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Re: info wanted
>From: email@example.com (Stuart Milliken)
> I've just finished reading a most interesting article by Mary Leakey
> (1982),and in it she describes the use of the Potassium/Argon technique
> to date her fossil finds.My understanding was that this is a fairly
> "new" method.
Well, "moderately new". It has been around some time really.
> When was the Potassium/Argon technique developed,by whom and how does
> it compare in terms of approximate accuracy to those more "traditional"
> techniques,i.e. Uranium and/or Carbon? ...
The C14 method is limited to no more than a few hundred thousand years.
The other radioactive dating methods have longer time ranges.
[Uranium dating has never been used much for dating Cenozoic, or
even Phanerozoic, rocks, since its resolution is too low with such
small times - it is more suited to dating *really* *old* rocks].
Somebody correct me if I am wrong, but wasn't Argon/Argon used alot
prior to K/Ar??
> Further,if a specimen contains little,or no,Uranium, Potassium or
> Carbon,(unlikely,I know),is the only remaining dating method
> comparative stratigraphy,or are there other comparative dating methods?
Only C14 is *ever* found in the actual specimens - it is the only
*direct* radio-dating method. All of the others actually date
volcanic rocks only. One then interpolates between the volcanic
layers and the fossil-bearing layer. In the Rift Valley this can
be done with great precision since the area has been so heavily
volcanic for many millions of years that there are numerous volcano-
genic layers interspersed between the sedimentary layers.
[There are dozens of basin-wide ash layers, for instance].
The peace of God be with you.