Northern Central Europe: glacial landforms from the Bølling–Allerød Interstadial

Central Europe was a periglacial zone with a discontinuous permafrost at the termination of the Last Glacial Cycle after the Last Glacial Maximum. Meltwater discharge of low-energy braided rivers decreased and after 14,450 cal years BP incised channel systems predominated. Successive warmings of Meinendorf, Bølling and Allerød Interstadials resulted in permafrost degradation, accompanied by the gradual melting of the buried dead ice and activation of mass movements on slopes. These processes transformed the fresh glacial landscape, resulting in the appearance of depressions and exhumation of glacial tunnel valleys, filled partly with lakes. The lake sedimentation was initiated already at the beginning of the Meiendorf (in northern Germany) and Bølling Interstadials but was most intensive during the mid-Allerød, although lakes have been subsequently incorporated in the established river network. Aeolian activity, open and shrub–steppe tundra vegetation were characteristic in a cold and dry environment. They were replaced by a denser vegetation cover, occasionally also with a birch–pine forest during warmer interstadials of the Bølling–Allerød complex, dated at 13,670–12,680 cal years BP, but interrupted by the brief cooling of the Older Dryas at 13,540–13,350 cal years BP when an open vegetation reoccupied Central Europe.