> No, it depends on how old the sample is and how
> much contamination has occurred which to explain
> the result would have to apply straight across the
> board, uniformly, to over 400 samples from 2 tests
> 11yrs apart tested in multiple labs. Modern
> contamination happens in the lab, not in the
BETA ANALYTIC LABORATORY
One of the basic assumptions in carbon-14 dating is that the sample being analyzed has undergone only radioactive decay and has remained unaltered by any other process over the years since it ceased interaction with the biosphere.
This assumption, however, is rarely true. The archaeological artifacts and geological specimens sent to labs for radiocarbon dating are usually found embedded or buried with other materials that may have affected their radiocarbon content. Any carbon-containing material that affects the carbon 14 content of any given sample is therefore a contaminant.
The occurrence of contamination can be natural or artificial. Natural contamination pertains to the introduction of contaminants to the sample by its surrounding material. For example, bone samples can be contaminated by the presence of limestone or organic acids in the soil (like humic or fulvic acids) where the bones were found. Another example of a natural contaminant is plant root penetration on wood, charcoal, or soil.
Artificial contamination refers to the introduction of contaminants by man during the collection, field conservation, or packaging of the samples. Labeling of bone samples with animal glue is an example of artificial contamination. Other contaminants that may be introduced during sample collection and packaging are biocides, conservation chemicals like polyvinyl acetate and polyethylene glycol, cigarette ash, and labels and wrappers that are made of paper.
> so are we to expect all of these labs to be
> tainting their samples in the same way sample
> after sample little different 11yrs apart? This
> does not seem reasonable if even possible.
> And regardless, modern contamination affects aQuote
The key issue in sample pretreatment is that there is no method, or methods, that can be universally applied to all types of material from archaeological or geological contexts. Pretreatments are designed to remove the contaminating substances that have affected the sample during its post-depositional history. If pretreatments were able to be uniformly implemented, there would have to be a uniform and predictable array of post-depositional characteristics between all samples. Clearly, this is not the case. Each sample submitted for dating has its own specific depositional history.
> sample less and less the younger it is and no
> matter what isn't going to tack on thousands of
> years. For convenience I quote Wikipedia:
> So if a 17,000yr (15,000BC) old sample appears
> only 600yrs younger with 1% modern contamination
> it would take 18-20% contamination to get that
> sample to appear to be 5,000yr (3,000BC) old.
> There is no stretch of the imagination to make
> this plausible.
It must be plausible because they have charts for it.
BETA ANALYTIC LABS