Dryas récent
One commonly cited date for the end of the Younger Dryas and the start of the Pre-Boreal is 11,500 Before Present calibrated. The start of the period is relatively sharply defined by a rise of 7 °C in 50 years in South Greenland. The date is based fairly solidly on Greenland ice cores, which give 11,640 BP for the late Younger Dryas and 11,400 BP for the early Pre-Boreal.