Species Response to the Theorized Clovis Comet Impact at Sheriden Cave, Ohio, 13 Ka BP, Brian G. Redmond, Kenneth B. Tankersley: Rich Murray 2013.05.09
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Species Response to the Theorized Clovis Comet Impact at Sheriden Cave, Ohio, 13 Ka BP, Brian G. Redmond, Kenneth B. Tankersley: Rich Murray 2013.05.09
 
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Species Response to the Theorized Clovis Comet Impact at Sheriden Cave, Ohio, 13 Ka BP, Brian G. Redmond, Kenneth B. Tankersley: Rich Murray 2013.05.09 [ to unsubscribe from this private list, just email me a request for immediate removal ]
P R O O F CURRENT RESEARCH IN THE PLEISTOCENE Vol. 28, 2011,141-142 Species Response to the Theorized Clovis Comet Impact at Sheriden Cave, Ohio Brian G. Redmond and Kenneth B. Tankersley
Brian G. Redmond, Cleveland Museum of Natural History, 1 Wade Oval Drive Cleveland, OH44106-1701; e-mail: bredmond@...
Kenneth B. Tankersley, Department of Anthropology, Department of Geology, University of Cincinnati, Cincinnati, OH 45221; e-mail: tankerkh@... 123457611
Keywords: Younger Dryas, climate change, comet impact Sheriden is a deeply stratified cave site situated in the glaciated Silurian karst plain of northwest Ohio.
The sinkhole entrance formed and exposed the cave after glacial ice covering the site retreated during the late Pleistocene. The cave rapidly filled with sediments, and the entrance was completely buried by the early Holocene.
During the Allerød, plants, animals, and Clovis people entered the sinkhole and cave (Tankersley 1999). Clovis artifacts and contemporary faunal remains include two complete bone projectile points made from dense cortical megamammal long bones, a Clovis fluted point, a scraper-knife made on a large flake, two biface fragments, a graver, a portion of an endscraper, 28 pieces of microdebitage, a cervical vertebra of Chelydra serpentine
(snapping turtle) with cut and chopmarks, and burned and disarticulated elements of Platygonus compressus (flat-headed peccary) and Castoroides ohioensis (giant beaver) (Redmond andTankersley 2005).
The age of the Clovis assemblage was determined by direct AMS radiocarbon dating of purified collagen extracted from one of the two bone points. The calibrated 14C age was 13,000 to 12,900 RCYBP at two standard deviations (Waters et al. 2009). This date overlaps the current, revised age range of Clovis and makes Sheriden Cave the twelfth firmly dated Clovis site in North America (Waters and Stafford 2007).
The age from the bone point also overlaps the AMS radiocarbon dates obtained from two extinct taxa, flat-headed peccary and giant beaver, and a distinctive charcoal layer (Tankersley 1999). Comparable organic layers have been identified at other Clovis sites across North America (Haynes 2008).
The charcoal layer contains above-background levels of carbon spherules,148/kg by weight and 100 microns to 1 mm in size, as well as magnetic grains, 2.5 g/kg by weight and up to 300 microns in size, magnetic microspherules, more than 100/kg by weight and 20 to 100 microns in size, nanometer-sized diamonds, 400 ppb by weight 0.5 microns to 0.5 mm in size,
and Lonsdaleite, a hexagonal nanodiamond polymorph found at other postulated Clovis comet impact sites across North America (Kennett et al. 2009). Lonsdaleite, nano-diamonds, magnetic microspherules, magnetic grains, and carbon spherules were absent in layers above and below the Clovis assemblage (Figure 1).
Of the 63 floral and faunal taxa recovered in direct stratigraphic association from the Clovis layer, 52 species of amphibians, arboreal plants, fish, mammals, and reptiles were unaffected by the theoretical Clovis comet impact event and are still living in the immediate vicinity of the cave today.
Only two species of megamammals in the assemblage went extinct, flat-headed peccary and giant beaver, while five microtines (Microtis xanthognathus, yellow-checked vole;
Phenacomys intermedius, heather vole; Sorex cinereus, masked shrew; Sorex hoyi, pygmy shrew; and Synaptomys borealis, northern bog lemming), three smallcarnivores (Martes americana,pine martin;
Martes pennanti, fisher; and Mustela erminea, ermine), and an artiodactyl (Rangifer tarandus, caribou) migrated northward to their present ranges in boreal and tundra environments.
Although the disappearance of two species of megamammals at Sheriden Cave coincides with the proposed Clovis comet impact event, the survival of more than 50 taxa of diverse plants and animals suggests that factors such as climate change during the subsequent Younger Dryas were more likely a contributing cause of their extinction instead of the theorized comet impact (Graham 1996).
This study was made possible with support from the National Science Foundation and the Court Family Foundation. The assistance and support of Keith Hendricks and the Cleveland Museum of Natural History is greatly appreciated.
Allen West provided sediment analyses and Greg McDonald and the late Fran King identified the faunal and floral species. References Cited Graham, R. W. (FAUNMAP Working Group) 1996
Spatial Response of Mammals to Late Quaternary Environmental Fluctuations. Science 272:5268:601–1606. Haynes, C. V. 2008 Younger Dryas “Black Mats” and the Rancholabrean Termination in North America.
Proceedings of the National Academy of Science 105:6520–25. Kennett, D. J., J. P. Kennett, A. West, C. Mercer, S. S. Que Hee, L. Bement, T. E. Bunch, M. Sellers,and W. S. Wolbach 2009
Nanodiamonds in the Younger Dryas Boundary Sediment Layer. Science 323:5910:94. Redmond, B. G., and K. B. Tankersley 2005 Evidence of Early Paleoindian Bone Modification and Use at the Sheriden Cave Site (33WY252), Wyandot County, Ohio.
American Antiquity 70(3):503–26. Tankersley, K. B. 1999 Sheriden: A Stratified Pleistocene-Holocene Cave Site in the Great Lakes Region of North America. BAR International Series 800:67–75.
Waters, M. R., and T. W. Stafford, Jr. 2007 Redefining the Age of Clovis: Implications for the Peopling of the Americas. Science 315:5815:1122–26. Waters, M. R., T. W. Stafford, Jr., B. G. Redmond, and K. B. Tankersley 2009
The Age of the Paleoindian Assemblage at Sheriden Cave, Ohio. American Antiquity 74:107–11. Figure 1. A, Stratigraphic profile of Sheriden Cave illustrating the charcoal layer and mean
RCYBP; B,TEM photomicrograph of Lonsdaleite; C, selected area electron diffraction pattern typical of a hexagonal nonodiamond. thanks for "Sudden Cold: an examination of the Younger Dryas cold reversal" (2009), Rodney Chilton: Rich Murray 2013.03.04 http://rmforall.blogspot.com/2013/03/thanks-for-sudden-cold-examination-of.html Napier: Not So Fast Bos... Bill Napier answers Mark Boslough dismissal of comet fragment swarm impact events, CosmicTusk blog: Rich Murray 2013.02.15 http://rmforall.blogspot.com/2013/02/napier-not-so-fast-bos.html Napier: Not So Fast Bos…. [ George A. Howard starts... ] Bill, will you help the Tusk out a bit and provide a response, which I can post, to the claim below by Dr. Mark Boslough? There are several ways to approach his statement, but I am interested in your take. “There’s no plausible mechanism to get airbursts over an entire continent,” said Boslough. Sent from my iPhone, George A. Howard Response from Bill Napier that day: You asked me to comment on Mark Boslough’s claim that “There’s no plausible mechanism to get airbursts over an entire continent.” As I’ve already demonstrated in the refereed literature that there is such a mechanism, I’m not sure what I can add! However, let me try to pinpoint where I believe Boslough is going wrong. I have in hand an abstract of a talk he gave a couple of years ago and I don’t suppose his stance has changed much since then: “The YDB impact hypothesis of Firestone et al. (2007) is so extremely improbable it can be considered statistically impossible in addition to being physically impossible. Comets make up only about 1% of the population of Earth-crossing objects. Broken comets are a vanishingly small fraction, and only exist as Earth-sized clusters for a very short period of time.” ~The Bos, Geol. Soc. America annual meeting (21-23 Nov 2010), Denver. It’s true that comets currently make up a minority of the population of Earth-crossing objects (1% is extreme but let that pass), but that’s only at the 1 km level or thereabouts. As you go to larger objects, the balance shifts profoundly. For example, there are no 10 km asteroids currently in Earth crossing orbits, but we do have large cometary Earth-crossers, e.g., Halley at 11 km, Swift-Tuttle at 27 km and so on. Asteroids of 10 km or more can’t be shifted out of the main belt at a sufficient rate to account for the large terrestrial impact craters: the transfer rate is an order of magnitude too slow. The action lies with the big comets. Large populations of them have been discovered on the fringes of the planetary system in recent years, thanks to deep, wide-angle surveys. Their number is still uncertain, and their orbital dynamics is still being worked out, but it is recognized that from time to time rare, giant comets will feed into short-period orbits from these populations, weaving between the giant planets in unstable orbits which may lead to their entering our neighbourhood on relatively short timescales. They do this for the most part by feeding through the Jupiter family of comets, that is short-period comets whose orbits are strongly influenced by that giant planet. Chiron, for example, which is over 200 km in diameter and orbiting beyond Saturn, has probably dipped in and out of our neighbourhood several times in its past. The half-life for doing so is about 0.2 million years, each episode lasting a few thousand years. It probably has several thousand times the mass of the entire near-Earth asteroid system. There are several known bodies in this size range and similarly unstable orbits, and the sample is likely incomplete. Large-scale orbital computations have shown that they have the propensity to become Earth-crossers on timescales (each) of order a million years. It follows from this that a giant comet residing in a short-period, Earth-crossing orbit is not uncommon on geological timescales. There is nothing anomalous about an erstwhile giant comet having been around say over the last 100,000 years. This is all by way of background because we know that in fact two such comets have indeed been around in the recent past. One is the progenitor of the Kreutz sungrazers, which was probably 100 km across and began to break up 1700 years ago. The other is the progenitor of comet Encke and the Taurids, which was probably of similar size but much greater age, at least 20,000 and perhaps up to 100,000 years. Kreutz was high inclination and its debris never came our way. Encke is in the ecliptic and we’re still immersed in the debris, the Taurid complex. Which leads to the question: what do we expect from a 100-200 km comet in a short-period Earth-crossing ecliptic orbit? “Broken comets are a vanishingly small fraction, and only exist as Earth-sized clusters for a very short period of time.” ~The Bos This one sentence contains two profound misconceptions. First, hierarchic disintegration is now generally recognised as the major route whereby comets die. It’s a common process. Second, ‘Earth-sized clusters’ have nothing to do with it. We are dealing with concentrations of fragments having, say, 10,000 times the cross-sectional area of the Earth. For a 100 km comet to undergo disintegration in our neighbourhood gives us a hugely enhanced impact hazard. Fragments totaling even a 1,000th the size of Chiron would have a mass of 10**18 g. Passage through such a debris field would yield about 10** 14 g of material impinging on the Earth. This is likely to be in the form of dust, pebbles, all the way up to super-Tunguska objects. The overall energy amounts to something like 5000 Tunguskas, striking a hemisphere of the Earth over a period of a few hours as we pass through. What are the odds that we would in fact pass through such debris in the course of a short-period, giant comet’s disintegration? This communication is already quite long enough, but detailed numerical modelling based on lifetimes, drift, shepherding resonances and the like reveal that one or two such encounters are reasonably probable events over the active lifetime of the Taurid progenitor (papers in preparation; see also my 2010 MNRAS paper). In a nutshell, Mark Boslough’s cometary model is irrelevant. It has nothing to do with the actual circumstances which prevailed in our environment over the Holocene and earlier. It takes no account of, and indeed shows no awareness of, modern developments in cometary dynamics. Any competent referee would reject it. I could say more, but perhaps that’s enough to be going on with. Best regards, Bill February 13th, 2013 | Tags: clovis, comet, LeCompte, mark boslough, pinter, pranks, sandia, surovell, younger dryas | Category: bill napier, Guest blogs, impact frequency, Mark Boslough, New Papers Rise of the Zombie: Harvard Discovers Evidence for Major Earth Impact at Younger Dryas Boundary [ George A. Howard comment ] “The theory has reached zombie status,” said Professor Andrew Scott from the Department of Earth Sciences at Royal Holloway. “Whenever we are able to show flaws and think it is dead, it reappears with new, equally unsatisfactory, arguments. -- January 30, 2013, Royal Holloway Press Release two weeks before the Harvard discovery Concluding remark: The main conclusion of our study is the detection of an unusual event during the Bølling-Allerød-YD transition period that resulted in deposition of a large amount of Pt to the Greenland ice.The nature of the event remains uncertain, but our results clearly rule out an impact or air burst of a chondritic bolide. If an impact was involved, the impactor had a very unusual composition deriving from a highly fractionated portion of a proto-planetary core. -- Petaev, Huang, 2013 [ free full text available via Scribd ] George Howard at cosmictusk.com blog cites reliance on Todd Surovell 2009 paper by Mark Boslough 2012 Dec. critique of 2007 Richard Firestone YD comet fragment impact storm hypothesis -- Malcome LeCompte 2012 Sept. backs up Firestone: Rich Murray 2013.02.10 http://rmforall.blogspot.com/2013/02/george-howard-at-cosmictuskcom-blog.html Aug 31 to meteorite-list@... smooth blue-black melt glaze on 2 sharp red-brown nearby surface rocks under left side of Mount Sharp in Curiosity Mars panorama? Rich Murray 2012.08.31 http://www.panoramas.dk/mars/curiosity-first-color-360.html high resolution adjustable view -- compare with surface glazes on sharp rocks in California and New Mexico: pertinent features near Campbell Mountain, studied by Dennis Cox, by his house in Fresno, CA: Rich Murray 2011.06.27 http://rmforall.blogspot.com/2011_06_01_archive.htm Monday, June 27, 2011 http://tech.groups.yahoo.com/group/astrodeep/message/87 It is easy in a few hours to locate pertinent features to the N, E, SE, and S of Campbell Mountain, studied by Dennis Cox, a few miles NE of his house in Fresno, CA. Maybe some of us can visit for a weekend and drive around, as many intriguing sites can be found by roads. http://craterhunter.wordpress.com/the-planetary-scaring-of-the-younger-dryas-imp\ act-event/california-melt/ https://skydrive.live.com/?cid=5d6b9f6c30c6fe9f&sc=photos&id=5D6B9F6C30C6FE9F%21\ \1348 19 images of Fresno mountains and rock samples Dennis Cox blog, plain text, with images of samples of magnetic black glaze on melt rocks from 13 Ka ice comet fragment extreme plasma storm geoablation in Fresno, California: Rich Murray 2010.07.02 http://rmforall.blogspot.com/2010_07_01_archive.htm Friday, July 2, 2010 http://tech.groups.yahoo.com/group/astrodeep/message/53 photo of typical air burst geoablation glaze on hard bedrock at top of Mount Helix park, E San Diego: Rich Murray 2012.03.15 http://rmforall.blogspot.com/2012/03/redbrown-glaze-on-hard-crystalline.html http://rmforall.blogspot.com/2012/03/photo-of-typical-air-burst-geoablation.html http://tech.groups.yahoo.com/group/astrodeep/message/98 10 m broken rock hill with black glazes, W of Rancho Alegre Road, S of Coyote Trail, W of Hwy 14, S of Santa Fe, New Mexico, tour of 50 photos 1 MB size each via DropBox: Rich Murray 2011.07.28 2011.08.03 http://rmforall.blogspot.com/2011/08/10-m-broken-rock-hill-with-black-glazes.htm\ l http://rmforall.blogspot.com/2011/08/35479730-106085926-1865-km-el-top-10-m.html photos 3-5 of 50 http://tech.groups.yahoo.com/group/astrodeep/message/92 within the fellowship of service, Rich Murray Rich Murray, MA Boston University Graduate School 1967 psychology, BS MIT 1964 history and physics, 254-A Donax Avenue, Imperial Beach, CA 91932-1918 rmforall@... <a href="tel:505-819-7388" value="+15058197388" target="_blank">505-819-7388 cell <a href="tel:619-623-3468" value="+16196233468" target="_blank">619-623-3468 home http://rmforall.blogspot.com ============================================================ FRIAM Applied Complexity Group listserv Meets Fridays 9a-11:30 at cafe at St. John's College to unsubscribe http://redfish.com/mailman/listinfo/friam_redfish.com |
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