Re: Radiocarbon dating part II

On Nov 1, 6:18 pm, iaoua iaoua <iaoua.ia...@xxxxxxxxx> wrote:
On Nov 1, 8:11 pm, Boikat <boi...@xxxxxxxxxxxxx> wrote:

On Nov 1, 2:15 pm, iaoua iaoua <iaoua.ia...@xxxxxxxxx> wrote:> On Nov 1, 2:54 pm, John Stockwell <john.19071...@xxxxxxxxx> wrote:

On Oct 30, 10:41 am, iaoua iaoua <iaoua.ia...@xxxxxxxxx> wrote:

OK! I dropped the question in another thread. As expected lots of
misguided and gratuitously patronistic responses that, ironically,only
exemplified the level of ignorance of the scientific method to which I
have become accustomed around here.

The depth of your scientific ignorance approaches that of Pagano.

We saw lots of quotes directing to the radiocarbon wiki page.http://en.wikipedia.org/wiki/Radiocarbon_datingSolet'sstartthere
shall we. Examine the opening paragraph. Think untestable assumptions:

Radiocarbon dating (sometimes simply known as carbon dating) is a
radiometric dating method that uses the naturally occurring
radioisotope carbon-14 (14C) to estimate the age of carbon-bearing
materials up to about 58,000 to 62,000 years.[1] Raw, i.e.
uncalibrated, radiocarbon ages are usually reported in radiocarbon
years "Before Present" (BP), "Present" being defined as 1950. Such raw
ages can be calibrated to give calendar dates. One of the most
frequent uses of radiocarbon dating is to estimate the age of organic
remains from archaeological sites. When plants fix atmospheric carbon
dioxide (CO2) into organic material during photosynthesis they
incorporate a quantity of 14C that approximately matches the level of
this isotope in the atmosphere

Did you spot the blindingly obvious glaring assumption? For those who
aren't too bright around here (just about everybody evidently) I'll
give you a clue.

they incorporate a quantity of 14C that approximately matches the
level of this isotope in the atmosphere

If you still haven't got it let's zoom in even closer:

the level of this isotope in the atmosphere

Has the penny started to drop yet?

In anticipation of lots of nonsense answers about how we are so
presumptious that we think we can make reasonably accurate models of
the level of 14C in past states of the atmosphere that is what we, in
science, call AN UNTESTABLE ASSUMPTION a VARIABLE OVER WHICH WE HAVE
NO CONTROL!!!

CASE CLOSED!!!

Next up. Some other crappy dating technique that makes similar if not
worse assumptions.

The process of calibration of 14C dating is an iterative one.

Not so fast. The process of calibration of 14C dates gives an estimate
of the past 14C/12C ratios.

.
Here is a partial chronology of the
development of the calibration of carbon-14 dating and related
developments in 14C studies, which includes consideration
of sources of fluctuations in the background level of 14C.

Much of creationist commentary on the possible errors in 14C is
intended
to portray the scientific community as being either incompetent or
dishonest regarding such issues as the consideration of potential
errors
in radiometric dating methods. Creationists never discuss the fact
that given these analyses, scientists have found ways of identifying
and mitigating the effects of these potential sources of error.

What follows is a summary from chapter 14.1.3, p.364-366 of Dickin
[1995]:

1941 Thellier proposed that Earth's magnetic field experiences
secular variations.

1949 Arnold and Libby publish radiocarbon dates of items of known
age.

1952 Libby publishes first book on radiocarbon dating.

1954 Forbush observed that the 11-year cycle of sunspot activity
was inversely correlated with cosmic-ray intensity.

1955 Suess proposed dilution due to the burning of fossil fuels
for the 2% depletion of 14C activity seen in 20th century wood
compared to 19th century wood.

1956 Elsasser, et al. predicted variations in the cosmic ray flux
due to secular variations in Earth's magnetic field.

1958 de Vries found that 17-th century wood had a 2% higher activity
than 19th century wood.

1961 Stuiver used historical records of sunspot activity to calculate
cosmic ray intensity, and hence 14C production for the past 1500
years, and suggesting that the observations of de Vries,
correlated with a sunspot minima.

1965 Stuiver used more detailed records to confirm the correlation of
a sunspot minimum with de Vries observations.

1967 Bucha and Neustupny provided paleomagnetic intensity measurments
that supported the existence of secular variations in the
Earth's
magnetic field first proposed by Thellier. They were able to
model the variations of 14C production, and almost exactly match
the deviations between the tree-ring and radiocarbon time scales.

By 1969, it became apparent that calibration of the 14C dating method
was both possible, and required, to make radiocarbon dates
useful for the determination of calendar dates. (See the issues of
the journal ``Radiocarbon'' between 1960 and 1969 for published 14C
date lists.)
Indeed, it is often material from prior to 1969 that creationists
use as ammunition against the 14C dating method.

One useful method of calibrating 14C is dendrochronology, or age
dating
by counting tree rings. The basic idea of calibration is simple.
Plot
the true date determined from counting tree rings versus the
radiocarbon
date. The result is a plot that can be used to both determine the
actual original 14C/12C ratios (useful for studies in
paleoclimatology)
and can be used to convert radiocarbon dates of other samples into
calendar dates.

The first use of dendrochronlogy to calibrate 14C was made by

1970 Furgeson used dendrochronology of bristlcode pines to calibrate
radiocarbon dating back to 7484- years b.p. (before the
present).

Through comparison with tree ring dates, the 14C method has
been calibrated back to more than 13,000 years before the present,

1991 Becker, et al publish a stable dendrochronological calibration
of 14C back to 11,000 years before the present using tree rings.
The chronology consists of a 9,928-year absolutely dated
dendrochronological record of Holocene oak (Quercus robur,
Quercus petraea) and a 1,604-year floating Late Glacial and
Early Holocene chronology of pine (Pinus sylvestris) from
subfossil tree remains deposited in alluvial terraces of central
European rivers.

In addition, 14C dating has also been calibrated back to more
than 30,000 years before the present using uranium-thorium (isochron)
dating of corals [Bard, et al, 1990] and [Edwards, et al, 1993].
While it is unlikely that 14C will be useful for objects older
than 50,000 years, owing to the problems of background contamination
[Dickin, 1995] and [Lowe, 1991], there is a recent paper by
[Kitagawa, H., and van der Plicht, J., 1998] discusses calibration
of 14C dating back to 45,000 b.p. using U-Th dates of glacial lake
varve sediments (periodic sedimentary layers).

References:
Arnold, J. R. and Libby, W. F. (1949) Age determinations by
radiocarbon
content: Checks of samples with known age. Science 110,
678-680.

Bard, E., Hamelin, B., Fairbanks, R.G., and Zinder, A., (1990),
Calibration of the 14C timescale over the past 30,000 years
using mass spectrometric U-Th ages from Barbados corals,
Nature, 345, 405-410.

Becker, B., Kromer, B., and Trimborn P., 1991, A stable-isotope
tree-ring timescale of the Late Glacial/Holocene boundary:
Nature, vol. 353 (17 Oct 1991), 647-649.

Bucha, V. and Neustupny, E. (1967). Changes in the
Earth's magnetic field and radiocarbon dating. Nature 215,
261)3.

de Vries, H. (1958). Variation in concentration of radiocarbon with
time and location on Earth. Proc. Konikl. Ned. Akad.
Wetenschap B 61, 94)102.

Dickin, A. P. (1995), Radiogenic Isotope Geology, Cambridge University
Press.

Dalrymple, G. Brent, (1991), The Age of the Earth. California:
Stanford
University Press, ISBN 0-8047-1569-6.

Edwards, R. L., Beck, J. W., Burr, G. S., Donahue, D. J.,
Chappell, J. M. A., Bloom, E. R. M., Druffel, E. R. M.,
Taylor, F. W., 1993, A large drop in atmospheric 14-C/12-C
and reduced melting in the Younger Dryas*, documented with
230-Th ages in corals: Science, vol. 260 (14 May 1993), 962-967

Elsasser, W., Ney, E. P. and Winckler, J. R. (1956). Cosmic-ray
intensity and geomagnetism. Nature 178, 1226)7.

Forbush, S. E. (1954). Worldwide cosmic-ray variations, 1937)1952.
J. Geophys. Res. 59, 525)42.

Furgeson, C. W. (1970), Dendrochronology of bristlecone pines, Pinus
aristata. Establishment of a 7484-year chronology in the
White Mountains of eastern-central California, USA.
In: I. U. Olsson (Ed.), Radiocarbon Variations and
Absolute Chronology, Proc. 12th Nobel Symp. Wiley, pp.
629-40.

Kitagawa, H., and van der Plicht, J., (1998), Atmospheric radiocarbon
calibration to 45,000 yr B.P>: Late glacial fluctuations and
cosmogenic isotope production, Science, v. 279, 20 Feb 1998.

Libby, W. F. (1952) Radiocarbon dating, University of Chicago Press.

Libby, W. F. (1970) Ruminations on radiocarbon dating
In: I. U. Olsson (Ed.), Radiocarbon Variations and
Absolute Chronology, Proc. 12th Nobel Symp. Wiley, pp. 629-40.

Lowe, J. John, ed. (1991) Radiocarbon Dating: Recent Applications and
Future Potential, Quaternary Proceedings, Number 1, 1991,
Published
for the Quaternary Research Association, Wiley.

Stuiver, M. (1961). Variations in radiocarbon concentration and
sunspot activity. J. Geophys. Res. 66, 273)6.

Stuiver, M. (1965). Carbon-14 content of 18th- and 19th-century
wood: variations correlated with sunspot activity. Science
149, 533)4.

Suess, H. E. (1955). Radiocarbon concentrations in modern wood.
Science 122, 415)7.

Thellier, E. O. (1941). Sur la verification d'une methode permettant
de
determiner l'intensite du champ magnetique terrestre dans le
passe.
Compte Rendu Acad. Sci. Paris 212, 281.

-John

JC

I'm pleasantly surprised. This was actually a good post. But I still
think you need to dig a little bit deeper. I'm not very impressed by
the data used in calibration. Not enough. Too regional to make
worldwide conclusions.

Dipshit! It's used for regional conclusions, and add to that, world
wide variations at any given time BP was not so significant that it
would throw off to the point of being useless.

Who said it was useless? I distinctly remember saying it was useful
for relative approximations. i.e. this object from this site is older
than this other object from a nearby site.

Plus, introduction of new assumptions.

Is thate a logical basis for those assumptions? If you care to
challenge them, feel free.

However, undoubtedly a better attempt than before calibration was
taken seriously. This much I agree.

Damn, you are one arrogant fool!

Noting an improvement that can further be improved is not tantamount
to arrogance.

Your arrogance is that you seem to think that since accuracy improves,
then there is some Big Problem(TM) with RC dating methods, and that
for some reason you are fantasizing that you are going to make it
right.

If you believe it is then your summary of the history of
the literature would be one of outright arrogance. We scientists

You are not a scientist.

call
it critique of former work. Would you like to become a scientist my
immature emotional friend?

Talk about a pot calling a kettle black!

Boikat

.

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