BIRM-166 and Open Water
Archived: 24 September 2026
Thirty thousand seven hundred and forty-four BCE is a notional filing point within Marine Isotope Stage 3, not a dated event. Derryvree, County Fermanagh, preserves freshwater organic sediments between glacial tills, radiocarbon-dated broadly to 36,900–31,700 calibrated years BP. Its pollen, plants, insects and bogbean seed indicate cold, open, treeless wetland with pools, sedges, mosses and Arctic-alpine vegetation. Castlepook Cave, County Cork, records a time-averaged pre-Last Glacial Maximum fauna including mammoth, giant deer, reindeer, bear and hyaena. Ireland’s ice, coastlines and habitats fluctuated greatly. Human presence remains unproven for this period, despite a possible cut-marked bone; later glaciation destroyed much evidence.