[Download not found]We developed a plasma-chemical technique to remove carbon from rock paintings. This extraction is followed by accelerator mass spectrometric analysis of the 14C to yield direct estimates of the ages of rock paintings. We have demonstrated use of the technique on charcoal as well as iron and manganese pigmented paintings. Unfortunately, there are no rock paintings made with inorganic pigments that have accurately known ages. That means there are no primary standards for checking the accuracy and validity of our technique on this type of samples. To compensate for this, known age samples (charcoal and Third International Radiocarbon Intercomparison wood) were dated: these support the general validity of this technique.
Also supporting this technique, the dates we obtained on numerous rock paitings agree in general with the age ranges expected base on archaeological inference. However, a date is not convincing only because it agrees with current archaeological inference. Real verification awaits confirmation by an independent technique. Future work will concentrate on the removal of background organic contamination in the basal rock and mineral accretions associated with rock paintings. Overcoming that problem will remove an impediment to our extraction technique routinely giving accurate and reliable ages.
1997-13 Rock-art Image in Fern Cave, Lava Beds National Monument, California: not the AD 1054 (Crab Nebula) supernova
1998-22 Effect of Water on Lower Pecos River Rock Paintings in Texas
This research was made possible through Grant MT-2255-6-NC-14 from the National Center for Preservation Technology and Training (NCPTT).