JAMES KING-HOLMES / SCIENCE PHOTO LIBRARY JAMES KING-HOLMES / SCIENCE PHOTO LIBRARY
Radiocarbon dating. A tiny sample of amino acids from a bone being combusted in oxygen prior to being radiocarbon dated. The carbon in the bone is converted to carbon dioxide gas, which then is assessed to measure the ratio between the radioactive isotope carbon-14 (14C) and the stable carbon-12 (12C) isotope in the gas. The ratio of 14C to 12C may be related to the time since the death of the animal or plant being investigated. Convention states that 14C has a half-life of 5568 years (+/- 30 years), although this is now thought to be too short. Dates from the process are given either as radiocarbon dates, or as solar dates after various corrections have been made.
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