The degree of isoleucine epimerization in the benthic foraminiferal species Elphidium excavatum and Bulimina marginata have been measured in four boreholes, penetrating marine interglacial beds, from northern Jutland. The results of these analyses are compiled with results obtained from other sites in Denmark and the North Sea region, and four aminozones (AZs) have been erected. AZ1 (aIle/Ile < 0.05) include the Late Weichselian and the Holocene part of the record. AZ2 (0.08–0.12) includes samples of last interglacial age. AZ3 (0.14–0.16) includes samples from sites that have been previously correlated with the Holsteinian, and marine isotope stage 7 age for this zone is suggested. An age close to 400±100 ka is assigned to AZ4 (0.21–0.26). AZ4 is recorded in corings at Skagen and Nørre Lyngby, and includes the here defined Skagerrak Interglacial, which is tentatively correlated with marine isotope stage 11.

The Skagerrak Interglacial sediments are characterized by boreal lusitanian benthic foraminiferal faunas evidencing strong input of Atlantic water to the North Sea. These faunas are replaced by assemblages indicating cooler conditions at least twice during this period. The sedimentation pattern in northern Jutland during this interglacial seems to be different from the sedimentation regimes in the same area at the classical Eemian sites and during the Holocene, which were characterized by large sediment input from the Jutland Current. This difference may be attributed to a change in the geometry of the sedimentary basin through the later part of the Quaternary, which is a result of repeated periods of intense erosion in the confluence area of the Norwegian Channel ice stream. A strong influx of Atlantic water to the North Sea during stage 11 has been suggested earlier, based on records from the Devil's Hole area. However, the correlation of this event to the classic biostratigraphic based schemes of northwest Europe is still problematic.