Australia: The Land Where Time Began

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Thermoluminescence Dating of Flint from Palaeolithic sites - Advantages and Limitations

For the dating of Palaeolithic sites thermoluminescence (TL) has been widely used. The underlying assumptions of this method of dating are not considered to be trivial, though the basic principle of TL dating are simple. The external dose rate is one of the major sources of error, contributing to the denominator of the age formula to a varying degree, therefore the amount of its influence on the dating result is variable. According to the author1 the aim of this paper is to enable the evaluation of TL age determinations of flint that has been heated, with some of the parameters used for the determination of age and some of their relationships being discussed. It is shown that for heated flint the reliability of the TL results depend on the proportion of the various dose-rate parameters, and the importance of these in the evaluation of ages. The author1 discusses the limitations of the method as well as its advantages, the dating of 2 Near Eastern Palaeolithic sites, Rosh Ein Mor and Jerf al-Ajla, being used as examples.

Richter's conclusions

For any chronometric dating of an archaeological site the accuracy is most dependent on the relationship of the sample to the archaeological event (association), but it is also dependent on environment of the deposition and the quality of the samples. The precision of a result of dating is dependent on the latter 2 as well as on the method being used. The making of a number of assumptions are required by all dating methods, and it is necessary that these be carefully evaluated for each individual site.

To establish the elapsed time since the last time the object, such as a flint, has been heated, dating by thermoluminescence is a useful tool. The direct association of the of the event with past activity of humans on a linear timescale, and its lower vulnerability to variation of certain parameters that are unknown, are advantages of TL over other methods. It is necessary to take great care in the evaluation of TL dates and when publishing the results of dating certain standards need to be met. Included among these are the presentation of glow curves, heating plateaus and DE plateaus, growth curve(s) ( including correction for supralinearity) and the determination of the alpha sensitivity of each sample, and it is required that equal care be taken in the evaluation of parameters that are prone to variation over time. Results of TL dating that have large components of external dose need to be evaluated critically, with great care being taken when the models used and errors associated with this component are considered. γ- or α-spectrometry should be carried out on sediment samples to obtain at least the information on the state of the equilibrium of the U-chain for the more recent history of the external radiation field (D*γ-external). The sum of the 2 constant dose rates (D*internal and D*cosmic) contribute largely to the total dose rate, making such dating results less vulnerable to variations, providing confidence in TL dating as powerful tool for dating Palaeolithic sites.

Sources & Further reading

  1. Richter, Daniel. "Advantages and Limitations of Thermoluminescence Dating of Heated Flint from Paleolithic Sites." Geoarchaeology 22, no. 6 (2007): 671-83.

 

Author: M. H. Monroe
Email:  admin@austhrutime.com
Last Updated 13/07/2013
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                                                                                           Author: M.H.Monroe  Email: admin@austhrutime.com     Sources & Further reading