The Bølling oscillation, a warm interstadial period between the Oldest Dryas and Older Dryas stadials, at the end of the last glacial period, is used to describe a period of time in relation to Pollen zone Ib -- in regions where the Older Dryas is not not detected in climatological evidence, the Bølling-Allerød is considered a single interstadial period.

The beginning of the Bølling is also the high-resolution date for the sharp temperature rise marking the end of the Oldest Dryas at 14,670 BP.