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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 <david.marjanovic@gmx.at> 

> >  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 
still considered 
relatively 'new-fangled' (even though it was first used for radiocarbon dates 
in the late 70s).


Dann Pigdon
GIS Specialist                         Australian Dinosaurs
Melbourne, Australia               http://home.alphalink.com.au/~dannj