Bogbean Beside the Drumlins
The conventional radiocarbon determination most relevant to this period is BIRM-166 from Derryvree: 30,500 radiocarbon years before present, with a large published error range of +1,170/−1,030 years. “Before present” is conventionally counted from AD 1950; it is not the same as a BCE date. Because atmospheric radiocarbon changed over millennia, such measurements must be calibrated, and their calendar equivalents at this age are broad rather than annual. Modern calibration curves extend this far back, but they do not turn a single legacy sample into a precise historical timestamp. Derryvree can responsibly illuminate conditions spanning the later 30th millennium calibrated years before present, not prove what occurred on a particular day, or even in a particular human lifetime, in 30,561 BCE.