 The Oldest Dryas occurred about 1,770 calendar years before the Younger Dryas and lasted about 400 calendar years.According to the GISP2 ice core from Greenland, the Oldest Dryas occurred between about 15,070 and 14,670 calendar years BP.In Ireland, the Younger Dryas has also been known as the Nahanagan Stadial, and in Great Britain, it has been called the Loch Lomond Stadial.