Derryvree’s Pleistocene Herbarium
Organic material from Derryvree produced a conventional radiocarbon determination of 30,500 years BP, with a large laboratory uncertainty. Published discussion converts this broadly to about 31,700–36,900 calibrated years BP, or roughly 29,750–34,950 BCE. The notional date of 30,845 BCE lies within that wide span. Yet the range should not be mistaken for a precise age of every fossil in the deposit, still less for a single season in Irish history. Radiocarbon years and calendar years are not interchangeable: they must be calibrated against changing atmospheric carbon levels, and calibration at this depth carries substantial uncertainty.