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Proactive disclosure Print version   | |  Radiocarbon Dating Age Calculations The Geological Survey of Canada Radiocarbon Dating Laboratory ceased operation at the end of 2005. This site will be maintained to provide reference information on the samples dated during the 45 years of operation of the GSC laboratory from 1960 to 2005.
Age calculations are based on a C-14 half-life of 5568 ± 30 years and 0.95 of the activity of the NBS oxalic acid standard. Ages are quoted in radiocarbon years before 'present' (BP), where 'present' is taken to be A.D. 1950. The error assigned to each age has been calculated using only the counting errors of sample, background, and standard, and the error in the half-life of C-14 (Lowdon and Blake, 1973, GSC Radiocarbon Dates XIII. GSC Paper 73-7).
In addition, all GSC dates are rounded according to the following criteria: If C-13/C-12 ratios (del C-13) were available, a 'correction' for isotopic fractionation has been applied to the sample's age, and the del C-13 value reported. All del C-13 determinations were made on aliquots of the sample gas used for age determinations. For terrestrial and non-marine organic materials, and bones GSC ages are conventionally 'normalized', in addition, marine shells are unconventionally 'corrected', but freshwater shells are not 'corrected'.
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