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Author Topic:   Carbon-14 Dating Debate Assistance Thread
Peg
Member (Idle past 5007 days)
Posts: 2703
From: melbourne, australia
Joined: 11-22-2008


Message 31 of 38 (492672)
01-02-2009 2:47 AM
Reply to: Message 30 by Coyote
01-02-2009 1:19 AM


Re: Bump for Peg to air her skepticism regarding carbon dating
thank you coyote for keeping it civil
here a few points of contention for C14 that i have found in print in various places
contamination of the samples tested for instance. Its always possible that a bit of wood, for example, from the heart of an old tree might contain live sap. Or if it was extracted with an organic solvent (often made from petroleum), a trace of the solvent might be left in the portion analyzed. Charcoal could have been penetrated by rootlets from living plants. Any of these senarios could affect the levels of C14
Live shellfish have been found with carbonate from minerals long buried or from seawater upwelling from the deep ocean where it had been for thousands of years. Such things can make a specimen appear either older or younger than it really is.
there is also the assumption that the level of carbon 14 in the atmosphere has always been the same as it is now. But we know that the carbon level has increased a lot since the explosion of neuclar bombs into the atmosphere and since the use of burning fossil fuels. So how do we really know what the levels were thousands of years ago?
volcanic eruptions also add to the stable carbon-dioxide reservoir, thus diluting the radiocarbon....so how do they account for all these possible variences in c14 in the atmosphere??? How can they honestly know how much to make allowance for???

This message is a reply to:
 Message 30 by Coyote, posted 01-02-2009 1:19 AM Coyote has replied

Replies to this message:
 Message 32 by fallacycop, posted 01-02-2009 3:14 AM Peg has not replied
 Message 35 by JonF, posted 01-02-2009 10:13 AM Peg has not replied
 Message 36 by Coyote, posted 01-02-2009 11:28 AM Peg has not replied
 Message 38 by RAZD, posted 01-03-2009 12:08 AM Peg has not replied

  
fallacycop
Member (Idle past 5598 days)
Posts: 692
From: Fortaleza-CE Brazil
Joined: 02-18-2006


Message 32 of 38 (492679)
01-02-2009 3:14 AM
Reply to: Message 31 by Peg
01-02-2009 2:47 AM


Re: Bump for Peg to air her skepticism regarding carbon dating
Many of your questions are actually quite relevant. I'll answer the last one.
How can they honestly know how much to make allowance for?
All those issues have been raised and thoroughly analysed in peer reviewed literature and are taken into account by researchers in the field. (What? you didn't think scientists would be that smart?)
Edited by fallacycop, : typo

This message is a reply to:
 Message 31 by Peg, posted 01-02-2009 2:47 AM Peg has not replied

  
Otto Tellick
Member (Idle past 2408 days)
Posts: 288
From: PA, USA
Joined: 02-17-2008


Message 33 of 38 (492694)
01-02-2009 5:05 AM
Reply to: Message 29 by Peg
01-02-2009 1:05 AM


Re: Bump for Peg to air her skepticism regarding carbon dating
Peg writes:
... I am not a YEC and do not have a problem with the age of old homosapien/erectus etc or even that these exist. I merely doubt that they are human.
I apologize for having misunderstood your position. I was confused by things you have posted recently in other EvC threads -- like this item in Message 26 (your reply to Mr Jack on Jan. 1):
Peg writes:
about the dates though, the jews kept the dates of their history meticulously...so meticulously in fact that we know the exact year of the flood, of Adams creation, of the exodus from egypt ect
You didn't mention the actual dates you were referring to there (at least not yet), so I don't know what you consider these exact dates to be. But usually, when people have made assertions like that, the dates have tended to be "YEC-ish" in magnitude (less than 8000 years ago).
If you don't have a problem with age estimates of rocks, fossils, artifacts, etc, that are much older than 8000 years, then what are these "exact years" that you are referring to for the various "historical events" in Genesis, and what is the basis for this claim about meticulous keeping of dates in ancient Hebrew texts?
If you can accept the validity of various scientific dating methods (even leaving out C14 completely), how can you reconcile this with the Genesis account of the flood, considering that so much evidence (already cited by RAZD and Coyote in replies to your posts) contradicts the flood story, no matter what year it supposedly happened?
You must think that folks here are persecuting you, but you have to understand that when you make statements like this in a science forum, you are bringing it upon yourself. Most other people are content to view the flood story and other parts of Genesis as allegorical or metaphorical -- as having a value that goes far beyond (and is quite distinct from) mere historical reportage.

autotelic adj. (of an entity or event) having within itself the purpose of its existence or happening.

This message is a reply to:
 Message 29 by Peg, posted 01-02-2009 1:05 AM Peg has not replied

  
lyx2no
Member (Idle past 4794 days)
Posts: 1277
From: A vast, undifferentiated plane.
Joined: 02-28-2008


Message 34 of 38 (492710)
01-02-2009 9:56 AM
Reply to: Message 27 by RAZD
01-01-2009 7:16 PM


Re: A Short Aside - marine reservoirs
Thank you, RAZD, that's a great site. I've learned many things form it. Some only marginally related; i.e., lake muds have a name: gyttja. I can't wait to drop that on my aunt.
But it also brings up a new problem (opportunity). In the K-12 section (read through most of the sight last night) it gives a list of things that carbon dating can be used on. On the list is Iron & Meteroites. Now I've got to find out how it could apply to either.
Again, Thanks.

Don't do that Dave.

This message is a reply to:
 Message 27 by RAZD, posted 01-01-2009 7:16 PM RAZD has seen this message but not replied

  
JonF
Member (Idle past 246 days)
Posts: 6174
Joined: 06-23-2003


Message 35 of 38 (492712)
01-02-2009 10:13 AM
Reply to: Message 31 by Peg
01-02-2009 2:47 AM


You're not reading any of what others write, are you.
Peg, you really need to get your information from different sources. The sources you are using are totally ignorant of the subject. Or maybe they are lying. One way or another, they are useless as sources of true information.
Most of your points of contention are relevant to some measurements. For your beliefs to be true, you need to come up with some problem that makes all 14C measurements older than, say, 10,000 years false. Don't bother with anything that applies only to some samples.
contamination of the samples tested for instance. Its always possible that a bit of wood, for example, from the heart of an old tree might contain live sap. Or if it was extracted with an organic solvent (often made from petroleum), a trace of the solvent might be left in the portion analyzed. Charcoal could have been penetrated by rootlets from living plants. Any of these scenarios could affect the levels of C14
Yes they could. Of course, nobody would use an organic solvent to extract a 14C sample. The other scenarios are possible, but would make the sample appear younger than it really is… no help to you, you're arguing that the results are older than the samples really are.
These kinds of contamination can often be detected. For your charcoal sample, test samples from different parts of the piece of charcoal. If the results vary significantly, there's a problem.
Live shellfish have been found with carbonate from minerals long buried or from seawater upwelling from the deep ocean where it had been for thousands of years. Such things can make a specimen appear either older or younger than it really is.
Oh, please. This is an old canard. Read some of the links given in this thread before you spew such garbage. Of course shellfish don't carbon-date correctly, 14C dating works on samples that get their carbon from the atmosphere directly or near-directly. It's well known that shellfish and most marine life don't fit that requirement, and we don't use 14C dating on such samples.
there is also the assumption that the level of carbon 14 in the atmosphere has always been the same as it is now. But we know that the carbon level has increased a lot since the explosion of nuclear bombs into the atmosphere and since the use of burning fossil fuels. So how do we really know what the levels were thousands of years ago
Well, at least this is relevant to whether the method itself is useful. But, Lord love a duck, it's an even worse PRATT and one that has been already discussed in this very thread. No, there is absolutely no assumption that the level of 14C in the atmosphere has been stable. It is well known that it has not been stable (although it hasn't varied a heck of a lot). See Message 23, read it, make sure you understand it, especially the calibration curve part. Then we can continue.
volcanic eruptions also add to the stable carbon-dioxide reservoir, thus diluting the radiocarbon....so how do they account for all these possible variances in c14 in the atmosphere??? How can they honestly know how much to make allowance for???
By cross-correlation with other, independent measurements. See Message 23.
And read some or all of the links in Message 24

This message is a reply to:
 Message 31 by Peg, posted 01-02-2009 2:47 AM Peg has not replied

  
Coyote
Member (Idle past 2184 days)
Posts: 6117
Joined: 01-12-2008


Message 36 of 38 (492716)
01-02-2009 11:28 AM
Reply to: Message 31 by Peg
01-02-2009 2:47 AM


Re: Bump for Peg to air her skepticism regarding carbon dating
Peg, its clear that you don't know anything about C14 dating from your own research and that you are reading about it only on creationist websites. They are lying to you.
On this site you have several people who are very familiar with the method. I've done nearly 600 samples in my career as an archaeologist, and I've both written and lectured on the subject. Now, to your creationist websites' objections:
contamination of the samples tested for instance. Its always possible that a bit of wood, for example, from the heart of an old tree might contain live sap. Or if it was extracted with an organic solvent (often made from petroleum), a trace of the solvent might be left in the portion analyzed. Charcoal could have been penetrated by rootlets from living plants. Any of these senarios could affect the levels of C14
That's why you never rely on just one sample! My last major excavation included 31 radiocarbon dates on a variety of materials, and those results were compared to two other dating methods and the results from other local sites.
There is also a method for estimating the trustworthiness of your sample--establishing the C13/C12 ratio. C13 is a stable isotope, and because it is heavier it is taken up slightly differently into different parts of the food chain. If you find a piece of marine shellfish with a -26.0 ratio, or a piece of wood charcoal with a 1.0 ratio you know those samples are questionable!
Sap is not a problem. And if there was sap, it would make the sample artificially younger. A more serious problem is dating part of a 1,000 year old tree that was collected and burned on an archaeological site. That would make your date artificially old.
Extraction is not a problem. Give the laboratories some credit for not being total dolts, eh? And rootlets! Don't you think the professionals have thought of that one too? The pretreatment methods include a procedure for dissolving those rootlets!
Live shellfish have been found with carbonate from minerals long buried or from seawater upwelling from the deep ocean where it had been for thousands of years. Such things can make a specimen appear either older or younger than it really is.
No, only older. Dating freshwater shellfish in an area heavily influenced by old carbonates is just not done. That's where you get your living shellfish that are thousands of years old. But marine shellfish are different--they make a fine dating material. They are short-lived, so you don't have the problem of a 300 year old abalone. They are usually dense, so you don't have much rootlet or ground water penetration. And they represent a single event--a person collecting a shellfish from the ocean and bringing it back to the site.
But its still too old, you say? The laboratories correct for that. They have established a worldwide correction for marine shellfish. To that you add your local correction, called the Delta-R. In my area the Delta-R is 225 years. This was established by dating 1) marine shells collected at a known time prior to the beginning of nuclear testing, and 2) comparison of charcoal/shellfish pairs from identical proveniences. The last such test I ran produced a difference, following calibrations, of 15 years between the shellfish and the charcoal. That's well within the limit of error.
there is also the assumption that the level of carbon 14 in the atmosphere has always been the same as it is now. But we know that the carbon level has increased a lot since the explosion of neuclar bombs into the atmosphere and since the use of burning fossil fuels. So how do we really know what the levels were thousands of years ago?
This is probably the biggest creationist mistake. We don't just assume the levels of C14 in the atmosphere have been the same! De Vries published on this back in 1958, and by comparison to tree rings and other annualar materials a calibration curve has been worked out which corrects for atmospheric variation. There are examples of these charts upthread, if you had bothered to read those long posts.
The nuclear testing only effects organisms that are taking up carbon after that testing began. It does not effect older samples.
volcanic eruptions also add to the stable carbon-dioxide reservoir, thus diluting the radiocarbon....so how do they account for all these possible variences in c14 in the atmosphere??? How can they honestly know how much to make allowance for???
By tree rings! If you date a tree ring that is 11,000 years old (and you know its age by direct counting) then you can tell how far off the measured or conventional radiocarbon age is and correct for it, resulting in an accurately calibrated date.
Peg, your objections are all standard creationist fodder, and have been answered thousands of times.
Admit it--you just want radiocarbon dating to be worthless so it fits with your a priori beliefs, and no amount of evidence that we present will make any difference to those beliefs. That's the usual pattern that we see.
If you are willing to read some basic information try this article (which I already linked to you above) I suggest you begin with:
Radiometric Dating: A Christian Perspective by Dr. Roger C. Wiens
If your response shows that you have not seriously considered any of this, and that you are still relying only on creationist websites, you can expect a somewhat less polite response.

Religious belief does not constitute scientific evidence, nor does it convey scientific knowledge.

This message is a reply to:
 Message 31 by Peg, posted 01-02-2009 2:47 AM Peg has not replied

Replies to this message:
 Message 37 by JonF, posted 01-02-2009 12:26 PM Coyote has not replied

  
JonF
Member (Idle past 246 days)
Posts: 6174
Joined: 06-23-2003


Message 37 of 38 (492721)
01-02-2009 12:26 PM
Reply to: Message 36 by Coyote
01-02-2009 11:28 AM


Re: Bump for Peg to air her skepticism regarding carbon dating
volcanic eruptions also add to the stable carbon-dioxide reservoir, thus diluting the radiocarbon....so how do they account for all these possible variences in c14 in the atmosphere??? How can they honestly know how much to make allowance for???
By tree rings! If you date a tree ring that is 11,000 years old (and you know its age by direct counting) then you can tell how far off the measured or conventional radiocarbon age is and correct for it, resulting in an accurately calibrated date.
And varves, and (my personal favorite) U-Th disequlibrium dating of corals, and ...

This message is a reply to:
 Message 36 by Coyote, posted 01-02-2009 11:28 AM Coyote has not replied

  
RAZD
Member (Idle past 1483 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 38 of 38 (492794)
01-03-2009 12:08 AM
Reply to: Message 31 by Peg
01-02-2009 2:47 AM


Re: Bump for Peg to air her skepticism regarding carbon dating
Hello Peg,
It appears you didn't really read my Message 23 ...
here a few points of contention for C14 that i have found in print in various places
And curiously each one was addressed above. In fact from the information provided to you and lyx2no one could have predicted before the sample was tested that the seal from McMurdo Sound would test (uncorrected for the KNOWN marine reservoir effect) to be over 1000 years old.
Of course an honest skeptical person would want to know why a creationist would go to Antarctica to obtain a sample from a seal to subject to C-14 dating (it is not a cheap process), if they didn't know before hand that this is precisely what results they could expect. That they then pretend that they are using the method correctly (which they are NOT doing without the reservoir correction) means that they are intentionally misrepresenting the truth.
....so how do they account for all these possible variences in c14 in the atmosphere??? How can they honestly know how much to make allowance for???
By using the calibration curves given in Message 23, the ones developed from testing items of known actual age. By comparing calibration curves from hundreds of different places.
Curiously scientists don't just throw up there hands and give up when they have questions like this - they look for answers. Strangely C-14 is so well tested and improved method, that different laboratories with blind samples produce the same results.
The most recent calibration review was done in 2004, and it goes by the name of INTCAL04 (the previous, INTCAL98, was done in 1998):
http://www.radiocarbon.org/IntCal04_TOC.pdf
See: INTCAL04 TERRESTRIAL RADIOCARBON AGE CALIBRATION, 0-26 CAL KYR BP
http://www.radiocarbon.org/IntCal04.htm
from http://www.radiocarbon.org/ (Radiocarbon Journal on line archives) Volume 46 Number 3, where number 2 and 3 contain the proceedings of the conference.
Notice that they did not use the bristlecone pine data, as over a period of some 8000 years covered by the tree rings in three different dendrochronologies, the data was off by 37 years to the other two chronologies:
quote:
The replicate measurements have a mean offset of 37 6 14C yr (n = 21) from the Tucson measurements. Applying this shift to the Tucson data results in a close fit to the wiggles of the German oak, which would not occur if there were an error in the dendrochronology of either series. Because of this offset, the IntCal working group has decided not to include the BCP record in IntCal04.
(IntCal04 Terrestrial 14C Age Calibration, 0-26 cal kyr BP page 1033)
That's an error of 0.5% ...
In other words, the effects have been very closely studied and accounted for.
Here's a curve that I like: it also answers your question about volcanic effects:
Where:
age is the hoizontal axis,
sediment depth is the vertical axis
varve age is represented by a solid line
C-14 age is represented by the circles (the actual samples)
I want you to look at 4 things shown on this graph:
  1. at ~10kyr ago the slope of the varve line changes,
  2. the change in slope is matched by the C-14 age data (with the same offset you see in the calibration curves given previously)
  3. the ash from several volcano eruptions is included,
  4. the age of known volcanic eruptions (labelled) matches evidence from other sources.
From this graph you can see that the effect of the volcanoes is not significant to the ages of the samples measured.
Note that varve age is linear, every varve represents one year, while C-14 content is exponential, due to decay, and it is converted to age by an exponential formula, and yet the ages match regardless of the rate of sediment deposit for each of the different layers.
BTW, the samples tested were leaves, twigs and insects that fell into the lake, and thus their C-14 came from the atmosphere when they were living.
there is also the assumption that the level of carbon 14 in the atmosphere has always been the same as it is now. But we know that the carbon level has increased a lot since the explosion of neuclar bombs into the atmosphere and since the use of burning fossil fuels. So how do we really know what the levels were thousands of years ago?
Here's that calibration curve from the same data again:
That's how scientists know. Because they find out what the effects are.
Enjoy.
Edited by RAZD, : clarity
Edited by RAZD, : added
Edited by RAZD, : clarity again

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This message is a reply to:
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