Jim Kennett, Malcom LeCompte, Allen West and Tom Stafford (Clockwise from the hat)
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Regular readers have surely noticed the annoying and unsightly formatting problems here at the Tusk. In particular, blogs which use “block quotes” of outside material are superimposing themselves on older blogs, rendering them both nearly unreadable. While surely embarrassing for me, please rest easy. Technical personnel have been alerted and we will have it repaired soon. This is only the latest in a string of incidents which have ham-strung my efforts to keep you up-to-speed. At the AMQUA conference almost three weeks ago, my formerly trusty Dell laptop blogging tool completely failed (and is still being repaired). That took me off the air until I returned to the office. Work has been wild lately, so no time to blog at work, though I’ve made the effort of late. (I bought an Ipad last week, but it is a poor substitute for the laptop as far as blogging is concerned). So, dear reader, for the time being I can only steal away to the blog at work, fervently typing when the line of workers asking dumb questions slackens for a moment. Hang in there. When I get up and running I will try to give you a full run-down of the AMQUA conference. It was a great time, incidentally, with the home team prevailing 65-35 in my humble estimation.
From an email from Bunch to Leroy Ellenberger: Dear Leroy – not to worry, Dalton is a competent scientist and did what he could do with the materials given to him. The problem lies with Scott and Pinter. Some brief reasons why the Dalton et al paper is inept: 1.They did not collect from the YDB layer at the Arlington site that was used in the two Kennett et al papers, but from layers that contained “carbonaceous particles”, mostly charcoal – there are no diamonds in charcoal and it is not clear that they even sampled the YDB. 2. They did not collect or at least process the YDB sediment at Murray Springs, which contains most of the nanodiamonds in the YDB as loose nanodiamonds – probably too much work because the work is labor intensive – need to separate kilos of material. The diamonds average about 50 to 100 ppb and you need a lot of diamonds, processed by the correct separation protocol. 3. Yes, we saw graphene, graphane and chaoite, but these are not diamonds. 4. They analyzed microcharcoal and glassy carbon for diamonds and found none, neither did we! These “carbon particles” were made outside the constrains for diamond production and survival. 5. Two reviewers for the Kennett papers are world class shock and diamond experts – they had no problem. 6. One independent stratigrapher who read the Daulton paper was astonished at the “complete ineptness of field protocol and sample characterization”. Of course, you and others can judge for yourselves. 7. The Greenland paper (Glaciology) will appear in September and there are sufficient diamond data in this paper (STEM, HRTEM, RAMAN, EELS, etc.) to prove once and for all that diamonds do, indeed, occur in the YDB. More later, Ted Press Release: Daulton, Pinter and Scott publish finding NO diamonds in Younger Dryas Boundary layerImpact hypothesis loses its sparkle Link to Press Release from the Washington University in St. Louis About 12,900 years ago, a sudden cold snap interrupted the gradual warming that had followed the last Ice Age. The cold lasted for the 1,300-year interval known as the Younger Dryas (YD) before the climate began to warm again. In North America, large animals known as megafauna, such as mammoths, mastodons, saber-tooth tigers and giant short-faced bears, became extinct. The Paleo-Indian culture known as the Clovis culture for distinctively shaped fluted stone spear points abruptly vanished, eventually replaced by more localized regional cultures. What had happened? One theory is that either a comet airburst or a meteor impact somewhere in North America set off massive environmental changes that killed animals and disrupted human communities. In sedimentary deposits dating to the beginning of the YD, impact proponents have reported finding carbon spherules containing tiny nano-scale diamonds, which they thought to be created by shock metamorphism or chemical vapor deposition when the impactor struck. The nanodiamonds included lonsdaleite, an unusal form of diamond that has a hexagonal lattice rather than the usual cubic crystal lattice. Lonsdaleite is particularly interesting because it has been found inside meteorites and at known impact sites. In the August 30 issue of the Proceedings of the National Academy of Sciences, a team of scientists led by Tyrone Daulton, PhD, a research scientist in the physics department at Washington University in St. Louis, reported that they could find no diamonds in YD boundary layer material. Daulton and his colleagues, including Nicholas Pinter, PhD, professor of geology at Southern Illinois University In Carbondale and Andrew C. Scott, PhD, professor of applied paleobotany of Royal Holloway University of London, show that the material reported as diamond is instead forms of carbon related to commonplace graphite, the material used for pencils. “Of all the evidence reported for a YD impact event, the presence of hexagonal diamond in YD boundary sediments represented the strongest evidence suggesting shock processing,” Daulton, who is also a member of WUSTL’s Center for Materials Innovation, says. However, a close examination of carbon spherules from the YD boundary using transmission electron microscopy by the Daulton team found no nanodiamonds. Instead, graphene- and graphene/graphane-oxide aggregates were found in all the specimens examined (including carbon spherules dated from before the YD to the present). Importantly, the researchers demonstrated that previous YD studies misidentified graphene/graphane-oxides as hexagonal diamond and likely misidentified graphene as cubic diamond. The YD impact hypothesis was in trouble already before this latest finding. Many other lines of evidence — including: fullerenes, extraterrestrial forms of helium, purported spikes in radioactivity and iridium, and claims of unique spikes in magnetic meteorite particles — had already been discredited. According to Pinter, “nanodiamonds were the last man standing.” “We should always have a skeptical attitude to new theories and test them thoroughly,” Scott says, “and if the evidence goes against them they should be abandoned.”
Dave, As you probably know, the Sep/Oct Skeptical Inquirer (whose cover features Martin Gardner) contains letters by Clark Chapman and Paul Hilfinger, reacting to your May/Jun article on the claimed impact at the Younger Dryas boundary (also with a letter from Mark Bosslough commenting on his sidebar about scientists changing their minds, citing the recent example of Wallace Broecker) This is not just improbable; in common usage we would have to call it impossible.” Dave, I almost hate to say this, but in almost every particular here you are WRONG because 1) the British astronomer Bill Napier has explained this year in MNRAS how Earth might well have encountered such huge swarms of super-Tunguska impactors from the debris of a recently disintegrated comet only 13,000 years ago (despite Chapman seconding you on this point), and; 2) American geologist Adrian Melott et al. have this year presented evidence in GEOLOGY for a large impact at the YDB based on the ammonium signal in the Greenland ice. The publication of the paper contradicts Chapman’s statement in his letter, “Nor has the Greenland paper been published in any peer-reviewed scientific journal during the subsequent year.” Furthermore, there need not have been two events IF the admittedly controversial extra-terrestrial origin of the Carolina bays was part of the same impact event at the YDB, but this issue is beyond the scope of my concerns here. Your failure to take into account these two developments vitiates the thrust of your article. Also, I find it of passing interest that Hilfinger’s letter correcting you on a probability issue (“That is, Tunguska does not ‘protect’ us from immediate future impacts.”) is the same issue on which my unpublished letter to Sky & Telescope in Sept. 2009 corrected Mark Boslough, i.e., the occurrence of a low probability event does not mean that a second, similar low probability event cannot happen very soon after the first. The letter below was submitted to Skeptical Inquirer in early July, possibly too late to be included in the Sep/Oct issue, but in light of the tenor of Clark Chapman’s letter (“I wish to expand on David Morrison’s excellent special report . . . on the widely publicized claim that a huge broken-up comet collided with Earth just 13,000 years ago, wiping out mammoths, Clovis culture, and so on. . . .”), excoriating the AAAS for awarding top prize to the NOVA TV documentary on the Younger Dryas Impact shown on PBS. Perhaps I was too optimistic about SI’s interest in “fair and balanced” scientific reporting. [ letter to SI by C. Leroy Ellenberger ] Cosmic Impact at Younger Dryas Boundary In response to David Morrison’s attempt to quash the possibility that a cosmic impact killed the mammoths approximately 12,900 years ago (SI, May/June 2010), Mark Twain might have responded that the report that such an impact has been disproved is exaggerated. Certainly Morrison correctly points out scientific problems in some descriptions of the event; but he fails to deal with recent developments that nevertheless support a cosmic impact at the Younger Dryas boundary. Three issues merit comment here: Morrison claims, “There was apparently no way to get a swarm of impactors to target North America alone,” while assuming that a comet disintegrated just before encountering Earth; but this objection has been overcome by British astronomer Bill Napier who, in a recent publication, describes how robust meteorid streams (comet debris trails) would be the inevitable result of the disintegration within the past 20-30 KYr of the progenitor of the Taurid Complex in near-Earth space, and that, “encounters with dense swarms of material, sufficient to produce a 12.9 ka cosmic event, are indeed reasonable expectations of recent Earth history.” Morrison’s criticism concerning impact frequencies does not envision the former existence of a large comet in a short period orbit whose disintegration gave rise to the Earth-orbit-crossing Taurid Complex which then contained myriads of large debris. Concerning the presence of nanodiamonds, Morrison misstates D.J. Kennett et al.’s position in Science, who stated, “Nanodiamonds . . . are associated with known impacts, during which they may arrive inside the impactor or form through shock metamorphism. . . .” Morrison improperly ignored the prospect of their arrival inside the impactor, which was the case with the Tagish Lake meteorite (arguably part of the Taurid Complex) that fell over British Columbia in January 2000, and contained the highest abundance of nanodiamonds yet seen. Conversely, Morrison’s remark, “Most impact experts agree that nanodiamonds were unlikely to have been formed in the impact,” is contradicted by the discovery of nanodiamonds at the Cretaceous-Tertiary boundary, that most likely formed from terrestrial material during the impact. Finally, airbursts from cometary fragments can be expected to produce copious amounts of ammonium ion, which are captured and preserved in glaciers, especially the Greenland ice cap. A.L. Melott et al. in the April 2010 Geology analyzed the ammonium signals in the Greenland ice from the Tunguska airburst of June 30, 1908, which cannot be explained by wildfires from the explosion, and also at a depth in the ice corresponding to the onset of the Younger Dryas 12,900 years ago. This is presumptive evidence for a cosmic impact at that time, regardless Morrison’s attempts to discount such a possibility. References Napier, W. M. 2010. Kennett, D. J. et al. 2009. Gilmour, I. et al. 1992. Melott, A. L. et al. 2010. C. Leroy Ellenberger URLs to Napier and Melott: Napier: Melott: All the best, August 27th, 2010, Category: Uncategorized, One comment [ Rich Murray adds: http://www.csicop.org/si/archive/category/volume_34.3 Skeptical Inquirer — Volume 34.3 May / June 2010 http://www.csicop.org/si/show/when_scientists_actually_change_their_minds/ When Scientists Actually Change Their Minds http://www.csicop.org/si/show/did_a_cosmic_impact_kill_the_mammoths Did a Cosmic Impact Kill the Mammoths?
David Morrison Dr. David Morrison is the Senior Scientist at the NASA Astrobiology Institute. His primary interests are the new multidisciplinary science of astrobiology, the protection of Earth from asteroid impacts, and science outreach and education. Dr. David Morrison is the Director of the NASA Lunar Science Institute and Senior Scientist for Astrobiology at the NASA Ames Research Center. He is also the Director of the Carl Sagan Center for Study of Life in the Universe at the SETI Institute, in Mountain View CA. http://www.sandia.gov/news/resources/releases/2007/asteroid.html See the Mark Boslough supercomputer 3D simulations of meteor air bursts  Senator Bill Nelson (D-Florida)
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