A post-LGM European climate regime where the retreat of the ice was reversed. The evidence for this event, which started at about 9000 BC, is strongest for the North Atlantic Basin, although there is some evidence for it in other parts of the world. The most probable hypothesis as to the cause of this involves the significant amount of glacial meltwater inducing changes in the atmosphere-ocean circulation, i.e. the outflow of low-salinity water into the subpolar North Atlantic may have affected the rate of deep-sea mixing and thus the production rate of North Atlantic Deep Water. It was preceded by the Allerod oscillation and followed by the Pre-Boreal period.