Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Carbon Dating

  1. Aug 30, 2004 #1
    I am reading an old book about Carbon Dating and it is really boring, I dstill havenot found out there is anything interesting for me to keep going with time continuum, continuum continuum, again and again...So would you please introduce me some (old or new) interesting books on the topic for me to get going ? I am a newie in Earth Science, please help me....

    Thanks a lot
     
  2. jcsd
  3. Aug 31, 2004 #2
    Well, You don't reveal what is boring and what is exiting about carbon dating. The evolution and increasing perfection of modern carbon dating may be called sensational, if you are sensitive to it (using mass spectrometry, including d13C in the equation, calibration to dendrochronology and lacustrine varve counting for instance). Also, there are several spectacular dating results. So, what is exciting and what's not?
     
  4. Sep 1, 2004 #3
    Thanks Andre, how can You know I am reading it for evolution study ?(Study here means A Student Studies not A Researcher Studies...). You gave me so many terms, difficult, I don't even understand them all...
    I felt bored with the book I am reading, but since there are not many books on the topic in my library, I asked if people could give me some interesting book titles for me to search again... Can Andre help me ?
    Again Thanks Andre a lot..
     
  5. Sep 1, 2004 #4
    Well, why not try this link for a start. When you're finished with all the sub-links, you're an expert in the field.

    Anyway, for the interested bystanders, a short abstract about modern carbon dating, and those hanky panky words.

    this would pretty much explains the basics.

    Carbon dating was developed in the 1950. Ik works simply with measuring heavy radioactive 14C atoms (normal –light- carbon is 12C). These isotopes come into being in the air due to a radiogenic reaction of nitrogen with cosmic radioactivity. It decays again with a half time of some 5700 years Consequently live tissue is supposed to have the same heavy 14C – 12C carbon ratio as the air, while dead tissue starts to loose the 14C, and the 14C – 12C ratio decreases. This can be used measuring it’s age.

    In the early days, it was as simple as that. Just have a radioactivity geiger counter, count the ticks, assume that it is decaying 14C that you count. Do the math and there you are, the age of the thing. Well, in fact, the calculation brought anything but the correct age because of numerous complications, that have been neglected or could not be accounted for. The large errors were mostly attributed to sample contamination but this is something that really doesn’t happen that often.

    So what are the real problems exactly?
    - Other radioactive noise
    - Variation of the concentration of carbon dioxide in the air, depending on the activity of sources and sinks
    - The ratio of carbon isotopes changes in live tissue. Normally there are less heavy 14C atoms in tissues because the plants have a preference for light isotopes during photo synthetic processes.

    - Variation of radiogenic production of heavy 14C. The more cosmic activity, the more 14C
    - The temperature dependency of these fractionation processes also change those ratios of heavy atoms in the processes of building that particular tissue.
    These problems have been addressed in the recent past resulting in more or less adequate solutions.

    So what was done?

    radioactive noise: counting 14C nowadays is done with a mass spectrometer, not with radioactivity anymore, just like all the other isotope counting procedures, a tremendous improvement. (there is also a intermediate method called Liquid Scintillation Counting (LSC) but that has virtually been outdated already.

    Now the actual ratio of heavy carbon (14C,) intermediate and stable carbon (13C) and light carbon (12C). Since 13C is also reacting differently to all those fractination processes but only half as explicit as 14C, we can calculate the original 14C content after all those processes.

    Variation of carbon dioxide and all the processes that change the 14C concentration in the air are now adjusted by a calibration table that has been build by comparing carbon age with annual layer counting, annual layers of tree rings (dendrochronology) ice cores layers and yearly lake sedimentation layers (lacustrine varves). Differences up to 2500 years are normal in the ice age period.

    The way the dating techniques are applied are reflected in the date details. Original geiger counting work is indicated with "carbon years" When the mass spectrometer is used and the 13C fractination technique is used, the age is expressed as for instance 1200 years "BP" (Before Present) And "present" being the year 1950. When also the calibration tables are used then the dating is expressed as 1200 Cal years BP. Curiously enough "cal years" is explained both as "calender years" and "calibrated years". Te correct answer is somewhere in the linx.

    Since carbon dating is a very important instrument for basic dating we have put a lot of effort in correcting for all the errors, we could think of. Finally, we have a system with a reasonable degree of accuracy and trustworthiness.
     
    Last edited: Sep 1, 2004
  6. Sep 3, 2004 #5
    Now i think I should read abstracts rather than boring books in my school's library. Abstracts like this sound better...-sal--

    Thanks Andre so much,
     
  7. Sep 3, 2004 #6

    Phobos

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Andre wasn't talking about biological evolution, but that's ok.

    Note that carbon dating is not too useful for studying biological evolution. Due to the short half-life, carbon dating is only accurate for organic things a few 10s of thousands of years old. Biological evolution typically occurs (on a more dramatic level anyway) over a longer timeframe than that.

    Carbon dating is a great archaeological tool though.
     
  8. Sep 4, 2004 #7
    Right Half time of 14C is some 5700 years. The maximum useable limit is about 48,000 thousand years. Fortunately there are some more usefull dating tools for the shorter term say one to a few million years, like thermo/opto luminiscence or some of these.
     
  9. Sep 5, 2004 #8
    Andre, What would you say the accuracy is in carbon dating now, from say when the technique was used 30 years ago?

    The shroud of Turin, which was tested first in 1970-s, indicted a age from carbon dating of between 1200 AD and 1500 AD. I do not have the info on what was actually carbon dated the cloth, blood, or other things found in the cloth. I would presume the fibers in the cloth were tested among other objects, within it. How can you determine with great accuracy how many carbon atoms a fiber has? A fiber does not have a fixed diameter to work with. The fibers were of different type and size, so carbon percentage would be different, within the same volume. A red blood cell would or pollen would have similar volumes. Is it just a very good measurement of a guess?

    For your information in case you might not know, pollen from plants that are now extinct and abound in and around the area of Palestine 2,000 years ago, were found in the shroud. There was also 12 other types of pollen found, that coincide with written information that we have, on where the shroud moved around during the centuries.

    Also there was only a certain fiber in the shroud which abosorbed a unknown radiation which left the 3D image, the others were not affected. Would radiations from any source also affect the cabon being dated?

    This seems a simple process you only need know the half life of carbon 14 and the amount of carbon 14 atoms in the object.
    How do you know how many carbon atoms a snowflake, cornflake or cupcake has? Do you compact them under a certain pressure and then measure? Where is the extra accuracy in the machinery or the knowing of how many atoms there is in something? This seems to be a difficult task in accuracy, maybe if you might know, how do you technically go about measureing the carbon content in a object?
     
  10. Sep 7, 2004 #9
    Not really. It is about ratios of isotopes. The ratio between the abnormal isotopes and the most common isotope. For instance the standard (PDB) ratio for 13C/12C is 0.011237 or 11.237 mil (PDB = Pee Dee Belemnite, just happens to be the standard like a meter). A abbaration to standards are indicated with a "d" in front of the abnormal isotope, so "d13C". We also see very commonly d18O SMOW, d2H (dD) SMOW, etc. SMOW stands for Standard Mean Ocean Water.

    Some indications of d13C and carbon datings: here. Don't underestimate the accuracy of the mass spectrometer. It registers basically each atom and after the different processes a "BP" date will normally have a 2-rho certainty range of about 2-5%. The problems come however when converting to "Cal BP". Of course there is a repeatedly cross-checked and very accurate converting table but at moments when the atmosphere gets an spike injection of carbon dioxide of different sources with different isotope "signatures" even tables don't help very much. The current injection of fossil fuels is free of 14C and hence the d14C is also dropping independant of the time. This means that objects of an ancienity between now and 1700 AD have about the same "BP" dating. Other of those "Platforms" have been identified around 9000 "BP" is for instance about 9200-11,000 "Cal BP" years, 11,000 BP is something like 13,000 - 14,500 Cal years BP. Here are a few calibration tables.

    Back for the shroud of Turin
     
    Last edited: Sep 7, 2004
  11. Sep 7, 2004 #10
    There is a whole lot to do about the The shroud of Turin. The calibrated dating range AD 1260 - 1390 of that specific sample seems to be a bit too narrow nowadays. I would suggest adding another 100 years but not much more. But apparantly we're talking about a single carbon dating. With controversial results on objects of high interests it is no problem to take a few dozen samples for dating. After all, only a few fibers is enough as a sample.

    I can't get rid ofthe impression that objects like this are subject to considerable bias. Creationists will probably always reject carbon dating, no matter how much scientific proof is available for it's (limited) accuracy. I also have my doubts about the pollen story.

    We are talking alleged images of flowers and pollen. The main interest seems to be the Zygophyllum dumosum. However when I see common pollen research, the identification is mostly restricted to genus, not species, since the detectable differences are usually very small if any. There are several more species of bean capers. So I would normaly expect a DNA investigation to be required to determine the species. But the investigation was done in 1973, long before DNA techniques? Is there an accepted publication about it? I'm not saying that it's all wrong but the methodology is not clear and hence also the accuracy of identification of the species.
     
    Last edited: Sep 7, 2004
  12. Sep 8, 2004 #11
    This link on mass spectrometer has got me quite excited. This type of accuracy is just what is needed to determine the dating of Tartessos tombs in Almuñecar, that we have found containing bronze knife blades, ceramics, jewelry and bone material. If we find what we are looking for, Almuñecar predates Cadiz.

    Well the reason for doing the carbon dating was in affect to determine if the shroud of Turin was that which wrapped Jesus Christ after his death. It has been said there was 26 irregularities when the first carbon testing was done in 1978. The carbon dating of the shoud was 1260 to 1390 to be exact. In my personal forensic investigation of this, there is a lot of other evidence to give a credulous or not validity to the first carbon datings.

    Lets look at some facts as they have been told. The shoud of Turin was first carbon dated at AD 1260 - 1390. There is written archives stating that the shoud after 5 centuries was found inside a sealed cave in Edessa in AD 525.
    It stayed in Edessa until AD 944 when it then is found in Constantanople. The 4th Crusade on the 10th of Abril 1204 then takes possesion. In 1291 it is found to move from Arra Chipre Besagon to Israel where the templarios have it in the old remains of Solomons Temple. In 1307 then reappears in Paris. In 1314 in possesion of the Order of templarios. In 1349 Pope Clemente V makes mention of it. In 1415 Margarita puts it on exposition for the public. In 1453 there is a public contract to turn it over to the King of Italy. In 1502 it is in Chambury France. In 1532 it is almost destroyed by fire and silver drops damage the cloth and is repaired by nuns. In 1578 during the epidemic it is finally taken to Turin where it lies till today. All these things are know facts, part of written history so far.

    01-The first pictures taken in 1898 to discover the shroud is a negative.
    02- No paints, pigments or dyes.
    03- The shoud contains cotton fibers. No cotton cloth was produced in the middle ages until AD 1500.
    04- 200 different types of fibers are contained in the shroud only a few produce the negative found on the cloth.
    05- The images left on the shoud are 3D that Jackson and Jumper found, through computer imaging.
    06- Max Frei finds pollen from the area around Palestine in the shroud.
    07- DNA testing of the blood shows type AB typical of Hebrew origen.
    08- Details of the wounds found in the shroud coincide with some 200 marks on the shround that are not smeared but perfectly contoured.
    09- The lanze wound, crown of thorns, the broken nose and pumulo of the cheek wound, the nonexistence of the thumbs, appearing on the shround do to the hyper extension of the nerve from the nailing in the wrist not the palm of the hand, so the thumb is pulled inward to the center of the hand.
    10- The Roman bronze coin that appears in the shoud where the eyes were. The letters read UCAI, it is a bronze Roman Lepton 29-32, Pontio y reign of Julius Caesar. Was custom to put the coins on the eyes of the burried dead.
    11- There is no putrification in the shroud, whatsoever. The imprint is instantanious ageing process by some type of radiation.
    12- The deltoids did not touch the shroud and the marks appear to be made by the body suspended in the air. Certain parts of the body that touched the cloth with more pressure had more luminosity than those that did not.

    http://www.jesusisreal.org/shroudofturin/
    http://www.shroud.com/guscin.htm

    Could anyone be so clever to produce, such a artifact, in the middle ages? Maybe this mass spectrometer and DNA testing could finally lay and end to this enigma. I have seen no official journals on this type of testing yet, let me know if you find some. The STURP Papers.
    http://www.shroud.com/78papers.htm

    There are thousands on thousands of pieces of funerary linen going back to millennia before Christ, and another huge number of linens of Coptic Christian burials. On none of these is there any image of any kind. A few have blood and stains on them, but no image.
    http://ctct.essortment.com/shroudturinhol_rdbs.htm
     
    Last edited: Sep 8, 2004
  13. Sep 9, 2004 #12
    There have been other conclusions:

    Metal and jewelry are hard to date. Ceramics can be date by thermo-luminicense but it destroys the sample. Bone material can be dated very well, using thse modern carbon dating techniques. You need an address for that?
     
  14. Sep 9, 2004 #13
    Yes the debate goes on. Let us assume the tests are correct as the link shows and the shroud was painted. Painted over what were the carecteristic marks on the shroud. Did a artist with a mind as great as Da Vinci paint a 3D image in a negative, knowing in the future that photography would some day be used to see the real image? How do you paint in 3D, a negative image? Then what was the object, battles were fought over, since Edessa in AD 525?

    Quess what, if the link you gave is accurate, they tested the wrong area. The area of the shroud to be tested is an area not mended from the fire and that has no marks at all, it is possible that the marks were painted over intentianally, or not even knowing what they were painting over, no one new of a negative in the middle ages, photography was invented centuries later. The logical thing to do would be to test the shrould with this mass spectrometer and do a complete survey, not just the marked areas.

    We have found much Phoenician and Roman jewlery ceramics along with coins so it is not to hard to date the tombs but Tartessos artifacts is another story. We have found slabs of metal and stone with there Alphabet and iron objects badly oxigenated, this being the bronze age we are talking about. It would be quite a accomplishment to determine from bone sample dates +or- 50yr, artifacts found with them, that Tartessos used and engraved in iron before before the bronze age.

    Yes, where is the lab that does the testing with this mass spectrometer in Europe? From the links you showed the results are quite exciting.
     
  15. Sep 9, 2004 #14
    Well I don't want to disturb any ideas about the shroud and it's origine but what would happen if you tried this test. Take a guy with a beard and paint all of his body with grease. next, wrap him in a white sheet. Be sure to rub the grease in the sheet a bit and unwrap him again. Then compare the inprint of the grease in the sheet with the inprint of the shroud of Turin. It may be a desillusion.

    here are the active AMS carbon dating laboratories. I don't want to influence your choice but it should be known that Hans van der Plicht of the University of Groningen (the Netherlands) is one of the pioneers of the modern calibration techniques. He also performed a some biblical important carbon datings.

    Expect rates of about perhaps 250 euro per sample datings. Perhaps have an university to support you.
     
    Last edited: Sep 9, 2004
  16. Sep 9, 2004 #15
    :smile:

    Thanks for the info.
     
  17. Sep 9, 2004 #16
    You guys give all the websites promoting C14 Dating, now feel free to post some that are against it. You cant show only 1 side of the story. I dont know much about it but I heard it is subject to large fluctations in the readings and they take the average ones? Also heard something about the amount of C14 we put into our atmosphere affecting the readings?
     
  18. Sep 10, 2004 #17
    musky ox.

    You are right about the problems with C14 dating but this thread was attempting to explain how those problems were identified and dealt with. For instance:

    But I said:

    Perhaps try some links too.
     
  19. Sep 10, 2004 #18
    Its not a matter of being for carbon dating or not. Its a usefull tool for dating archaeological material. The problem is, the shroud of Turin, is controversial subject matter, with a lot of bias and self interest. Look at my link below, there was blood on the shroud.
    http://www.shroud.com/78papers.htm

    On this link they claim, there is no blood in any image area.
    http://www.mcri.org/Shroud.html

    So who do you believe.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Carbon Dating
  1. Dating methods (Replies: 10)

Loading...