- Was reminded of this subject while reading CANE, J. Sasson, 2000, V. II, Choronology: Issues and Problems, Frederich Cryer.
The plus or minus accuracy rating of 70-100 years for the first millenium B.C. was in line with estimates I had read in a recent article about the ancient Egyptian chronology from the time of Thutmosis III in the LBA mid-second millenium being about plus or minus 100 years. Plus or minus 100 years is a range of accuracy spanning about 200 yrs. if one eliminates data points that are obvious outliers
According to F. Cryer callibration charts have been designed for regional variances in callibration. I had not guessed the distribution of C14 in the atmosphere greatly differed from region to region. I had suspected that variances in data might be caused by contamination of samples. While I do not have the chemical background to designate a path whereby C14 might be more or less reactive to solutions in ground water than C12. I have knowledge of cases where wood was replaced or fossilized by solutions containing silicates/agate/opal, iron pyrite, and calcium or calcium-magnesium carbonates. In the abscense of replacement of cellulose and lignim with amorphous minerial concretion, there is the possiblity that some C-14 or C-12 might react with solutions and be transported from the sample, or new dissolved C-14 might be added to a sample.
Turning to the Internet I found there are a number of articles about the contamination of C-14 samples by groundwater.
Findings at Tel Rehov indicated two grain samples from the same fiery destruction strata varied in age by 80 yrs. I assume this was a typical case, else why was it published?
David Q. Hall
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