Leolaia, thank you for your thorough response. I realize and had always assumed that a particular archaeologist would not necessarily do the science on 14 C dating or even date the samples in order for others to determine the age after some calibration. My impression has always been that they (archeologists) usually send the sample to a lab or to an expert for testing. I've also understood and agree with your description of how 14 C becomes part of an organism and was aware that the absorption of 14 C occurs fairly consistently and thoroughly throughout the organism. But the fact that contamination does occur is precisely what has made me question (not reject) the idea that readings can be accurate. I suppose I have to take your word for it that the margin of error is not significant. Nevertheless, it seems to me that the very idea of petrifaction, especially via permineralization, can substantially alter a specimen (ironically preserving its cellular structure) to include all kinds of components that were never part of the specimen (which contradicts Miles3's last assertion). Therefore, the accuracy of the dating can greatly depend on the state of the specimen. In the case of some of the Egyptian items you mention, the error would probably be negligible to none.
In other cases, I think about the idea that if we determined there was a global increase in the production of 14 C somewhere in the middle of a specimens life span (let's say a tree that lived 2000 years), even with a constant absorption rate, for a good deal of time, the "sudden" jump in newer 14 C may skew the dating. I do grant you that the difference may not be temporally significant, but it could be. I said:"The only thing that is for sure about 14 C is that it has a specific rate of decay or half life." To which you replied: " This is not true at all. " I'm not sure what you mean. If you mean that 14 C does not have a specific half-life, then I'm dumbfounded as to why it would be used for dating at all. My understanding is that it is invariably 5,730 years (give or take a few decades). As far as I know, that is a physical and accurately deducible scientific conclusion. I have to admit that I cheated a bit and did not read the entire article you refer to ( http://www.arch.unipi.it/Arias/Materiali_Web/Radiocarbonio/Kromer_2009_14C%20and%20dendrochron.pdf ) What I did was to search for "half life" or "half-life" and found no entries. Did you mean a different link?
Of course, I didn't mean to imply that 14 C dating should be 100% accurate. What I implied is that the possibility is there for the dating to be sufficiently inaccurate. Even if that seldom happens, it casts doubt on the dating, such as those conducted on the Shroud of Turin (1988), which place it in the 12th to 13th century but which is contradicted by Raymond Rogers (2005) for the inaccuracy (inconsistency?) of the sample used. Therefore, what the sample is and what happened to it seems to be critical in determining its age. Even though that sample was not subject to petrefaction, the reasons given by Rogers allude to "contamination" and exterior influences in the sample. That experts disagree on that makes a lay person like me more concerned and confused.
While I realize that dating methods have improved, the actual measuring of 14 C has barely budged since its conception, unless you count that the tools used today are much more expensive, sophisticated and easier to use than ever, even though they yield more or less the same results as before. The only thing I have found that is a significant improvement is a new method of 14 C testing on the entire object while submerged in a combination of gasses in a chamber in order to get a "greater" or more homogenous reading. For me that only leaves advancements in calibration and the interpretation and adjustment of things like dendrochronology as the greater explanation for "advancement". If you have a few more examples that fall outside either category, I would appreciate it if you let me know about them. I'm not trying to dump the research on you. It's just that I wouldn't know where to begin.
As for "diluvial" mentions, I can see how you could rightly interpret Ninja's reference as being biblically supportive. I gave Ninja the benefit of the doubt because I have read about evidence of ancient "green house" effects throughout geological time as well as the suggestion that significant flooding in certain areas (even after Pangaea) have been detected in rock sediments. I suppose only Ninja can say how it was meant. But the evidence I'm referring to is subject for a different consideration. The "amulet" scrolls you mention are precisely what I was referring to, those found outside the walls of Jerusalem. They contain copies of prayers that are indeed also contained in the Dead Sea Scrolls. The difference is that they pre-date the Dead Sea Scrolls by about 400 years. What caught my attention was not their content but the idea that the conception of the Bible (not so much the Pentateuch) is the manifestation of a change, particularly after the exodus from captivity in Babylon, of the Hebrews from polytheistic to monotheistic, thereby reinforcing the idea that they weren't setting down their past as much as that they were inventing it.
Etude.
