How, exactly, is dating done?

Still totally irrelevant. But one thing is worth a response. Yes, we should test all things, and discard those that fail the tests. Your hypothesis about the age of life on Earth was tested long before radioisotope dating was invented ... and it failed the test. Life on Earth is old.

What magma chamber? And, of course, this is irrelevant to the subject of this thread. Walt's "theory" is no such thing ... if he improved it significantly, he might be able to get it up to the level of an opium dream. But the evidence and observations that we have do mean that the different ages we measure for rocks are not related to your imaginary argon rising up from any magma chamber, and are not related to your fantasy of argon concentrations 20,000 times greater in the inner earth compared to atmospheric concentrations, and are not related to any of the other fictions you have posted.Until you have addressed the fact that so many totally different dating methods agree, you haven't addressed anything. Until you learn something about the subject, you will continue to be unable to make anything other than meaningless and irrelevant posts.Mods, is this thread ready for euthanasia? Mr. whatever certainly appears to be incapable of and uninterested in addressing the subject of the accuracy of radioisotope dating.[This message has been edited by JonF, 01-15-2004]

It's not polite to make a claim like that without providing the reference in the message where you make the claim.Of course and as usual, you are wrong. At http://www.geo.cornell.edu/...6notes03/656%2003Lecture06.pdf we find:"Atmospheric argon has a constant 40Ar/36Ar ratio of 295.5 ... some samples can have "initial" 40Ar/36Ar ratios greatert than the atmospheric ratio; this can lead to too old an age if not properly accounted for {emphasis added - JRF} ... For example, mantle-derived basalts have been shown in some cases to have 40Ar/36Ar ratios in excess of 20,000. The 40Ar/36Ar ratio reflecs the production of 40Ar by decay of 40K within the mantle. Minerals crystallizing in the presence of this gas will trap some of this 40Ar, which will result in an anomolously old age upon analysis."The rest of the lecture is concerned with how this problem is detected and accounted for.So, some but not all basalts have a 40Ar/36Ar ratio that is 20000/295.5 = 67.7 times larger than the atmospheric ratio, not 20,00 times larger as you claimed, and more than two orders of magnitude less than you claimed. Your 20,000 times larger is a pipe dream that you made up, based on an incredible misreading of a plainly written paragraph..The situation mentioned does not occur in all analyses and can be detected and corrected in the manners described in that paper and the literature. This is known because Ar-Ar dating results agree with so many other results that are not affected by high Ar40/Ar36 ratios. Until you have addressed the consistent results obtained by different dating methods, you have not done anything.We are taking contamination into account.We are not dating sediments, we are dating igneous rocks. If you don't understand this and understand why, you know nothing.You have no idea of the realities of how diffusion works, or how mass transport works, or the theories or the realities of how dating is done, or the real-world data that has been collected.

Yes, I know. I was trying to avoid that complication, but you are correct. You didn't mention the SHRIMP results on xenotime, which I love because the mineral appears to be so aptly named ...