|13 December 2009
A new method for absolute dating of Rock Art
An Italian scientist has developed a method for absolute dating of rock art applied to the sites on marble outcrops surfaces in the Apuane mountain chains in the north-west of Tuscany (Italy). Probably these carvings are not of prehistoric origin, but they date from historical times instead - and the new method seems to confirm this.
The mathematical technique used by Paolo Emilio Bagnoli is the so-called Montecarlo method which consists of the study of the macroscopic properties of a granular system starting from the continuous repetition of microscopic stochastic events whose probability laws is supposed to be known. These laws were related to the speeds of the various erosion mechanisms for limestone. By using the above described procedure, it was possible to observe the time evolution of the cross-section of the engravings subjected to natural erosion processes (freeze-thaw, chemical dissolution) in a time range spanning about 2000 years and to evaluate the trend behaviours of both depth and width of the small moat.
This procedure allowed to study the evolutions of both depth and width, to write analytical formulas of the average trend behaviors which can be inverted in order to yield the elapsed time from the engraving execution. This is only the beginning phase of the research but the first experimental data gathered from the so-called 'Billhook Step' (Mount Gabberi, Camaiore , Lucca) seems to be encouraging. Beside the uncertainty of the input data required by the
mathematical analysis, Paolo Emilio Bagnoli believes that the new method is very promising for obtaining reliable absolute dates for rock art, at least on limestone rocks, horizontal flat surfaces, open air exposure and figures traced in contour.
A copy of the original study can be downloaded from www2.ing.unipi.it/~a005962/rupestre/Valcamonica.pdf
Source: Rock Art Mailing List
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