The Younger Dryas is to be considered as a biostratigraphic zone which
in the Netherlands started 10 900 (radiocarbon) years ago and ended 1
0 200 BP. It is subdivided in two parts. The first half (up to 10 500
BP) is characterized by severe, continental conditions which resemble
those at the end of the Pleniglacial; a permafrost was present. The se
cond half shows milder conditions as a transition to the Holocene; per
mafrost disappeared at about 10 500 BP.