Direct Correlation of Terrestrial and Marine Records of MIS 7 Using High Precision U-series Dating

The marine isotopic record indicates that climate instability occurs within interglacial episodes on Milankovitch timescales (i.e. isotopic sub-stage variation). In terrestrial records, identifying such climatic oscillations is difficult, whilst proving that such oscillations are synchronous with sub-stage forcing in the marine isotopic record has been almost impossible. Here we present a direct correlation between terrestrial deposits of the penultimate interglacial (MIS 7, ca 245,000 to 190,000 years B.P.) from northwest Europe and the marine isotopic record. This correlation is based on high precision MC-ICP-MS U-series tufa/travertine ages and high-resolution mammalian biostratigraphy. Ages of tufa formation are of high enough precision to allow correlation with the major `warm' sub-stages (7e and 7c). Large-scale turnovers in mammalian fauna, however, correlate with the major `cold climate' sub-stages (7d and 7b), reflecting reconnection of Britain with the continent, and consequent migration of fauna, during periods of low global sea levels. The climatic framework of MIS 7 as preserved in the marine isotopic record can, therefore, be identified in the terrestrial deposits attributed to this interglacial. Frequently, interglacial periods in northwest Europe have been considered simple events consisting of a single climatic optimum. Clearly, however, terrestrial records of interglacial climates are complex and this complexity is driven by the climatic events recorded in the marine record. This study concludes by discussing new ways of developing high precision U-series chronologies for terrestrial interglacial sequences in temperate latitudes, with regard to both new technologies and new materials for dating.