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Thread: Carbon Dating

  1. #1 Carbon Dating 
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    Is this the only method used in fossil dating?


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    No.

    http://en.wikipedia.org/wiki/Geochronology


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    Thanks. I understand the dating techniques now (at least the basics) but how accurate are they? How do we know that decay of isotopes isn't accelerated in some instances, making something appear to be older than it actually is?
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    Quote Originally Posted by gottspieler
    Thanks. I understand the dating techniques now (at least the basics) but how accurate are they? How do we know that decay of isotopes isn't accelerated in some instances, making something appear to be older than it actually is?
    If I'm not mistaken, some elements have been shown to have changing decay rates through time. That said, there is no evidence of that happening in those elements relevant to radiometric dating. It's one of the assumptions made by scientists who do this kind of work.

    A lot in geology operates on the uniformitarian idea that the present is the key to the past. It may not be true in the absolute sense, but just by thinking about it for awhile, you can see that it's the most reasoned approach.
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    Also, it's important to realize that scientists are CAREFUL about what dating methods are used. You can't use carbon dating from a volcano site, for example, due to how it fucks with C14. There are a variety of different methods used to date things like rocks and volcanic ash, for example, so it's really no concern as long as you use the right tool for the job. Sadly, many creationists often use the WRONG tool for the job to prove their point(s). Avoid this at all costs.
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  7. #6 There are many ways to date things 
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    Dating happens in lots of ways. There are layers on lake bottoms. When lakes freeze over in winter even the fine materials settle out as wave action to churn the water ends. There are tree rings. Quartz grains in the dark can trap electrons that can be released to see how long the grain was in the dark. Radioactivity is a nuclear process that is unaffected by heat and chemical processes. Corals can add layers over the years. Layers can be seen in ice and rocks. There is a range of dating methods that can be relative and others absolute.
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    http://toarchive.org/faqs/dating.html

    There's a whole list of pages related to the age of the earth on TalkOrigins as well, if you're interested in more beyond what's discussed in the page above.
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  9. #8  
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    I avoid dating fossils because they are a bit stiff for my taste on the dance floor.
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    you obviously never have tried carbon dating :wink:
    "Reality is that which, when you stop believing in it, doesn't go away." (Philip K. Dick)
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  11. #10  
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    On the other hand, fossils never say no.
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    not according to Duane Gish
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  13. #12 Re: Carbon Dating 
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    Quote Originally Posted by gottspieler
    Is this the only method used in fossil dating?
    You can only use C14 on substances which contain carbon, and it'll only be accurate up to about 60,000 years. It's also no good for new stuff, it'll give inaccurate readings for anything that's died recently. Bit like trying to measure the diameter of sand grains with a meter stick. C14 works best within a specific age range. But that overlaps with loads of other dating techniques including other radiometric decay techniques.

    As for the rate of decay changing over time, it can happen but only in very specific circumstances that are typically quite easy to spot evidence of.
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    Anyhoo, God could have easily planted radioactive substance in fossils similar to that he put them all in the proper place as well. In order to mislead people easily tempted by Satan, such as scientists.

    So no matter what evidence you bring forward, it is all in vane. I wouldn't bother personally.
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    Anyone know how they date fossil footprints?

    I've been trying to find a source that explains the method, without success.
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    Quote Originally Posted by samcdkey
    Anyone know how they date fossil footprints?

    I've been trying to find a source that explains the method, without success.
    Well, I would guess that you simply date the rock.

    Just in case you were wondering about those dinosaur and human footprints that were found together in the riverbed; they were exposed as fake. If you weren't wondering, nevermind...
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  17. #16  
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    Quote Originally Posted by samcdkey
    Anyone know how they date fossil footprints?
    Yes, see the following quote:

    Quote Originally Posted by samcdkey
    I've been trying to find a source that explains the method, without success.
    What's the method then?
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  18. #17  
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    Oh come on spurious, not even I am that mean.
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  19. #18 A slight correction on the fake dinosaur and human footprint 
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    The dinosaur prints were real. The human prints were modified dinosaur marks. Seems that 5 perfect toes were added to a rough mark in the rock.
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    Quote Originally Posted by spuriousmonkey
    Quote Originally Posted by samcdkey
    Anyone know how they date fossil footprints?
    Yes, see the following quote:

    Quote Originally Posted by samcdkey
    I've been trying to find a source that explains the method, without success.
    What's the method then?
    Let me ratify that. I am trying to find a source that explains ANY method.
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    It'll depend on the stratum the footprints are in.

    If the stratum is dated elsewhere by a fossil of a living organism, then that date can be relatively applied to the foot prints. You can even bracket the footprints with dates in this manner from neighboring strata.

    If, however, the stratum that the prints are in is from deposition caused by volcanic eruption or flow, then you can date the eruption using a few methods such as paleomagnatism, uranium/lead (U/Pb)dating, and thermoluminescence dating. The latter was probably used in dating the Laetoli prints in northern Tanzania, though I'm sure there have been multiple dating techniques employed.
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  22. #21  
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    Quote Originally Posted by samcdkey
    Quote Originally Posted by spuriousmonkey
    Quote Originally Posted by samcdkey
    Anyone know how they date fossil footprints?
    Yes, see the following quote:

    Quote Originally Posted by samcdkey
    I've been trying to find a source that explains the method, without success.
    What's the method then?
    Let me ratify that. I am trying to find a source that explains ANY method.
    Sam, as Kalster already mentioned, they use isotope dating methods on samples of the surrounding rock. The Laetoli beds in particular were made of volcanic ash, so they can be dated with potassium-argon isotopes. There is no particular method beyond that.

    Edit - and as Skinwalker explained. Too slow on the draw!
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    Oh, yeah... don't forget potassium-argon and argon-argon dating! Paralith reminded me of this ... there are others as well.

    I think I read an online article somewhere about the recent "oldest human footprints" in Egypt where they (whoever "they" are) are using "carbon dating techniques" to analyze plant and/or animal remains in the strata surrounding the footprints, but this didn't make a lot of sense to me. I suspect a journalist misheard or mis-typed something.

    Carbon dating techniques are really only useful at a maximum of 50,000 years with an ever widening margin for error and even then only with augmentation of scanning electron microscopy.
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    Quote Originally Posted by SkinWalker
    It'll depend on the stratum the footprints are in.

    If the stratum is dated elsewhere by a fossil of a living organism, then that date can be relatively applied to the foot prints. You can even bracket the footprints with dates in this manner from neighboring strata.

    If, however, the stratum that the prints are in is from deposition caused by volcanic eruption or flow, then you can date the eruption using a few methods such as paleomagnatism, uranium/lead (U/Pb)dating, and thermoluminescence dating. The latter was probably used in dating the Laetoli prints in northern Tanzania, though I'm sure there have been multiple dating techniques employed.
    No clue about any of those. Suggest an article?
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  25. #24  
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    http://www.sciencemag.org/cgi/conten.../323/5918/1197

    the footprints occur within a 9-m-thick sequence of fine-grained, normally graded, silt and sand units deposited as overbank flood deposits with evidence of paleosol development. Interbedded within this succession are three fluvially reworked volcanic ashes; the upper ash (Northern Ileret Tuff) forms a prominent landscape bench that correlates with other nearby sites where traces of hominin activity have been recovered (15) and is unconformably overlain by the Galana Boi Formation of Holocene age (12). The ash layers are correlated geochemically to dated tuffs within the Turkana Basin, thereby providing an age of 1.51 to 1.52 Ma for the upper tuff and 1.53 Ma for the lower tuff (Fig. 1) (14, 16).
    It seems that they just use standard reference method. No rocket science needed.
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  26. #25  
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    Quote Originally Posted by samcdkey
    Quote Originally Posted by SkinWalker
    It'll depend on the stratum the footprints are in.

    If the stratum is dated elsewhere by a fossil of a living organism, then that date can be relatively applied to the foot prints. You can even bracket the footprints with dates in this manner from neighboring strata.

    If, however, the stratum that the prints are in is from deposition caused by volcanic eruption or flow, then you can date the eruption using a few methods such as paleomagnatism, uranium/lead (U/Pb)dating, and thermoluminescence dating. The latter was probably used in dating the Laetoli prints in northern Tanzania, though I'm sure there have been multiple dating techniques employed.
    No clue about any of those. Suggest an article?
    Check the second post. there are others also.
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  27. #26  
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    From the supplemental method section:

    The geochemistry and age (40Ar/39Ar) of the tuffs of the Turkana Basin have been well document
    (S2,S3), providing a robust tephra chronology for the region. Bulk samples of volcanics were collected
    from all the tuffs present at FwJj14E and at GaJi10 and were sent to Professor Frank Brown at the
    University of Utah for analysis and comparison with the dated standards (Fig. S5). Each of the
    samples contains a range of volcanic shards consistent with them being fluvially re-worked tephra;
    although in cases they are geochemically distinct allowing them to be correlated with a known and
    dated ash. The trace element data obtained from each of the samples is presented in Table S1.
    • Samples JWKH-1. Upper tuff at FwJj14E and with a geochemistry that correlates with the
    Northern Ileret Tuff which is dated to between 1.51 and 1.52 Ma.
    • Samples JWKH-2. Taken from the middle tuff at FwJj14E. This tuff is most likely the Ileret
    Tuff dated to around 1.52 Ma. However, it contains a range of glass shards which can be
    correlated with a number of different potential tuffs, including: the Northern Ileret Tuff, a tuff
    referred to informally as the Southern Ileret Tuff, one similar to a secondary mode of the Okote
    Tuff which outcrops in Area 131, and the Black Pumice Tuff (c. 1.53 Ma).
    • Sample JWKH-4. Taken from the lower tuff at FwJj14 East. This is probably the Lower Ileret
    Tuff, but it also contains shards similar in composition to the Elomaling’a Tuff, the Orange Tuff,
    and two unknown tuffs. On the basis of the age of the Lower Ileret and Elomaling’a tuffs it is
    likely to have an age of approximately 1.53 Ma.
    • Sample JWKH-5. Taken from the tuff at GaJi10 stratigraphically overlying the footprint site
    reported by Behrensmeyer and Laporte (S1). The principal composition corresponds to the
    Akait Tuff (c. 1.435 Ma) and the Naiyena Epul Tuff (West of Lake Turkana) which lies below
    the Akait Tuff, although one shard closely resembles the Karari Grey Tuff dated to
    approximately 1.428 Ma. The most likely date for this tuff is therefore 1.43 ± 0.01 Ma.
    Although the samples clearly contain a range of volcanic material consistent with them being
    emplaced both by air fall and by fluvial re-working, they provide a robust geochronological framework
    for both the footprints at FwJj14E and GaJi10, with the former being approximately 1.5 Ma and the
    later slightly younger at 1.4 Ma.
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  28. #27  
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    This is geek speak

    What is "fluvially re-worked tephra"

    edit: wait, I shall read the article and then pose questions
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  29. #28  
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    It's just a detail. Details do not matter. Unless they are incorrect.
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  30. #29  
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    From Wiki. ppl here can judge the valiity of the article, as Wiki isn't always 100% correct:


    Tephra is air-fall material produced by a volcanic eruption regardless of composition or fragment size.[1] Tephra is typically rhyolitic in composition, as most explosive volcanoes are the product of the more viscous felsic or high silica magmas.

    Volcanologists also refer to airborne fragments as pyroclasts or sometimes just clasts. Once clasts have fallen to the ground they remain as tephra unless hot enough to fuse together into pyroclastic rock or tuff. The distribution of tephra following an eruption usually involves the largest boulders falling to the ground quickest and therefore closest to the vent, while smaller fragments travel further—ash can often travel for thousands of miles, even circumglobal, as it can stay in the stratosphere for several weeks. When large amounts of tephra accumulate in the atmosphere from massive volcanic eruptions (or from a multitude of smaller eruptions occurring simultaneously), they can reflect light and heat from the sun back through the atmosphere, in some cases causing the temperature to drop, resulting in a climate change: "volcanic winter". Tephra mixed in with precipitation can also be acidic and cause acid rain and snowfall.

    Tephra fragments are classified by size:

    Ash - particles less than 2 mm in diameter
    Lapilli or volcanic cinders - between 2 and 64 mm in diameter
    Volcanic bombs or volcanic blocks - greater than 64 mm in diameter
    The words "tephra" and "pyroclast" both derive from Greek. Tephra means "ash". Pyro means "fire" and klastos means "broken"; thus pyroclasts carry the connotation of "broken by fire".

    The use of tephra layers, which bear their own unique chemistry and character, as temporal marker horizons in archaeological and geological sites is known as tephrochronology.
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  31. #30  
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    I know that carbon dating is used by measuring the decay of radioisotope carbon 14 from once living organisms, based on the exponential decay of C-14 after death.

    I was puzzled how they applied such dating to footprints. My knowledge is very superficial in this field. :P
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    Quote Originally Posted by samcdkey
    I know that carbon dating is used by measuring the decay of radioisotope carbon 14 from once living organisms, based on the exponential decay of C-14 after death.

    I was puzzled how they applied such dating to footprints. My knowledge is very superficial in this field. :P
    If there is organic material embedded in the same sediment layer as the footprints they can be dated with carbon isotopes. Non-organic volcanic material in the same sediment layer contains other elements whose isotopes can be dated according to the same principles as carbon dating. The isotopes in volcanic material only start to decay once the lava etc they are from has cooled.
    Man can will nothing unless he has first understood that he must count on no one but himself; that he is alone, abandoned on earth in the midst of his infinite responsibilities, without help, with no other aim than the one he sets himself, with no other destiny than the one he forges for himself on this earth.
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    Quote Originally Posted by paralith
    The isotopes in volcanic material only start to decay once the lava etc they are from has cooled.
    Isotopes do not stop decaying when it is warm.
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  34. #33  
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    Quote Originally Posted by paralith

    If there is organic material embedded in the same sediment layer as the footprints they can be dated with carbon isotopes. Non-organic volcanic material in the same sediment layer contains other elements whose isotopes can be dated according to the same principles as carbon dating. The isotopes in volcanic material only start to decay once the lava etc they are from has cooled.
    Thanks.

    This may sound dumb, but how do they identify organic vs non-organic material in silt?
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  35. #34  
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    Quote Originally Posted by spuriousmonkey
    Quote Originally Posted by paralith
    The isotopes in volcanic material only start to decay once the lava etc they are from has cooled.
    Isotopes do not stop decaying when it is warm.
    * caught with foot in mouth * The point is you can date the sediment layer because the methods used are measuring a quantity which changes at a known rate after formation.

    More details on argon-argon dating

    Sam, I'd imagine it takes a seasoned paleontologist and/or geologist to tell the difference between the remains of a plant or animal and a rock formation.
    Man can will nothing unless he has first understood that he must count on no one but himself; that he is alone, abandoned on earth in the midst of his infinite responsibilities, without help, with no other aim than the one he sets himself, with no other destiny than the one he forges for himself on this earth.
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  36. #35  
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    Quote Originally Posted by samcdkey
    I know that carbon dating is used by measuring the decay of radioisotope carbon 14 from once living organisms, based on the exponential decay of C-14 after death.

    I was puzzled how they applied such dating to footprints. My knowledge is very superficial in this field. :P
    you don't - instead you date the layers where the footprints are made in either through direct radiometric dating (if the footprints are made in volcanic ash), interpolation of the sediment between 2 volcanic ash layers that can be dated, or through correlation with sediments of a known age if such volcanic layers are not available in the vicinity
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    Quote Originally Posted by samcdkey
    Quote Originally Posted by SkinWalker
    It'll depend on the stratum the footprints are in.

    If the stratum is dated elsewhere by a fossil of a living organism, then that date can be relatively applied to the foot prints. You can even bracket the footprints with dates in this manner from neighboring strata.

    If, however, the stratum that the prints are in is from deposition caused by volcanic eruption or flow, then you can date the eruption using a few methods such as paleomagnatism, uranium/lead (U/Pb)dating, and thermoluminescence dating. The latter was probably used in dating the Laetoli prints in northern Tanzania, though I'm sure there have been multiple dating techniques employed.
    No clue about any of those. Suggest an article?
    If you can get it (i.e. library, ILL, Amazon, etc.), you might check Principles of Archaeology.

    There's a chapter that includes the thermoluminescence dating on the Laetoli prints.

    Were you wanting an article specific to dating methods only, or did you want one or more exclusive to ancient foot prints?

    Edit - Here's a few articles:

    Eighmy, Jeffrey L., Randall S. Taylor, and Pamela Y. Klein (1993) Archaeomagnetic dating on the Great Plains. Plains Anthropologist 38(142):21-50.

    Eighmy, Jeffrey L. (1994) Archaeomagnetic dating at Pueblo Grande. Journal of Archaeological Science 21445-453.

    Jacobs, Z. and R.G. Roberts (2007) Advances in optically stimulated luminescence dating of individual grains of quartz from archeological deposits. Evolutionary Anthropology 16(6):210-223.

    Mercier, N., et al. (2007) Hayonim Cave: a TL-based chronology for this Levantine Mousterian sequence. Journal of Archaeological Science 34:1064-1077.

    Chronological Methods 9 - Potassium-Argon Dating
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    Quote Originally Posted by samcdkey
    This may sound dumb, but how do they identify organic vs non-organic material in silt?
    One way would be to pour silt into a barrel of water. The organic material will float to the top. Archaeologists use this method quite frequently (too, too frequently -ugh) to obtain organic material like seeds, nuts, charcoal, even small bits of bone, etc.

    Bodner, Connie C. and Ralph M. Rowlett (1980) Separation of bone, charcoal, and seeds by chemical flotation. American Antiquity 45(1):110-116.
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  39. #38  
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    Quote Originally Posted by SkinWalker
    If you can get it (i.e. library, ILL, Amazon, etc.), you might check Principles of Archaeology.

    There's a chapter that includes the thermoluminescence dating on the Laetoli prints.

    Were you wanting an article specific to dating methods only, or did you want one or more exclusive to ancient foot prints?

    Edit - Here's a few articles:

    Eighmy, Jeffrey L., Randall S. Taylor, and Pamela Y. Klein (1993) Archaeomagnetic dating on the Great Plains. Plains Anthropologist 38(142):21-50.

    Eighmy, Jeffrey L. (1994) Archaeomagnetic dating at Pueblo Grande. Journal of Archaeological Science 21445-453.

    Jacobs, Z. and R.G. Roberts (2007) Advances in optically stimulated luminescence dating of individual grains of quartz from archeological deposits. Evolutionary Anthropology 16(6):210-223.

    Mercier, N., et al. (2007) Hayonim Cave: a TL-based chronology for this Levantine Mousterian sequence. Journal of Archaeological Science 34:1064-1077.

    Chronological Methods 9 - Potassium-Argon Dating
    Thanks, what I was looking for was a way of knowing how they could date what I presume to be undead material. Just the difference between carbon dating based on radioactive decay after death and methods used for non-living stuff like footprints. Just curious.

    I'll take a dekko at the articles.
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  40. #39  
    Administrator KALSTER's Avatar
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    Just the difference between carbon dating based on radioactive decay after death and methods used for non-living stuff like footprints.
    Just to make sure; did you get what you were looking for, i.e. dating the rock they were made in?
    Disclaimer: I do not declare myself to be an expert on ANY subject. If I state something as fact that is obviously wrong, please don't hesitate to correct me. I welcome such corrections in an attempt to be as truthful and accurate as possible.

    "Gullibility kills" - Carl Sagan
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    Yeah, the link on potassium to argon decay was very clear.

    Thanks

    Quote Originally Posted by SkinWalker
    One way would be to pour silt into a barrel of water. The organic material will float to the top. Archaeologists use this method quite frequently (too, too frequently -ugh) to obtain organic material like seeds, nuts, charcoal, even small bits of bone, etc.

    Bodner, Connie C. and Ralph M. Rowlett (1980) Separation of bone, charcoal, and seeds by chemical flotation. American Antiquity 45(1):110-116.
    Thats interesting. And simple, thanks.

    Doesn't putting it in water cause any changes, though? Doesn't any inroganic matter float? [I should probably read the paper before asking more questions]
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    I think it is just a quick way to get at the organic matter, but testing has to be done to make sure on some of it I'd guess. Testing for organic compounds will do it and I guess there are other methods to test for compounds produced by living organisms, like relative a consentrations.
    Disclaimer: I do not declare myself to be an expert on ANY subject. If I state something as fact that is obviously wrong, please don't hesitate to correct me. I welcome such corrections in an attempt to be as truthful and accurate as possible.

    "Gullibility kills" - Carl Sagan
    "All people know the same truth. Our lives consist of how we chose to distort it." - Harry Block
    "It is the mark of an educated mind to be able to entertain a thought without accepting it." - Aristotle
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