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Radiocarbon dates - from the horses mouth
#21
Actually I would take columns 1 and 2 into serious consideration. For all of the talk on this thread about the calibration of C14 dates and how that might alter the date range, to my mind, the most important aspect is ensuring that the sample from which the date is obtained can be accurately provenanced and secured within the site sequence....otherwise it's a random date 'full of sound and fury but signifying nothing' as someone more famous than I might once have writ...
With peace and consolation hath dismist, And calm of mind all passion spent...
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#22
That's very true: but it also depends on where we are treating the matter. If it is at an Archaeology convention all columns are obviously important a cannot be overlooked. But here - in the presence of one who has to double check his sentences AND is even worse off in Archaeology (that's me, of course!) who has a very low level problem in understanding the very basic things - perhaps a somewhat more "casual" attitude may be allowed, I hope.
I may add that, regerttably, strict scientific methods (and mainly their high costs) are not very popular in Sardinia, so they are less frequently applied then elsewhere... And when they are applied, more likely they are performed by foreign labs.
There are other obstacles, of course: for instance dendrochronology still may not count on a complete referrement series, becouse of the climate, influencing the quality of predominant trees (domestic and wild olive trees cavitate and cannot be used; other trees - such as oaks - where harvested for wood or do not live long enough)...
But we might discuss this later, I hope...
In the Barumini Nuraghe (called "Su Nuraxi", as if it were the only one) a thick piece of wood stuck rather high in the main dome of the building was used for C14 dating. Initially it was thought to be "a lever, or tool that could not be extracted after its use by the builders", but the most probable hypothesis is that it was a support to a larger wooden structure, a floor possibly, that helped better utilize the vertical space of the high dome.
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#23
maurizio feo Wrote:OK, thank you both for the encouragement...
My question is about a paper I found in the Internet. It' by Robert Tykot and it's about carbon dating of a number of different sardinian locations: its title is: "Social Dynamics of the prehistoric central mediterranean" (Univ. London - 1999)
In the table reporting his (and other researchers') results there appear 7 columns, some of which I badly need help with (because I cannot find any agreement between this table and the Author's final conclusions)...
From left to right they read: (1) Site, (2) Context, (3) Lab N?, (4) 14C age, (5) Error, (6) 2sigma Calibrated age range (CALIB 3,0,3), (7)Reference. I do not think that column (3) and (7) are of any interest here and column (1) and (2) only serve the purpose of making the example complete.
In particular, what baffles me is the actual final dating of nuragic towers.
One example: (1) Nuraghe Duos Nuraghes, (2) Tower A floor , (3) I-14,774, (4) 4180, (5)+- 320, (6) cal. BC3333 (3075, 3067,3040) 2915, (7) MMA 3(1992): 278.

According to my (scarce and primitive) understanding, I should subtract 1995 from 4180 and then allow for a mistake of plus or minus 320 yrs.: this procedure should yeld two hypothetical dates (in my reckoning: 1905 - 2545) high and low limits to which the building of the tower may be attributed. In column (6) I dont find any of these numbers, though. Not that this bothers me, really, though if any of you can explain my mistake I would very much appreciate it...
My final question is, in fact:
How does this table (existing for many different Nuraghi, of course, with slightly different figures) accord with the Author's conclusions that attribute the prehistoric period Nuragic I to 1600-1300 a.C.?
Thank you in advance, for your patience Smile

The crux is: Is column 4 the calibrated radiocarbon age or the uncalibrated age?
To calibrate a radiocarbon measurement of 'age at death' of the sample to a calendar date it has to be filtered through a calibration curve.

Also why are you subtracting 1995 from 4180? Is this a reference to BP (before present)? If so BP measurements are take from before 1950.

Column 6 is the calibrated date range which is an expression of a statistical function. Not just a simple high and low limits of the date. It would make more sense if you saw the density plots, which are graphs showing a visual representation of the date range.

Hope this helps.
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#24
maurizio feo Wrote:OK, thank you both for the encouragement...
My question is about a paper I found in the Internet. It' by Robert Tykot and it's about carbon dating of a number of different sardinian locations: its title is: "Social Dynamics of the prehistoric central mediterranean" (Univ. London - 1999)
In the table reporting his (and other researchers') results there appear 7 columns, some of which I badly need help with (because I cannot find any agreement between this table and the Author's final conclusions)...
From left to right they read: (1) Site, (2) Context, (3) Lab N?, (4) 14C age, (5) Error, (6) 2sigma Calibrated age range (CALIB 3,0,3), (7)Reference. I do not think that column (3) and (7) are of any interest here and column (1) and (2) only serve the purpose of making the example complete.
In particular, what baffles me is the actual final dating of nuragic towers.
One example: (1) Nuraghe Duos Nuraghes, (2) Tower A floor , (3) I-14,774, (4) 4180, (5)+- 320, (6) cal. BC3333 (3075, 3067,3040) 2915, (7) MMA 3(1992): 278.

According to my (scarce and primitive) understanding, I should subtract 1995 from 4180 and then allow for a mistake of plus or minus 320 yrs.: this procedure should yeld two hypothetical dates (in my reckoning: 1905 - 2545) high and low limits to which the building of the tower may be attributed. In column (6) I dont find any of these numbers, though. Not that this bothers me, really, though if any of you can explain my mistake I would very much appreciate it...
My final question is, in fact:
How does this table (existing for many different Nuraghi, of course, with slightly different figures) accord with the Author's conclusions that attribute the prehistoric period Nuragic I to 1600-1300 a.C.?
Thank you in advance, for your patience Smile

given calib uses BP dates then 4180 means before 1950 and this is only 60 years ago so wont much figure
the calibrated range you state as 3333 BC - 2915 BC and is no way anything to do with 1600 -1300 bc (uncalibrated) so i can only summise that these are calibrated 3333 - 2915 BP which puts you in the right ball-park (correct BC date)

what you dont say is if any of the dates in the table have been combined in a sequence to allow one to influence another

remember BC is calibrated and bc is not

this being said the contentious Su Nuraxi date of i believ 1478 BC is on a single piece of olive wood found in the structure and only dates the wood not the structure

good luck
If they can get you asking the wrong questions, they don't have to worry about answers
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#25
Thank you, Jack and Prentice! And sorry for the mess I made (both miscalculating and miswriting, 1950 turning into 1995, for reasons unknown, probably just confusion). I didn't mean to waste your time in such a silly way... And thank you for your patience!
Now, please allow for some time, enough for me to ponder your suggestions and look ober these figures again....

I also just found another work , more recent than Tykot's (regrettably it's in Spanish, so it will take a lot of sweat): RUBINOS, A., y RUIZ-G?LVEZ, M., "La cronologia absoluta del periodo nuragico a la luz del proyecto Pranemuru", TRABAJOS DE PREHISTORIA 60, n.o 2, 2003, pp. 91 a 115. This is the link (I hope it is OK to post it), in case some of you understand the language:
http://tp.revistas.csic.es/index.ph...e/view/83/83

I will be back!
:face-approve:
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#26
No worries.......:face-approve:
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