The Doneraile Reindeer Clue
Ireland was then in the Late Pleistocene, within a long and unstable cold phase of the last Ice Age. This was not yet the Last Glacial Maximum, the period when the British–Irish Ice Sheet reached its greatest known extent, broadly between 27,000 and 21,000 years ago. Nor was it a stable prelude to that maximum. Climate, sea level, ice extent, vegetation and animal distributions changed repeatedly over millennia. The evidence for the exact position of Irish ice margins before about 31,000 years ago remains sparse; it cannot justify a map showing every coast, valley or upland as either certainly ice-covered or certainly open at this notional date.