Radiocarbon dating in the future; Thirty years after inception

Abstract

The future of Radiocarbon Dating lies largely in the applications to geoscience and archaeology. We now know of many applications which have never been fully tried, many of them requiring samples which are too small for the present measuring techniques. All present techniques require several grams of carbon per sample, and many applications provide samples of only a few milligrams each. Think of sea cores; quite a few millimeters of precious sea core are required to furnish only a few milligrams of organic material. Radiocarbon dating consists of determining the radiocarbon content of the organic matter of once living materials. The ratio of radiocarbon-14 to ordinary carbon-12 in the old sample can be compared with the ratio in living material, and the radiocarbon age thereby computed. Of course one must take all due precautions about cleaning out contaminations f rom modern substances, which have radiocarbon content greater than that of ancient matter. Failure to do so gives a falsely young age. The whole matter of laundering of samples, namely cleaning the sample of modern carbon contamination (or cleaning it f rom oil seeps, millions of years old, which contain no radiocarbon at all) offers enormous opportuni ty for improvement . The elegant techniques of modern analytical chemistry have hardly been brought to bear in full strength on this problem. We have done quite well in the past, finding that samples from different parts of a given site do check, or samples from a given geophysical event, for example the retreat of the last ice age, do check, although collected f rom widely separated areas, in the case of the last ice age from each of the states of the great lakes region. So apparently contaminat ion can be dealt with as we originally envisaged, if samples of large enough size can be obtained. But by pursuing new and heroic modifications of the laundering and of the measuring techniques, for example by isotope enrichment before measuring, it seems likely that Radiocarbon Dates of the future will extend back to a hundred thousand years, and it may be 205 calibrated further by the use of t ime clocks not yet invented and not yet brought to bear on the problem. I have great hopes for chemical clocks such as amino acid dating. What is possible under conditions in the relatively short span of t ime in which we think in Radiocarbon Dating is to learn something about the history of the climate.