Geological Survey of Canada Radiocarbon Dates IV

Most of the determinations reported here were obtained with the 2 L counter described in our first date list (GSC I). All age calculations are based on a C 14 half-life of 5568 ± 30 yr and 0.95 of the activity of the NBS oxalic-acid standard, and the ages are quoted in years before 1950. The age errors include: counting errors of sample, background, and standard, the error in the half-life of C 14 , and an error term to account for the average variation of ±1.5% in the C 14 concentration during the past 1100 yr. ‘Greater than’ ages are based on the 4 σ criterion (GSC II).