Radiocarbon Age Calibration of Marine Samples Back to 9000 Cal Yr BP

Calibration curves spanning several millennia are now available in this special issue of R adiocarbon . These curves, nearly all derived from the 14 C age determinations of wood samples, are to be used for the age conversion of samples that were formed through use of atmospheric CO 2 . When samples are formed in reservoirs (eg, lakes and oceans) that differ in specific 14 C content from the atmosphere, an age adjustment is needed because a conventional 14 C age, although taking into account 14 C (and 13 C) fractionation, does not correct for the difference in specific 14 C activity (Stuiver & Polach, 1977). The 14 C ages of samples grown in these environments are too old, and a reservoir age correction has to be applied. This phenomenon has been referred to as the reservoir effect (Stuiver & Polach, 1977).