Loess and palaeosols on the High Terrace at Sierentz (France), and implications for the chronology of terrace formation in the Upper Rhine Graben

Pedological investigations in combination with luminescence dating havebeen used to reconstruct the genesis and chronology of a sediment successionat Sierentz, France. The sequence comprises loess and palaeosols on top ofgravel attributed to the High Terrace of River Rhine. According to the datingresults, three phases of soil development occurred during different warmphases of Marine Isotope Stage (MIS) 7 (245–190 ka). Soil development ontop of the gravel occurred either during early MIS 7 or during an earlier warmphase, possibly MIS 9. The results imply a minimum age of 250 ka for the formationof the High Terrace in this part of the Upper Rhine Graben, contraryto previous assumptions that correlated gravel sheet deposition with MIS 6(ca. 150 ka). These results and recent findings at other sites suggest that thechronological setting of terrace formation north of the Alps is much morecomplex than previously assumed.