Changes

==Uranium-Lead Dating==

==Uranium-Lead Dating==

In your article, you do mention uranium-lead decay, and that lead in the sample originally would skew the resulting age.  Zircon, which is often used in dating, has the the property that, when crystallizing, it will exclude all lead and will trap surrounding uranium.  The lead that is found in zircon, then, can only have been the product of uranium decay.<ref>http://www.astronomy.ohio-state.edu/~pogge/Ast161/Unit5/deeptime.html</ref> <ref>http://www.geology.wisc.edu/zircon/zircon_home.html</ref> Also, one can calculate the amount of contamination.  Any process that allows one isotope of will let in the others found on Earth.  By measuring the amount of lead 204 (which is non-radiogenic and therefore could not have been produced by the decay of the uranium), we would know the amounts of the other isotopes (through the relative amounts on Earth, which are nearly uniform) that contaminated the sample.<ref>http://mightylib.mit.edu/Course%20Materials/22.01/Fall%202001/radiometric%20dating.pdf</ref> (page 8 by the way).  From this, the age could be calculated. --[[User:Phillipps|Phillipps]] 12:53, 8 March 2008 (EST)

In your article, you do mention uranium-lead decay, and that lead in the sample originally would skew the resulting age.  Zircon, which is often used in dating, has the the property that, when crystallizing, it will exclude all lead and will trap surrounding uranium.  The lead that is found in zircon, then, can only have been the product of uranium decay.[http://www.astronomy.ohio-state.edu/~pogge/Ast161/Unit5/deeptime.html] [http://www.geology.wisc.edu/zircon/zircon_home.html] Also, one can calculate the amount of contamination.  Any process that allows one isotope of will let in the others found on Earth.  By measuring the amount of lead 204 (which is non-radiogenic and therefore could not have been produced by the decay of the uranium), we would know the amounts of the other isotopes (through the relative amounts on Earth, which are nearly uniform) that contaminated the sample.[http://mightylib.mit.edu/Course%20Materials/22.01/Fall%202001/radiometric%20dating.pdf] (page 8 by the way).  From this, the age could be calculated. --[[User:Phillipps|Phillipps]] 12:53, 8 March 2008 (EST)

: This uses the same faulty circular reasoning the decay-based approaches.  You're assuming something about aging to prove aging.  It's like using a political poll today to predict the outcome of an election in a few months.  For obvious reasons, that approach is often wrong.--[[User:Aschlafly|Aschlafly]] 13:43, 8 March 2008 (EST)

: This uses the same faulty circular reasoning the decay-based approaches.  You're assuming something about aging to prove aging.  It's like using a political poll today to predict the outcome of an election in a few months.  For obvious reasons, that approach is often wrong.--[[User:Aschlafly|Aschlafly]] 13:43, 8 March 2008 (EST)