Topic: Evolution
Quote: \xe2\x80\x9dWell, the first popular technique of creationists is to try to find examples of bad radiometric dates and offer these up as proof that radiometric dating is totally unreliable. Henry Morris, in his 1974 book "Scientific Creationism" made the claim that K/Ar dates for lava from the 1801 Hulalalei volcano lava flow ranged from 160 million years to 3 billion years old. With results like these, radiometric dating must be totally useless - how could scientists possibly be so stupid as to believe that radiometric dating could be of any merit when a simple lava flow gives such a wide range of dates - right in their own research? As usual with such claims, we\'ll have to dig a little further to get at the truth. Morris cited a study by Funkhouser and Norton \xe2\x80\x93 "Radiogenic Helium and Argon in Ultramafic Inclusions from Hawaii" published in the Journal of Geophysics Research, vol. 73, pgs. 4601 - 4607. What Morris didn\'t bother to inform his readers was that the study concerned xenoliths - fragments of foreign rock broken off by the magmas intrusion through the crust. Since they are not completely melted by the magma, they are in fact much older than the lava flow (with K/Ar dating, what you are really dating is how long it has been since the rock solidified from the molten state - at this point the daughter Argon can no longer escape from the rock). That particular study confirmed (as geologists already suspected) that xenoliths could not be properly dated with the K/Ar method. The Funkhouser and Norton study clearly stated that the "ages" determined by K/Ar dating had no geological meaning and also determined that the xenoliths contained excess argon trapped in "air" bubbles inside the rock. Of course there was no mention of these details by Morris or any of the internet postings I have seen that still list this "problem" - despite the fact that Dalrymple answered it over 10 years ago. In the same paper, Dalrymple goes on to describe in detail several other quotes taken out of context by Creationists.\xe2\x80\x9d (http://www.gate.net/~rwms/AgeEarth.html)
Response: So the radiometric data stand: the Earth, moon, and older meteorites are all 4 or so billion years old, not just a few thousand.\nChanging Decay Rates?\nAnother Creationist attempt to counter radiometric dates that are incompatible with their young-Earth religious position is to claim that decay rates are not constant, thereby throwing a monkey wrench into the calculations. There are at least two problems with this argument. \nFirst, it is not at all clear how varying decay rates could result in multiple decay sequences all agreeing on the age of an object. Remember, for example, the oldest exposed rocks on earth, dated using different parent radioisotopes? All five of the decay sequences (Rb-Sr, Pb-Pb, U-Pb, Th-Pb, and Lu-Hf) clustered right around 3.7 billion years. If decay rates vary enough to throw off dates by billions of years, why would they vary in exactly the way needed to consistently produce the same results?\nSecond, radioactive decay of nuclei is not comparable to chemical reactions. In chemistry, the rate at which chemical reaction proceeds can be altered in a number of ways, such as by changing the temperature, acidity, pressure, or reactant concentrations. Such changes, however, have essentially no effect on nuclear decay. In fact, experimental attempts to alter decay rates have been made, but failed.\n
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