FACTOID #53: If you thought Antarctica was inhospitable, think again - its land area is only ninety-eight percent ice. Reassuringly, the other 2% is categorised as "barren rock".
Developed by Willard F. Libby of the University of Chicago, radiocarbon dating is based on the fact that carbon isotope carbon-14 enters the carbon dioxide of the atmosphere with carbon-12, ordinary carbon (c).
As soon as an organism dies, no further radiocarbon is incorporated into it and the carbon-14 left therein disintegrates at a known rate, only half remaining after 5,730 years.
The C-14 atoms in radiocarbon samples taken from tiny samples of bone, charcoal, shell, wood, and other organic substances found in archaeological sites are counted by accelerator mass spectrometry, resulting in age determinations that are statistical approximations of the date of the sample.
Radiocarbon dating was the first chronometric technique widely available to archaeologists and was especially useful because it allowed researchers to directly date the panoply of organic remains often found in archaeological sites including artifacts made from bone, shell, wood, and other carbon based materials.
Radiocarbon dating is especially good for determining the age of sites occupied within the last 26,000 years or so (but has the potential for sites over 50,000), can be used on carbon-based materials (organic or inorganic), and can be accurate to within ±30-50 years.
Radiocarbon analyses are carried out at specialized laboratories around the world (see a list of labs at: http://www.radiocarbon.org/Info/index.html#labs).
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