The Castlepook Threshold
Archived: 20 September 2026
Around 31,101 BCE, Ireland experienced fluctuating Ice-Age conditions during Marine Isotope Stage 3, with expanding ice, periglacial landscapes and occasional open grazing ground. Lower sea levels altered coasts but do not prove a land bridge to Britain. Castlepook Cave, County Cork, preserves Ireland’s richest pre-Last Glacial Maximum faunal archive, containing mammoth, reindeer, giant deer, bear and hyaena remains accumulated over millennia. A cut-marked reindeer femur, dated broadly around 31,000 BC, may indicate mobile Upper Palaeolithic people processing carcasses. However, it cannot prove settlement, hunting, culture or social organisation. The evidence instead reveals changing environments and a possible early human presence.