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WHAT IS RADIOCARBON DATING AND IS IT A RELIABLE METHOD OF DATING ARCHAEOLOGICAL SITES? (cont)

By Sean Hancock
December 2000

Into The Laboratory

With all of these facts (and they are facts), it is confusing then to pick up Radiocarbon (Journal that lists worldwide radiocarbon laboratory results) and read:

"Six reputable dating laboratories performed 18 age determinations on wood from Chelford, Cheshire. The finite ages reported ranged between 26,200 and 60,000 BP [11], a spread of 34,600 years" [12]

Here is another fact for you; whilst the theory of radiocarbon dating is convincing, when its principles are practically applied to samples in a laboratory human processes come into the fray. In short mistakes are made, big ones. Furthermore, samples are contaminated in laboratories by background radiation that can and do pollute the residual level of C14 to be measured [13].

As pointed out by Renfrew in 1973 and Taylor in 1986, Radiocarbon dating relies on a series of unsubstantiated assumptions that were made by Libby when he was developing his theory. For example there has been much debate in recent years about Libby's measurement of the half-life to 5568 years. Indeed, today it is generally agreed that Libby was wrong and that the half-life of C14 is actually closer to 5730 years [14]. This is a discrepancy of 162 years and becomes very significant when dating samples thousands of years old.

But with his Nobel Prize for chemistry came complete belief from Libby in his new system. Libby radiocarbon dated Egyptian archaeological samples that had already been historically dated - the ancient Egyptians kept good records of their chronology. Unfortunately Libby's results kept coming up to young, in some cases by 800 years. Amazingly though, Libby concluded,

"This plot of the data suggests that the Egyptian historical dates beyond 4000 years ago may be somewhat too old, perhaps five centuries too old at 5000 years ago" [15]

This is a classic case of scientific arrogance and blind religious belief in the superiority of the scientific method over the archaeological - Libby was wrong, his method had failed him. Now this problem has been addressed but has this attitude of self-authority given radiocarbon dating a reputation above its level of reliability?

Similar problems such as these, and there are many of them [16], have been addressed and are accounted for in modern radiocarbon studies. However, my research has indicated that there are two serious issues of concern with radiocarbon dating that still cause serious problems today. These are 1) Sample contamination, 2) Measuring the levels of C14 in our atmosphere over the geological ages.

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References:

  1. BP means before present - this date is set at 1950
  2. Switsur, Roy Radiocarbon 1990, V0l 32, No. 3, 341
  3. Renfrew, 257
  4. Wigley and Muller 1981, 176
  5. Libby, Willard, "The accuracy of Radiocarbon Dates", Science, 140, 278-9 (1963)
  6. See Renfrew, 261-268

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