Membership is completely free, giving members unlimited access to all available resources, services, features, and benefits without any restrictions or fees.
Welcome back. Sign in to continue enjoying unlimited access to all available resources, services, features, and member benefits at no cost.
The closest evidence does not provide a diary entry for 30,348 BCE. It consists of sediments, plant remains, insect fragments, animal bones and glacial landforms, each formed over periods far longer than a single year. The most important northern archive is Derryvree, near Maguiresbridge in County Fermanagh. Road-cutting in 1969 exposed organic silts and fine sands trapped between two distinct tills within a drumlin. The deposit produced the conventional radiocarbon determination BIRM-166, 30,500 radiocarbon years BP, with a large laboratory range of +1,170 and −1,030 years. A later published calibration cited for this material gives an approximate range of 36.9–31.7 thousand calibrated years BP.
The nearest important Irish environmental anchor is the freshwater deposit exposed at Derryvree, near Maguiresbridge in County Fermanagh. Roadworks in 1969 cut through a drumlin and revealed silts, sands and organic material lying between two thick layers of till: sediment deposited directly by ice. This sequence is unusually revealing. It demonstrates that ice had occupied the locality, that a period sufficiently free of local glacier ice followed for freshwater and wetland deposits to accumulate, and that ice later returned and sealed the evidence beneath another till sheet.
Radiocarbon results are not calendar dates. The amount of radioactive carbon available in the atmosphere has changed through time, so a laboratory measurement must be calibrated against independently dated records. At more than 30,000 years ago, even improved calibration curves produce substantial probability ranges. Stratigraphy adds another qualification: a sediment layer may have accumulated over a period, while an animal bone dates the animal’s death rather than every later event in the history of that object.
The closest particularly useful Irish record comes from Derryvree, near Maguiresbridge in County Fermanagh. Road cutting in 1969 exposed fine sands, freshwater silts and organic material sealed between two distinct beds of till, the stony debris deposited by glacier ice. The sequence gives a secure relative order: ice occupied the locality; an ice-free interval then allowed water, mud and organic remains to accumulate; later ice overrode and buried the deposit. That survival is exceptional, because subsequent glaciation removed or disturbed much of Ireland’s older Pleistocene landscape.
Ireland at this point was neither the familiar green island of later history nor a single, uniform sheet of ice. Its geography changed with climate, ice growth and sea level; conditions could differ sharply between coasts, lowlands, uplands and areas influenced by ice moving from Irish or Scottish centres. The later Last Glacial Maximum would bring a far more extensive British–Irish Ice Sheet, but that maximum lay in the future. Modern reconstructions show that ice-sheet expansion was asynchronous, beginning in some sectors before others and reaching its greatest overall volume much later, around 23,000 years ago. A date in the 31,450s BCE should therefore not be portrayed as the moment when Ireland was wholly frozen over, nor as a benign interlude across the entire island.
The crucial evidence comes not from a settlement but from sediment buried beneath later glacial deposits. At Derryvree, near Maguiresbridge in County Fermanagh, road works exposed freshwater silts and fine sands trapped between two layers of till. The organic material within them produced a radiocarbon determination of 30,500 ± 1,100 radiocarbon years BP. Calibrated estimates cited in later glacial reconstructions place the deposit broadly between about 36,900 and 31,700 calendar years BP. That wide range embraces a notional date of 31,666 BCE, but it does not identify a particular season, year or even human generation.
Ireland was in the last Ice Age, but that does not mean that the whole island was necessarily sealed beneath one unbroken sheet of ice at this precise moment. Ice extent changed markedly through the glacial cycle and did not advance or retreat everywhere at once. Recent reconstructions of the British–Irish Ice Sheet suggest that much of the last Irish ice sheet expanded from relatively ice-free conditions from about 34,000 years ago, with ice reaching the south coast only substantially later, after about 24,000 years ago. That broad reconstruction is more secure than any claim about a single winter or summer in 31,789 BCE.
