========================================================================= Date: Wed, 1 Feb 1995 10:04:18 +0000 Reply-To: R.A.Marchant@geography.hull.ac.uk Sender: Radiocarbon & Other Radioisotope/Scientific Dating Methods From: "R.A.Marchant" Subject: Re: Extinct species from archaeological sites On Fri, 27 Jan 1995, TIM HEATON wrote: > I wondered if anyone knows of cases where extinct species, such as American > horses, were found in Archaeological sites of Holocene age and have been > C14 dated to learn the true age of the fossils. I have heard of old cases > of such finds, where they were dated by stratigraphy, but have never > learned if radiocarbon techniques have resolved them. They are probably > reworked, but only C14 dating could tell for sure. > > FYI, I study Quaternary mammals. I'm currently waiting on a new batch of > C14 dates on fossil bears from caves on Prince of Wales Island. > > Timothy H. Heaton /|Mountains /| theaton@charlie.usd.edu > Professor of Earth Sciences /::|Deserts /::| Phone: (605) 677-6122 > University of South Dakota /::::|Caves /::::| FAX: (605) 677-6121 > Vermillion, SD 57069 /::::::| /::::::| Radio: WB7NMY > In reply to your request I'll direct you to the work on the infamous Holocene mega-faunal extinctions on Madagascar (if you are not alrady familiar with this). Several approachs have been taken to date and 'account for' the extinctions, two article in particular spring to mind... Burney, D.A. (1987). Late Holocene vegetation change in Central Madagasar. Quat Res 28, 130-143. Dewar, R.E (1984) Recent extinctions in Madagasgar: The loss of subfosiil fauna. In Quaternary extinctions: A prehistoric revolution (P.S. MArtin, and R.G. Klien eds), pp 574-593 Uni Arizona press, Tucson Happy reading, if yuu find any other friuitful line of enquiry please let me know All the best Bob Marchant ========================================================================= Date: Wed, 1 Feb 1995 10:32:04 -0500 Reply-To: Radiocarbon & Other Radioisotope/Scientific Dating Methods Sender: Radiocarbon & Other Radioisotope/Scientific Dating Methods From: "Robert H. Tykot" Subject: Dating Holocene mammal extinctions Regarding the dating of Holocene animal extinctions, Professor Paul Sondaar (University of Utrecht) and others (J.D. Vigne, S. Swiny, A. Simmons) have published a number of papers on Mediterranean sites, particularly islands where the endemic fauna were wiped out once the islands were colonized by humans. Now-extinct species include pygmy elephants, pygmy hippos, dwarf deer, and the Sardinian hare. Excavations of stratified sequences in Sardinia and Corsica are among those that have been radiocarbon dated. Here are a few references: Vigne, J.E. 1990. Biogeographical history of the mammals on Corsica (and Sardinia) since the final Pleistocene. Proc. Int. Symp. on Biogeographical Aspects of Insularity (Rome 1987). Accademia Nazionale dei Lincei, Rome. Sondaar, P.Y. 1987. Pleistocene man and extinctions of island endemics. Memoires de la Societe Geologique de France 150:159-165. Klein Hofmeijer, G. et al. 1989. Dating of the upper pleistocene lithic industry of Sardinia. Radiocarbon 31(3):986-991. Burleigh, R.; Clutton-Brock, J. 1980. The survival of Myotragus Balearicus Bate into the neolithic on Mallorca. J. Arch. Sci. 7:385-388. Robert Tykot ********************************************************** * Robert H. Tykot Tykot@Fas.Harvard.Edu * * Archaeometry Laboratories 617 496-8991 * * Department of Anthropology 617 495-8925 (fax) * * Harvard University * * Cambridge, MA 02138 USA * ********************************************************** ========================================================================= Date: Mon, 6 Feb 1995 08:51:38 -0700 Reply-To: Radiocarbon & Other Radioisotope/Scientific Dating Methods Sender: Radiocarbon & Other Radioisotope/Scientific Dating Methods From: David Sewell Subject: New features on RADIOCARBON WWW server I've added a couple of features to our WWW server to make it a little more interactive. 1) You can sign up for automatic notification of changes/additions to the server (once a week or whenever anything substantive is added, whichever is longer). 2) You can contribute to the world's first online archive of C14 jokes in the "radiocarbon humor" section. [Experimental?] In the future, most development/addition of material is likely to occur on the WWW server rather than the gopher server, which will persist mainly as a pointer to the former. And since we're in the middle of working on three separate conference proceedings volumes, there's not a lot of time to put up new stuff. If anyone has online material that you would like to be linked to the RADIOCARBON server, please let me know. Radiocarbon WWW address: http://packrat.aml.arizona.edu/ David Sewell Assistant Editor & ex officio Internet hacker -- David Sewell, Assistant Editor RADIOCARBON: An International Journal of Cosmogenic Isotope Research Department of Geosciences, University of Arizona 4717 E. Ft. Lowell Rd., Tucson, Arizona 85712 USA Telephone: 1-602-881-0857 Fax: 1-602-881-0554 NEW AREA CODE: use "520" instead of "602" after 19 March 1995! ========================================================================= Date: Thu, 9 Feb 1995 21:54:08 EDT Reply-To: Radiocarbon & Other Radioisotope/Scientific Dating Methods Sender: Radiocarbon & Other Radioisotope/Scientific Dating Methods From: Juan de Dios Garrido Arrate Subject: Workshop The Institute of Nuclear Sciences and Thecnology of Havana, Cuba, invite you, to the Ish Workshop of the Departament of Environment.This workshop is to be held in Havana, on Jun 15-16, 1995. Several of topics will be exposed: - Environmental Simulation; - Ecological Protection; - Environmental Radiological Protection; - Clean Thecnology. Authors submitting papers should send an abstract written in English or Spanish not exceeding 500 words to the Organizing Commitee before May 1, 1995. For more information: Dr. Francisco Martinez Luzardo ISCTN, Ave. Salvador Allende y Luaces Quinta de los Molinos, Plaza, C. Habana, Cuba FAX: (537) 33-1188, 33-1325 E-Mail: CEADEN@CENIAI.CU Telex: 511418, 511837sean.cu ========================================================================= Date: Thu, 9 Feb 1995 20:05:38 -0600 Reply-To: Radiocarbon & Other Radioisotope/Scientific Dating Methods Sender: Radiocarbon & Other Radioisotope/Scientific Dating Methods From: USS@SPACE-SOCIETY.UH.EDU Subject: Questioning C14 Validity? Hello, Call me a skeptic but I have recently been exposed to some general questions on the philosophy of science (what counts as proof, that sort) and have started wondering how accurate our dating methods are (C14, Potassium Argon, etc.)? Does anyone know of a good source that deals with this type of subject matter? I would very much appreciate any help you could give. Thanks ahead of time. James Benthall Dept. of Anthropology University of Houston Houston, Texas 77204 ========================================================================= Date: Fri, 10 Feb 1995 09:28:31 -0500 Reply-To: Radiocarbon & Other Radioisotope/Scientific Dating Methods Sender: Radiocarbon & Other Radioisotope/Scientific Dating Methods From: Greg Laden Subject: Re: Questioning C14 Validity? In-Reply-To: <01HMUVYZTC9UHSJ7EW@Jetson.UH.EDU> James: I think it would be important for you to specify the nature (and even some detail) of the questions about 14C that you have been "exposed" to. Such questions run the gammut from issues of calibration, to how deep in time we can go with certain methods, to alleged changes in the speed of light over time that invalidate all radiometric techniques and thus prove that Noa fit even the dino's in the ark! Please help to narrow down and focus the discussion by telling us what the questions are that have been raised! Thanks GTL On Thu, 9 Feb 1995 USS@SPACE-SOCIETY.UH.EDU wrote: > Hello, > > Call me a skeptic but I have recently been exposed to some general questions > on the philosophy of science (what counts as proof, that sort) and have started > wondering how accurate our dating methods are (C14, Potassium Argon, etc.)? > > Does anyone know of a good source that deals with this type of subject matter? > I would very much appreciate any help you could give. Thanks ahead of time. > > James Benthall > Dept. of Anthropology > University of Houston > Houston, Texas 77204 > Greg Laden Department of Anthropology Harvard University 11 Divinity Avenue Cambridge MA 02138 ========================================================================= Date: Tue, 21 Feb 1995 14:31:14 -0500 Reply-To: Radiocarbon & Other Radioisotope/Scientific Dating Methods Sender: Radiocarbon & Other Radioisotope/Scientific Dating Methods From: "Donald M. Thieme" Subject: Dating late Pleistocene and older samples The most frequently mentioned advantage of AMS is that much smaller samples of organic material are required than for beta decay counting. As Gove (1992: 219) states, "a measurement can be made of the date of an artifact 34,000 years old with a statistical accuracy of 10% (+/- 830 yr) in 7 minutes using a 0.25 mg sample, whereas a sample of 50 g would be required for decay counting to obtain the same accuracy in the same 7 minutes." Since we are measuring smaller and smaller traces of C-14 as sample age increases, it seems the me that AMS should also give more accurate dates for older samples. If so, this advantage is not widely known. I would be interested in a discussion of the following hypothetical situation. One has an entire charred log (> 200 g) suspected to be late glacial or older. Would the AMS date be any more accurate? Gove, H. E., 1992, The history of AMS, its advantage over decay counting: applications and prospects. In "Radiocarbon after Four Decades...," edited by R. E. Taylor, A. Long, and R. S. Kra. Springer-V ========================================================================= Date: Tue, 21 Feb 1995 14:16:25 -0700 Reply-To: Radiocarbon & Other Radioisotope/Scientific Dating Methods Sender: Radiocarbon & Other Radioisotope/Scientific Dating Methods From: Ian Campbell Subject: Re: Dating late Pleistocene and older samples > I would be interested in a discussion of the following hypothetical >situation. One has an entire charred log (> 200 g) suspected to be >late glacial or older. Would the AMS date be any more accurate? > Presumably, if the log is like most such material heavily fissured, a bulk date would run the risk of including contaminants (perhaps younger humic acids percolating down from above); with an AMS date, you could clean the sample more thoroughly (perhaps taking just one chunk of charcoal and removing the edges) to reduce the risk of contamination. And of course, if something goes wrong, you still have lots of material to work with! Why, you could even contemplate using the rest of the log as part of a display, if the site and the log are important enough to warrant that. | Ian D. Campbell o8o | | Canadian Forest Service 8Oo8oOoO | | 5320-122 St. Edmonton, AB ^ oO8O88o8o8 | | Canada T6H 3S5 ^^^ o8Oo8ooOooO ^ | | Tel: +1-403-435-7300 Fax: +1-403-435-7359 ^^^^^ 88oo8O88 ^^^ | | e-mail: icampbell@nofc.forestry.ca ^^^|^^^ || | | ========================================================================= Date: Tue, 21 Feb 1995 16:50:23 -0500 Reply-To: Radiocarbon & Other Radioisotope/Scientific Dating Methods Sender: Radiocarbon & Other Radioisotope/Scientific Dating Methods From: "Tristram C. Hussey" Subject: Re: Dating late Pleistocene and older samples >> I would be interested in a discussion of the following hypothetical >>situation. One has an entire charred log (> 200 g) suspected to be >>late glacial or older. Would the AMS date be any more accurate? >> > >Presumably, if the log is like most such material heavily fissured, a bulk >date would run the risk of including contaminants (perhaps younger humic acids >percolating down from above); with an AMS date, you could clean the sample >more thoroughly (perhaps taking just one chunk of charcoal and removing >the edges) to reduce the risk of contamination. And of course, if something >goes wrong, you still have lots of material to work with! Why, you could even >contemplate using the rest of the log as part of a display, if the site and >the log are important enough to warrant that. But aren't _most_ samples for conventional dating pre-treated with KOH (or the like) to get rid of humics? I think that sometimes too much faith is put in the "better" accuracy of AMS. A collegue of mine here at Duke dated discreet macrofossil from a core in a Blue Hole. These dates came back screwy because the material dated was the contaminate in the sediment. The best way to avoid contamination, as noted above, is to know what you're dating and make sure that is clean. And on the tack of having more sample left, with AMS you could more easily date the log at several different labs (assumely a rather large grant to do so) to get a good date. If my memory serves me, the researchers working on the "Ice Man" did this, as did the Roman Catholic Church when they dated the Shroud of Turin. Cheers, Tris Tristram C. Hussey, Research technician Department of Botany, Duke University Durham, NC 27708 Ph: (919) 660-7403 Fax (919) 660-7425 Brevis esse laboro, obscurus fio ========================================================================= Date: Wed, 22 Feb 1995 13:57:14 +1200 Reply-To: Radiocarbon & Other Radioisotope/Scientific Dating Methods Sender: Radiocarbon & Other Radioisotope/Scientific Dating Methods From: Tom Higham Subject: Re: Dating late Pleistocene and older samples >>> I would be interested in a discussion of the following hypothetical >>>situation. One has an entire charred log (> 200 g) suspected to be >>>late glacial or older. Would the AMS date be any more accurate? In terms of _accuracy_, I would suggest that anyone interested examine the IAEA and TIRI intercalibration results (given in Radiocarbon - I can get the ref's if required and in IAEA reports) detailing the intercomparison exercises undertaken within the C14 community. There is of course, accuracy and precision, and one can be accurate without necessarily being precise and vice versa. For instance if I dated a sample of Harold 1sts battle garment at Hastings and gave you a result of AD 1060+/-200 I would be be accurate but imprecise, If I gave you a result of 1060+/-15 I would be accurate and precise, if you received 950+/-20 I would be precise and innaccurate! There are very accurate radiocarbon labs and there are inaccurate radiocarbon labs, regardless of the technique employed and it is up to users to consider seriously the performance of individual labs prior to sending precious samples for dating. In the 1990 IAEA intercomparison, the coordinators assessed performance by technique and they found that AMS labs had greater tightness around the IAEA mean values than did GPC or LSC labs although all were statistically indistinguishable from one another (actually they found more difference based upon the modern standard used than the type of technique employed). There are interesting questions concerning the statistical methods at which the mean values are arrived at however. For example, two high precision labs submitted results that were much more precise than most other labs and found they were outliers and rejected from the analysis to compute the mean IAEA values. This begs the question in these exercises of just what is the correct value or date? The age old problem is that there are very few available standards for which the absolute age is known, so stats play a key role. The recent intercomparison found that at modern and background there was a large range of measurements and many had to be rejected from analysis to calculate a mean value. I think all labs submitting results from intercomparisons should be required to submit them a certain level of precision because it is just too easy to increase standard errors to maximise the likelihood of your result being indistiguishable from the calculated mean. Thats another issue though. Put simply, my answer to the first question concerning accuracy, based upon the IAEA results and other more recent analyses, would be that an AMS lab could not supply you with a "more accurate" date than a conventional lab at this stage, especially given the sample size you mention. In addition, a conventional lab would probably supply a more precise measurement. --------------------------------------------------------------------------- Dr Thomas Higham, * Email: Thigham@waikato.ac.nz Research Officer-Archaeological Dating * Phone: +(64) 07 838 4278 Radiocarbon Dating Laboratory, * GlobalFax: +(64) 7 838 4192 University of Waikato, * World Wide Web server (incl. Hamilton, * Online submission forms):- NEW ZEALAND. * http://www2.waikato.ac.nz/c14/ --------------------------------------------------------------------------- ========================================================================= Date: Wed, 22 Feb 1995 18:14:02 -0800 Reply-To: Radiocarbon & Other Radioisotope/Scientific Dating Methods Sender: Radiocarbon & Other Radioisotope/Scientific Dating Methods From: Dick Meehan Subject: Re: Dating late Pleistocene and older samples In-Reply-To: <950221.143558.EST.DTHIEME@UGA.CC.UGA.EDU> Is there a handy list of commercial labs and prices available? Thanks in advance. Dick Meehan ========================================================================= Date: Fri, 24 Feb 1995 08:58:33 +1200 Reply-To: Radiocarbon & Other Radioisotope/Scientific Dating Methods Sender: Radiocarbon & Other Radioisotope/Scientific Dating Methods From: Tom Higham Subject: Re: Dating late Pleistocene and older samples >Is there a handy list of commercial labs and prices available? > >Thanks in advance. > Check out the World Wide Web pages on the Arizona web server. The address is: http://packrat.aml.arizona.edu/ Four laboratories have information on dating and prices. If you can't access the web, some editions of the journal Radiocarbon have lists of laboratories and addresses. Regards, --------------------------------------------------------------------------- Dr Thomas Higham, * Email: Thigham@waikato.ac.nz Research Officer-Archaeological Dating * Phone: +(64) 07 838 4278 Radiocarbon Dating Laboratory, * GlobalFax: +(64) 7 838 4192 University of Waikato, * World Wide Web server (incl. Hamilton, * Online submission forms):- NEW ZEALAND. * http://www2.waikato.ac.nz/c14/ --------------------------------------------------------------------------- ========================================================================= Date: Fri, 24 Feb 1995 14:54:00 -0500 Reply-To: Radiocarbon Mailing List Sender: Radiocarbon Mailing List From: "Donald M. Thieme" Subject: Re: Dating late Pleistocene In-Reply-To: <950223.203733.EST.DTHIEME@UGA.CC.UGA.EDU> My previous message was truncated. I really was interested in whether the loss of precision with increasing sample age was different with AMS than with beta decay counting. In other words, is probable age of sample something to consider as well as sample size in choosing the dating method?