in the boring show a development from a boreal Turritella communis community on a muddy bottom to a cold fauna with Portlandia arctica in an environment with drop till. This cold zone is divided into assemblage-zones characterized by, from below, Turritella erosa, Balanus crenatus and Macoma calcarea. The difference between the boreo-lusitanian community in the boring and the typical Eem community is regarded as difference in facies and not in time.

The marine sequence of the boring has been divided into nine assemblage-zones on the basis of ecologically conditioned changes in the foraminifera faunas. The lower two zones indicate boreo-lusitanian to boreal conditions and are probably referable to the Eemian Interglacial. The upper seven zones contain arctic faunas, some of which possess variable boreal elements. This is regarded as indication of three interstadials before the main Weichselian glaciation.