posted on Apr, 26 2003 @ 04:18 PM
Information on the "new" technique would be interesting: is it new, or is it a refinement of existing (e.g. carbon-based) techniques? Posted by
It mentions a radiometric dating technique using unstable isotopes of aluminum and berryllium and Cosmic Rays (this must be new, I have never heard of
it). Carbon 14 dating usually only has a an effective range of about 100 years to 75,000 years with a margin for error of between 200-1000 years
(error margin increases the further back you go). I have heard something about a new technique for Carbon 14 that they can get up to 150,000 years
effective range, but have never tried it, so dont know much about it.
Sedimentary deposits are notoriously difficult to date accurately, because they are not what is called parent deposition. In other words, if you find
a fossil buried in sand and gravel, and you date that gravel using a normal radiometric method (say, potassium/argon), the date you get is the date
that the original magma crystallized... it could be millions of years from the time this magma crystallized until it weathered, broke down, and formed
gravel that found its way into wherever you found it... and it could then be many more years until your fossil find was deposited where you found
There are some dating methods where you measure mineral formation on the fossil, or inside voids of the fossil, if such minerals form at a known rate.
However, such methods are not any more accurate, and have a limited date range as well.