Derryvree–Castlepook Horizon
Archived: 19 September 2026
31,116 BCE is a modern label for a broad, uncertain Late Pleistocene horizon rather than a recoverable Irish year. At Derryvree, County Fermanagh, organic sediments between glacial tills record a locally ice-free, treeless wetland of tundra plants, shallow water and severe seasonal freezing. Castlepook Cave, County Cork, preserves a disturbed, time-spanning assemblage including mammoth, giant deer, reindeer, bear and hyaena. A marked reindeer femur may indicate human butchery, but cannot demonstrate settlement. No social institutions or occupation sites are known. Advancing ice later damaged evidence, leaving environmental archives, cave bones and carefully qualified possibilities of transient human presence in Ireland.