Mammoth Cave, Derryvree, and Ice
Archived: 15 September 2026
About 31,651 BCE, Ireland was not experiencing a datable historical year but a fluctuating Late Pleistocene interval within MIS 3. Organic deposits at Derryvree and Greenagho indicate local ice-free or withdrawn conditions before renewed glaciation, supporting cold open wetlands with grasses, sedges, juniper, mosses and insects. Castlepook Cave in Cork preserves remains of mammoth, reindeer, hyaena, bear and lemming, though accumulated deposits cannot define one ecosystem. A cut-marked reindeer femur may indicate Upper Palaeolithic carcass processing, but not settlement or permanent occupation. No evidence supports farming, monuments, political communities or regular trade. Expanding ice obscured this fragile, regionally varied landscape.