Radiocarbon dating to calendar years
It is estimated that nearly 90% of all measurements made at the more than 50 active accelerator mass spectrometry laboratories are radiocarbon dates.This dramatic increase in the number of radiocarbon dates is driving the demand for a radiocarbon calibration program that spans the entire radiocarbon timescale from the present to 55,000 years BP.However, to calibrate shell dates, there are some additional steps.If the shell samples are all marine in origin, you must use the Marine (marine98.14c) dataset for calibrating these samples.During a creature's lifetime, processes such as breathing replenish carbon 14.
The latest information about available correction dates is published in the journal Radiocarbon and available for download in a free file called Int Cal09 Supplemental Data. Numerous software programs have been developed to complete the calibrations for the investigator, including a new online version of the best known software CALIB. Pearson 1986 High-precision calibration of the radiocarbon time scale, AD 1950-500 BC. Calibrated dates are typically listed in publications with the word "cal" after it. Stuiver, Minze and Bernd Becker 1986 High-precision decadal calibration of the radiocarbon time scale, AD 1950-2500 BC. Scientists know the rate at which carbon 14 decays, and by determining how much has been lost compared with carbon 12, they can decide upon the age of an object.The ratio of carbon 14 to carbon 12 in the atmosphere is not constant, which alters the baseline for calibrating dates.