The simple fact is that carbon dating refutes YEC claims, so YECs like Answers in Genesis make up excuses to try to deny the truth,
The simple fact is that dendrochronology does give an independant check because the dates are established by tree-ring counts. Different fragments are matched by comparing patterns within the rings.
(see
http://web.utk.edu/~grissino/ for plenty of information
http://web.utk.edu/~grissino/principles.htm describes the methods actually used)
Other methods to check C14 dating include lake varves and ice cores.
(e.g
http://www.cio.phys.rug.nl/HTML-docs/Verslag/97/PE-04.htma more popular article is at
http://more.abcnews.go.com/...ence/dailynews/carbon0220.html)
C14 is quite accurate enough to disprove YEC claims - and that has been proven beyond reasonable doubt.
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