BIRM 166 Calibration
Archived: 2 October 2026
30,380 BCE is not a recoverable Irish historical year but falls within the climatically unstable Marine Isotope Stage 3. At Derryvree, County Fermanagh, BIRM-166 dated freshwater organic deposits between glacial tills to roughly 36,900–31,700 calibrated years before present, indicating an ice-free interval before later ice-sheet expansion. Plant remains reveal cold, treeless wetlands with open water, sedges, mosses and hardy shrubs. Southern cave finds show that large mammals occurred during the wider period, though not necessarily together. No secure evidence identifies human occupation, society or culture. The record instead documents dynamic glacial change and ecologically active landscapes, while retaining considerable uncertainty.