It appears from the abstract and email chatter that Meltzer and Holiday have embarrassed themselves again here. Long time deniers of an ice age American catastrophe, I suspect their tone and attention to detail will match co-author Vance Holiday’s shrill and poorly composed 2011 submission to the Tusk.
I have seen a devastating graphic conflicting their findings, and heard tell of a response paper well underway. But instead of attempting a substantive response here let me stick my neck out with a social science take.
The claim that 27 out of 29 sites were misdated and\or misinterpreted by over 50 researchers in dozens of papers and many labs is half-too-cute. Colleagues of Meltzer and Holiday, like YDB co-authors Goodyear, Bement and Daniels — not to mention Stafford — have poured over data and draft after draft of papers supportive of the YDB dates and endorsed them all as good science.
That many people can be wrong (many more are now, or this blog would not be) but that many established scientists are unlikely to put their careers at risk to make easily identified errors when providing controversial data.
The people who do put their reputations at risk are those who lose their reputations if established understandings of history are incorrect (with regard to impacts or otherwise). Holiday and Meltzer know the story of Ales Hrdlicka. Their very own field was viciously opposed by this detestable and bitter man just eighty years ago, who insisted the early data supporting the presence of Ice Age humans in North America were wrong — ALL wrong! — just like they do today.
American paleo-archeology has a tendency to produce very determined — and fearful — opponents to new data. It must have something to do with the paucity of artifacts and evidence they are forced to accept. If you spend thirty years studying evidence that could fit in a dump trunk a lot of personal id is invested in their interpretation. That makes it even more painful to accept change — and it shows by their overreach here.
According to the Younger Dryas Impact Hypothesis (YDIH), ∼12,800 calendar years before present, North America experienced an extraterrestrial impact that triggered the Younger Dryas and devastated human populations and biotic communities on this continent and elsewhere. This supposed event is reportedly marked by multiple impact indicators, but critics have challenged this evidence, and considerable controversy now surrounds the YDIH. Proponents of the YDIH state that a key test of the hypothesis is whether those indicators are isochronous and securely dated to the Younger Dryas onset. They are not. We have examined the age basis of the supposed Younger Dryas boundary layer at the 29 sites and regions in North and South America, Europe, and the Middle East in which proponents report its occurrence. Several of the sites lack any age control, others have radiometric ages that are chronologically irrelevant, nearly a dozen have ages inferred by statistically and chronologically flawed age–depth interpolations, and in several the ages directly on the supposed impact layer are older or younger than ∼12,800 calendar years ago. Only 3 of the 29 sites fall within the temporal window of the YD onset as defined by YDIH proponents. The YDIH fails the critical chronological test of an isochronous event at the YD onset, which, coupled with the many published concerns about the extraterrestrial origin of the purported impact markers, renders the YDIH unsupported. There is no reason or compelling evidence to accept the claim that a cosmic impact occurred ∼12,800 y ago and caused the Younger Dryas.