Accuracy of c 14 dating
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.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.This gives the clam shell an artificially old radiocarbon age.This problem, known as the "," is not of very great practical importance for radiocarbon dating since most of the artifacts which are useful for radiocarbon dating purposes and are of interest to archaeology derive from terrestrial organisms which ultimately obtain their carbon atoms from air, not the water. Samples of coal have been found with radiocarbon ages of only 20,000 radiocarbon years or less, thus proving the recent origin of fossil fuels, probably in the Flood.In the early days of radiocarbon analysis this limit was often around 20,000 radiocarbon years.Thus, all the researcher was able to say about samples with low levels of radiocarbon was that their age was greater than or equal to 20,000 radiocarbon years (or whatever the sensitivity limit of his apparatus was).
There are two characteristics of the instrumental measurement of radiocarbon which, if the lay observer is unaware, could easily lead to such an idea.
The field of radiocarbon dating has become a technical one far removed from the naive simplicity which characterized its initial introduction by Libby in the late 1940's.
It is, therefore, not surprising that many misconceptions about what radiocarbon can or cannot do and what it has or has not shown are prevalent among creationists and evolutionists - lay people as well as scientists not directly involved in this field.
By radiocarbon dating a piece of wood which has been dated by counting the annual growth rings of trees back to when that piece of wood grew, a calibration table can be constructed to convert radiocarbon years to true calendar years.
Of course, the table, so constructed, will only give the correct calibration if the tree-ring chronology which was used to construct it had placed each ring in the true calendar year in which it grew.
Other radiometric dating methods such as potassium-argon or rubidium-strontium are used for such purposes by those who believe that the earth is billions of years old.