Remote Sensing in Archaeology
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RADIOCARBON DATING R. E. Taylor Emeritus, Department of Anthropology, University of California, Riverside, Riverside, CA, USA
Synonyms 14 C dating; Carbon-14 dating Definition Radiocarbon is a naturally occurring radioactive isotope of carbon used as the basis for a nuclear decay method of inferring age for terminal Pleistocene and Holocene Age organic materials. Radiocarbon time scale provides a common chronometric time scale of worldwide applicability on a routine basis using the radiocarbon (14C) method. It is effective in age determination for the terminal Pleistocene and, except for the last few centuries, all of the Holocene. Introduction Carbon contains three naturally occurring isotopes, two of which are stable (12C, 13C) and one (14C or radiocarbon) which is, at the nuclear level, naturally unstable or radioactive and decays with a half-life of ~5,700 years. Radiocarbon (14C) dating is an isotopic or nuclear decay method of inferring age for organic materials, and it provides a common chronometric time scale of worldwide applicability for the late Quaternary. The technique is widely viewed as the geochronological “gold standard” from the perspective of its potential ability to provide generally accurate and relatively precise chronometric age assignments for a variety of organics for that time interval. Radiocarbon measurements can be obtained on a broad spectrum of carbon-containing samples including charcoal, wood,
marine shell, and bone. Using conventional decay or beta counting, the 14C method can be routinely employed within the age range of about 300 years ago to between 40,000 and 50,000 years ago for sample sizes between 1 and 10 g of carbon. With isotopic enrichment and larger sample sizes, ages up to 75,000 years have been measured using decay counting (Taylor, 1996, 2001). The 14C dating technique was developed at the University of Chicago immediately following World War II by Willard F. Libby (1908–1980) and his collaborators James R. Arnold and Ernest C. Anderson (Arnold and Libby, 1949; Libby et al., 1949). Libby received the Nobel Prize in Chemistry in 1960 for developing the method (Arnold, 1981). Since the 1970s, the development of accelerator mass spectrometry (AMS) for direct or ion counting of 14C permits measurements to be obtained routinely on samples of 0.5–1 mg of carbon – and with additional effort on as little as 20–100 mg of carbon – with ages up to 40,000–50,000 years. In the future, the use of AMS technology may permit a significant extension of the 14C time frame to as much as 80,000 years if routine strategies can be developed and consistently employed to exclude microcontamination in samples (Knezovich et al., 2007; Calcagnile et al., 2010; Chen et al., 2011).
Dating model Carbon reservoirs Carbon-containing compounds in a wide variety of forms are distributed throughout the Earth’s highly diverse atmospheric, terrestrial, and hydrological (primarily marine, but also freshwater) environments. On different time scales and by a variety of physical or chemical mechanisms, th
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