InThomas Higham and co-workers suggested that many of the dates published for Neanderthal artefacts are too recent because of contamination by "young carbon". Radioactive carbon is being created by this process at the rate of about two atoms per second for every square centimeter of the earth's surface. The carbon exchange between atmospheric CO 2 and carbonate at the ocean surface is also subject to fractionation, with 14 C in the atmosphere more likely than 12 C to dissolve in the ocean. Increasingly though, students are learning about the principles of radiocarbon dates in archaeology, palaeontology and climate science degrees and can combine cross-disciplinary studies. Krane suggests that this might have doubled the concentration compared to the carbon from cosmic ray production. This can be done with a thermal diffusion column. The Wikibook Historical Geology has a page on the topic of:
The results were summarized in a paper in Science inin which the authors commented that their results implied it would be possible to date materials containing carbon of organic origin.
Method of chronological dating using radioactive carbon isotopes. The older a sample is, the less 14 C there is to be detected, and because the half-life of 14 C the period of time after which half of a given sample will have decayed is about 5, years, the oldest dates that can be reliably measured by this process date to around 50, years ago, although special preparation methods occasionally permit accurate analysis of older samples. Before the advent of radiocarbon dating, the fossilized trees had been dated by correlating sequences of annually deposited layers of sediment at Two Creeks with sequences in Scandinavia. The radiocarbon age of a certain sample of unknown age can be determined by measuring its carbon 14 content and comparing the result to the carbon 14 activity in modern and background samples. It is based on the fact that radiocarbon 14 C is constantly being created in the atmosphere by the interaction of cosmic rays with atmospheric nitrogen. Email Required, but never shown.