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There are many types of meteorites. There are 3 important things to know about the ages in Table 1. Is this a remarkable coincidence? Try, for example, wearing a watch that is not waterproof while swimming. These methods provide valuable and valid age data in most instances, although there is a small percentage of cases in which even these generally reliable methods yield incorrect .
Not only that, they have to show the flaws in those dating studies that provide independent corroborative evidence that radiometric methods work. Second, it is an approach doomed to failure at the outset. And yet, they all give the same result to within a few percent. Because of their importance, meteorites have been extensively dated radiometrically; the vast majority appear to be 4. This is extremely powerful verification of the validity of both the theory and practice of radiometric dating.
The from three meteorites are shown in Table 1. Numerous thin beds of volcanic ash occur within these coals just centimeters above the K-T boundary, and some of these ash beds contain minerals that can be dated radiometrically.
Such rock may be due to laboratory errors mistakes happenunrecognized geologic factors nature sometimes fools usor misapplication of the techniques no one is perfect. First, the Cretaceous and Tertiary periods were defined by geologists in the early s. Scientists have concluded that it is not; it is instead a consequence of the fact that radiometric dating actually works and works quite well.
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. Where are the data and age calculations that result in a consistent set of ages for all rocks on earth, as well as those from the moon and the meteorites, no greater than dating years?
There are several important things to note about these. No — it Dakota the result of extremely careful analyses using a technique that works. Scientists from the US Geological Survey were the first to obtain radiometric ages for the tektites and laboratories in Berkeley, Stanford, Canada, and France soon followed suit.
We have even discredited entire techniques. The most primitive type of meteorites are called chondrites, because they contain little spheres of olivine crystals known as chondrules. Others are from larger asteroids that got hot enough to melt and send lava flows to the surface. Incremental heating experiments on 12 samples of sanidine yielded 46 data points that resulted in an isochron age of 94 years.
The second thing is that some of the have been repeated using the same technique, which is another check against analytical errors. The actual age of the flow in was years. As a result, this method is not used except in rare and highly specialized applications. It will probably fail, but what would a reasonable person conclude from that?
The impact also created shocked quartz crystals that were blasted into the air and subsequently fell to the west into the inland sea that occupied much of central North America at that time. Since both the ash beds and the tektites occur rock at or very near the K-T boundary, as determined by diagnostic fossils, the tektites and the Dakota beds should be very nearly dating same age, and they are Table 2.
In most instances, these efforts are flawed because the authors have misunderstood or misrepresented the data they attempt to analyze for example, Woodmorappe ; Morris HM ; Morris JD Only rarely does a creationist actually find an incorrect radiometric result Austin ; Rugg and Austin that has not already been revealed and discussed in the scientific literature. Some are from primitive asteroids whose material is little modified since they formed from the early solar nebula.
In order to accomplish their goal of discrediting radiometric dating, however, creationists are faced with the daunting task of showing that a preponderance of radiometric ages are wrong — that the methods are untrustworthy most of the time. The K-T tektites were ejected into the atmosphere and deposited some distance away. It is rare for a study involving radiometric dating to contain a single determination of age. Second, ages were measured on two very different minerals, sanidine and biotite, from several of the ash beds.
Usually determinations of age are repeated to avoid laboratory errors, are obtained on more than one rock unit or more than one mineral from a rock unit in order to provide a cross-check, or are evaluated using other geologic information that can be used to test and corroborate the radiometric ages. The Pierre Shale also contains volcanic ash that was erupted from volcanoes and then fell into the sea, where it was preserved as thin beds. These flows buried and destroyed Pompeii and other nearby Roman cities.
We rock the exact day of this eruption because Pliny the Younger carefully recorded the event. Scientists who use radiometric dating typically use every means at their disposal to check, recheck, and verify theirand the more important the the more they are apt to be checked and rechecked by others. 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. All they indicate is that the methods are not infallible.
Third, the radiometric ages agree, within analytical error, with the relative positions of the dated ash beds as determined by the geologic mapping and the fossil assemblages; that is, the ages get older from top to bottom as they should. This is not the only dating study to be done on an historic lava flow.
A few verified examples of incorrect radiometric ages are simply insufficient to prove that radiometric dating is invalid. In the early afternoon of August 24, 79 CE, Mt Vesuvius erupted violently, sending hot ash flows speeding down its flanks. The boundary between these periods the K-T boundary is marked by an abrupt change in fossils found in sedimentary rocks worldwide.
Many more, plus a discussion of the different types of meteorites and their origins, can be found in Dalrymple Table 1. The Pierre Dakota, which is divided into identifiable sedimentary beds called members, also contains abundant fossils of numerous species of ammonites, ancestors of the chambered nautilus. One of the most exciting and important scientific findings in decades was the discovery that a large asteroid, about 10 kilometers diameter, struck the earth at the end of the Cretaceous Period.
The fallout from this enormous impact, including shocked quartz and high concentrations of the element iridium, has been found in sedimentary rocks at more than locations worldwide at the precise stratigraphic location of the Cretaceous-Tertiary K-T boundary Alvarez and Asaro ; Alvarez We now know that the impact site is located on the Yucatan Peninsula.
The collision threw many tons of debris into the atmosphere and possibly led to the extinction of the dinosaurs and many other life forms. I could have selected many more examples but then this would have turned into a book rather than the intended short paper. Measuring the age of this impact event independently of the stratigraphic evidence is an obvious test for radiometric methods, and a of scientists in laboratories around the world set to work. In addition to shocked quartz grains and high concentrations of iridium, the K-T impact produced tektites, which are small glass spherules that form from rock that is instantaneously melted by a large impact.
I have selected four examples from recent literature, mostly studies involving my work and that of a few close colleagues because it was easy to do so. The fossils, when combined with geologic mapping, allow the various exposed sections of the Pierre Dakota to be pieced together in their proper relative positions to form a complete composite section Figure 1.
There are three important things to note about these. Glaringly absent, it seems. Table 2. Rock yet the are the same dating analytical error.
The manson meteorite impact and the pierre shale
This pretty much eliminates any ificant laboratory biases or any major analytical mistakes. Its exact location in the stratigraphic column at any locality has nothing to do with radiometric dating — it is located by careful study of the fossils and the rocks that contain them, and nothing more.
Figure 1. Creationists seem to think that a few examples of incorrect radiometric ages invalidate all of the of radiometric dating, but such a conclusion is illogical. A few are even from the Moon and Mars. Some so-called creation scientists have attempted to show that radiometric dating does not work on theoretical grounds for example, Arndts and Overn ; Gill but such attempts invariably have fatal flaws see Dalrymple ; York and Dalrymple Other creationists have focused on instances in which radiometric dating seems to yield incorrect .
We often test them under controlled conditions to learn when and why they fail so we will not use them incorrectly. They separated sanidine crystals rock a sample of one of the ash flows. Furthermore, the dating was done in 6 different laboratories and the materials were collected from 5 different locations in the Western Hemisphere. As a result, it is nearly impossible to be completely fooled by a good set of radiometric age data collected as part of a well-deed experiment.
Today this shocked quartz is found in South Dakota, Colorado, and Nebraska in a thin layer the Dating Creek Member within a thick rock formation known as the Pierre Shale. The first is that each meteorite was dated by more than one laboratory — Allende by 2 laboratories, Guarena by 2 laboratories, and St Severin by four laboratories. This is a tall order and the creationists have made no progress so far. Even things that work well do not work well all of the time and under all circumstances. For example, after extensive testing over many years, it was concluded that uranium-helium dating is highly unreliable because the small helium atom diffuses easily out of minerals over geologic time.
First, it provides no evidence whatsoever to support their claim that the earth is very young. Rock who wants to dispute the conclusion that primitive meteorites, and therefore the solar system, are about 4. The purpose of this paper is to describe briefly a few typical radiometric dating studies, out dating hundreds of possible examples documented in the scientific literature, in which the ages are validated by other available information.
Is this just a coincidence? 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. Finally, the inferred age of the shocked quartz, as determined from the age of the melted feldspar in the Manson impact structure 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.
Tektites are easily recognizable and form in no other way, so the discovery of a sedimentary bed the Beloc Formation in Haiti that contained Dakota and Dakota, from fossil evidence, coincided with the K-T boundary provided an obvious candidate Dakota dating. If the earth were only —10 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. In the case of St Severin, for example, we have 4 different natural clocks actually 5, for the Pb-Pb method involves 2 different radioactive uranium isotopeseach running at a different rate and each using elements that respond to chemical and physical conditions in much different ways.
In the Cretaceous Period, a large meteorite struck the earth at a location near the present town of Manson, Iowa. First, each age is based on numerous measurements; laboratory errors, had there been any, would be readily apparent. The from dating of the laboratories were remarkably consistent with the measured ages ranging only from Similar tektites were also found in Mexico, and the Rock lab found that they were the same age as the Haiti tektites.
The creationist approach of focusing on examples where radiometric dating yields incorrect is a curious one for two reasons. That watches do not work? 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. The K-T boundary is recorded in numerous sedimentary beds around the world. The heat of the impact melted some of the feldspar crystals in the granitic rocks of the impact zone, thereby resetting their internal radiometric clocks.