The Ages of Meteorites Meteorites, most of which are fragments of asteroids, are very interesting objects to study because they provide important evidence about the age, composition, and history of the early solar system. The majority of flows, however, had no detectable excess 40Ar and thus gave correct ages as expected. Some meteorites, because of their mineralogy, can be dated by more than one radiometric dating technique, which provides scientists with a powerful check of the validity of the results. Even the article we are directing you to could, in principle, change without notice on sites we do not control. The Manson Meteorite Impact and the Pierre Shale In the Cretaceous Period, a large meteorite struck the earth at a location near the present town of Manson, Iowa. Whenever a new date is introduced it has to find its pecking order within the geological community.
If the earth were only 6000—10 000 years old, then surely there should be some scientific evidence to confirm that hypothesis; yet the creationists have produced not a shred of it so far. And yet, they all give the same result to within a few percent. These flows buried and destroyed Pompeii and other nearby Roman cities. This is extremely powerful verification of the validity of both the theory and practice of radiometric dating. Earth and Planetary Science Letters 1969; 6: 47—55.
Argon-36 in the sample accounts for any air contamination. The youngest crystal in the footprint layer would represent the oldest possible age for the prints; the oldest crystal in the layer above it would represent the youngest they could be. Minerals usually only record the last time they cooled down below the closure temperature, and this may not represent all of the events which the rock has undergone, and may not match the age of intrusion. I do not think that decays into Argon-39 as the article states, at least not all by itself. In this case the method is again salvaged by changing his assumptions about the past.
Bible-Science Newsletter 1981; 14 4 : 5—6. Such failures may be due to laboratory errors mistakes happen , unrecognized geologic factors nature sometimes fools us , or misapplication of the techniques no one is perfect. Potassium-40 decays in 2 different ways. . The second thing is that some of the results have been repeated using the same technique, which is another check against analytical errors. The J factor relates to the of the neutron bombardment during the irradiation process; a denser flow of neutron particles will convert more atoms of 40K to 40Ar than a less dense one.
Other creationists have focused on instances in which radiometric dating seems to yield incorrect results. Modern methods of analysis allow individual regions of crystals to be investigated. Potassium-40 decays with a half-life of 1250 million years, meaning that half of the 40K atoms are gone after that span of time. Acknowledgments I thank Chris Stassen and 2 anonymous reviewers for their thoughtful comments, which led to important improvements in the manuscript. There are several important things to note about these results.
There are quite a few steps to the logic of how argon-argon dating works but none are too complicated, although I won't go into all of the possible interferences. He assumes that any argon-40 that he measures in his rock sample must have been produced by the radioactive decay of potassium-40 since the time the rock solidified. The third is that all three meteorites were dated by more than one method — two methods each for Allende and Guarena, and four methods for St Severin. The fossils, when combined with geologic mapping, allow the various exposed sections of the Pierre Shale to be pieced together in their proper relative positions to form a complete composite section Figure 1. We have supplied this link to an article on an external website in good faith.
As a result, this method is not used except in rare and highly specialized applications. These steps help remove as much atmospheric 40Ar from the sample as possible before making the measurement. Heating causes the crystal structure of the mineral or minerals to degrade, and, as the sample melts, trapped gases are released. Those of us who have developed and used dating techniques to solve scientific problems are well aware that the systems are not perfect; we ourselves have provided numerous examples of instances in which the techniques fail. Thus the when the dinosaurs died out - previously dated at 65. Today this shocked quartz is found in South Dakota, Colorado, and Nebraska in a thin layer the Crow Creek Member within a thick rock formation known as the Pierre Shale.
Summary In this short paper I have briefly described 4 examples of radiometric dating studies where there is both internal and independent evidence that the results have yielded valid ages for significant geologic events. So, how do we work out how much excess argon we have? The creationist approach of focusing on examples where radiometric dating yields incorrect results is a curious one for two reasons. It is these studies, and the many more like them documented in the scientific literature, that the creationists need to address before they can discredit radiometric dating. Because of this, we can assume that the potassium-40:potassium-39 ratio in minerals at any time is a constant. Measuring the age of this impact event independently of the stratigraphic evidence is an obvious test for radiometric methods, and a number of scientists in laboratories around the world set to work.
Some so-called creation scientists have attempted to show that radiometric dating does not work on theoretical grounds for example, Arndts and Overn 1981; Gill 1996 but such attempts invariably have fatal flaws see Dalrymple 1984; York and Dalrymple 2000. Creationists who wants to dispute the conclusion that primitive meteorites, and therefore the solar system, are about 4. Rock samples are recorded, marked, sealed and kept free of contamination and excessive heat on the way to the lab. Scientists who use radiometric dating typically use every means at their disposal to check, recheck, and verify their results, and the more important the results the more they are apt to be checked and rechecked by others. The purpose of this paper is to describe briefly a few typical radiometric dating studies, out of hundreds of possible examples documented in the scientific literature, in which the ages are validated by other available information. Young rocks have low levels of 40Ar, so as much as several kilograms may be needed.
He assumes the initial argon content is zero. And yet the results are the same within analytical error. Radiometric dating of rocks and minerals using naturally occurring, long-lived radioactive isotopes is troublesome for young-earth creationists because the techniques have provided overwhelming evidence of the antiquity of the earth and life. This is a tall order and the creationists have made no progress so far. Geological Society of America Bulletin 1998; 110: 361—76.