Carbon dating circular reasoning
13-Nov-2019 01:05
Nor can it tell if a much older spearhead was attached to a brand-new shaft.
Most archaeological items can’t be directly carbon dated, so their dating is based on testing done on nearby objects or materials.
For this reason, it’s preferable to date objects using multiple methods, rather than relying on one single test.
Carbon dating is reliable within certain parameters but certainly not infallible.
This provides good information, but it only indicates how long ago that piece of wood was cut from a living tree.
Radiocarbon dating can’t tell the difference between wood that was cut and immediately used for the spear, and wood that was cut years before being re-used for that purpose.
"Wood specimens considered for 'long chronologies' are first radiocarbon dated. Continuing use of the method depends on a 'fix-it-as-we-go' approach, allowing for contamination here, fractionation here, and calibration whenever possible.
If the date is old enough (perhaps by an erroneous reading), tree-ring specialists look at ring thicknesses for a way to extend the 'long chronology'. It should be no surprise, then, that fully half of the dates are rejected.
And finally, they count all of the tree-rings, using the matching patterns to connect all the pieces, and they determine the age of the oldest piece of wood.
This is how it works: scientists begin with a living tree or dead wood specimen which can be accurately dated by some reliable means.
Then they look for pieces of dead wood which are older than the specimen which they started with and whose tree-ring patterns match up with and overlap those of the first specimen (tree-rings can vary greatly in width due to environmental factors and thus produce a pattern by which we can match specimens which grew in the same environment).
This is called a "long chronology." By dating the oldest piece of wood using the Carbon dating method and comparing the two dates, scientists can make the necessary adjustments to their calculations. Aardsma, "Myths Regarding Radiocarbon Dating," Impact, No.
Unfortunately, this method of calibrating Carbon dating by using tree-ring dating is itself flawed. 189, March 1989.)Carbon Dating - What Do The Experts Think?
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