========================================================================= Date: Tue, 2 Apr 1996 15:23:14 -0700 Reply-To: Radiocarbon Mailing List Sender: Radiocarbon Mailing List From: David Sewell Subject: REALLY basic references on C-14 dating? Here's one of the occupational hazards of having a WWW site with your name as an e-mail contact: >Hi- >I'm doing a short report in 9th grade for biology. I was wondering if you >could send me an email by wed that tells me about carbon dating and it's >reliability. If you can i would be eternally thankful. Thankyou. Actually, you'd be surprised how many similar requests we get from college and post-college-age folk... But what I'm wondering is, apart from the standard encyclopedia articles, does anyone know of a good basic introduction to scientific dating that someone at the early high school level could handle? (People with some technical background I usually point to Taylor's "Radiocarbon Dating", but that's probably too advanced here.) David Sewell -- RADIOCARBON: An International Journal of Cosmogenic Isotope Research Department of Geosciences, University of Arizona 4717 E. Ft. Lowell Rd., Tucson, Arizona 85712 USA Telephone: 1-520-881-0857 Fax: 1-520-881-0554 General e-mail address: c14@packrat.aml.arizona.edu WWW server: http://packrat.aml.arizona.edu/ ========================================================================= Date: Wed, 3 Apr 1996 11:04:20 +1200 Reply-To: Radiocarbon Mailing List Sender: Radiocarbon Mailing List From: Tom Higham Subject: Re: REALLY basic references on C-14 dating? >Here's one of the occupational hazards of having a WWW site with >your name as an e-mail contact: I get about 5-10 of these a week David! I really try to answer them if I have time but it does get to be a pain. Last week I had a kid from an American school asking about rock art dating and after I told her that in prehistory it is thought alot of art was done by mixing a slurry of charcoal in the mouth and spitting it onto the rock surface, she expressed a keen interest in trying to reproduce this for her school project! I really felt for the parents at that stage! Jon Lizee, who runs the ArchNet WWW Virtual Library of Archaeology wanted me to do a K-12 version of WEBinfo and I guess something like that would be useful as a pointer for this type of enquiry. Last week I participated in an archaeological excavation. A film was being made for schools and they came over to the lab and I explained everything. It was very hard because I had to do 2 versions one for 10 yr olds and another for 16-17 yr olds. The 10 yr old section was really hard to do, to explain it in simple language. I may, if I have time, try to get something together in the future, until now I'll go on dealing with individual cases. Taylor is too complicated for younger students. Cheers David, ------------------------------------------------------------------------- Dr Thomas Higham, * Email: Thigham@waikato.ac.nz Radiocarbon Dating Laboratory, * Phone: +(64) 07 838 4278 University of Waikato, * Fax: +(64) 7 838 4192 Hamilton, * WWW: Radiocarbon WEB-info: NEW ZEALAND. * http://www2/waikato.ac.nz/c14/webinfo/index.html ------------------------------------------------------------------------- ========================================================================= Date: Tue, 2 Apr 1996 15:17:57 -0800 Reply-To: Radiocarbon Mailing List Sender: Radiocarbon Mailing List From: Thomas George Arnold Subject: Re: REALLY basic references on C-14 dating? In-Reply-To: from "David Sewell" at Apr 2, 96 03:23:14 pm David, How about Sheridan Bowman's Radiocarbon Dating, 1990, University of California Press. Its thin and quite readable. It helped me and I'm a PhD grad student in archaeology ;-}. Tom A. ========================================================================= Date: Tue, 2 Apr 1996 16:29:52 -0700 Reply-To: Radiocarbon Mailing List Sender: Radiocarbon Mailing List From: Owen Davis Subject: Re: REALLY basic references on C-14 dating? David, Based on his grammar and spelling, I fear there's little hope. But, being optimistic, I'd recommend Sheridan Bowman. 1990. Radiocarbon dating: interpreting the past. University of California Press ISBN 0-520-07037-2 Owen. Owen K. Davis, Professor 520 621-7953 Department of Geosciences FAX 621-2672 University of Arizona palynolo@geo.arizona.edu Tucson, Arizona 85721 http://geo.arizona.edu/palynology ========================================================================= Date: Wed, 3 Apr 1996 11:44:34 +1200 Reply-To: Radiocarbon Mailing List Sender: Radiocarbon Mailing List From: Tom Higham Subject: Re: REALLY basic references on C-14 dating? Dear List, Apologies for another reply to the List which was mistakenly sent as an intended personal message! I thought the message on "REALLY basic reference" was sent only to me. The reply was supposed to go to David Sewell only. Another lesson in reading mail addresses more closely. Sorry again, Cheers, ------------------------------------------------------------------------- Dr Thomas Higham, * Email: Thigham@waikato.ac.nz Radiocarbon Dating Laboratory, * Phone: +(64) 07 838 4278 University of Waikato, * Fax: +(64) 7 838 4192 Hamilton, * WWW: Radiocarbon WEB-info: NEW ZEALAND. * http://www2/waikato.ac.nz/c14/webinfo/index.html ------------------------------------------------------------------------- ========================================================================= Date: Tue, 2 Apr 1996 18:54:50 -0400 Reply-To: Radiocarbon Mailing List Sender: Radiocarbon Mailing List From: June Mirecki Organization: College of Charleston Subject: Really basic C-14 refs Most introductory historical geology books have a distilled version of radiocarbon dating, which may be useful. I have also used the "coin toss" experiment to show the concept of half-life (this may be good for groups of kids): Give each person a penny, heads up. At 0 half-lives, all heads are up. Have the group flip their coins (passage of one half-life...), count the number of heads-up coins remaining (approx 50%) and so on, until no heads are left. I understand that these "extras" are often a burden on our scarce lab and research time; but for us Americans, consider that an patient explanation of radiometric dating at a tender age may help offset the "scientific creationist" of tomorrow. Having formerly taught at a university in Tennessee, I can see the value in an early warning system! (:-o _________________________________________________________________________ June Mirecki MIRECKIJ@COFC.EDU |-----| Department of Geology phone: 803/953-8278 |-----| 58 George St. fax: 803/953-5446 |-.-.-| College of Charleston |-.-.-| Charleston, SC 29424 |:::::| __________________________________________________________|:::::|________ ========================================================================= Date: Tue, 2 Apr 1996 19:22:09 -0500 Reply-To: Radiocarbon Mailing List Sender: Radiocarbon Mailing List From: stephanie Walrath Subject: Re: Really basic C-14 refs Personally, I first learned abut C-14 dating my first introductory class in jr. colloege. It was further advanced in my Intro .to Archaeological Theory at the Humboldt State University in Ca. I vaguely remember reading about it in various books......Just my .2cents Stephanie ========================================================================= Date: Tue, 2 Apr 1996 20:31:46 -0500 Reply-To: Radiocarbon Mailing List Sender: Radiocarbon Mailing List From: "Gary S. Breschini, Ph.D. and Trudy Haversat, M.A." Subject: Re: REALLY basic references on C-14 dating? A shameless plug for Coyote Press. We sell Bowman's "Radiocarbon Dating" book for $9.60 (retail $12.00). It is very worthwhile for younger readers. Taylor's "Radiocarbon Dating" is good, but being from Academic Press it is expensive. It retails for $66.00 (we have it for $51.95), but it is not really suitable for younger readers. For more information visit our page at http://www.coyotepress.com Gary S. Breschini, Ph.D. Archaeological Consulting/Coyote Press ========================================================================= Date: Tue, 2 Apr 1996 22:10:04 +0000 Reply-To: Radiocarbon Mailing List Sender: Radiocarbon Mailing List From: James Burton Subject: Re: REALLY basic references on C-14 dating? Though the post about C-14 K-12 sources might not have been intended for the list, i think we're glad we got it. I agree - sounds like a consensus - Taylor's too much; Bowman's lightweight and affordable - I'd be happy if our undergrads could grasp so much, though. But the main thought I wanted to add to the thread is my delight at the RESPONSE to the student's original request. I've seen far too many protests on the anthro/archy lists about non-professional inquiries . The Internet is an awesome resource and we're REALLY lucky if K-12 kids are getting on-line and asking us. It's also an awesome medium for outreach. I'd like to amplify what June Mirecki said. The national media are broadcasting that humans existed along side the dinoaurs. If we don't care to bother to answer those K-12 questions, the next congress won't care to bother to fund us to ask ours! Anyhow - I was thoroughly delighted by evereyone's positive response...thanks!! james burton (jhburton@facstaff.wisc.edu) Anthropology Dept./Univ. of Wisconsin-Madison ========================================================================= Date: Wed, 3 Apr 1996 06:42:27 -0500 Reply-To: Radiocarbon Mailing List Sender: Radiocarbon Mailing List From: Nikolaas VanderMerwe Subject: Re: REALLY basic references on C-14 dating? In-Reply-To: Like Burton, I am very pleased at the response to the questions from junior scientists in the making. Bowman's book is the best available text for all ages at this point, although something more rudimentary for grade schoolers (and archaeology students!) would be very welcome. I have been asked to lecture to senior primary and junior high school pupils on the subject in two countries on various occasions, have been appalled at how poorly I did it the first time around,and have been delighted at how well some of them respond. Some of the students in my Freshman Seminar at Harvard (admittedly, those with A level science or the equivalent) arrive from high school with a full grasp of radiometric dating, so someone out there must be doing a good job.Some of these students have been from countries like India and Poland, so the subject receives worldwide atttention. At the same time, I am astounded at the lack of technical knowledge of the average anthropology trained graduate student in archaeology.There is a large vacuum out there, waiting to be filled. Nick van der Merwe Peabody Museum Harvard Univ. ========================================================================= Date: Wed, 3 Apr 1996 07:56:27 -0700 Reply-To: Radiocarbon Mailing List Sender: Radiocarbon Mailing List From: David Killick Subject: Re: REALLY basic references on C-14 dating? Comments: To: David Sewell In-Reply-To: In my opinion the best short introduction by far to C14 is Sheridan Bowman's "Radiocarbon Dating" (London:British Museum Publications, 1990). It is an authoritative, clearly-written and well illustrated short booklet (about 70 pp) that retails for about ten dollars in the U.S. Any bookseller can get it on special order and it is in most university libraries. Dave Killick Department of Anthropology University of Arizona On Tue, 2 Apr 1996, David Sewell wrote: > Here's one of the occupational hazards of having a WWW site with > your name as an e-mail contact: > > >Hi- > >I'm doing a short report in 9th grade for biology. I was wondering if you > >could send me an email by wed that tells me about carbon dating and it's > >reliability. If you can i would be eternally thankful. Thankyou. > > Actually, you'd be surprised how many similar requests we get from > college and post-college-age folk... But what I'm wondering is, > apart from the standard encyclopedia articles, does anyone know of > a good basic introduction to scientific dating that someone at > the early high school level could handle? (People with some > technical background I usually point to Taylor's "Radiocarbon > Dating", but that's probably too advanced here.) > > David Sewell > -- > RADIOCARBON: An International Journal of Cosmogenic Isotope Research > Department of Geosciences, University of Arizona > 4717 E. Ft. Lowell Rd., Tucson, Arizona 85712 USA > Telephone: 1-520-881-0857 Fax: 1-520-881-0554 > General e-mail address: c14@packrat.aml.arizona.edu > WWW server: http://packrat.aml.arizona.edu/ > ========================================================================= Date: Mon, 15 Apr 1996 13:19:04 -0400 Reply-To: Radiocarbon Mailing List Sender: Radiocarbon Mailing List From: Chris Beekman Subject: decadal vs. bidecadal problem I am an archaeologist working in western and northern Mexico, and I am trying to draw together the scattered references to radiocarbon dates across the region and provide calibrations for them as part of a larger chronology project. I plan on using the CALIB 3.0 program for this work, and I wondered whether the radiocarbon community had any suggestions as to whether it was more appropriate to use the decadal or bidecadal dataset in that program. All of the conventional ages that I have gathered are less than 3500 radiocarbon years old - should I take advantage of this and use the decadal set? The authors suggest not, as the curve is less smooth and precise. I'm curious as to what the decadal set is usually used for if that is the case. Any comments/suggestions are appreciated. Chris Beekman Vanderbilt University CBEEKMAN@AOL.COM ========================================================================= Date: Tue, 16 Apr 1996 16:37:00 +1200 Reply-To: Radiocarbon Mailing List Sender: Radiocarbon Mailing List From: Tom Higham Subject: Re: decadal vs. bidecadal problem Chris Beekman wrote: > I am an archaeologist working in western and northern Mexico, and I am >trying to draw together the scattered references to radiocarbon dates across >the region and provide calibrations for them as part of a larger chronology >project. I plan on using the CALIB 3.0 program for this work, and I wondered >whether the radiocarbon community had any suggestions as to whether it was >more appropriate to use the decadal or bidecadal dataset in that program. All >of the conventional ages that I have gathered are less than 3500 radiocarbon >years old - should I take advantage of this and use the decadal set? The >authors suggest not, as the curve is less smooth and precise. I'm curious as >to what the decadal set is usually used for if that is the case. > Any comments/suggestions are appreciated. My view is that the selection of the calibration curve should mirror the characteristics of the sample in terms of the extent to which it dates the archaeological event in question, for example, the degree of inbuilt or presample age it embraces. If, for instance, I had a date from a piece of timber, whose species was unknown but had upwards of 30 tree rings visible, it would not seem appropriate to calibrate it using a high precision _decadal_ curve since the characteristics of the sample are not compatible with the precision of the calibrated decadal sample. If on the other hand I had a date of a sample of identified, short lived charcoal and twigs, it would be appropriate to use the high precision decadal curve because of the similarity in precision. In essence, then, the selection of the calibration curve should relate to the sample type, and the extent to which it accurately dates the archaeological event in question. Just my 0.05c worth. ------------------------------------------------------------------------- Dr Thomas Higham, * Email: Thigham@waikato.ac.nz Radiocarbon Dating Laboratory, * Phone: +(64) 07 838 4278 University of Waikato, * Fax: +(64) 7 838 4192 Hamilton, * WWW: Radiocarbon WEB-info: NEW ZEALAND. * http://www2/waikato.ac.nz/c14/webinfo/index.html ------------------------------------------------------------------------- ========================================================================= Date: Tue, 16 Apr 1996 16:41:55 +1200 Reply-To: Radiocarbon Mailing List Sender: Radiocarbon Mailing List From: Tom Higham Subject: Sample type question Does anyone on the list have any references to, or experience of, radiocarbon dating of tubers from archaeological sites. I'm particularly interested in Polynesian tubers such as taro, yam and kumara (sweet potato), but any info on other examples would be useful as well. Thanks in advance, ------------------------------------------------------------------------- Dr Thomas Higham, * Email: Thigham@waikato.ac.nz Radiocarbon Dating Laboratory, * Phone: +(64) 07 838 4278 University of Waikato, * Fax: +(64) 7 838 4192 Hamilton, * WWW: Radiocarbon WEB-info: NEW ZEALAND. * http://www2/waikato.ac.nz/c14/webinfo/index.html ------------------------------------------------------------------------- ========================================================================= Date: Tue, 16 Apr 1996 16:31:25 GMT Reply-To: Radiocarbon Mailing List Sender: Radiocarbon Mailing List From: "Joseph F Whelan, Geologist, Denver, CO" Subject: "dead" calcite for AMS blanks Hello I am currently attempting to date small amounts of calcite by AMS and have some concern about the overall blank of the sample handling/extraction/measurement process, which becomes more of a problem as sample size decreases. Even though we are going to extremes to ensure that I do not contaminate the samples during handling and sampling and I have confidence in the laboratories performing the extraction and measurement of the 14C, it seems prudent to have some estimation of the total blank, just as a means of distinguishing real "live" samples from the background. My search is therefore to find some 14C characterized calcite that is known to be "dead", preferably some bulk material that I can subject to the entire procedure, from handling/ sampling to measurement. Can someone help. Thanks -- Joe Whelan "Whatever we do to the web, we do to ourselves" - Chief Seattle Joseph F. Whelan - jfwhelan@usgs.gov Yucca Mountain Project Branch - U.S. Geological Survey (Mail Stop 963, PO Box 25046, Denver Federal Center Denver, Colorado, 80225 USA ========================================================================= Date: Tue, 16 Apr 1996 10:35:18 -0700 Reply-To: Radiocarbon Mailing List Sender: Radiocarbon Mailing List From: Timothy Jull Subject: Re: "dead" calcite for AMS blanks Comments: To: "Joseph F Whelan, Geologist, Denver, CO" In-Reply-To: <199604161631.QAA01276@ympbnwis1.cr.usgs.gov> We use Iceland spar calcite which you can get in reasonable clear crystals as a really "dead" blank. You should still remove a significant amount of the calcite surface with an acid wash. Tim Jull -------------------------------------------------------------- A. J. Timothy Jull tel. (520) 621-6816 NSF Arizona AMS Facility, fax. (520) 621-9619 Physics Building, University of Arizona, Tucson, AZ 85721 University of Arizona AMS Lab Web-Page: http://www.physics.arizona.edu/ams/www1.html ========================================================================= Date: Wed, 17 Apr 1996 00:32:12 +0000 Reply-To: Radiocarbon Mailing List Sender: Radiocarbon Mailing List From: "Jose M. Bello Dieguez" Organization: ArqueoGalicia Subject: C14 dates for a passage-grave of the NW Spain At http://www.geocities.com/RainForest/1185/dombate.htm there is an article about the megalithic monument of Dombate (La Corunha, Galicia, NW Spain) wit several C14 dates for diferent moments of the life of the monument. Friendly Jose M. Bello jmbello@ctv.es ========================================================================= Date: Wed, 17 Apr 1996 11:45:36 -0700 Reply-To: Radiocarbon Mailing List Sender: Radiocarbon Mailing List From: Dick Meehan Subject: Re: C14 dates for a passage-grave of the NW Spain In-Reply-To: <31743C0C.3B35@ctv.es> Re: jmbello post These dates are interesting because they correspond quite closely to dates of construction of monuments at Stonehenge, Newgrange, and Brittany. Does anyone know of any recent summary of all of the dating material from these various sites? I seem to recall that we were taught that the simple folk of northern europe learned monument building from the Egyptians, but perhaps it was the other way around! In any event it certainly appears that there was a great flurry of organized contemporaneous building activity. Thanks for an interesting post and www page! Dick Meehan meehan@blume.stanford.edu ========================================================================= Date: Wed, 17 Apr 1996 14:57:53 -0400 Reply-To: Radiocarbon Mailing List Sender: Radiocarbon Mailing List From: Chris Beekman Subject: fractionation When did radiocarbon laboratories begin to systematically apply corrections for fractionation when reporting age determinations? I am dealing with a number of radiocarbon dates from the 1960s through the 1990s, but none of them report fractionation corrections until the 1990s. As many of the samples were from maize, I'm thinking that this should be calculated, even if only as an estimate based on the type of material. Chris Beekman CBEEKMAN@AOL.COM ========================================================================= Date: Wed, 17 Apr 1996 14:25:26 -0700 Reply-To: Radiocarbon Mailing List Sender: Radiocarbon Mailing List From: Timothy Jull Subject: Re: fractionation In-Reply-To: <960417145752_193030392@emout14.mail.aol.com> Radiocarbon laboratories have done this at least from the early '60s. A casual perusal of the 1962 Radiocarbon volume shows most date lists used 13C corrections. Tim Jull On Wed, 17 Apr 1996, Chris Beekman wrote: > When did radiocarbon laboratories begin to systematically apply corrections > for fractionation when reporting age determinations? I am dealing with a > number of radiocarbon dates from the 1960s through the 1990s, but none of > them report fractionation corrections until the 1990s. As many of the samples > were from maize, I'm thinking that this should be calculated, even if only as > an estimate based on the type of material. > > Chris Beekman > CBEEKMAN@AOL.COM > -------------------------------------------------------------- A. J. Timothy Jull tel. (520) 621-6816 NSF Arizona AMS Facility, fax. (520) 621-9619 Physics Building, University of Arizona, Tucson, AZ 85721 University of Arizona AMS Lab Web-Page: http://www.physics.arizona.edu/ams/www1.html ========================================================================= Date: Wed, 17 Apr 1996 16:12:21 -1000 Reply-To: Radiocarbon Mailing List Sender: Radiocarbon Mailing List From: Tom Dye Subject: Re: fractionation In-Reply-To: <960417145752_193030392@emout14.mail.aol.com> Chris, In my experience tracking down this type of information for more than 1,000 age determinations in Hawaii, the only way to be sure is to query the laboratory for each determination. For many years some labs left the fractionation corrections an additional charge option, so you're likely to find that some determinations were corrected and that others from the same lab were not. BTW, it took me a couple of years to contact all of the submitters, so that I could get the permissions required by the dating laboratories before they would release data to me. An understandable precaution on the part of the labs, but a difficult task in the best of circumstances. Good luck! Tom On Wed, 17 Apr 1996, Chris Beekman wrote: > When did radiocarbon laboratories begin to systematically apply corrections > for fractionation when reporting age determinations? I am dealing with a > number of radiocarbon dates from the 1960s through the 1990s, but none of > them report fractionation corrections until the 1990s. As many of the samples > were from maize, I'm thinking that this should be calculated, even if only as > an estimate based on the type of material. > > Chris Beekman > CBEEKMAN@AOL.COM > ========================================================================= Date: Wed, 17 Apr 1996 22:31:09 -0500 Reply-To: Radiocarbon Mailing List Sender: Radiocarbon Mailing List From: "Melissa C. Winans" Subject: Re: fractionation Chris -- You're right - it should be taken into account. The Radiocarbon Lab here at the University of Texas started to do routine d13C corrections some time in the late 1960's. If any of your dates have a Tx- prefix send me the numbers and I will check our records. One good source for an estimated value (if someone knows of an updated source, please feel free to correct me) is Fig. 1 in: Stuiver, Minze, and Henry A. Polach, 1977. Reporting of 14C data. Radiocarbon, 19(3):355-363. This chart lists maize as: Minimum ca. -7, maximum ca. -13, mean ca. -10 per mil. >When did radiocarbon laboratories begin to systematically apply corrections >for fractionation when reporting age determinations? I am dealing with a >number of radiocarbon dates from the 1960s through the 1990s, but none of >them report fractionation corrections until the 1990s. As many of the samples >were from maize, I'm thinking that this should be calculated, even if only as >an estimate based on the type of material. **************************************************************** Melissa C. Winans, Collection Manager (mcwinans@mail.utexas.edu) Vertebrate Paleontology Laboratory Phone: 512-471-6087 J.J. Pickle Research Campus Fax: 512-471-5973 University of Texas, Austin, TX 78712 ========================================================================= Date: Fri, 19 Apr 1996 16:05:38 GMT Reply-To: Radiocarbon Mailing List Sender: Radiocarbon Mailing List From: "A.Bayliss" Subject: Re: C14 dates for a passage-grave of the NW Spain re Stonehenge see http://www.eng-h.gov.uk/stoneh Alex Bayliss English Heritage ========================================================================= Date: Fri, 19 Apr 1996 18:48:23 +0000 Reply-To: Radiocarbon Mailing List Sender: Radiocarbon Mailing List From: "Jose M. Bello Dieguez" Organization: ArqueoGalicia Subject: Re: C14 dates for a passage-grave of the NW Spain A.Bayliss wrote: > > re Stonehenge > > see http://www.eng-h.gov.uk/stoneh I know that page, and it's wonderfull. But I hadn't be able to get an answer yesterday... :-?¿ Friendly, Jose M. Bello jmbello@ctv.es Museo Arqueologico de La Corunha ========================================================================= Date: Fri, 19 Apr 1996 19:18:16 +0000 Reply-To: Radiocarbon Mailing List Sender: Radiocarbon Mailing List From: "Jose M. Bello Dieguez" Organization: ArqueoGalicia Subject: Re: C14 dates for a passage-grave of the NW Spain Dick Meehan wrote: > These dates are interesting because they correspond quite closely to > dates of construction of monuments at Stonehenge, Newgrange, and > Brittany. Does anyone know of any recent summary of all of the dating > material from these various sites? I don't know any recent summary. But you can find C14 dates from Newgrange: http://www1.tip.nl/users/t755096/eng/knowth.htm (taken from George Eogan) Knowth: http://www1.tip.nl/users/t755096/eng/newgrang.htm (taken from M.J. O'Kelly) > > I seem to recall that we were taught that the simple folk of northern > europe learned monument building from the Egyptians, but perhaps it was > the other way around! In any event it certainly appears that there was a > great flurry of organized contemporaneous building activity. I think it's so from the 70's (at less...) > > Thanks for an interesting post and www page! Thanks. I'm translating it into English. When it's ready, I shall tell you. Friendly, Jose M. Bello jmbello@ctv.es ========================================================================= Date: Sat, 20 Apr 1996 11:41:50 +0100 Reply-To: vrs1@cam.ac.uk Sender: Radiocarbon Mailing List From: "Dr V.R. Switsur" Subject: Re: fractionation In-Reply-To: <960417145752_193030392@emout14.mail.aol.com> On Wed, 17 Apr 1996, Chris Beekman wrote: > When did radiocarbon laboratories begin to systematically apply corrections > for fractionation when reporting age determinations? I am dealing with a > number of radiocarbon dates from the 1960s through the 1990s, but none of > them report fractionation corrections until the 1990s. As many of the samples > were from maize, I'm thinking that this should be calculated, even if only as > an estimate based on the type of material. > > Chris Beekman > CBEEKMAN@AOL.COM > Dear Chris, In the early days around 1960 not many radiocarbon laboratories had their own mass spectrometer and if correction for fractionation was carried out the sample had to be sent away. In Cambridge we set up a mass spectrometer for this work and were applying corrections regualarly to all samples since 1964. I believe that all C-14 laboratories now apply the correction, but in case of doubt for any given sample you should contact the lab to find out. Roy Switsur, Godwin Institute, Cambridge. U K