Rock varnish dating
Dorn's method involves scraping varnish off a rock surface, treating this sample, and then analysing the remaining substance using accelerator mass spectrometry (AMS) to determine its age.
Working with scientists around the world, Dorn has dated surfaces near rock art in the United States, Australia and Portugal, and used the same method for an earlier published study on rock formation age near Yucca Mountain.
Warren Beck, a University of Arizona geochemist and a lead author of the Science article.
Beck and colleagues found no coal or charcoal in rock varnish samples they collected and analysed to try to duplicate Dorn's work.
In an accompanying rebuttal, Dorn acknowledged that his method for dating rock surfaces was fundamentally flawed.
ASU officials in Phoenix then began interviewing Arizona scientists involved in the controversy.
Rock Varnish: that this pattern was indeed global, then variations of its color and chemical com- we would have strong evidence that a position.
Varnish from Death Valley Recorder of major change in the dynamics of the at- shows a particularly large range, with mosphere’s Hadley cell (upwelling of air Mn O2 concentrations extending from a Desert Wetness? This greater the rainfall, the higher the Mn O2Palisades, NY 10964, USA is especially true for times beyond the content of varnish.
In particular, Dorn cites an unpublished article by ASU geologist J.
Ramon Arrowsmith, who Dorn writes “replicated in an independent study” his work after being “trained in sample collection and preparation procedures”.