BIRM-166’s Open Fen
Archived: 23 September 2026
Around 30,813 BCE, Ireland cannot be described through annual precision or documented human history. The BIRM-166 deposit at Derryvree, County Fermanagh, dated broadly to 34,950–29,750 BCE, preserves an ice-free interval between glacial advances. Its organic sediments indicate a treeless, waterlogged tundra of mosses, sedges, dwarf shrubs and shallow pools. This local evidence demonstrates episodic, regionally uneven glaciation as ice expanded towards the later Last Glacial Maximum. Cave remains at Castlepook, County Cork, show a diverse cold-stage fauna, including reindeer, mammoth, giant deer, predators and small mammals. A possibly cut-marked reindeer bone suggests unconfirmed, brief human presence, not settlement or continuity.