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Author Topic:   14C Calibration and Correlations
RAZD
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Message 1 of 59 (574073)
08-13-2010 9:50 PM


From Uranium Dating Message 102 where it is off topic:

Hi archaeologist and welcome to the fray.

It appears you have a lot to say and no embarrassment about whether it is correct or not.

While these values do not compute an age for the Earth, they do establish a lower limit (the Earth must be at least as old as any formation on it). This lower limit is at least concordant with the independently derived figure of 4.55 billion years for the Earth's actual age

the bolded parts are a very big assumption ...

Denial is not refutation.

Conceptually it is entirely logical and consistent that some evidence of age can be less than the actual age of the earth, however it is not possible for evidence to be older than the earth.

This is not an assumption, it is an objective, impartial and unbiased logial conclusion

... and cannot be verified nor confirmed. such conclusions mean nothing.

Let's start with the basics: what we can know from annual layer counting from various sets of information. Consider these bits of information and see if you can explain why they correlate so well:

Tree Rings & C-14 correlations

There are three long continuous (unbroken from today) dendrochronologies (and a lot of short ones) and one (of many) "floating" ones (where they are not directly connected to today), and they are:

  1. The Irish Oaks, extending continuously back over 7,000 years before the present day (2010).

    http://www.jstor.org/pss/20567947
    A major radiocarbon calibration excercise was carried out between 1975 and 1985, and precisely dated samples of irish oak were obtained for all periods back to 5,000 BCE (7,000 years ago)

    More work has been done since then, however this is sufficient for this excercise.

  2. The bristlecone pines, including two trees that are over 4,000 years old in continous growth to the day measured, and overall to an age of ~9,000 years before the present day (2010).

    http://www.biologie.uni-hamburg.de/...le/pi/pin/longaeva.htm
    The "Methusulah" specimen was sampled (by boring) in 1957, the measured germination date is ~2,832 years BCE, so by this one tree alone the minimum age for the earth is 4,8342 years (in 2010 ... and counting).

    http://www.nps.gov/...%20Pines/bristleconepineprometheus.htm
    The "Prometheus" specimen was was 4,844 years old when it was cut down in 1964. This is a minimum as the core of the tree had eroded away, and this gives a latest germination date of 2,880 BCE. By this one tree alone the minimum age for the earth is 4,890 years (in 2010 ... and counting).

    http://www.sonic.net/bristlecone/dendro.html (7)
    The bristlecone pine chronology in the White Mountains currently extended back almost 9,000 years continuously in 2007 (no updates on additional data since then). That's to 7,000 BC!

    Again, further research has likely extended this chronology, however this is sufficient for this excercise.

  3. The Geman Oaks, extending back continuously over 9,197 years before the present day (2010).

    http://radiocarbon.library.arizona.edu/...bon/GetFileServlet?
    file=file:///data1/pdf/Radiocarbon/Volume46/Number3/azu_radiocarbon
    _v46_n3_1029_1058_v.pdf&type=application/pdf
    The German and Irish oak chronologies were cross-dated until back into the 3rd millennium BC (Pilcher et al. 1984), and the German oak chronologies from the Main River, built independently in the GΓΆttingen and Hohenheim tree-ring laboratories, cross-date back to 9147 cal BP.

  4. The German & Swiss Pines, a floating dendrochronology, that is cross-linked to the oak chronology to extend the combined unbroken chronology to over 12,460 years before the present day (2010).

    http://courses.washington.edu/...S%20Readings/Reimer2004.pdf (10)
    The German Preboreal pine chronology has been linked and cross-matched to the absolutely-dated oak chronology. These pine chronologies from Switzerland and eastern Germany extend the measured age back to 12,410 cal BP.

Now the accumulated counting error between the two oak chronologies was 41 years over 8,000 years of cross-linked data comparisons - an error of 0.5% - and between the bristlecone pine chronology and the is off from the combined oak chronolgy by 37 years in 7,600 years of cross-linked data comparisons (younger than the oak average values) - also an error of 0.5%.

These chronologies are then used to make a calibration curve for determining a more likely actual age from the 14C age calculations. To do this they took samples from the tree rings and measured the actual 14C values. The amount of 14C in a tree ring is locked in by the growth of the tree, and represents the amount of 14C available in the atmosphere when the tree grew, when corrected for decay.

Not only was there a strong correlation between the three dendrochronologies, there was also a strong correlation in each one with the actual amount of 14C left in the tree rings. When calculated for radioactive decay and compared to the dendrochronology they showed this calibration curve:

Note that the curve has almost continuous small jagged variations around a smooth curve.

The production of 14C is related to cosmic ray emissions from the sun:

http://science.howstuffworks.com/carbon-14.htm/printable
Cosmic rays enter the atmosphere in large numbers every day, and their interaction with the atmosphere causes 14C to be produced at a rate proportional to the amount of cosmic rays that penetrate the atmosphere.

Over long geological periods, changes in the long term climate can affect this proportion to a slight degree (the long term trend in the graph).

http://en.wikipedia.org/wiki/Solar_cycle
The production of cosmic rays also varies with a solar cycle of ~11 years. This cycle is responsible for the small jagged teeth in the graph.

In addition to age and 14C, the tree rings record the climate for each year that the tree grew.

The correlations you need to explain then are:

  • between each of the oak chronologies for age and climate changes and patterns,
  • between the bristlecone pine and the oak chronologies for age and climate changes and patterns,
  • between the irish oak and 14C age,
  • between the bristlecone pine and 14C age,
  • between the german oak and 14C age,
  • the 14C ages between each of these sets,
  • the correlation between each dendrochronolgy, 14C age, and the solar cosmic ray cycle.

Note that this last item acts as a clock check on the other data, a steady clock tick of solar cycle in each set of data confirms that the same solar cycle is in effect in each one, and also shows that there has been no change in the rate that the clock ticks.

As noted, the accuracy of this data is +/-0.5% maximum in absolute age. The possible error in 14C age is higher due to the 11 year cycle jags such that a 14C date can correlate with 3 different points on the curve, however the overall accuracy of 14C dating with this calibration is less than 10% maximum.

The tree ring chronology is continuous and unbroken for 12,460 years before the present day (2010).

And this is only the beginning of the correlations that validate 14C.

Lake Suigetsu Varves and 14C

This is a single chronology formed by alternating biological deposition (diatoms in summer) and sediment deposition (clay in winter). The clay is being deposited all year, but settles slower than the diatoms, so in the summer (when a lot of diatoms grow and die) there are more diatom shells than clay, while in the winter (when diatom growth is halted) there is more clay deposited than diatoms.

http://www.sciencemag.org/cgi/content/abstract/279/5354/1187
If the above link is not accessible try http://www.accuracyingenesis.com/varves.html

This is another floating chronology, but it is over 29,000 years long, and it overlaps and lines up perfectly with the dendrochronology above. The annual varves run for a period of 29,100 years (from 8,830 back to 37,930 cal yr BP when aligned with the tree chronology).

The varve layers continue down below the limits of C-14 dating to ~100,000 years, however the data below 37,930 cal yr BP level uses an estimated rate of sedimentation rather than actual layer counts. Using only the actual layer counts we end up with either of these two scenarios:

  1. This chronology does not overlap the one from the tree-ring data (in spite of several thousand years of matching Carbon-14 levels), and the minimum age of the earth is 12,460 + 29,100 (+/-) = ~39,560 (+/-) years old (and likely more depending on the length of the gap), OR
  2. These chronologies do overlap, as determined by matching the "C-14 age" curves, and the minimum age of the earth is 37,930 (+/-) years BP (1950) = ~35,980 (+/-) years old in 2010.

Here's the combined calibration curve:

Where the green line is the calibration curve from the tree rings shown previously, and the blue circles are the data from the lake varve samples (from organic matter deposited in the layers).

The data from the lake is taken from one long core and four shorter cores, taken from different locations in the lake, and thus there is a lot of samples up to ~20,000 years ago and then fewer samples after that, but all the samples still fall on a general curve. The multiple cores also eliminate the possibility that a mud slide could contaminate the data and cause false layering (a common creationist attempt at discrediting the data).

Now the problem for you is not just the correlations between the dendrochronologies and the lake varve chronology, but with the rate of sedimentation - the deposition rate of the layers - with the 14C concentrations:

http://radiocarbon.library.arizona.edu/...bon/GetFileServlet

This graph shows the varve and 14C chronologies as a function of depth. As shown, the sedimentation or annual varve thickness is relatively uniform (typically 1.2 mm yr-1 during the Holocene and 0.62 mm yr-1 during the Glacial). At the end of the glacial period the rate of deposition changed, as would be expected when less water is tied up in ice and the climate warms.

The correlations you need to explain then are:

  • between the varve age and 14C age,
  • between the varve age and deposition rate change with climate,
  • between the 14C age and the deposition rate change with climate.

Note the correlation between C-14 and depth with C-14 and varve count. See how at about 11,000 years ago ("BP" means "before present" with "present" defined as 1950 CE), both show a matching change in slope of the curves with depth.

When you realize that one is a linear system of varve counting and the other is a mathematical model based on actual measurements that are along an exponential distribution:


Graph of actual 14C content versus actual time intervals from time "X"

There is no rational reason for the 14C curve to make the same change in slope at the same time as the varve age curve, unless it measures the same thing that the varve counting does - age.

This is another example of internally consistent correlations of three sets of information from the same basic data source: age, depth and 14C/12C radiometric age.

Summary

This is just a small sampling of the objective data that shows a consistent and intercorrelated pattern of age. This data does not extend back to the extreme age of the earth, but it does extend back to well beyond any creationist YEC age known.

Curiously, the actual age of the earth does not need to be proven to be extremely old to falsify the typical YEC assertion, it just needs to be sufficiently old that the YEC position is untenable.

This data does that.

Once you accept that the YEC age is false, then we can move on to other information on how old the earth really is.

Enjoy.

Edited by RAZD, : only only

Edited by RAZD, : minor corrections


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Replies to this message:
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Adminnemooseus
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Message 2 of 59 (574075)
08-13-2010 9:53 PM


Thread Copied from Proposed New Topics Forum
Thread copied here from the 14C Calibration and Correlations thread in the Proposed New Topics forum.
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RAZD
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Posts: 18241
From: the other end of the sidewalk
Joined: 03-14-2004
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Message 3 of 59 (574077)
08-13-2010 10:10 PM
Reply to: Message 2 by Adminnemooseus
08-13-2010 9:53 PM


Re: Thread Copied from Proposed New Topics Forum
Thank you. I was in the middle of setting this up when you zapped me.
This message is a reply to:
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archaeologist
Inactive Member


Message 4 of 59 (574093)
08-14-2010 12:20 AM
Reply to: Message 1 by RAZD
08-13-2010 9:50 PM


Hi archaeologist and welcome to the fray.

i doubt it, you all are like ravenous lions looking for the next piece of lunch meat to come along.

This is not an assumption, it is an objective, impartial and unbiased logial conclusion

please do not say this because this isimpossible and i have quoted dever on this issue that shows that every reputable scholar has gven up on this idea and just make it an ideal.

when it comes to carbon 14 i amprepared to say that it can be on target with dates less than 11,000 years, approx.. anything more than 2 half-lifes i discard, dismiss and doubt.

dendrochronology would confirm some of those dates if it could date the same isotopes but all it can do is possibly give the age of the tree and since we do not know what form they were created in this method fails to be accurate for the age of the earth.

having studied archaeology and knowing that there is a possibility that archaeological remains only go back -possibly--ten thousand years anything beyond that is pure speculation. i even have a little trouble at 10,000 because the ancient records do not record their histories that far back.

then factoring in the truth that everything before Noah's flood wa sdestroyed, we do not know what records were kept or lost thus speculation sets in. oh, people may claim that there is no evidence for the flood but they cannot disprove it either. absence of evidence is not evidence of absence.

lack of evidence also means that they may not have found any.

back to tree rings, and since dendrochronology is not an exact science and the developement of rings depend upon many factors and one is subjectivity which relly cancels out its reliability.

http://web.utk.edu/~grissino/principles.htm

and this:

http://eo.nso.edu/tlrbse/treerings/index.htm

Caution: in given years (due to various stresses or climatic anomalies) false rings or missing rings may occur. Therefore, we need to crossdate the years we assign to individual rings.

notice that the crossdating and assigning of years to rings comes from humans and not the trees which mean there is no verification that they are correct and this throws dendrochronology out as a reliable calibration tool.

Crossdating
Crossdating is the most basic principle of dendrochronology. Crossdating is a technique that ensures each individual tree ring is assigned its exact year of formation. This is accomplished by matching patterns of wide and narrow rings between cores from the same tree, and between trees from different locations.

again subjective and no way to verify that they got it correct.

You can clearly see how these two cores crossdate against each other. Notice how the narrower rings (those pointed out with lines between the samples) are common between the two different trees. If the upper core had already been crossdated against a master tree-ring dating chronology, then we could now easily assign calendar dates to the lower core as well.

i quoted from dr. ratzsch's book {pg. 123} that people will see what they want to see while others having the same equipment fail to see it. this is inconclusive and depends upon the state of mind of the research and their beliefs or lack of them.

sorry but you haven't proven to me that calibration and accuracy is there and it depends more on who is doing the calibrating and their beliefs than actual science.

Edited by archaeologist, : No reason given.


This message is a reply to:
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bluescat48
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Posts: 2347
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Joined: 10-06-2007


Message 5 of 59 (574106)
08-14-2010 1:38 AM
Reply to: Message 4 by archaeologist
08-14-2010 12:20 AM


then factoring in the truth that everything before Noah's flood wa sdestroyed, we do not know what records were kept or lost thus speculation sets in. oh, people may claim that there is no evidence for the flood but they cannot disprove it either. absence of evidence is not evidence of absence.

The point is you are making the claim there was a flood, therefore it is up to you to show the evidence. The claimant has to show evidence not the denier. The denier can't show evidence since there is none.
What the denier does is show whether any evidence is reliable or not ie: falsification. I can't attempt to falsify evidence that does not exist.

Edited by Adminnemooseus, : Off-topic banner.


There is no better love between 2 people than mutual respect for each other WT Young, 2002

Who gave anyone the authority to call me an authority on anything. WT Young, 1969

Since Evolution is only ~90% correct it should be thrown out and replaced by Creation which has even a lower % of correctness. W T Young, 2008


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archaeologist
Inactive Member


Message 6 of 59 (574114)
08-14-2010 3:38 AM


just to throw this out there:

http://www.conservapedia.com/Carbon_dating

Carbon dating, like other radiometric dating methods, requires certain assumptions that cannot be scientifically proved. These include the starting conditions, the constancy of the rate of decay, and that no material has left or entered the sample.

and

Unlike other radiometric dating techniques where it is not possible to calibrate the method against historically-known dates, limited calibration is possible for carbon dating. That is, samples with dates known from historical records can be used to check the accuracy of the method. Despite this, however, caution is still necessary in accepting dates derived from carbon dating.

Claims have been made of the method being calibrated back to 10,000 years using dendrochronology,[1] however these older dates derived via dendrochronology have themselves been derived with the assistance of carbon dating[3], making this circular reasoning

and i stand by my argument that using 5 or more different dating systems is not proof of correct dating and I will add that it mounts to as the above quote mentions--circular reasoning.

evolutionist speaking: our dates our correct because our dating systems say so and our dating systems are correct because we say so.

you have no verification

Edited by archaeologist, : No reason given.


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nwr
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From: Geneva, Illinois
Joined: 08-08-2005
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Message 7 of 59 (574132)
08-14-2010 8:28 AM
Reply to: Message 6 by archaeologist
08-14-2010 3:38 AM


archaeologist writes:
just to throw this out there:

http://www.conservapedia.com/Carbon_dating


Almost nobody, other than Andy Schlafly, takes conservapedia seriously. People mainly go there when looking for a good laugh.
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Theodoric
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Message 8 of 59 (574181)
08-14-2010 1:43 PM
Reply to: Message 6 by archaeologist
08-14-2010 3:38 AM


Well I guess using conservapedia as a reference settles it. You are a christianist troll. This is the last time a feed you.

Here are the latest hits from conservapedia.

quote:
Despite censorship of dissent about relativity, evidence contrary to the theory is discussed outside of liberal universities.

Source

quote:
The theory of relativity is a mathematical system that allows no exceptions. It is heavily promoted by liberals who like its encouragement of relativism and its tendency to mislead people in how they view the world.[1]

Source

oh hand here is the footnote.

quote:
See, e.g., historian Paul Johnson's book about the 20th century, and the article written by liberal law professor Laurence Tribe as allegedly assisted by Barack Obama. Virtually no one who is taught and believes relativity continues to read the Bible, a book that outsells New York Times bestsellers by a hundred-fold.

Talk about having an agenda.

You and your ilk truly want people to be uneducated and ignorant. Do you not realize that everything around you and everything you use everyday in your life is due to science? How would you function day to day without all for the advances science has produced?

If ignorance is bliss you must be the happiest SOB in the whole world.


Facts don't lie or have an agenda. Facts are just facts
This message is a reply to:
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Adminnemooseus
Director
Posts: 3740
Joined: 09-26-2002


(1)
Message 9 of 59 (574222)
08-14-2010 8:43 PM
Reply to: Message 8 by Theodoric
08-14-2010 1:43 PM


Snarking Conservapedia off-topic and a bad thing
OK, maybe a little snark, but let's strive to be nice.

To all - Remember, Carbon 14 dating is the topic theme.

Adminnemooseus


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Dr Adequate
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Message 10 of 59 (574226)
08-14-2010 9:49 PM
Reply to: Message 6 by archaeologist
08-14-2010 3:38 AM


and i stand by my argument that using 5 or more different dating systems is not proof of correct dating and I will add that it mounts to as the above quote mentions--circular reasoning.

An assertion is not an argument, and verifying one thing by reference to another thing is not circular reasoning.

As for the conservapedia article, the claim of "circular reasoning" in it is supported (and I use the term loosely) by a statement in an article by a creationist which is supported by nothing.

Now, back in the real world, the guys who came up with carbon dating verified its accuracy by reference to objects the dating of which did not depend in the least on carbon ratios:

(See Arnold and Libby, "Age determinations by radiocarbon content: Checks with samples of known age", Science, 1949.)

This is not circular reasoning. This is this thing called "the scientific method" that you may have heard of. It beats creationists making stuff up every time.


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Dr Jack
Member
Posts: 3500
From: Leicester, England
Joined: 07-14-2003


Message 11 of 59 (574281)
08-15-2010 6:49 AM
Reply to: Message 4 by archaeologist
08-14-2010 12:20 AM


The two half life horizon
when it comes to carbon 14 i amprepared to say that it can be on target with dates less than 11,000 years, approx.. anything more than 2 half-lifes i discard, dismiss and doubt.

Could you perhaps provide your justification for this claim? What occurs at two half-lives that renders the technique suddenly invalid and subject to being discarded, dismissed and doubted?


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RAZD
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Posts: 18241
From: the other end of the sidewalk
Joined: 03-14-2004
Member Rating: 3.0


Message 12 of 59 (574454)
08-15-2010 11:43 PM
Reply to: Message 4 by archaeologist
08-14-2010 12:20 AM


Let's review some of this information ...
Hi again archaeologist, and I repeat my welcome. If you don't want it then that is your affair.

This is not an assumption, it is an objective, impartial and unbiased logial conclusion

please do not say this because this isimpossible and i have quoted dever on this issue that shows that every reputable scholar has gven up on this idea and just make it an ideal.

This is known as the logical fallacy of the appeal to authority, coupled with confirmation bias: just because someone says something that you like, that doesn't mean that it is true.

In this case I think the argument can be made that life on earth did not exist before the earth itself did.

If you have evidence of this not being the case, then please present it, rather than just deny the obvious conclusion that therefore the age of the earth must be at least as old as the oldest reliably dated remains of organic terrestrial life.

This ties in nicely to the topic of this thread, "14C Calibration and Correlations", as only organic remains of terrestrial life can be reliably dated by the 14C method. In fact, it is more specific than that: it can be reliably used to date organic terrestrial life that absorbed atmospheric carbon during life on earth. Organisms that obtain carbon from other sources (say the carbon in the sea) need to be corrected for the "reservoir effect" for the particular source of carbon involved (and this can be discussed later in greater detail if you wish).

The reason for this is that 14C is produced in the atmosphere at a relatively steady rate, and it is removed at a fairly steady rate by decay, so the parameters and dynamics of atmospheric 14C are fairly well known.

when it comes to carbon 14 i amprepared to say that it can be on target with dates less than 11,000 years, approx..

Well, we can take that as a beginning and build on that.

dendrochronology would confirm some of those dates if it could date the same isotopes but all it can do is possibly give the age of the tree ...

Interestingly, what actually can be confirmed, is the proportion of 14C to 12C for each of the tree rings, because the 14C absorbed from the atmosphere by the living tree is incorporated into the annual tree ring: every ring records the 14C in the atmosphere when the ring was formed. Only the outer layer of cambium has living cells, and all the inner rings are composed of dead cells, with the 14C locked in those cells from the year that they were formed.

quote:
http://en.wikipedia.org/wiki/Tree_rings#Growth_rings
Growth rings, also referred to as tree rings or annual rings, can be seen in a horizontal cross section cut through the trunk of a tree. Growth rings are the result of new growth in the vascular cambium, a lateral meristem, and are synonymous with secondary growth. Visible rings result from the change in growth speed through the seasons of the year, thus one ring usually marks the passage of one year in the life of the tree. The rings are more visible in temperate zones, where the seasons differ more markedly.

This means we can count the tree ring and measure the 14C/12C ratio for each ring and see how they correlate.

back to tree rings, and since dendrochronology is not an exact science and the developement of rings depend upon many factors and one is subjectivity which relly cancels out its reliability.

Actually it can be (and I believe is being) done by computers comparing the climate\season patterns in the samples. The comparisons can also be (and have been) done by different independent labs and the results compared. As noted the three rings come from three different sources that are independent of the others, and with an 0.5% error this shows an empirically validated objective result, with little room for human subjectivity.

When we compare the tree ring counts from the three independent, we see an overall error of ~0.5% in 8,000 years between them. The Bristlecone pine appears to be ~37 years younger than the oaks for the same climate patterns, and likely has some errors due to some years of extremely cold summers at the peaks of the Sierra Nevadas that would cause missing rings. Such a ring is marked by a thicker winter ring than normal, as it is actually two winters plus growth during a cold summer similar to winter growth. This is actually documented for a year known as the "year without a summer" in the tree rings.

quote:
http://en.wikipedia.org/wiki/Year_Without_a_Summer
The Year Without a Summer (also known as the Poverty Year, Year There Was No Summer and Eighteen Hundred and Froze to Death[1]) was 1816, in which severe summer climate abnormalities destroyed crops in Northern Europe, the Northeastern United States and eastern Canada.[2][3] Average global temperatures decreased about 0.4–0.7 °C (0.7–1.3 °F),[4] enough to cause significant agricultural problems around the globe.

We also have two known living trees (when measured) from the Bristlecone Pine chronology that are known to be (~2,832 years BCE + 2010 =) 4,842 and (>2,880 BCE + 2010 =) 4,890 years old minimum. These two trees corroborate each other and the chronology built from the oak trees by their correlations with climate\season patterns.

notice that the crossdating and assigning of years to rings comes from humans and not the trees which mean there is no verification that they are correct and this throws dendrochronology out as a reliable calibration tool.

Which doesn't explain how the error between the three independent chronologies is only 0.5% in 8,000 years of data.

You are confusing accuracy with precision and calibration.

Accuracy means your ability to hit the target. If we take a bow and arrow and shoot 50 times at a target, and all the arrows average out to a bull's eye, then the average result is accurate, even though there may be significant error in any one shot.

Precision means the ability to replicate the same results. With our bow and arrow example we now have 50 arrow all clustered very close together, but they may or may not be located near the bull's eye.

Calibration means taking a precise system and determining what needs to be done to correct the precise result to be an accurate result.

when it comes to carbon 14 i amprepared to say that it can be on target with dates less than 11,000 years, approx..

As I said above, we can build on this. Notice that the age of the tree ring chronologies extends back to 12,460 years before the present day (2010), and that this fits your "less than 11,000 years" of accepted accuracy, and thus we can certainly compare the tree rings to the 14C data for this period of time.

To do this we do not need to actually calculate the 14C age but just measure the proportion of 14C to 12C in the tree rings.

Precision:

The measurement of 14C to 12C is highly precise, with different labs repeatedly getting the same results from samples from the same tree ring.

  • each ring formed captures the 14C/12C ratio of the atmosphere for the year the ring was formed.
  • trees anywhere on earth, in Germany, in Ireland and or high in the Sierra Nevadas, all have the same atmospheric 14C/12C ratio to absorb into the growth rings in the same year.
    :. tree rings for the same age from each of the chronologies should have the same proportion of 14C/12C: curiously, they do.

Thus we see a correlation between the tree ring count, the climate\season pattern and the 14C/12C proportions within the tree rings for the three different chronologies even without using 14C to measure the age.

This also objectively validates the tree ring data as measuring different years for each ring.

Accuracy (1)

How can we check the accuracy of the tree rings?

... but all it can do is possibly give the age of the tree and since we do not know what form they were created in this method ...

Because 14C is produced in the atmosphere by cosmic rays, and the incidence of cosmic rays from the sun varies on a ~11 year cycle(1), we can look for this pattern in the 14C/12C data in the tree rings.

Using the measured half-life for 14C we can project a probable 14C/12C ratio for the atmosphere on the year the ring was formed. Because of the amount of variation over this cycle we do not need to be highly accurate with the projection, as all we are looking for is the peak high and peak low points.

Any significant change from this 11 year pattern would be a signal that something has changed, or that there is an error in the data. In essence, we can count the high points (or low points) and multiply that number by 11 and we should get the same end result for the chronology, it if is accurate.

This 11 year pattern consistently shows up in the 14C/12C data for each of the three chronologies in the same way, and this confirms that the tree ring counting method is accurate (in addition to the 0.5% accuracy already measured).

Accuracy (2)

How can we check the accuracy of the 14C age?

By comparing it to the (accurate) tree ring data.

Here we see two things:

  1. the data forms a jagged curve, and
  2. the curve follows the pattern of exponential decay

If we connect the 11 year high points in the data we have an upper limit.

If we connect the 11 year low points in the data we have a lower limit.

The gap between these two curves then is the known error in accuracy caused by the 11 year cycle. We can have a high degree of confidence that the actual age is accurately contained by these two limits.

The (highly precise) 14C/12C proportion measured from the sample can then be projected to each of these curves to generate an accurate low age and an accurate high age, resulting in an accurate range of dates for the sample.

We know with a high degree of confidence that the actual age falls between these two curves.

Note that this does not use the calculation of age from the half-life of 14C, but the accurate age of the tree rings and the precise measurement of the 14C/12C ratio in the tree rings.

Calibration

To use the measured 14C/12C ratio in a sample to estimate the age of the sample we use the measured half-life and the exponential curve of decay for that half-life:


Graph of actual 14C content versus actual time intervals from time "X"

This gives us an estimated age of the sample based on the proportion of 14C/12C as compared to the proportion of 14C/12C in the atmosphere in 1950 (chosen as an arbitrary date for consistency in reporting results, hence all 14C ages are reported in "years BP" where BP means 1950. Seems a bit funny I know, but scientists are like that, they need a standard for objective comparisons).

Now when we compare those estimated ages with the known ages for the tree ring samples we can see that the 14C/12C data, while being highly precise, is not necessarily accurate.

In addition to the known error introduced by the solar cosmic ray 11 year cycle, we have an offset in the results from the "ideal" curve (which is based on an assumption that the 14C/12C proportion in 1950 is the same in the past).

The current proportion seems to hold fairly well for ~2,000 years into the past, and then there is a shift in the slope of the line, with the curve from ~2,500 years ago on being ~10% below the "ideal" line.

This curve can then be used to correct the precise estimated age from the 14C/12C data to a more accurate estimated age based on the calibration of the 14C method by the dendrochronological data (and their cross correlations).

One thing to note, is that the original 14C estimated age from the 14C/12C data is consistently younger than the calibrated age.

This means that the uncalibrated 14C age calculation is less than the actual age of the sample.

Thus one can say with a high degree of confidence, that the uncorrected age gives a highly accurate minimum age for the sample/s.

having studied archaeology and knowing that there is a possibility that archaeological remains only go back -possibly--ten thousand years anything beyond that is pure speculation. i even have a little trouble at 10,000 because the ancient records do not record their histories that far back.

Here you are confusing archaeology with history. Archeology does not depend on, nor is it limited by, history.

Many Cro-Magnon sites have been accurately dated with the 14C method. We can discuss this information later if you wish. These artifacts are most certainly not speculation, but objective evidence of reality.

... and since we do not know what form they were created in this method fails to be accurate for the age of the earth.

And this method, which is only accurate to <50,000 years, is not capable of measuring anything older than that, nor is it capable of measuring the age of non organic material: all it can measure is the age of organic terrestrial samples that came from living organisms that used the atmosphere for their source of carbon.

So 14C cannot itself be used to measure the age of the earth.

What this does measure is a minimum age of organic terrestrial life on the earth, and the earth should logically be older than the life that grew on it. The oldest organisms accurately measured by 14C dating are between 40,000 and 50,000 years old.

:. the earth must be older than 40,000 and 50,000 years old. Just for starters.

Enjoy.

(1) http://en.wikipedia.org/wiki/Solar_cycle

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This message is a reply to:
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faith24
Junior Member (Idle past 793 days)
Posts: 27
Joined: 09-10-2010


Message 13 of 59 (580830)
09-11-2010 4:04 PM


There is very little C-14 to begin with that can be calibrated back to a few 6-10k years based on historical data. I am confused about the half life thing. Can someone please explain what that is? This is confusing.... it is like playing chess - it takes time to learn each pieces have certain moves and all the number of possible moves you can make.

I guess i would have to say the correlation is only as good as your guess assuming the decay rate is a constant.

But somehow people will say " oh but it is constant"!

I am lost right here....

Edited by faith24, : No reason given.


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Coyote
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Message 14 of 59 (580834)
09-11-2010 4:21 PM
Reply to: Message 13 by faith24
09-11-2010 4:04 PM


There is very little C-14 to begin with that can be calibrated back to a few 6-10k years based on historical data.

Not sure what you are saying here.

If you are saying that the levels of C14 are very small, that is true. But there is no problem detecting enough C14 in samples to get age estimates back to about 50,000 years. Beyond that it takes very special equipment, but some experiments are being done with 80,000 years.

But it is easy to find historical samples going back past 6,000 years. Tree rings are one source. You can count the rings back about 12,500 years using the bristlecone pines from Southern California and determine how much C14 is in each ring.

I am confused about the half life thing. Can someone please explain what that is?

The quantity of C14 drops by half every 5730 years. We know the approximate amount that a sample started with by the amount in the atmosphere, as shown by the tree-rings.

Every 5730 years that amount drops by half, so we can use that information to estimate the age.

I guess i would have to say the correlation is only as good as your guess assuming the decay rate is a constant.

But somehow people will say " oh but it is constant"!

All the evidence so far shows that it is.

The RATE project tried to show that it is not a constant (funded by ICR), but they had to conclude that scientists were right. See the link I posted in the amino acid thread dealing with the RATE project for details.


Religious belief does not constitute scientific evidence, nor does it convey scientific knowledge.
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faith24
Junior Member (Idle past 793 days)
Posts: 27
Joined: 09-10-2010


Message 15 of 59 (580841)
09-11-2010 5:16 PM
Reply to: Message 14 by Coyote
09-11-2010 4:21 PM


quote:
The quantity of C14 drops by half every 5730 years. We know the approximate amount that a sample started with by the amount in the atmosphere, as shown by the tree-rings.

Every 5730 years that amount drops by half, so we can use that information to estimate the age.


Oh i see. So C-14 are turning back into nitrogen about half rate, then fourth and so on. Hrmm... So the assumption is based on the amount of C-14 in the atmosphere is the same found in plants/animals.

quote:
All the evidence so far shows that it is.

I still don't see how it is a constant? How do i determine what is constant and what is not?

Side note: let me read the irc article first.

Edited by faith24, : No reason given.


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