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Radiometric Dating and the Geological Time Scale

radiometric dating controversy

Dalrymple would extend that to 50, years in special laboratories. Perhaps the damage created by all this radiation can be increased by chemical action and be etched by acid to appear like fission tracks. It needs to be remembered that observational science can only measure things in the here-and-now, in a manner which can be repeated. Even before the bristlecone pine calibration of C dating was worked out by Ferguson, Bucha predicted that this change in the magnetic field would make radiocarbon dates too young.

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This observation led to attempts to explain the fossil succession by various mechanisms. Background Stratigraphic Principles and Relative Time Much of the Earth's geology consists of successional layers of different rock types, piled one on top of another. In , the S. Professor Harry Gove, director of Rochester's laboratory one of the laboratories not selected to conduct the testing , once hypothesised that a "bioplastic" bacterial contamination, which was unknown during the testing, could have rendered the tests inaccurate. This type of decay is electron capture e. Instead of questioning the method, he would say that the radiometric date was not recording the time that the rock solidified. Estimates of the age of the Earth again returned to the prior methods.

Now, the fuller that barrel gets the more water is going to leak out the thoroughly perforated sides, just as more carbon will decay if you have more of it around. Finally, when the water reaches a certain level in the barrel, the amount of water going into the barrel is equal to the amount leaking out the perforated sides. We say that the input and output of water is in equilibrium. The water level just sits there even though the hose is going full blast. The barrel is made deep enough so that we don't have to worry about water overflowing the rim.

Henry Morris argued that if we started filling up our empty barrel it would take 30, years to reach the equilibrium point. Thus, he concluded, if our Earth were older than 30, years the. That is, the equilibrium point should have long since been reached given the present rate of carbon production and the old age of the earth. The next step in Henry Morris' argument was to show that the water level in our barrel analogy was not in equilibrium, that considerably more water was coming in than leaking out.

To that end, he quoted some authorities, including Richard Lingenfelter. Having accomplished that, Morris concluded that the barrel was still in the process of being filled up and that, given the present rate of water coming in and leaking out, the filling process began only 10, years ago.

It's a great argument except for one, little thing. The water is not coming out of the hose at a steady rate as our model assumed! Sometimes it slows down to a trickle so that much more water is leaking out the barrel than is coming in; sometimes it goes full blast so that a lot more water is coming into the barrel than is leaking out. Thus, the mere fact that the present rate of water coming in exceeds that of the water leaking out cannot be extrapolated back to a starting time.

And, that destroys the entire argument. Lingenfelter's paper was written in , before the cycles of C variation we described had been fully documented.

The point is that fluctuations in the rate of C production mean that at times the production rate will exceed the decay rate, while at other times the decay rate will be the larger. Lingenfelter actually attributed the discrepancy between the production and decay rates to possible variations in the earth's magnetic field, a conclusion which would have ruined Morris's argument. Henry Morris chose not to mention that portion of the paper! Creationists don't want their readers to be distracted with problems like that -- unless the cat is already out of the bag and something has to be said.

Tree-ring dating see Topic 27 gives us a wonderful check on the radiocarbon dating method for the last years. That is, we can use carbon dating on a given tree-ring the year sequence having been assembled from the overlapping tree-ring patterns of living and dead trees and compare the resulting age with the tree-ring date. A study of the deviations from the accurate tree-ring dating sequence shows that the earth's magnetic field has an important effect on carbon production.

When the dipole moment is strong, carbon production is suppressed below normal; when it is weak, carbon production is boosted above normal. What the magnetic field does is to partially shield the earth from cosmic rays which produce carbon high in the atmosphere.

Contrary to creationist Barnes' totally discredited claims, which I've covered in Topic 11 , the earth's magnetic field dipole moment has, indeed, increased and decreased over time.

Strahler presents a graph of the earth's dipole moment going back years. The curve is roughly fitted to mean values determined about every to 1, years The curve is roughly degrees out of phase with the C curve. The idea [that the fluctuating magnetic field affects influx of cosmic rays, which in turn affects C formation rates] has been taken up by the Czech geophysicist, V.

Bucha, who has been able to determine, using samples of baked clay from archeological sites, what the intensity of the earth's magnetic field was at the time in question. Even before the tree-ring calibration data were available to them, he and the archeologist, Evzen Neustupny, were able to suggest how much this would affect the radiocarbon dates. Thus, at least within the last years, the earth's magnetic field has fluctuated and those fluctuations have induced fluctuations in the production of carbon to a noticeable extent.

Therefore, as already noted, Dr. Hovind's claim that carbon has been slowly building up towards a 30, year equilibrium is worthless. You now have the technical reason for the failure of Morris' model. It may interest the reader to know that within this year period, where the radiocarbon method can be checked by tree-ring data, objects older than BC receive a carbon date which makes them appear younger than they really are! An uncorrected carbon date of years for an object would actually mean that the object was years old.

Seven hundred years or so is about as far as the carbon method strays from tree-ring dating on the average. Individual dates given on a correlation chart Bailey, , p. As it turns out, we have a check on the carbon production which goes back even further than years:. Evidence of past history of C concentration in the atmosphere is now available through the past 22, years, using ages of lake sediments in which organic carbon compounds are preserved.

Reporting before a conference on past climates, Professor Minze Stuiver of the University of Washington found that magnetic ages of the lake sediments remained within years of the radiocarbon ages throughout the entire period.

He reported that the concentration of C in the atmosphere during that long interval did not vary by more than 10 percent Stuiver, , p. Thus, the available evidence is sufficient to validate the radiocarbon method of age determination with an error of about 10 percent for twice as long a period as the creation scenario calls for.

Yes, the atmospheric content of carbon can vary somewhat. The dipole moment of the earth's magnetic field, sunspot activity, the Suess effect, possible nearby supernova explosions, and even ocean absorption can have some effect on the carbon concentration. However, these factors don't affect the radiocarbon dates by more than about percent, judging from the above studies. Of course, when we reach the upper limit of the method, around 40, years for the standard techniques, we should allow for much greater uncertainty as the small amounts of C remaining are much harder to measure.

Tree-ring data gives us a precise correction table for carbon dates as far back as 8,, years. The above study by Stuiver shows that the C fluctuations in the atmosphere were quite reasonable as far back as 22, years ago.

The earth's magnetic field seems to have the greatest effect on C production, and there is no reason to believe that its strength was greatly different even 40, years ago. For a refutation of Barnes' argument see Topic Therefore, atmospheric variation in C production is not a serious problem for the carbon method.

The evidence refutes Dr. Hovind's claim that the C content of our atmosphere is in the middle of a 30,year buildup. Thus, we can dismiss this young-earth argument. It is painfully obvious that Dr. Hovind knows next to nothing about carbon dating! Changes in the sunspot cycle do have a noticeable, short-term effect on the rate of C production inasmuch as sunspots are associated with solar flares, which produce magnetic storms on Earth, and the condition of the earth's magnetic field does affect the number of cosmic rays reaching the earth's upper atmosphere.

Carbon is produced by energetic collisions between cosmic rays and molecules of nitrogen in the upper atmosphere. Sunspots have absolutely nothing to do with the rate of C decay , which defines the half-life of that radioactive element. Hovind has confused two completely different concepts. Quantum mechanics, that stout pillar of modern physics, which has been verified in so many different ways that I couldn't begin to list them all even if I had them at hand, gives us no theoretical reason for believing that the C rate of decay has changed or can be significantly affected by any reasonable process.

We also have direct observation:. That radiocarbon ages agree so closely with tree-ring counts over at least years, when the observed magnetic effect upon the production rate of C is taken into account, suggests that the decay constant itself can be assumed to be reliable. Since years is almost two half-lives for carbon, it's half-life being years plus or minus 40 years , we have excellent observational evidence that the decay rate is constant.

We also have laboratory studies which support the constancy of all the decay rates used in radiometric dating. A great many experiments have been done in attempts to change radioactive decay rates, but these experiments have invariably failed to produce any significant changes. It has been found, for example, that decay constants are the same at a temperature of degrees C or at a temperature of degrees C and are the same in a vacuum or under a pressure of several thousand atmospheres.

Measurements of decay rates under differing gravitational and magnetic fields also have yielded negative results. Although changes in alpha and beta decay rates are theoretically possible, theory also predicts that such changes would be very small [ Emery, ] and thus would not affect dating methods.

There is a fourth type of decay that can be affected by physical and chemical conditions, though only very slightly. This type of decay is electron capture e. Because this type of decay involves a particle outside the nucleus, the decay rate may be affected by variations in the electron density near the nucleus of the atom. For example, the decay constant of Be-7 in different beryllium chemical compounds varies by as much as 0. The only isotope of geologic interest that undergoes e.

Measurements of the decay rate of K in different substances under various conditions indicate that variations in the chemical and physical environment have no detectable effect on its e.

Believe it or not, a number of creationist attacks against radiometric decay rates are aimed at a kind of "decay" called internal conversion IC , which has absolutely nothing to do with the radiometric dating methods Dalrymple, , p. Harold Slusher, a prominent member of the Institute for Creation Research, claimed that "Experiments have shown that the decay rates of cesium and iron 57 vary, hence there may be similar variations in other radioactive decay rates.

These are both stable isotopes so there is no decay rate to be changed. This statement merely reveals Slusher's ignorance of nuclear physics. Gamma decay of an excited state of iron 57 has been studied, but this has nothing to do with the kinds of decays used in radiometric dating. DeYoung [ ] lists 20 isotopes whose decay rates have been changed by environmental conditions, alluding to the possible significance of these changes to geochronology, but the only significant changes are for isotopes that "decay" by internal conversion.

These changes are irrelevant to radiometric dating methods. Keep an eye on those creationists! They will switch tracks faster than you can say "tiddlywinks. Morris claimed that free neutrons might change the decay rates. However, Henry Morris, that icon of creationism, only demonstrated that he knew no more about radiometric dating than does Dr.

Free neutrons might change one element into another, but the decay rates all remain true to their elements. Morris [ ] also suggests that neutrinos might change decay rates, citing a column by Jueneman 72 in Industrial Research. The subtitle of Jueneman's columns, which appear regularly, is, appropriately, "Scientific Speculation. Jueneman describes a highly speculative hypothesis that would account for radioactive decay by interaction with neutrinos rather than by spontaneous decay, and he notes that an event that temporarily increased the neutrino flux might "reset" the clocks.

Jueneman, however, does not propose that decay rates would be changed, nor does he state how the clocks would be reset; in addition, there is no evidence to support his speculation. There was also an attempt by Slusher and Rybka to invoke neutrinos.

Those mysterious neutrinos seem to be a hot topic! Slusher and Rybka also propose that neutrinos can change decay rates, citing an hypothesis by Dudley 40 that decay is triggered by neutrinos in a "neutrino sea" and that changes in the neutrino flux might affect decay rates. This argument has been refuted by Brush 20 , who points out that Dudley's hypothesis not only requires rejection of both relativity and quantum mechanics, two of the most spectacularly successful theories in modern science, but is disproved by recent experiments.

Dudley himself rejects the conclusions drawn from his hypothesis by Slusher and Rybka , noting that the observed changes in decay rates are insufficient to change the age of the Earth by more than a few percent Dudley, personal communication, , quoted in 20, p.

Thus, even if Slusher and Rybka were correct--which they are not--the measured age of the Earth would still exceed 4 billion years. Dalrymple goes on to debunk several other creationists attacks on the reliability of the radiometric decay rates used in geochronology. Judging from the above, it is easy to see that creationists are indulging in wild fishing expeditions.

Compare their flighty arguments to the solid support provided by theoretical work, laboratory testing, and, for the shorter half-lives, actual observation, and add to that the statistical consistency of the dates obtained, including numerous cross-checks between different "clocks," and only one conclusion is left.

The radiometric decay rates used in dating are totally reliable. They are one of the safest bets in all of science. With at least one notable exception on the books, plants and animals get their carbon from the atmosphere.

Plants take it in directly, and animals eat the plants. Thus, it gets passed up the food chain. It is not surprising, therefore, to find that the carbon in living plants and animals is in reasonable equilibrium with the atmospheric carbon Some creationists, however, have claimed that certain plants can reject carbon in favor of carbon Because of the chemical similarity of carbon and carbon, it is unlikely that such plants could deviate much from the ratio of C to C found in the atmosphere.

Neither freak cases nor small deviations pose much of a problem for radiocarbon dating, which, after all, works well with a wide variety of plant and animal species. Hence, we only have to worry about the initial concentration of C in the atmosphere.

Topic R1 shows that the level of C in the atmosphere has not varied appreciably over tens of thousands of years. Therefore, the initial C content is known for any reasonable sample! The notable exception involves certain mollusks, which get much of their carbon from dissolved limestone. Since limestone is very old it contains very little carbon Thus, in getting some of their carbon from limestone, these mollusks "inherit" some of the limestone's old age! That is, the limestone carbon skews the normal ratio between C and C found in living things.

If one dates such mollusks, one must be extra careful in interpreting the data. Not every mollusk shell presents such problems, and the dating of other material might yield a cross-check. Further study might even allow correction tables. The discovery has strengthened the carbon method, not weakened it!

But we do not have an instrument that directly measures age. Before we can calculate the age of a rock from its measured chemical composition, we must assume what radioactive elements were in the rock when it formed.

It may be surprising to learn that evolutionary geologists themselves will not accept a radiometric date unless they think it is correct—i. It is one thing to calculate a date. It is another thing to understand what it means.

A geologist works out the relative age of a rock by carefully studying where the rock is found in the field. The field relationships, as they are called, are of primary importance and all radiometric dates are evaluated against them.

For example, a geologist may examine a cutting where the rocks appear as shown in Figure 1. Here he can see that some curved sedimentary rocks have been cut vertically by a sheet of volcanic rock called a dyke. It is clear that the sedimentary rock was deposited and folded before the dyke was squeezed into place. By looking at other outcrops in the area, our geologist is able to draw a geological map which records how the rocks are related to each other in the field.

From the mapped field relationships, it is a simple matter to work out a geological cross-section and the relative timing of the geologic events. His geological cross-section may look something like Figure 2. These were then eroded and Sedimentary Rocks B were deposited. The geologist may have found some fossils in Sedimentary Rocks A and discovered that they are similar to fossils found in some other rocks in the region.

He assumes therefore that Sedimentary Rocks A are the same age as the other rocks in the region, which have already been dated by other geologists. In the same way, by identifying fossils, he may have related Sedimentary Rocks B with some other rocks.

From his research, our evolutionary geologist may have discovered that other geologists believe that Sedimentary Rocks A are million years old and Sedimentary Rocks B are 30 million years old. Creationists do not agree with these ages of millions of years because of the assumptions they are based on. Because of his interest in the volcanic dyke, he collects a sample, being careful to select rock that looks fresh and unaltered. On his return, he sends his sample to the laboratory for dating, and after a few weeks receives the lab report.

Let us imagine that the date reported by the lab was Our geologist would be very happy with this result. He would say that the date represents the time when the volcanic lava solidified. Such an interpretation fits nicely into the range of what he already believes the age to be. In fact, he would have been equally happy with any date a bit less than million years or a bit more than 30 million years. They would all have fitted nicely into the field relationships that he had observed and his interpretation of them.

What would our geologist have thought if the date from the lab had been greater than million years, say Would he have concluded that the fossil date for the sediments was wrong? Would he have thought that the radiometric dating method was flawed? Instead of questioning the method, he would say that the radiometric date was not recording the time that the rock solidified. He may suggest that the rock contained crystals called xenocrysts that formed long before the rock solidified and that these crystals gave an older date.

The convention for reporting dates e. In other words, the age should lie between However, this error is not the real error on the date. It relates only to the accuracy of the measuring equipment in the laboratory.

Even different samples of rock collected from the same outcrop would give a larger scatter of results. These include the assumption that decay rates have never changed.

In fact, decay rates have been increased in the laboratory by factors of billions of times. What would our geologist think if the date from the lab were less than 30 million years, say Would he query the dating method, the chronometer? He would again say that the calculated age did not represent the time when the rock solidified.

He may suggest that some of the chemicals in the rock had been disturbed by groundwater or weathering. He would simply change his assumptions about the history of the rock to explain the result in a plausible way.

The dates calculated are based on the isotopic composition of the rock. And the composition is a characteristic of the molten lava from which the rock solidified. So, although the assumptions behind the calculation are wrong and the dates are incorrect, there may be a pattern in the results that can help geologists understand the relationships between igneous rocks in a region. Contrary to the impression that we are given, radiometric dating does not prove that the Earth is millions of years old.

The vast age has simply been assumed. The results are only accepted if they agree with what is already believed. The only foolproof method for determining the age of something is based on eyewitness reports and a written record. We have both in the Bible. And that is why creationists use the historical evidence in the Bible to constrain their interpretations of the geological evidence.

Recently, I conducted a geological field trip in the Townsville area, North Queensland. A geological guidebook, 1 prepared by two geologists, was available from a government department. Thus … a result of two hundred million years is expected to be quite close within, say, 4 million to the true age. This gives the impression that radiometric dating is very precise and very reliable—the impression generally held by the public. However, the appendix concludes with this qualification: This is exactly what our main article explains.

Imsges: radiometric dating controversy

radiometric dating controversy

A great many experiments have been done in attempts to change radioactive decay rates, but these experiments have invariably failed to produce any significant changes. If the new data have a large inconsistency by "large" I mean orders of magnitude , it 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.

radiometric dating controversy

It benefits from the comments of several informal reviewers. However, in either case, the background beta radiation has to be compensated for, and, in the older objects, the amount of C they have left is less than the margin of error in measuring background radiation. Errors get handed down in the creationist literature like the family jewels!

radiometric dating controversy

Help us design more information for this site. Therefore, by dating a series of rocks in a radiometric dating controversy succession of strata previously recognized with basic geologic principles see Stratigraphic principles and relative timeit can provide a numerical calibration for what would otherwise be only an ordering of events -- i. Invoking the assumption of good faith while you've been edit warring with Jclerman and calling him a vandal over his identification of you as the creator of this pointless straw poll takes a remarkable amount of chutzpah. He may suggest that radiometric dating controversy of the chemicals in the rock had been disturbed by groundwater or weathering. Well, standard scientific procedure is to collect more data to test the possible explanations -- is radiometric dating controversy the time scale or the data that are incorrect? Retrieved 10 Gnostic dating