http://reasonablefaithadelaide.org.au/g ... g-methods/
(OEC facing up to scientific reality; I had to search for this as CMI failed by supply a direct link under their article)http://creation.com/geochronology-uncertainties
(YEC attacking OEC; I have flagged this to 'Reasonable Faith Adelaide')
Quoting the OEC Christians at ReasonableFaithAdelaide:
"Young Earth Creationists claim that radioactive dating makes the following assumptions:
1. The decay rate has been constant throughout time.
2. The isotope abundances in the specimen have not been altered during its history by the addition or removal of either parent or daughter elements.
3. When the rock was formed it contained a known amount of the daughter material.
The first item is indeed an assumption. However, there is no evidence to the contrary and the decay rates conform with atomic theory.
The second item is not an assumption. Methods do exist for detecting loss or removal of the parent or daughter elements and also for estimating when these events occurred.
The third item is also not an assumption. For Uranium/lead dating, molten Zircon rejects Lead. This can be tested in the laboratory in the here and now. Hence, the initial composition of the Zircon crystal is known.
Justin [Payne] claims the Young Earth Creationists (YECs) highlight the minor instance where dating methods do not work and do not properly acknowledge the majority of cases where they do. Geochronologists are aware of the assumptions in the method and of possible causes of erroneous readings."
I note that (a) the Mason response is exceedingly long-winded and (b) only belatedly seeks to address the specific points by Payne as summarised by Rogers on how YECs over-claim about the number of 'assumptions' involved when undertaking radiometric dating via two uranium-lead decay processes (dating zircons which contain tiny amounts of uranium but which 'reject' lead). On (b) the section headed 'Assumptions: Initial composition and closed system' by Mason suggests (verbosely and rather technically) that potassium-argon dating involves assumptions and uncertainties .... Yes, really! Never mind that the material from ReasonableFaithAdelaide was discussing two uranium-lead dating methods ... To quote from the first link above (which I think Mason does not want CMI supporters to read): "Zircon crystals are small crystals that form within rocks, such as granite. In its molten state, Zircon rejects lead. Thus, when Zircon crystals are formed, they will not contain any lead. Thus the age of a Zircon crystal can be dated from the Uranium/Lead ratio".
So does Mason even address this specific point? No! He TOTALLY fails - after mentioning them just once - to discuss the known properties of zircon crystals with respect to ReasonableFaithAdelaide's point 3 (quoted above) where they discussed a dating 'assumption' that is not really an assumption at all.
Mason does discuss zircons - but ONLY when speculating (wildly), when discussing the perfectly reasonable 'constant half-life' assumption, that radioactive decay rates - 'must' if YEC-ism can possibly be true - have been 'very much different' (my paraphrase of his position) in the recent past. (Because of Noah's Flood - of course.) He then discusses the supposed refutation of uranium-lead dating methods offered by the non-peer reviewed YEC 'RATE Project'. At this point I gave up trying to read every paragraph, due to the article's excessive length and inclusion of what look like irrelevancies (though I did not watch the actual ReasonableFaithAdelaide lecture), and merely skimmed the text.
However, I have read Mason's 'Conclusion'. Where he again completely FAILS to deal with the zircon issue removing the need for 'assumptions' on the point that when a "rock was formed it contained a known amount of the daughter material" (ie no lead measured today could have been there at the outset and therefore all of it is very likely to have been formed during radioactive decay at a constant and measured rate).
I quote Mason: "Some evidence (derived from radioactive decay), when interpreted using assumptions known to be invalid (or, at least, highly suspect), an interpretative framework (uniformitarianism) known to give erroneous answers in commonplace situations and a presupposition (naturalism) known to preclude correct explanations, can be misinterpreted as indicating that the earth is ca. 4.54 billion years old. However, to interpret the bulk of the evidence under the first hypothesis requires numerous unknown processes, several of which contradict known laws of physics and chemistry, as well as many disjointed, “unsubstantiated just-so stories”." NOT convincing if you believe in science.
I'm also flagging this at that ex-YECs Facebook page.