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No written records, named communities or recognisable political institutions survive from Ireland at this time. There are no securely dated houses, hearths, cemeteries, tool-making floors or art sites that permit a year-by-year human narrative. The evidence instead comes from animal bones, cave deposits, pollen and plant remains, glacial sediments, landforms, and the modern re-examination of old museum collections. Each has a different strength. A directly dated bone can show that an animal was present within a statistical range; it cannot, by itself, describe a whole landscape or prove the presence of people. A buried organic layer can record vegetation and water conditions, but may not be precisely contemporary with a fossil from another county.
The closest Irish environmental evidence is at Derryvree, near Maguiresbridge in County Fermanagh. Roadworks in 1969 cut through a drumlin and exposed fine sands, freshwater silts and organic material lying between two tills: unsorted sediment deposited by glacial ice. The sequence establishes an important order of events. Ice had laid down the lower till; later, an ice-free local basin held water, plants and animals; another glacial advance subsequently covered and preserved those deposits beneath upper till.
The principal chronological difficulty is that radiocarbon years are not calendar years. The most important dated deposit for this broad horizon is the organic freshwater layer found beneath a drumlin at Derryvree. Road works in 1969 exposed fine sands and silts, including organic material, trapped between two distinct tills: sediments left by separate episodes of glacial action. The original radiocarbon determination, Birm-166, was 30,500 radiocarbon years BP, with a substantial laboratory uncertainty of +1,170/−1,030 years. Calibration against modern atmospheric curves converts such a measurement into a broad calendar range rather than a single date.
Radiocarbon dating is central to this subject, but it does not produce the kind of precision implied by a numbered BCE year. A radiocarbon determination dates the death of organic material, such as an animal bone, and must then be calibrated against changing atmospheric carbon levels. Calibration converts a radiocarbon age into one or more ranges of calendar probability; it does not identify a particular season, event or human action. At more than 30,000 years ago, the ranges are especially important. The current IntCal20 calibration curve extends to 55,000 calendar years before present, but the curve’s structure means that apparently modest laboratory uncertainties can translate into broad calendar intervals.
