Derryvree’s Thawwater Margin
Archived: 6 October 2026
Around 30,214 BCE, Ireland lay within the fluctuating cold of Marine Isotope Stage 3, preceding Last Glacial Maximum ice cover. Derryvree, County Fermanagh, preserves freshwater organic sediments between glacial tills, indicating treeless, open wetland with mosses, sedges and aquatic plants during an ice-free interval. Greenagho and Crag Cave likewise indicate episodic environmental improvement. Castlepook Cave demonstrates a diverse MIS 3 fauna, including mammoth, reindeer, predators and cold-adapted mammals, although dates and associations remain uncertain. Lower sea levels altered coasts and possible routes. No secure evidence proves settlement; a modified reindeer bone only tentatively suggests human activity. Later ice buried evidence.