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Re: Australia's oldest painting was of a flightless dinosaur
On Mon, May 31st, 2010 at 8:39 PM, David Marjanovic <firstname.lastname@example.org>
> > As far as I know, the oldest dated rock art in Australia is about
> > 40,000 years - which is suspiciously right at the limits of
> > radiocarbon dating.
> Those limits are closer to 60,000 years (10 half-lives is 57,000),
> though it's not very precise for dates that old.
Yes. 40KYA is more the practical limit, before your standard deviations begin
to get unacceptable.
I also seem to recall that pre-AMS methods tended to yield maximum dates of
around 40KYA even
for older material, due to the problems of accurately detecting such small
amounts of remaining
C14. Hence why the initial occupation date for Australia tended to hover around
the 40KYA mark
for a long time, before other dating techniques starting yielding older dates.
Even then it took a
while to convince many archaeologists that thermoluminescence dates were
reliable, since they
occasionally violated the precious 40KYA limit that was accepted for so long.
I started my BA in archaeology twenty years ago, when the AMS technique was
relatively 'new-fangled' (even though it was first used for radiocarbon dates
in the late 70s).
GIS Specialist Australian Dinosaurs
Melbourne, Australia http://home.alphalink.com.au/~dannj