Who is dating the rock
I will close with one last problem that must be overcome for the final validation of all techniques for dating rock art.It can be summarized by a quote here from the book, A second opinion was going to be necessary, no matter how reliable … There was always some possibility of error in such research, and the standard operating procedure for an important experiment was and still is to have it repeated in another laboratory.The major advancement that laid the groundwork for the later dating revolution was the development of accelerator mass spectrometry (AMS).That innovation led to a drastic reduction in the amount of carbon necessary for a radiocarbon date - from a few grams to less than 1 mg of carbon.That can be ascertained by extracting carbon from a nearby rock surface.When that background contamination is found to be too high, no further attempt is made to date that painting.Reds, oranges, browns, and yellows are iron oxide/hydroxide mixtures and black is quite often manganese oxide/hydroxide mixtures; none of these pigments can be dated directly.The third major dating technique utilizes plasma-chemistry to extract any organic material that is present in the mineral-pigmented paints. The first is when no organic matter was added initially to produce the paint.
Until more determinations are made on replicate samples by different laboratories, using different techniques, and agreement is observed, we cannot be completely confident in the dates.
A piece of charcoal may be quite old before being picked up to construct a drawing. The main disadvantage of this is that such “beeswax” rock art is very rare, as far as I know occurring only in one area in Australia.
A documented example of that occurred at a site in Australia. Inorganic pigments were far more frequently used than charcoal or other organic pigments in making rock paintings.
And finally, the chemical identity of the material being dated is unknown.
And some organic materials are unsuitable for radiocarbon dating.
Finally, one additional technique has been used only rarely, but is useful for both paintings and carvings.