Re: [dinosaur] Size of the Chicxulub crater

[Dann Pigdon <dannj@alphalink.com.au>]

On Fri, Jun 16th, 2017 at 9:51 PM, Thomas Richard Holtz <tholtz@umd.edu> wrote:

> Yes, the 180 km is probably the most accurate, and current dating for the
> boundary is 66 Ma. Those who still use 65.5 or 65 have not kept up with the
> new dating techniques and results.

The date given by Renne et all in 2013 seems to have a surprisingly small 
standard deviation;
66.043 +/- 0.011 MYA. That would seem to narrow it down to within a 44,000 year 
time span
(at two standard deviations). Is Argon-Argon dating really that precise?

I worked as an archaeologist for many years, and I was used to seeing much 
larger standard
deviations on much more recent dates (C14, thermoluminescence, Uranium-Thorium, 
etc).
Admittedly that was around the turn of the century, so technology may have (in 
fact, most
likely *has*) advanced somewhat since then. :-) 

-- 
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 Dann Pigdon
 GIS Officer
 Melbourne, Australia
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