Methods for dating artifacts

First, any instrument which is built to measure radiocarbon has a limit beyond which it cannot separate the signal due to radiocarbon in the sample from the signal due to background processes within the measuring apparatus.

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Some may have mistaken this to mean that the sample had been dated to 20,000 radiocarbon years.

The second characteristic of the measurement of radiocarbon is that it is easy to contaminate a sample which contains very little radiocarbon with enough radiocarbon from the research environment to give it an apparent radiocarbon age which is much less than its actual radiocarbon age.

For example, a sample with a true radiocarbon age of 100,000 radiocarbon years will yield a measured radiocarbon age of about 20,000 radiocarbon years if the sample is contaminated with a weight of modern carbon of just 5% of the weight of the sample's carbon.

It is not too difficult to supply contaminating radiocarbon since it is present in relatively high concentrations in the air and in the tissues of all living things including any individuals handling the sample.

For this reason special precautions need to be exercised when sampling materials which contain only small amounts of radiocarbon.

Reports of young radiocarbon ages for coal probably all stem from a misunderstanding of one or both of these two factors.

It is not correct to state or imply from this evidence that the radiocarbon dating technique is thus shown to be generally invalid.

The problem with freshwater clams arises because these organisms derive the carbon atoms which they use to build their shells from the water in their environment.

If this water is in contact with significant quantities of limestone, it will contain many carbon atoms from dissolved limestone.

Since limestone contains very little, if any, radiocarbon, clam shells will contain less radiocarbon than would have been the case if they had gotten their carbon atoms from the air.

MYTH #2 Radiocarbon dating has established the date of some organic materials (e.g., some peat deposits) to be well in excess of 50,000 years, thus rendering a recent creation (6 to 10 thousand years ago) impossible.

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