The Irish Sea Ice Margin
Archived: 2 October 2026
Around 30,381 BCE, Ireland lay within the unstable cold conditions of Marine Isotope Stage 3, not a securely dated historical year. Derryvree, County Fermanagh, preserves freshwater sediments between glacial tills, indicating temporary ice-free wetlands with tundra vegetation before renewed ice advance. Castlepook Cave, County Cork, yielded remains of reindeer, mammoth, giant deer, predators and other cold-adapted animals, demonstrating changing open habitats. A possibly cut-marked reindeer bone may indicate brief Upper Palaeolithic human activity, but its interpretation and context remain uncertain. No settlement, society or continuous occupation is established. Glaciation later erased or buried much evidence, leaving an environmentally dynamic frontier.