The Age of the Earth
Our confidence in radiometric dating techniques comes from years of careful. Feb 18, Claim CD Radiometric dating gives unreliable results. Radiometric dates are consistent with several nonradiometric dating methods. Aug 12, While doing so, we will have to learn about how radiometric dating One of the most beneficial things about it is that it can check itself for accuracy; the closed systems. mawatari.info
They test for it and take it into account when interpreting radiocarbon data. In cases where corrections for presence of dead carbon cannot be made, such dates are readily recognized as erroneous and can be safely disregarded.
This is not the fatal flaw to radiometric dating that some creationists claim it to be. It just shows that dates from mollusks from streams and lakes need to be carefully evaluated as to their reliability. Other materials, such as wood, charcoal, bone, and hide, would remain unaffected by this type of reservoir effect. If found with shells in the same layer, these materials could be dated to determine if shells are locally affected by the reservoir effect and, if so, how much their radiocarbon dates have been skewed by it.
See also the Cdating of a seal for another example of the reservoir effect. How good are those young-earth arguments? Fictitious results with mollusk shells. It can, and has been, tested in innumerable ways since the 19th century, in some cases by physically tracing distinct units laterally for hundreds or thousands of kilometres and looking very carefully to see if the order of events changes.
Geologists do sometimes find events that are "diachronous" i. Because any newly-studied locality will have independent fossil, superpositional, or radiometric data that have not yet been incorporated into the global geological time scale, all data types serve as both an independent test of each other on a local scaleand of the global geological time scale itself.
The test is more than just a "right" or "wrong" assessment, because there is a certain level of uncertainty in all age determinations. For example, an inconsistency may indicate that a particular geological boundary occurred 76 million years ago, rather than 75 million years ago, which might be cause for revising the age estimate, but does not make the original estimate flagrantly "wrong". It depends upon the exact situation, and how much data are present to test hypotheses e.
Whatever the situation, the current global geological time scale makes predictions about relationships between relative and absolute age-dating at a local scale, and the input of new data means the global geologic time scale is continually refined and is known with increasing precision.
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This trend can be seen by looking at the history of proposed geologic time scales described in the first chapter of [Harland et al,p. The unfortunate part of the natural process of refinement of time scales is the appearance of circularity if people do not look at the source of the data carefully enough.
Most commonly, this is characterised by oversimplified statements like: When a geologist collects a rock sample for radiometric age dating, or collects a fossil, there are independent constraints on the relative and numerical age of the resulting data.
Stratigraphic position is an obvious one, but there are many others. There is no way for a geologist to choose what numerical value a radiometric date will yield, or what position a fossil will be found at in a stratigraphic section. Every piece of data collected like this is an independent check of what has been previously studied. The data are determined by the rocks, not by preconceived notions about what will be found. Every time a rock is picked up it is a test of the predictions made by the current understanding of the geological time scale.
The time scale is refined to reflect the relatively few and progressively smaller inconsistencies that are found. This is not circularity, it is the normal scientific process of refining one's understanding with new data. It happens in all sciences. If an inconsistent data point is found, geologists ask the question: However, this statistical likelihood is not assumed, it is tested, usually by using other methods e. Geologists search for an explanation of the inconsistency, and will not arbitrarily decide that, "because it conflicts, the data must be wrong.
The continued revision of the time scale as a result of new data demonstrates that geologists are willing to question it and change it. The geological time scale is far from dogma. If the new data have a large inconsistency by "large" I mean orders of magnitudeit is far more likely to be a problem with the new data, but geologists are not satisfied until a specific geological explanation is found and tested.
An inconsistency often means something geologically interesting is happening, and there is always a tiny possibility that it could be the tip of a revolution in understanding about geological history. Admittedly, this latter possibility is VERY unlikely. There is almost zero chance that the broad understanding of geological history e.
The amount of data supporting that interpretation is immense, is derived from many fields and methods not only radiometric datingand a discovery would have to be found that invalidated practically all previous data in order for the interpretation to change greatly. So far, I know of no valid theory that explains how this could occur, let alone evidence in support of such a theory, although there have been highly fallacious attempts e.
Refuting “Radiometric Dating Methods Makes Untenable Assumptions!”
When Radiometric Dating "Just Works" or not A poor example There are many situations where radiometric dating is not possible, or where a dating attempt will be fraught with difficulty. This is the inevitable nature of rocks that have experienced millions of years of history: The real question is what happens when conditions are ideal, versus when they are marginal, because ideal samples should give the most reliable dates.
If there are good reasons to expect problems with a sample, it is hardly surprising if there are! It contains a mixture of minerals from a volcanic eruption and detrital mineral grains eroded from other, older rocks. If the age of this unit were not so crucial to important associated hominid fossils, it probably would not have been dated at all because of the potential problems.
After some initial and prolonged troubles over many years, the bed was eventually dated successfully by careful sample preparation that eliminated the detrital minerals. Lubenow's work is fairly unique in characterising the normal scientific process of refining a difficult date as an arbitrary and inappropriate "game", and documenting the history of the process in some detail, as if such problems were typical. Another example is "John Woodmorappe's" paper on radiometric datingwhich adopts a "compilation" approach, and gives only superficial treatment to the individual dates.
Among other problems documented in an FAQ by Steven Schimmrichmany of Woodmorappe's examples neglect the geological complexities that are expected to cause problems for some radiometrically-dated samples. A good example By contrast, the example presented here is a geologically simple situation -- it consists of several primary i. It demonstrates how consistent radiometric data can be when the rocks are more suitable for dating.
For most geological samples like this, radiometric dating "just works". Consider this stratigraphic section from the Bearpaw Formation of Saskatchewan, Canada Baadsgaard et al. Modified from Baadsgaard et al. The section is measured in metres, starting with 0m at the bottom oldest. This section is important because it places a limit on the youngest age for a specific ammonite shell -- Baculites reesidei -- which is used as a zonal fossil in western North America.
It consistently occurs below the first occurrence of Bacultes jenseni and above the occurrence of Baculites cuneatus within the upper part of the Campanian, the second to last "stage" of the Cretaceous Period in the global geological time scale. The biostratigraphic situation can be summarized as a vertically-stacked sequence of "zones" defined by the first appearance of each ammonite species: About 40 of these ammonite zones are used to subdivide the upper part of the Cretaceous Period in this area.
Dinosaurs and many other types of fossils are also found in this interval, and in broad context it occurs shortly before the extinction of the dinosaurs, and the extinction of all ammonites.
The Bearpaw Formation is a marine unit that occurs over much of Alberta and Saskatchewan, and it continues into Montana and North Dakota in the United States, although it adopts a different name in the U. The numbers above are just summary values.
Other examples yield similar results - i. The results are therefore highly consistent given the analytical uncertainties in any measurement. Eberth and Braman described the vertebrate paleontology and sedimentology of the Judith River Formation, a dinosaur-bearing unit that occurs stratigraphically below the Baculites reesidei zone the Judith River Formation is below the Bearpaw Formation.
It should therefore be older than the results from Baadsgaard et al. An ash bed near the top of the Judith River Fm. Again, this is compatible with the age determined for the Baculites reesidei zone and its relative stratigraphic position, and even with the relative position of the two samples within the same formation.
How do these dates compare to the then current geological time scale? Here are the numbers they applied to the geological boundaries in this interval, compared to the numbers in the newer studies: Comparison of newer data with the Harland et al.
As you can see, the numbers in the rightmost column are basically compatible. Skeptics of radiometric dating procedures sometimes claim these techniques should not work reliably, or only infrequently, but clearly the results are similar: Most of the time, the technique works exceedingly well to a first approximation.
- The General Anti-Creationism FAQ
- How Old is the Earth
- How Good Are Those Young-Earth Arguments?
However, there are some smaller differences. The date for the Baculites reesidei zone is at least 0. Well, standard scientific procedure is to collect more data to test the possible explanations -- is it the time scale or the data that are incorrect?
Radiometric Dating and the Geological Time Scale
Obradovich has measured a large number of high-quality radiometric dates from the Cretaceous Period, and has revised the geological time scale for this interval. Specifically, he proposes an age of This is completely compatible with the data in Baadsgaard et al. Conclusions Skeptics of conventional geology might think scientists would expect, or at least prefer, every date to be perfectly consistent with the current geological time scale, but realistically, this is not how science works. The age of a particular sample, and a particular geological time scale, only represents the current understanding, and science is a process of refinement of that understanding.
In support of this pattern, there is an unmistakable trend of smaller and smaller revisions of the time scale as the dataset gets larger and more precise Harland et al. If something were seriously wrong with the current geologic time scale, one would expect inconsistencies to grow in number and severity, but they do not.
The same trend can be observed for other time periods. The fact that the process is probabilistic, and the exponential dependence on time, are straightforward consequences of quantum mechanics. The time dependence is a case of "Fermi's golden rule" see, for example, page of Ohanion. An exact computation of decay rates is, of course, much more complicated, since it requires a detailed understanding of the shape of the potential barrier.
In principle, this is computable from quantum chromodynamics, but in practice the computation is much too complex to be done in the near future. There are, however, reliable approximations available, and in addition the shape of the potential can be measured experimentally.
For beta decay, the underlying fundamental theory is different; one begins with electroweak theory for which Glashow, Weinberg and Salam won their Nobel prize rather than quantum chromodynamics. As described above, the process of radioactive decay is predicated on rather fundamental properties of matter. In order to explain old isotopic ages on a young Earth by means of accelerated decay, an increase of six to ten orders of magnitude in rates of decay would be needed depending on whether the acceleration was spread out over the entire pre-Flood period, or accomplished entirely during the Flood.
So there has been a lot of creative work on how to look for evidence of such changes. A nice technical summary is given by Sisterna and Vucetich Among the phenomena they look at are: While it is not obvious, each of these observations is sensitive to changes in the physical constants that control radioactive decay.
For example, a change in the strength of weak interactions which govern beta decay would have different effects on the binding energy, and therefore the gravitational attraction, of different elements. Similarly, such changes in binding energy would affect orbital motion, while more directly changes in interaction strengths would affect the spectra we observe in distant stars.
The observations are a mixture of very sensitive laboratory tests, which do not go very far back in time but are able to detect extremely small changes, and astronomical observations, which are somewhat less precise but which look back in time. Remember that processes we observe in a star a million light years away are telling us about physics a million years ago.