The Significance of Accelerator Dating in Archaeological Method and Theory
Radiocarbon dating is an important feature in archaeology; for over 35 years, there have been two types of counting systems. The first was developed by Libby and featured a screen-wall Geiger counter and a sample of solid elemental carbon; the second is based on a liquid or gas scintillation detector and was developed “to avoid contamination from radioactive fallout, to reduce counting errors and sample size, and to increase counting efficiency, operational efficiency, and dating range”.
The third system is more recent and is based on the use of tandem accelerators. This system is more commonly referred to as ‘AMS’ and provides a much more capable means of utilizing smaller samples through high-energy mass spectrometry. In addition to this, AMS has the potential to extend the 14C range to between 60,000 and 100,000.
AMS has several advantages when used in archaeology. Firstly, samples which contain very small samples of carbon can be dated; secondly, archaeological artefacts can be dated accurately without their destruction; and thirdly, the dating of artefacts are just as accurate as the earlier two methods.
“In addition, the method will have some impact on archaeological method and theory. The archaeological dating process has been modelled in intricately theoretical ways to permit the association of independently-dated specimens with past cultural events. Owing to the previously un-datable character of many archaeological specimens and artefacts such a multistage theory was necessary. Now that bones, seeds, ceramics, and other cultural materials can be dated directly by the AMS method we may simplify our dating theory. Also we may use suites of AMS-derived 14C dates to cross-check other kinds of evidence and to study broad archaeological problems not resolvable using prior chronological methods”.
Because AMS has the capability of accurately dating samples with smaller amounts of carbon, previous archaeological artefacts that had been deemed unsuitable or would be damaged through either the first two means of dating, could now be dated without unnecessary risk. These can include seeds, pottery, ceramics, bone, ivory, wood, any organics in pottery and many others. Through dating these objects, we can gain access to the time periods and, with plants (for example) see the changes that occurred as they went from wild to domesticated.
Discrepancies in archaeological dating are big concerns for archaeologists. AMS dating offers a way to “implement these theoretical concerns focuses on identifying disjunctions or disparities between the dated events and the targeted behavioural events”. As the years go on, and the technique in carbon dating improves, so will the accuracy of our knowledge on the past.
Hester, James J. (1987) The Significance of Accelerator Dating in Archaeological Method and Theory, Journal of Field Archaeology, Boston University.