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Author Topic:   Peanut Gallery for Great debate: radiocarbon dating, Mindspawn and Coyote/RAZD
RAZD
Member (Idle past 1395 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 31 of 305 (710997)
11-13-2013 8:13 PM
Reply to: Message 30 by RAZD
11-13-2013 6:48 PM


Re: Great Debate Message 8 ... perhaps time to educate
In Message 8 of the GD coyote says
You just don't understand radiocarbon dating enough to get the point I'm making. This is becoming frustrating!
So we are no longer talking about tree-rings, varves, corals, or any of those other methods of establishing a calibration curve.
We are talking about "conventional" radiocarbon ages. These are the measured age as corrected for isotopic fractionation. No calibration is done at all.
This is an opportunity to show how radiocarbon dating works, rather than vent frustration.
To use the measured 14C/12C ratio in a sample to estimate the age of the sample we use the measured half-life of 14C 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).
This is a purely mathematical conversion from the 14C/12C ratio in a sample. This calculation is not affected by "misunderstanding rainfall sensitive data" because it is entirely independent of climate and rainfall -- it depends solely on the 14C/12C ratio in a sample.
Thus any one specific 14C/12C ratio in a sample will produce precisely the same estimated age of the sample.
It is when we compare those estimated ages with the known ages for the tree ring samples (or other known sources) that we can see that the 14C/12C data, while being highly precise, is only ~90% accurate (with the radiocarbon age estimate being younger than the tree ring age).
What mindspawn throws out as objections to the system should be visible as increased scatter in the data -- less precision rather than less accuracy -- and that scatter and loss of precision just is not there, regardless of the accuracy.
Enjoy.
Edited by RAZD, : clarity

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This message is a reply to:
 Message 30 by RAZD, posted 11-13-2013 6:48 PM RAZD has replied

Replies to this message:
 Message 34 by RAZD, posted 11-14-2013 8:51 AM RAZD has replied

  
RAZD
Member (Idle past 1395 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 32 of 305 (710998)
11-13-2013 8:50 PM
Reply to: Message 26 by NoNukes
11-13-2013 3:02 PM


back to correlations again
... varves are expected by spring tides, and tree rings counts are affected by rain. So, I wonder how he explains the extremely tight correspondence between the two. The correspondence is actually much better than uncalibrated C-14 data and either of the aforementioned non-radiometric indications. That's the kind of info he should be slammed with, because the conformance pretty much proves that his objection is absolutely wrong.
Exactly -- it is the correlations between the rings and the varves and the respective 14C/12C ratios over their period of overlap that show a consistent pattern.
Enjoy

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JonF
Member (Idle past 158 days)
Posts: 6174
Joined: 06-23-2003


Message 33 of 305 (711014)
11-14-2013 8:44 AM


Mindie writes:
...your graph was referring to various forms of corroboration, and comparing these to calibrated radiocarbon dates (dates that had been adjusted for variation of the magnetic field and calibrated according to other forms of dating).
Wow, he almost had it! Of course the radiocarbon dates on the graph (vertical axis) are raw and uncalibrated and not adjusted other than for background.

  
RAZD
Member (Idle past 1395 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


(1)
Message 34 of 305 (711015)
11-14-2013 8:51 AM
Reply to: Message 31 by RAZD
11-13-2013 8:13 PM


Re: Great Debate Message 9 and correlations again
Mindspawn admits to misunderstanding ... a beginning?
In Message 9 of the GD mindspawn says
You are correct, I don't understand what you are talking about. I am not focusing on the calibration curve, my arguments have been clearly focused on the dates at those 7 locations. 4 locations are precipitation sensitive more than seasonally sensitive, 3 of those locations use uranium-thorium dating.
mindspawn should be asked how the data would correlate into such a precise curve with very little scatter in the data if it were "precipitation sensitive" -- starting with the tree rings from three separate locations and ecosystems.
Why are the combined results precisely the same with 99.5% accuracy for the Irish Oak chronology, the German Oak chronology and the Bristlecone Pine cronology -- can mindspawn show that each area had precisely the same pattern of precipitation?
On the surface of it your argument appears sound, but as you delve into each location, the assumption of annual layers appears doubtful because the layers at 4 of those 7 locations would more likely reflect strong precipitation than actual seasonal layers. ie the layers are formed from each and every significant rainfall, and are not formed annually.
Then why do they correlate at all? Why is there a precise correlation if there is such a sensitivity?
Rather obviously, to me, mindspawn does not really understand how dendrochronology works and so he is clutching to a straw argument.
http://web.utk.edu/~grissino/principles.htm
quote:
tree ring
A layer of wood cells produced by a tree or shrub in one year, usually consisting of thin-walled cells formed early in the growing season (called earlywood) and thicker-walled cells produced later in the growing season (called latewood). The beginning of earlywood formation and the end of the latewood formation form one annual ring, which usually extends around the entire circumference of the tree.
tree-ring chronology
A series of measured tree-ring properties, such as tree-ring width or maximum latewood density, that has been converted to dimensionless indices through the process of standardization. A tree-ring chronology therefore represents departures of growth for any one year compared to average growth. For example, an index of 0.75 (or 75) for a given year indicates growth below normal (indicated by 1.00, or 100).
The Principle of Crossdating
This principle states that matching patterns in ring widths or other ring characteristics (such as ring density patterns) among several tree-ring series allow the identification of the exact year in which each tree ring was formed. For example, one can date the construction of a building, such as a barn or Indian pueblo, by matching the tree-ring patterns of wood taken from the buildings with tree-ring patterns from living trees. Crossdating is considered the fundamental principle of dendrochronology - without the precision given by crossdating, the dating of tree rings would be nothing more than simple ring counting!
The Principle of Replication
This principle states that the environmental signal being investigated can be maximized, and the amount of "noise" minimized, by sampling more than one stem radius per tree, and more than one tree per site. Obtaining more than one increment core per tree reduces the amount of "intra-tree variability", in other words, the amount of non-desirable environmental signal peculiar to only tree. Obtaining numerous trees from one site, and perhaps several sites in a region, ensures that the amount of "noise" (environmental factors not being studied, such as air pollution) is minimized.
Cross-dating and replication are used to eliminate the effects mindspawn is fixated on.
The tree ring chronologies also match with historical data for the "year without a summer" -- something that could not have occurred if the dendrochronologists had not been able to correctly identify annual rings ...
google site:http:http://web.utk.edu/~grissino/ "year without a summer" and you will get several results, of which this is one:
web.utk.edu/~grissino/downloads/van-west-grissino-mayer-2005.pdf
quote:
... A minor dry spell between A.D. 1809 and 1829 was broken by an exceptional three-year period between A.D. 1815 and 1817, during which each year expressed either an extreme wet or cool value. The year A.D. 1815, of course, is the year of the extraordinarily large eruption of Mount Tambora in Indonesia, and there were also several documented eruptions of lesser force from the western Pacific during the A.D. 1812B1817 period, including eruptions in Indonesia, the Philippines, and the Ryuku Islands (Salzer 2000a:115). It was so markedly cold in Europe and eastern North America in A.D. 1816 that it has been dubbed as the Ayear without summer@ (Harrington 1992). In addition to being wetter than normal, most of the first half of the nineteenth century (ca. A.D. 1809B1856) was considerably cooler than normal. Although the wetness continued through A.D. 1891, annual temperatures were moderate throughout much of the second half of the century. Of the four frost rings recorded in the SFPB chronology ( A.D. 1810, 1828, 1882, and 1884), only the first two correlate with volcanically active periods known to have lowered temperatures (Salzer 2000a:95, 115). The century ended with a 13-year dry-warm drought of modest proportions (Interval 192, spanning A.D. 1892B1904).
In spite of that wide variation in climate, from drought to extreme wet, the dendrochronology was both precise and accurate in identifying the "year with no summer" ... perhaps the dendrochronolgists DO know what they are doing?
His comments re Lake Suigetsu are also falsified by how the layers form, and they are not sensitive in the way he suggests. The clay layer only forms when there are months of no diatom deaths -- winter months -- as the clay settles so slowly that it cannot form a layer between summer blooms/busts as mindspawn conjectures.
The real problem for him, though, is to show that the correlations occur due to weather rather than annual formations in four locations around the globe: his weather patterns would have to be precisely the same in those locations to produce the same precise annual data.
This means that on the graph the carbon dates should be re-calibrated according to number of significant precipitations per year, and the actual dates should also be adjusted to reflect these multiple layers per year (of varves/tree rings/ice layers).
Curiously, dendrochronologists already check for multiple layers and have methods to identify them. As noted above they are accurately able to sort a wide variety of climate differences into their appropriate age chronologies. This is why the three dendrochronologies agree within 99.5% at over 8,000 years.
Enjoy

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This message is a reply to:
 Message 31 by RAZD, posted 11-13-2013 8:13 PM RAZD has replied

Replies to this message:
 Message 35 by RAZD, posted 11-14-2013 8:53 AM RAZD has replied
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RAZD
Member (Idle past 1395 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 35 of 305 (711016)
11-14-2013 8:53 AM
Reply to: Message 34 by RAZD
11-14-2013 8:51 AM


Re: Great Debate Message 10 and basics on radiometric systems
In Message 10 midspawn states
Regarding the last 3 of the 7 locations referred to on your graph, it appears the Carico Basin and Papua New Guinea dates are established through comparing Uranium-Thorium dating with Radiocarbon dating. I am still looking into how they originally calibrated Uranium-Thorium dating , if they calibrated this according to carbon dating, this ruins the claimed consilience, ...
They don't. All radiometric methods are "originally calibrated" by their specific decay rates. The shorter the half-life involved the more sensitive the system is to recent times.
Radiometric Dating
Radiometric Dating
A Christian Perspective
Dr. Roger C. Wiens
quote:
There are other ways to date some geologically young samples. Besides the cosmogenic radionuclides discussed above, there is one other class of short-lived radionuclides on Earth. These are ones produced by decay of the long-lived radionuclides given in the upper part of Table 1. ...
Like carbon-14, the shorter-lived uranium-series isotopes are constantly being replenished, in this case, by decaying uranium-238 supplied to the Earth during its original creation. Following the example of carbon-14, you may guess that one way to use these isotopes for dating is to remove them from their source of replenishment. This starts the dating clock. In carbon-14 this happens when a living thing (like a tree) dies and no longer takes in carbon-14-laden CO2. For the shorter-lived uranium-series radionuclides, there needs to be a physical removal from uranium. The chemistry of uranium and thorium are such that they are in fact easily removed from each other. Uranium tends to stay dissolved in water, but thorium is insoluble in water. So a number of applications of the thorium-230 method are based on this chemical partition between uranium and thorium.
On the other hand, calcium carbonates produced biologically (such as in corals, shells, teeth, and bones) take in small amounts of uranium, but essentially no thorium (because of its much lower concentrations in the water). This allows the dating of these materials by their lack of thorium. A brand-new coral reef will have essentially no thorium-230. As it ages, some of its uranium decays to thorium-230. While the thorium-230 itself is radioactive, this can be corrected for. The equations are more complex than for the simple systems described earlier, but the uranium-234 / thorium-230 method has been used to date corals now for several decades. Comparison of uranium-234 ages with ages obtained by counting annual growth bands of corals proves that the technique is highly accurate when properly used (Edwards et al., Earth Planet. Sci. Lett. 90, 371, 1988).
Dr Wiens is a good source of information regarding radiometric dating methods.
... In this way they can establish a calibration curve for uranium-thorium dating which they can use for periods earlier than carbon dating can function. ...
This comment shows he does not appear to understand the paper: 14C dating works on samples that formed last year ...
Enjoy.

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This message is a reply to:
 Message 34 by RAZD, posted 11-14-2013 8:51 AM RAZD has replied

Replies to this message:
 Message 38 by RAZD, posted 11-14-2013 9:38 AM RAZD has replied

  
NoNukes
Inactive Member


Message 36 of 305 (711019)
11-14-2013 9:27 AM


Spring tides
Has any ever told this buffoon that there are two spring tides per month rather than just one? Mindspawn thinks he needs to explain a factor of 11 or 12 for some reason.

Under a government which imprisons any unjustly, the true place for a just man is also in prison. Thoreau: Civil Disobedience (1846)
I believe that a scientist looking at nonscientific problems is just as dumb as the next guy.
Richard P. Feynman
If there is no struggle, there is no progress. Those who profess to favor freedom, and deprecate agitation, are men who want crops without plowing up the ground, they want rain without thunder and lightning. Frederick Douglass

Replies to this message:
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NoNukes
Inactive Member


Message 37 of 305 (711020)
11-14-2013 9:30 AM
Reply to: Message 34 by RAZD
11-14-2013 8:51 AM


Re: Great Debate Message 9 and correlations again
Rather obviously, to me, mindspawn does not really understand how dendrochronology works and so he is clutching to a straw argument.
That's pretty much his approach to everything. From neutrons affecting decay rates, to a world wide flood that might be, to carbon fourteen dating. No conscience at all.

Under a government which imprisons any unjustly, the true place for a just man is also in prison. Thoreau: Civil Disobedience (1846)
I believe that a scientist looking at nonscientific problems is just as dumb as the next guy.
Richard P. Feynman
If there is no struggle, there is no progress. Those who profess to favor freedom, and deprecate agitation, are men who want crops without plowing up the ground, they want rain without thunder and lightning. Frederick Douglass

This message is a reply to:
 Message 34 by RAZD, posted 11-14-2013 8:51 AM RAZD has seen this message but not replied

  
RAZD
Member (Idle past 1395 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


(3)
Message 38 of 305 (711021)
11-14-2013 9:38 AM
Reply to: Message 35 by RAZD
11-14-2013 8:53 AM


Re: Great Debate Message 11 and misunderstanding
In Message 11 midspawn states
I've been thinking about what you have been saying, and realize where the misunderstanding could have come in. I think your graph distracted me because that is the only supporting evidence that you have posted and your graph was referring to various forms of corroboration, and comparing these to calibrated radiocarbon dates (dates that had been adjusted for variation of the magnetic field and calibrated according to other forms of dating).
No. The dates calculated from the 14C/12C ratio are based on the exponential decay curve for 14C, there is no adjustment "for variation of the magnetic field" -- another red herring.
Annual counts on one axis, raw 14C/12C ratio dates on the other. Simple.
quote:
Age Correlations and An Old Earth, Version 2 No 1, Message 4
... The "carbon-14 age" of a sample is really a measurement of the quantity of carbon-14 in the sample compared to the total carbon in the sample. This quantity measurement is then transformed by a mathematical formula based on radioactive decay into a theoretical "age," but this "age" is really just a mathematical scale for displaying the actual amount of carbon-14 in the sample. ... two samples of the same age - that lived in the same atmospheric environment and absorbed the then existing levels of atmospheric carbon-12, carbon-13 and carbon-14 (the three common isotopes) - will have the same levels of carbon-14 in the samples today. ... Thus, when sample {A} is dated to {X} years by dendrochronology and it has level {Y} carbon-14 content, and when sample {B} is also dated to {X} years by dendrochronology and it has level {Y} carbon-14 content, the carbon-14 content validates the age - because, growing in the same environment, they could not be the same age and NOT have the same carbon-14 content.
Carbon-14 is a radioactive isotope of carbon.
carbon | Infoplease (1)
quote:
Carbon has 13 known isotopes, which have from 2 to 14 neutrons in the nucleus and mass numbers from 8 to 20. Carbon-12 was chosen by IUPAC in 1961 as the basis for atomic weights; it is assigned an atomic mass of exactly 12 atomic mass units. Carbon-13 absorbs radio waves and is used in nuclear magnetic resonance spectrometry to study organic compounds. Carbon-14, which has a half-life of 5,730 years, is a naturally occurring isotope that can also be produced in a nuclear reactor.
The method (8)
quote:
Three principal isotopes of carbon occur naturally - C-12, C-13 (both stable) and C-14 (unstable or radioactive). These isotopes are present in the following amounts C12 - 98.89%, C13 - 1.11% and C14 - 0.00000000010%.
How Carbon-14 Dating Works | HowStuffWorks (5)
quote:
Cosmic rays enter the earth's atmosphere in large numbers every day. For example, every person is hit by about half a million cosmic rays every hour. It is not uncommon for a cosmic ray to collide with an atom in the atmosphere, creating a secondary cosmic ray in the form of an energetic neutron, and for these energetic neutrons to collide with nitrogen atoms. When the neutron collides, a nitrogen-14 (seven protons, seven neutrons) atom turns into a carbon-14 atom (six protons, eight neutrons) and a hydrogen atom (one proton, zero neutrons). Carbon-14 is radioactive, with a half-life of about 5,700 years.
This takes energy to accomplish, and the decay releases this energy: Carbon-14 decays back to Nitrogen-14 by beta- decay:
Glossary Term - Beta Decay (7)
quote:

During beta-minus decay, a neutron in an atom's nucleus turns into a proton, an electron and an antineutrino. The electron and antineutrino fly away from the nucleus, which now has one more proton than it started with. Since an atom gains a proton during beta-minus decay, it changes from one element to another. For example, after undergoing beta-minus decay, an atom of carbon (with 6 protons) becomes an atom of nitrogen (with 7 protons).
Thus cosmic ray activity produces a "Carbon-14 environment" in the atmosphere, where Carbon-14 is being produced or replenished while also being removed by radioactive decay due to a short half-life. This results is a variable but fairly stable proportion of atmospheric Carbon-14 for absorption from the atmosphere by plants during photosynthesis in the proportions of C-12 and C-14 existing in the atmosphere at the time.
Age Correlations and An Old Earth, Version 2 No 1, Message 5
... The age calculation is based on the exponential decay curve for a radioactive element with a half-life of 5730 years:
How Carbon-14 Dating Works | HowStuffWorks (2)
t = {ln (Nf/No)/ln (1/2)} x t1/2

where t is the "C-14 age", ln is the natural logarithm, Nf/No is the percent of carbon-14 in the sample compared to the amount in living tissue, and t1/2 is the half-life of carbon-14.
t = {ln (Nf/No)/-0.69315} x 5730 = -8267 x ln (Nf/No)

Where No is the original level of the C-14 isotope in the sample (when it was alive and growing and absorbing atmospheric C-14), and Nf is the amount remaining. The value for No today is ~0.00000000010% of total organic carbon and Nf is smaller depending on how much time has passed.
Exponential curves look like this:
We can calculate (Nf/No) ratios for a number of decay ages and use those with the horizontal time frames to show what the approximate ratios would have been (we could refine those by multiplying by the ratio between the data point elevations and the 1:1 correlation line if we want to get more accurate numbers):
(Nf/No) = e^(t/-8267)
Age (yrs BP) Ratio (Nf/No)
5,730 0.5000 (= 1 half life)
8,000 0.3799
8,500 0.3576
8,830 0.3436
9,000 0.3366
9,500 0.3169
10,000 0.2983
10,500 0.2808
11,000 0.2643
11,460 0.2500 (= 2 half lives)
11,500 0.2488
12,000 0.2342
12,326 0.2251
12,500 0.2204
13,000 0.2075
13,500 0.1953
14,000 0.1839
14,500 0.1731
15,000 0.1629
15,500 0.1534
16,000 0.1444
16,500 0.1359
17,000 0.1279
17,190 0.1250 (= 3 half lives)

So you can take the raw data 14C/12C ratio and compare it to the exponential decay curve for 14C (half-life 5730 years) to determine the mathematical 14C age of the sample.
No correction or calibration.
Then, when you compare that to annual layer data (tree rings or lake varves) you see the difference between this mathematical age and the actual age, where the difference is caused by the variation in the levels of 14C in the environment at the time the sample formed (tree ring or leaf, whatever):
quote:
Age Correlations and An Old Earth, Version 2 No 1, Message 5
In the case of the Lake Suigetsu Lake Varves they present a calibration curve as well, and we can use this to represent the Carbon-14 environment in the same way we did for the tree-rings - as an indicator of what the levels of Carbon-14 were when the organic samples were alive and growing.
Just a moment... (3)
quote:

Fig. 1. (A) Radiocarbon calibration up to 45,000 yr B.P. reconstructed from annually laminated sediments of Lake Suigetsu, Japan. The small circles with 1s error represent the 14C ages against varve ages. For the oldest eight points (>38,000 years, filled circles), we assumed a constant sedimentation during the Glacial period. The green symbols correspond to the tree-ring calibration (2, 15), and the large red symbols represent calibration by combined 14C and U-Th dating of corals from Papua New Guinea (squares) (8), Mururoa (circles), and Barbados (triangles) (7). The line indicates that radiocarbon age equals calibrated age.
We are only concerned here with the open blue circles and their match to the green tree-ring data. We can note in passing, however, that the other data (red open squares and triangles) span from the dendrochronology to the lake chronology, and operate as a validating correlation link between them.
Note the lack of scatter in the graph, showing that the data is highly precise.
Enjoy.

we are limited in our ability to understand
by our ability to understand
Rebel American Zen Deist
... to learn ... to think ... to live ... to laugh ...
to share.


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This message is a reply to:
 Message 35 by RAZD, posted 11-14-2013 8:53 AM RAZD has replied

Replies to this message:
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Diomedes
Member
Posts: 995
From: Central Florida, USA
Joined: 09-13-2013


Message 39 of 305 (711027)
11-14-2013 10:41 AM
Reply to: Message 38 by RAZD
11-14-2013 9:38 AM


Re: Great Debate Message 11 and misunderstanding
Great post RAZD. Very thorough. I actually hope that Mindspawn decides to read it if he is still perusing the peanut gallery.

This message is a reply to:
 Message 38 by RAZD, posted 11-14-2013 9:38 AM RAZD has seen this message but not replied

  
JonF
Member (Idle past 158 days)
Posts: 6174
Joined: 06-23-2003


Message 40 of 305 (711030)
11-14-2013 10:52 AM
Reply to: Message 36 by NoNukes
11-14-2013 9:27 AM


Re: Spring tides
Has any ever told this buffoon that there are two spring tides per month rather than just one?
Percy did once.

This message is a reply to:
 Message 36 by NoNukes, posted 11-14-2013 9:27 AM NoNukes has not replied

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RAZD
Member (Idle past 1395 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 41 of 305 (711053)
11-14-2013 12:37 PM
Reply to: Message 40 by JonF
11-14-2013 10:52 AM


Re: Spring tides
Has any ever told this buffoon that there are two spring tides per month rather than just one?
Percy did once.
Actually there are ~25 per year ...
Lunar phase - Wikipedia
quote:
... The time between two full moons (a Lunar month) is about 29.53 days[1] (29 days, 12 hours, 44 minutes) on average ...
That's 2x365.24/29.53 = 24.74 per year ...
... and the calibration curve would be nearly vertical ...
... because the horizontal axis would be compressed while the mathematical calculation of age from the 14C/12C ratios in the samples would be unaffected.
As this is not the case it is patently obvious that tides are not a factor, which we knew anyway.
Enjoy

This message is a reply to:
 Message 40 by JonF, posted 11-14-2013 10:52 AM JonF has not replied

  
JonF
Member (Idle past 158 days)
Posts: 6174
Joined: 06-23-2003


Message 42 of 305 (711059)
11-14-2013 5:03 PM


Looks as if both Coyote and Mindspring missed something.
Mindie's saying that a higher (or lower) magnetic field would affect the 14C production rate. True. But it would only affect organisms that die while the Earth's magnetic field was high (or low). After death the atmosphere could be devoid of 14C or all carbon atoms in the atmosphere could be 14C and it wouldn't affect the measurement of the sample age.
Of course there are two questions to ask... does the Earth's magnetic field ahve a significant effect on the atmospheric 14C/12C ratio? I dunno, but let's assume it does for the sake of argument. Then, what effect would it have? From Earth's Magnetic Field Strength - Past 800,000 Years:
we can see that for much of the last 50,000 years1 the magnetic field has been weaker than it is now. So if the magnetic field weakening allowed more 14C production and increased the 14C/12C ratio in the atmosphere, then organisms that died during that period would have a higher initial 14C/12C ratio than we assume (absent calibration) and the raw ages would be too young by a large factor.
Poor Mindie can't see the simplest of problems with his wild fantasies.
----------------
1By conventional dating, of course. But no matter how you want to assign dates the last 50,000 years on that graph corresponds very closely with the last 50,000 years of raw carbon dates.
Edited by JonF, : No reason given.
Edited by JonF, : No reason given.

  
NoNukes
Inactive Member


Message 43 of 305 (711064)
11-14-2013 5:30 PM


Sigh...
The debate is going as I expected. Mindspring has raised the variability of C-14 formation in the atmosphere, which is pretty much the point to raise.
However, I note that he expects Coyote to rebut the effect of rainfall on tree rings, and if I'm correct varves. I don't believe he has established any such variation on varves.
I would recommend hammering mindspring with other radiometric data while making him do his homework on tree rings and varves. Of course he will then retreat to extrapolating from the tiny, unexplained variations in decay rates.
And the solution is to force mindspawn to explain why all variations seem to work in exactly the same direction and with the same magnitude and time dependence.

Under a government which imprisons any unjustly, the true place for a just man is also in prison. Thoreau: Civil Disobedience (1846)
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RAZD
Member (Idle past 1395 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


(1)
Message 44 of 305 (711075)
11-14-2013 10:02 PM
Reply to: Message 38 by RAZD
11-14-2013 9:38 AM


Re: Great Debate Message 13 and Message 14
In Message 13 midspawn states
Carbon-14 - Wikipedia
"Production rates vary because of changes to the cosmic ray flux incident, such as supernovae, and due to variations in the Earth's magnetic field. The latter can create significant variations in carbon-14 production rates, although the changes of the carbon cycle can make these effects difficult to tease out"
"The natural atmospheric yield of carbon-14 has been estimated to be about 22 000 atoms 14C per meter square of the surface of the earth per second, resulting in the global production rate of about 1 PBq/a.[11] Another estimate of the average production rate[12] gives a value of 20 500 atoms m−2s−1. Occasional spikes are possible; for example, there is evidence for an unusual 10-fold increase of the production rate in AD 774—775.[13]"
We have known for decades that the amount of 14C in the atmosphere varies, and we've also known that one of the causes of this variation is the 11 year sunspot cycle in the production of cosmic rays.
We have also known that the predominant area where 14C is produced is in the upper layers of the troposphere and the stratosphere by thermal neutrons absorbed by nitrogen atoms.
Carbon-14 - Wikipedia
quote:
The highest rate of carbon-14 production takes place at altitudes of 9 to 15 km (30,000 to 50,000 ft) and at high geomagnetic latitudes.
ie -- over the poles, due to the interaction of the cosmic rays with the magnetic field that shields most of the earth from them.
mindspawn quotes wiki (see above) and then claims
A ten-fold increase was recorded in AD 774-775. Spikes are possible. The strength of the magnetic field causes significant variation. It appears that the conventional carbon dates require significant calibration to be an accurate reflection of true dates. The accuracy of carbon dating is entirely dependent on calibration with known dates.
What we are seeing is a confusion of the production rate with the total reservoir of 14C in the atmosphere. Let's look at wiki a little further:
quote:
Dispersion in the environment
After production in the upper atmosphere, the carbon-14 atoms react rapidly to form mostly (about 93%) 14CO (carbon monoxide), which subsequently oxidizes at a slower rate to form 14CO2, radioactive carbon dioxide. The gas mixes rapidly and becomes evenly distributed throughout the atmosphere (the mixing timescale in the order of weeks). Carbon dioxide also dissolves in water and thus permeates the oceans, but at a slower rate.[10] The atmospheric half-life for removal of 14CO2 has been estimated to be roughly 12 to 16 years in the northern hemisphere. The transfer between the ocean shallow layer and the large reservoir of bicarbonates in the ocean depths occurs at a limited rate.[15]
Newly produced 14C gets transformed into 14CO2 and is dispersed world-wide in a matter or weeks, but it takes 12 to 16 years for half of that newly produced 14CO2 to be removed from the atmosphere -- ie taken up by plants or the ocean.
As an analogy consider a large canister of water, new water is introduced from a variable source, with spikes up to 10 times average rates of flow, out flow is at the bottom and is fairly steady, but varies with the depth of the water. When inflow exceeds outflow the level in the canister rises and outflow increases slightly, and when the outflow exceeds the inflow the level lowers and outflow decreases slightly. The larger the reservoir in the canister the smaller the effect of inflow spikes on the overall volume.
When we see that "atmospheric half-life for removal of 14CO2 has been estimated to be roughly 12 to 16 years in the northern hemisphere" we can see that this essentially means that the total reservoir is large in comparison to the production as the change to the total volume of 14C would be more related to a 14 year running average of production.
Thus the overall effects of variation in the production of 14C in the atmosphere are smoothed out by the total reservoir of 14C in the atmosphere.
Not surprisingly this is reflected in the actual graphs of 14C against known age samples.
A ten-fold increase was recorded in AD 774-775. Spikes are possible. The strength of the magnetic field causes significant variation. It appears that the conventional carbon dates require significant calibration to be an accurate reflection of true dates. The accuracy of carbon dating is entirely dependent on calibration with known dates.
Nope. Input variation does not equal total reservoir variation, just a fraction of it. Curiously 14C measurements are dependent on total reservoir levels, not on production.
In Message 14 coyote replies
And your objection that cosmic rays/magnetic field can cause radiocarbon dates to vary wildly is unfounded. That is what the calibration curve does--it permits correction of the conventional radiocarbon ages for the effects of cosmic rays and the changing magnetic field. In other words, the variations in C14 levels in the atmosphere are accounted for! There goes your objection.
Raw 14C results on the "y" axis, actual age on the "x" axis. This IS the calibration that shows the total reservoir variation over time.
Raw 14C dates have a series of spikes and jags, yes, due to variations in the total reservoir levels of 14C, yes, but the overall pattern is precise (there is a precise, repeatable, relation between 14C date and actual date) and a 90% overall accuracy.
Enjoy
Edited by RAZD, : added
Edited by RAZD, : clarity

we are limited in our ability to understand
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This message is a reply to:
 Message 38 by RAZD, posted 11-14-2013 9:38 AM RAZD has replied

Replies to this message:
 Message 45 by RAZD, posted 11-14-2013 10:29 PM RAZD has replied

  
RAZD
Member (Idle past 1395 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 45 of 305 (711078)
11-14-2013 10:29 PM
Reply to: Message 44 by RAZD
11-14-2013 10:02 PM


Re: Great Debate Message 15 and Message 16
In Message 13 midspawn states
I dealt with 7 of these "known dates". Your challenge is to show how the small catchment area leading into varves of Lake Suigetsu would not be rainfall dependent , and would be seasonal. I did mention tides before but I am currently focussed on precipitation causing regular sedimentation and varves in the lake.
Additionally please prove that layers from ice cores are not precipitation dependent, but are seasonal.
Additionally please prove that tree rings in arid conditions (bristlecone pines) are not rainfall dependent but are formed seasonally/annually.
Nope, these are NOT dealt with by handwaving gibberish about rainfall dependence, unless mindspawn thinks all scientists are gibbering idiots totally incapable of identifying and accounting for climate variations ...
His comments have each been dealt with in detail to show that his fantasy criticisms are invalid. He just won't read it.
My discussion is with you only, you are welcome to re-post anything you feel is significant from the peanut gallery into this thread.
Perhaps coyote should repost the entire peanut gallery thread so that mindspawn has no more excuse to ignore it. Certainly he has avoided confronting information in order to maintain his belief (cognitive dissonance in action).
In Message 14 coyote replies
You expect us to believe that all of the different elements that go into the calibration curve are all wrong, for a variety of different reasons, in the exact same manner?
Tree-rings in California and Europe, lake and glacial varves in a variety of locations, spelothems, and corals are all wrong but still give the same answers!
Yes, it is the correlations that show that these methods are accurate and precise ... and consistently agree.
Mindspawn needs to explain how a rainstorm over a lake in Japan affect the growth of trees on the Sierra Nevada mountains and in Ireland and Germany.
Enjoy

we are limited in our ability to understand
by our ability to understand
Rebel American Zen Deist
... to learn ... to think ... to live ... to laugh ...
to share.


Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click)

This message is a reply to:
 Message 44 by RAZD, posted 11-14-2013 10:02 PM RAZD has replied

Replies to this message:
 Message 46 by Coyote, posted 11-14-2013 10:32 PM RAZD has seen this message but not replied
 Message 68 by RAZD, posted 11-15-2013 6:17 PM RAZD has seen this message but not replied

  
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