Castlepook’s Iceward Threshold
Archived: 17 September 2026
About 31,457 BCE, Ireland lay within the unstable later Last Glacial Period, before the British–Irish Ice Sheet reached its fullest extent. Cold conditions, changing ice margins, lowered seas and altered coastlines shaped a variable landscape rather than a uniformly frozen island. Cave faunas, notably at Castlepook, include reindeer, mammoth, giant deer and predators, indicating intermittent tundra-steppe ecosystems. Wetland deposits show local environmental diversity between ice advances. A marked Castlepook reindeer bone may record stone-tool butchery and exceptionally early human visitation, but lacks secure archaeological context. No settlement, society or continuous occupation can be inferred. Ireland’s history remains geological and ecological.