1 Oct 2010
Responses to some of your comments (which are in italics):
Haynes did confirm our evidence for peaks in the magnetic fractions at the YD layer. He found more Ir than we did at nearly any site which is a smoking gun for an impact. He’s nuts if he thinks the Ir levels that he found in the stream bed are normal. Probably the Ir washed out of the YD layer into the streambed. Haynes believes that the mammoths and megafauna died in a sudden catastrophe but he won’t say what that catastrophe is.
As I predicted, Haynes is your hero when he finds Ir where you think he should (or proclaims a continent scale extinction at 129k) but when he finds an Ir spike where he shouldn’t and throws a ringer in your preconceived notions of an impact he “is nuts.” Nowthat is objectivity!
And you ignore the fact that Claeys lab in Belgium (the go-to lab for Ir, the impact people tell me) couldn’t find an Ir spike in your original batch of samples so they were sent to another lab that did get spikes so that is what you published. Claeys lab likewise failed to find Ir spikes in lots of other samples, including ours.
Your explanation for the Ir spike in the stream bed at Murray Springs is preposterous. You don’t need a PhD in nuclear physics to understand the basics of erosion, sediment transportation, and redeposition. The exposures at MS are several meters high with a thin Black Mat. Water washes down the entire section, eroding some of the black mat and the 12.9ka level plus the rest of the exposure. During a rain, this is going on all over the site. The water moves some sediment from the arroyo wall and then some of that sediment gets deposited on the floor. You really believe that the resulting deposit will be higher in Ir after all that??? Really???
Vance does indeed think that “something” happened at 12.9k but lots of other people don’t. We agree to disagree! Since this issue is obviously important to you, I suggest you look at the primary data, like the rest of us do! Also, look at his paper. On p. 6522 he refers to “the last of the Rancholabrean megafauna” just before 12.9ka. On Table 1, most of the megafauna are mammoth, which did persist to Clovis times, of course (and Waters & Stafford clearly show mammoth younger than 12.9ka). Otherwise, the next most common megafauna is bison, which didn’t becomes extinct.
As I said before, Russ Graham and Tom Stafford (you hang your hat on what Stafford says about the dating of Clovis) have devoted a lot of time to dating late Pleistocene megafauna and their data (I’ve seen Russ give two talks on this) clearly show that most critters were gone before 12.9ka.
Further, the work of Gill et al 2009 and Robinson et al 2005 also indicate that the megafauna declined significantly long before 12.9ka
“Pleistocene Megafaunal Collapse, Novel Plant Communities, and Enhanced Fire Regimes in North America” Jacquelyn L. Gill, John W. Williams, Stephen T. Jackson, Katherine B. Lininger, Guy S. Robinson, 2009 SCIENCE 326:1100-1103
“Landscape Paleoecology and Megafaunal Extinction in Southeastern New York State” G. S. Robinson, L. P. Burney, D. A. Burney, 2005 Ecological Monographs 75, 295-315
Surovell also took far larger samples than we did diluting his results by an order of magnitude yet he sees the same basic picture.
I keep hearing this argument about “dilution” of samples and it is ridiculous. In your PNAS paper (p. 16017) you state that theaverage thickness of the “YDB layer” is 3 cm. THE AVERAGE THICKNESS! (But NOWHERE are the sampling intervals for your samples published or available – I asked both Allan West and Jim Kennett and neither responded). Some of Todd’s samples were thicker than 3cm, some about 3cm, some less. So NO WAY did he dilute his samples by “an order of magnitude.” This is such an astonishing red herring. Your magnetic microsphere levels are as much as an order of magnitude higher than any other samples in your sections. Explain to me how anyone could samples a zone maybe twice or three times as thick as you did and “dilute” the spike so it couldn’t be seen. Not possible. FURTHER, you report near zero levels of spheres above and below the 12.9ka level. Explain to me how we could collect more sample with near zero levels of spheres and dilute it such that we found more spheres than you did??? Huh? Maybe next you could argue that Todd was creating matter with his lab methods!
BTW, Jim Kennett’s lab ran splits of samples from Lubbock Lake that Surovell also ran. One of the samples was 9cm thick and yielded a big microspherule and nanodiamond spike. Problem is, it from a zone 1000 years younger than 12.9k. So the idea of dilution because of sample thickness, as noted above, is a crock.
The Carolina Bays are the only place where the markers found in narrow sections elsewhere are found throughout the bay rims. For many years these bays were assumed to be impact formed. Revisionists came later but most of the recent arguments are unpublished meeting abstracts. Arguments based on questionable dating methods of samples of uncertain origin don’t carry much weight.
“Revisionists”??? Revising what? I’ve followed the literature on the Bays for several decades (I had a student working there years ago). The notion that they formed via an impact was rejected long ago. I gather you are branding Andrew Ivester a “revisionist.” But he was working on the Bays long before you came along. I agree that the OSL dating of the Bay Rims needs to be fully published. I’ve been pushing that for years. But meeting abstracts with solid data are perfectly legitimate to publish. Your arguments are just more canards. OSL is not a “questionable dating method” and the samples are not of “uncertain origin.” You were perfectly happy to cite and distort one of Ivester’s abstracts and his OSL dates to make your case in your book (p. 127)!
We have presented a wealth of data. Archaeologists and geologists have made a mess of much of the analysis of the Clovis sites yet they expound on theories made largely upon opinion and conjecture. The data will decide this subject not your opinion or mine. Opponents can try as hard as they want to suppress new ideas. That is the mantra of geology for the past 100 years. It won’t suppress the truth.
Archaeologists and geologists are exactly the people who should be investigating archaeological and geological questions. You present no evidence whatsoever that they “made a mess.” This is simply your way of rationalizing a lot of data that can’t support your arguments.
The attached paper just came out this week. In it we look at the arguments for impact-induced population changes in North America. The key is stratified and dated archaeological sites. I would argue that you and your colleagues, none of whom have any experience with Paleoindian archaeology or geoarchaeology or the late Pleistocene terrestrial record, are the ones who “made a mess” of the analysis of Clovis sites. Otherwise, by your logic I should be writing papers on nuclear physics!
I agree that the data will decide the argument. In the attached paper with commentary (incl D Kennett) (just out) Dave Meltzer and I actually looked at the data (rather than just waving our arms) on Clovis and other Paleoindian occupations, focusing on dated, stratified sites rather than surface finds, to see is there is any sort of occupation hiatus. No new data – just the extensive published record. And there is simply no indication of a hiatus.
But you ignore or belittle any and all data that you don’t like. Your problem is bringing in preconceived notions compounded by cherry-picked data and gross distortions of the work of others (distorted to fit your claims). After writing my last letter I felt like I should send you a bill for being your research assistant! Us mere mortals in geology and archaeology do our field and lab work first, analyze and think about ALL of the data, question the data, and think about various interpretations (this was developed in geology and is called “the method of multiple working hypotheses’). Then we offer our hypotheses. I recommend you try this sometime.
I am through banging my head against a wall of preconceived ideas. And I am through arguing. This is pointless. Adios.
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Lester Brown, Earth Policy Institute