Last time I posted on some hypothesis behind the Younger Dryas stadial. A large part of that post described the theories of Firestone, Kennett and their colleagues who suggested (implored readers) that an impact event may have caused rapid melting of the Laurentide Ice sheet. After largely being discredited by subsequent literature, Anson Mackay has pointed me to a new article (1), still in press, which seeks to end the debate on the impact event hypothesis. I thought it was necessary to include a short post here to review that paper.
Pinter and his colleagues, including Daulton, a previously cited opponent of the hypothesis, consider the evidence for the impact hypothesis in two sections. The first section involves those signatures of an impact event which have already been largely rejected in the literature. These include the magnetics within bones found at the YD onset, concentration variations in radioactivity, iridium and Helium isotopes.
A second section involves the evidence such as carboniferous spheroids, magnetism in particles, wildfire evidence and nanodiamonds pushed so far by Kennett et al (See my previous post). Within this second section, Pinter et al. reject the origin of each materials supposedly attributed to an impact event. The carbon spheres, attributed to large-scale wildfires across North America, have been re-identified as terrestrial deposits from fungal and arthropod fauna. The paper also rejects the discovery of grains which have magnetism which could only have been produced by a meteorite as the authors, in their own work and the work of colleagues, have yet to reproduce these findings. The absence of a large fire event around the onset of the YD is also seen suggesting that there is no evidence to suggest an impact event causing fires and melting the Laurentide Ice sheet. Finally, the identification of nanodiamonds is called into question. This paper confirms evidence in my last post that the nanodiamonds were likely incorrectly identified and that they should have been identified as graphene and graphane compounds.
Overall, Pinter and his colleagues say that 7 of the 12 evidence arguments for the YD impact hypothesis are non-reproducible. This sounds to me as if they are undermining the work of Firestone et al. Indeed, further to my last post when I suggested that the hypothesis proponents may have been embarrassed, take a look at the conclusion of Pinter's paper to find a rejection of the hypothesis and a belittling of the proponents whom 'will continue their quest until the hypothesis is confirmed'.
Pinter et al. have called this hypothesis now a requiem, defined as a celebratory ceremony for the dead, hoping to end any further research on the subject. However, from this paper's utter rejection of the hypothesis, I would suggest that a less decorated ceremonial event should take place.
(1) Pinter et al (2011) doi: 10.1016/j.earscirev.2011.02.00