carbon-14 dating


carbon-14 dating

Method of determining the age of once-living material, developed by U.S. physicist Willard Libby in 1947.

It depends on the decay of the radioactive isotope carbon-14 (radiocarbon) to nitrogen. All living plants and animals continually take in carbon: green plants absorb it in the form of carbon dioxide from the atmosphere, and it is passed to animals through the food chain. Some of this carbon is radioactive carbon-14, which slowly decays to the stable isotope nitrogen-14. When an organism dies it stops taking in carbon, so the amount of carbon-14 in its tissues steadily decreases. Because carbon-14 decays at a constant rate, the time since an organism died can be estimated by measuring the amount of radiocarbon in its remains. The method is a useful technique for dating fossils and archaeological specimens from 500 to 50,000 years old and is widely used by geologists, anthropologists, and archaeologists.

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▪ scientific technology
also called  radiocarbon dating,  

      method of age determination that depends upon the decay to nitrogen of radiocarbon (carbon-14). carbon-14 is continually formed in nature by the interaction of neutrons with nitrogen-14 in the Earth's atmosphere; the neutrons required for this reaction are produced by cosmic rays interacting with the atmosphere.

      Radiocarbon present in molecules of atmospheric carbon dioxide enters the biological carbon cycle: it is absorbed from the air by green plants and then passed on to animals through the food chain. Radiocarbon decays slowly in a living organism, and the amount lost is continually replenished as long as the organism takes in air or food. Once the organism dies, however, it ceases to absorb carbon-14, so that the amount of the radiocarbon in its tissues steadily decreases. Carbon-14 has a half-life of 5,730 ± 40 years—i.e., half the amount of the radioisotope present at any given time will undergo spontaneous disintegration during the succeeding 5,730 years. Because carbon-14 decays at this constant rate, an estimate of the date at which an organism died can be made by measuring the amount of its residual radiocarbon.

      The carbon-14 method was developed by the American physicist Willard F. Libby (Libby, Willard Frank) about 1946. It has proved to be a versatile technique of dating fossils and archaeological specimens from 500 to 50,000 years old. The method is widely used by Pleistocene geologists, anthropologists, archaeologists, and investigators in related fields.

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Universalium. 2010.

Look at other dictionaries:

  • carbon-14 dating — noun a chemical analysis used to determine the age of organic materials based on their content of the radioisotope carbon 14; believed to be reliable up to 40,000 years • Syn: ↑radiocarbon dating, ↑carbon dating • Hypernyms: ↑dating, ↑geological… …   Useful english dictionary

  • carbon-14 dating. — See radiocarbon dating. [1955 60] * * * …   Universalium

  • carbon-14 dating — n. ara gel radiocarbon dating • Etymology: 1955–60 …   From formal English to slang

  • carbon-14 dating. — See radiocarbon dating. [1955 60] …   Useful english dictionary

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  • carbon dating — n. a method of establishing the approximate age of carbonaceous materials, such as fossil remains or archaeological specimens, by measuring the amount of radioactive carbon 14 remaining in them: also carbon 14 dating * * * …   Universalium

  • carbon dating — n. a method of establishing the approximate age of carbonaceous materials, such as fossil remains or archaeological specimens, by measuring the amount of radioactive carbon 14 remaining in them: also carbon 14 dating …   English World dictionary

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  • dating — I In geology and archaeology, the process of determining an object s or event s place within a chronological scheme. Scientists may use either relative dating, in which items are sequenced on the basis of stratigraphic clues (see stratigraphy) or …   Universalium


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