Conventional vs ams radiocarbon dating

Figure PE-4 shows the best match between the tree-ring and the Lake Suigetsu chronologies, estimated by minimizing the weighted sum of squared differences between the 14C ages of macrofossils and the tree-ring calibration curve.

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Most information on the past 30,000 years or so is from sites or specimens that have been dated using radiocarbon (14C).

However, the radiocarbon age scale that would be calculated from first principles (based on the decay rate of the 14C isotope, assuming that 14C was at the same level of abundance as it is at present) is not always reliable, because there have been fluctuations in the rate of production in 14C at the top of the atmosphere.

Also the data seems to indicate no more that a 16.7 percent error due to deviation of C14 in the atmosphere for the past 40,000 years. plus or minus 627 years, a plus or minus 5.7 percent error range.

The above Table 2 from Palaeo 122(1996)p.114 summarizes published data concerning one proposed event, the termination of the Younger Dryas period, and illustrates the range of dating errors from various sources including tree rings, lake varves, coral dating and the Greenland ice cores. Conclusion: The apparent close correlation of the dating results from multiple sources appears to be strong evidence for an earth much older than 10,000 years!

The age below 30.45 m depth is obtained by assuming a constant sedimentation in the Glacial (0.62 mm yr-1).

In order to reconstruct the calendar time scale, we compared the Lake Suigetsu chronology with calibration curves obtained from recently revised absolute German oak and the floating German pine calibration curves (2).The problems are particularly great at about 10,000 14C y.a., when a large influx of 14C-depleted carbon from the oceans, combined with a decrease in the rate of 14C production at the top of the atmosphere, gives an 'age plateau' such that the same 14C age covers a wide span of real time, about 1,000 years. U/Th) can be used to attempt to check the 'true' age of specimens or sediment layers dated by 14C, although these all have substantial error margins of their own.The most convincing way to check the 14C age scale is through biological or sedimentological features which build up annual layers over long periods of time (e.g.Detailed comparison with short piston cores shows that the sampling does not cause significant loss of varves - typically 0-2 cm to a maximum of 3 cm, corresponding to ca. 20,000 cal BP) were estimated by varve counting of a single core, the ages quoted should be considered as minimum ages, the error increasing with depth.Based on the results of some duplicated countings of selected subsamples and independent counting of different subsamples collected from the same horizon, we estimate that the counting error is less than 1.5%, corresponding to 150 yr for 10,000 varve years.The sedimentation or annual varve thickness is relatively uniform, typically 1.2 mm per yr for present conditions in Lake Suigetsu which is located near the coast of the Sea of Japan.