Palaeo ice sheet reconstruction
We also avoided mummified material because of concerns about contamination from bitumen or other substances used in the mummification process and human material because of the possibility of riverine or marine components in the diet which might contain older carbon. Schematic diagram of IntCal04 and Marine04 calibration data set construction. They were purchased by the University Library of Leiden in from H. The branching ratio that is often used is 0. Now, the problem with this is that this excess argon 40 will probably be deposited as single atoms of argon distributed evenly within the sample. It must be emphasised that the 14 C decay is constant and spontaneous.
Explaining the science of Antarctic glaciers
This lava will take longer to cool down, giving more opportunity for enclosed argon to escape and leading to younger radiometric ages. In his foreword to a small catalogue he published, Wetzstein said he hoped these more than 1, kufic folios of the Qur'an he had collected would be of some interest to those involved in palaeography and Qur'anic criticism, and gave a brief entry for M a VI Now, the problem with this is that this excess argon 40 will probably be deposited as single atoms of argon distributed evenly within the sample. Fortunately, these physical relationships are reasonably well understood and can be fed into a computer model. It is not judicious to upscale palaeography for its reliability whilst, on the other hand, putting down radiocarbon dating for its alleged lack thereof. Others that this technique doesn't work for the Qur'an. Rezvan cites no historical sources supportive of his hypothesis, and, as far as we are aware, there is no recorded instance around the time of late antiquity of prepared blank parchment being stored for years.
Henke states in a reply to me, concerning the problem of detecting excess argon,. It is possible that such isochrons are not often done. One cannot always use an isochron, since many minerals may have about the same K and Ar40 concentrations, and there may be some fractionation of argon among the minerals.
It's not clear to me if this three dimensional plot always works, and how often it is used. I was not able to find any mention of it in Faure or Dickin It is true that by using additional isotopes if they are sufficiently abundant and do not fractionate , one can often detect mixings of multiple sources.
My point was that the usual mixing test can only detect two sources. But since these multiple mixing tests are more difficult and expensive, they may not be done very often. One also has to know which isotopes to examine. I was suprised that Dalrymple said nothing about mixings invalidating isochrons. Dalrymple goes to great lengths to explain this away, but I think this figure is very telling, and find his explanations unconvincing.
It is also remarkable that we have a test for mixing, which is commonly cited in support of the accuracy of radiometric dating, but when it gives contrary results, it is simply ignored. It is a fundamental assumption of the mantle isochron model that neither isotope nor elemental ratios are perturbed during magma ascent through the crust. However, it is now generally accepted that this assumption is not upheld with sufficient reliability to attribute age significance to erupted isochrons.
Dickin suggests that mixings may contribute to such isochrons. It seems reasonable, then, that mixings may be affecting all Rb-Sr isochrons in igneous rock. Your hypothetical example in "More Bad News for Radiometric Dating" is often hard to follow, but it is clearly invalid. This example is given to show that a mixing of three sources cannot be detected by the usual two sources test. It is not intended to be natural, but to demonstrate a mathematical fact. There is a lot of flexibility in the design of such examples, as I indicate, and it is reasonable to assume that some of these examples would be natural.
It's the responsibility of the geologist to show that such mixings have not occurred. To really understand what's going on you have to sample the recent works of many different authors. You have to follow arguments between experts on different issues and see where they go.
Overall, the geologic time scale is in great shape. Yes, scientists are still making minor adjustments. However, it's clear from Strahler , Dalrymple , etc. The problem with this approach is that it leaves ample room for the exercise of subjective judgment and evolutionary assumptions. Also, Dalrymple says essentially nothing about the phanerozoic, and thus gives little evidence of the accuracy of the conventional dating scheme on fossil-bearing rocks. I treated this issue of percentage of anomalies in considerable detail in my original "Radiometric Dating Game" article.
It is interesting that Woodmorappe gives a number of cases in which standard geological tests are ignored. For example, dates may be accepted even when there is evidence of weathering, and rejected when there is not.
There may be evidence of heating, but the date may be accepted, and there may be no such evidence, but a hypothetical heating event is assumed anyway.
If geological tests are not being applied consistently, one wonders what value they have. Let me clarify the problem with excess argon. It gives the diffusion equation for argon escaping from a rock as it cools. The rate of diffusion is proportional to the gradient of argon concentration, and increases rapidly with temperature. Suppose the partial pressure of argon 40 in the environment is p.
Suppose the partial pressure of argon 40 in lava or magma is initially at least p, as it cools. Then the partial pressure of argon 40 in the magma will never decrease below p; excess argon 40 will remain dissolved in the lava or magma as it cools. This argon 40 will then be trapped within the resulting rocks and lead to artificially old K-Ar dates.
Now, the problem with this is that this excess argon 40 will probably be deposited as single atoms of argon distributed evenly within the sample. This makes it very difficult or even theoretically impossible to distinguish this excess argon 40 from argon generated by radioactive decay.
This will make the sample appear artificially old right away. Even if crystals exclude argon as they form, argon will rapidly diffuse into them as the lava cools, by the diffusion equation mentioned above. A similar problem can occur if the excess argon 40 dissolved within lava or magma is not able to escape, due to rapid cooling or subsequent deposits of sediment or other lava on top. It is possible that in some cases an isochron might be able to detect such initial argon 40, but this can only happen if the potassium concentration varies significantly within the sample.
It is not clear to me, also, how often such a test for initial argon 40 is performed. And of course, such isochrons can be falsified by mixings or other problems. There are spectrum tests for adsorbed argon involving Ar-Ar dating; basically, one can see whether the argon 40 is concentrated near the surface of the sample or near the interior.
The former would indicated adsorbed argon 40, which would not give a true age. However, this test would not indicate excess argon 40 present during cooling. It seems reasonable to me that this is a uniform problem with K-Ar dating. To me the geological evidence suggests catastrophic conditions and rapid formation of the sedimentary layers in the past.
Thus the lava might have been covered before the excess argon was able to escape. Or the lava might have cooled quickly, due to rainfall. It only needs to cool to about degrees centigrade or less to trap most of the argon, at least for biotite. As I mentioned before, one sometimes finds significant argon 40 in a rock and no potassium at all, as mentioned in Snelling's article. This shows that excess argon is entering these rocks by some means, and calls K-Ar dating into question.
Excess argon could even cause different minerals in a given formation to yield similar K-Ar ages, since they all might have similar concentrations of K, approximately equal to its abundance in the earth's crust, and similar concentrations of argon 40, due to the partial pressure of argon 40 being similar during cooling.
Even sedimentary minerals might have a similar K-Ar age for the same reason. Also, lava magma that cooled within the earth is likely to have artificially old K-Ar ages, since the enclosed excess argon 40 might have a more difficult time escaping. One sedimentary mineral of particular importance for K-Ar dating is glaucony. The following message from a talk. For example, Plaisted's "explanation" for the correlation of isotopic age with vertical position in the geologic column is essentially that excess argon would have existed in lavas in greater quantity early in the Flood, and decreased as it was outgassed over time.
Had Plaisted actually bothered to look at the data e. Glaucony did not come from a "magma chamber," so Plaisted's explanation cannot possibly cover the majority of ages on the younger parts of the column. Of the or so "anomalous" dates in Woodmorappe , 94 Woodmorappe is clearly misusing illite and glauconite dates to simply pad his list. The fact that glauconies are unreliable is significant, since they provide such a large part of the dates for the mesozoic-cenozoic parts of the geological column.
Glauconies are formed in seawater from a variety of materials, and incorporate potassium from the seawater Faure, , p. The process of their formation gives a ready mechanism for their K-Ar ages, namely, the incorporation of argon 40 as well as potassium from the seawater. We can assume that as a result of a global catastrophe, the oceans were highly enriched in argon 40 in the past, and that the concentration of argon 40 gradually decreased over time, due to its diffusion into the atmosphere and due to a smaller amount being released into the seawater.
Therefore older glauconies would absorb more argon 40 from the seawater, resulting in old K-Ar dates for lower strata which become progressively younger for higher strata.
Another factor in this direction is that older glauconies have more time to absorb argon Some minerals contain argon 40 but no potassium, so this indicates excess argon 40, which in the presence of potassium leads to artificially old dates. Many historical volcanoes give K-Ar dates that are much too old, even if the reasons for this are understood. Finally, I want to comment on the circumstances of the interchange with Dr.
During most of our interchange, I was not aware that it would be published on talk. Now it has been web-immortalized on a radiometric dating web page. I was not informed that this exchange had been posted there.
In addition, the complete exchange was not posted, but only a portion of it. I do thank Tim Thomson for the courteous and professional manner in which he has interacted with me, and that he has included the rest of my exchange with Dr. Excuses for anomalies Another issue is that sometimes the geologic periods of rocks are revised to agree with the ages computed. This also makes data about percentages of anomalies less meaningful.
It sometimes seems that reasons can always be found for bad dates, especially on the geologic column. If a rock gives a too old date, one says there is excess argon. If it gives a too young date, one says that it was heated recently, or cannot hold its argon.
How do we know that maybe all the rocks have excess argon? It looks like geologists are taking the "majority view" of K-Ar dating, but there is no necessary reason why the majority of rocks should give the right date. The relationship of a radioisotope age with real-time must be based on an interpretation. A discussion of rubidium-strontium ages in the Isotope Geoscience Section of the journal, Chemical Geology, specifically states that a radioisotope age determination "does not certainly define a valid age information for a geological system.
Any interpretation will reflect the interpreters presuppositions bias. Need for a double-blind test Concerning the need for a double blind test, it would seem that there are many places where human judgment could influence the distribution of measured radiometric dates. It could increase the percentage of anomalies, if they were regarded as more interesting.
It could decrease them, if they were regarded as flukes. Human judgment could determine whether points were collinear enough to form an isochron. It could determine whether a point can justifiably be tossed out and the remaining points used as an isochron.
It could determine whether one should accept simple parent-to-daughter K-Ar ratios or whether some treatment needs to be applied first to get better ages. It could influence whether a spectrum is considered as flat, whether a rock is considered to have undergone leaching or heating, whether a rock is porous or not, or whether a sample has been disturbed in some way.
Since one of the main reasons for accepting radiometric dates at least I keep hearing it is that they agree with each other, I think that geologists have an obligation to show that they do agree, specifically on the geologic column.
Since we do not know whether or how much human judgment is influencing radiometric dating, a double blind study is most reasonable. And it should not be restricted to just one or two well-behaved places, but should be as comprehensive as possible. Possible changes in the decay rate The following information was sent to me by e-mail:. Radiometric dating is predicated on the assumption that throughout the earth's history radioactive decay rates of the various elements have remained constant.
Is this a warranted assumption? Has every radioactive nuclide proceeded on a rigid course of decay at a constant rate? This has been challenged by studies involving Carbon C At the temperature or pressure, collisions with stray cosmic rays or the emanations of other atoms may cause changes other than those of normal disintegration.
It seems very possible that spontaneous disintegration of radioactive elements are related to the action of cosmic rays and the rate of disintegration varying from century to century according to the intensity of the rays. The evidence for a strongly increasing change in the cosmic ray influx is most favorable especially in light of the decay of the earth's magnetic field.
Most geochronologists maintain that pleochroic haloes give evidence that decay constants have not changed. Crystals of biotite, for example, and other minerals in igneous or metamorphic rocks commonly enclose minute specks of minerals containing uranium or thorium.
The a- alpha particles emitted at high velocity by the disintegrating nuclides interact, because of their charge, with electrons of surrounding atoms which slow them down until they finally come to rest in the host material at a distance from their source that depends on their initial kinetic energy and the density and composition of the host. Where they finally stop to produce lattice distortions and defects there generally occurs discoloring or darkening.
Each of the 8 a-particles emitted during the disintegration of U to Pb produces a dark ring in biotite. Each ring has its own characteristic radius in a given mineral in this case biotite. This radius measures the kinetic energy, hence the probability of emission of the corresponding a-particle and also the half-life of the parent nuclide according to the Geiger-Nuttall law. The Geiger-Nuttall law is an empirical relation between half-life of the a-emitter and the range in air of the emitted a-particles.
If the radii of these haloes from the same nuclide vary, this would imply that the decay rates have varied and would invalidate these series as being actual clocks. Are the radii in the rocks constant in size or are there variable sizes? Most of the early studies of pleochroic haloes were made by Joly and Henderson. Joly concluded that the decay rates have varied on the basis of his finding a variation of the radii for rocks of alleged geological ages.
This rather damaging result was explained away saying that enough evidence of correct radii for defferent geologic periods and sufficient variation in the same period have been obtained that one is forced to look for a different explanation of such variations as were observed by Joly.
Measurements were later made in an excellent collection of samples with haloes. It was found that the extent of the haloes around the inclusions varies over a wide range, even with the same nuclear material in the same matrix, but all sizes fall into definite groups. The measurements are, in microns, 5,7,10,17,20,23,27, and More recent studies have been made by Robert V.
Gentry also finds a variation in the haloes leading him to conclude that the decay constants have not been constant in time. Gentry points out an argument for an instantaneous creation of the earth. He noted form his studies of haloes: For the Po half-life of 3 minutes only a matter of minutes could elapse between the formation of the Po and subsequent crystallization of the mica; otherwise the Po would have decayed, and no ring would be visible.
The occurrence of these halo types is quite widespread, one or more types having been observed in the micas from Canada Pre-Cambrian , Sweden, and Japan. So, then, careful scientists have measured variations in halo radii and their measurements indicate a variation in decay rates.
The radioactive series then would have no value as time clocks. This would knock our C, potassium-argon, and uranium-lead dating measurements into a cocked hat!
The age of prehistoric artifacts, the age of the earth, and that of the universe would be thrown into doubt. Flint, "Radiocarbon Dating," in Science, February 8, , p. This is significant because it is known that neutrinos do interact with the nucleii of atoms, and it is also believed that much of the energy of supernovae is carried away by neutrinos. Isochrons Isochrons are an attempt to avoid the need for an absence of daughter element initially in computing radiometric ages.
The idea is that one has a parent element, X, a daughter element, Y, and another isotope, Z, of the daughter that is not generated by decay. One would assume that initially, the concentration of Z and Y are proportional, since their chemical properties are very similar. Radioactive decay would generate a concentration of Y proportional to X.
So we would obtain an equation of the form. By taking enough measurements of the concentrations of X, Y, and Z, we can solve for c1 and c2, and from c1 we can determine the radiometric age of the sample. If the concentration of K varies in a rock, that it is unlikely for the concentration of added argon 40 to vary in a way that will yield an isochron. But if the concentration of K does not vary, then one can still get an isochron if the concentration of the non-radiogenic isotope Ar36 of the daughter product varies.
So let's call an isochron a "super-isochron" if the concentration of the parent element varies from one sample to another. Let's call it a "wimpy isochron" otherwise. The question is, what percentage of isochrons are super-isochrons, and how do their dates agree with the conventional dates for their geologic period? I would think that it may be rare to have a super-isochron.
If one is dealing with minerals that exclude parent or daughter, then one cannot get an isochron at all. If one is dealing with minerals that do not exclude parent and daughter elements, then most likely the parent element will be evenly distributed everywhere, and one will have a wimpy isochron that cannot detect added daughter product, and thus may give unreliable ages.
Whole rock isochrons may also tend to be wimpy, for the same reason. Even super isochrons can yield ages that are too old, due to mixings, however. False K-Ar isochrons can be produced if a lava flow starts out with a lot of excess Ar40 which becomes well mixed, along with potassium. Then while cooling or afterwards, a mixture of Ar36 and Ar40 can enter the rock, more in some places than others. Other isotopes of argon would work as well. I believe that this will produce a good K-Ar isochron, but the age calculated will be meaningless.
There is another way that false isochrons can be produced. For a wimpy isochron, say a K-Ar isochron, we can assume that initially there is a uniform concentration of K everywhere, and concentrations of Ar40 and Ar36 that form an isochron. Then a lot of Ar40 enters, uniformly, through cracks in the rock or heating. This will retain the isochron property, but will make the isochron look too old. My reasoning was that if the lava is thoroughly mixed, then the concentration of parent material should be fairly constant.
If the concentration of parent substance is not constant, it could indicate that the lava is not thoroughly mixed. Or it could have other explanations. If the lava is not thoroughly mixed, it is possible to obtain an isochron from the mixing of two different sources, in which case the radiometric age is inherited from the sources, and does not necessarily yield the age of the flow. Someone pointed out to me that many Rb-Sr isochrons are super isochrons.
I find this information very interesting, and thank him for it. I'd be curious to know which strata they occur in, as my main interest is the geologic column of Cambrian and above. My impression is that these are not on this part of the geologic column. And how well do the dates correlate with others for the same formation?
There are also mixing scenarios that can produce even super isochrons having invalid ages. And geologists admit in any event that isochrons can sometimes give false ages. Here is a mixing scenario for false isochrons. There are two sources of lava, A and B. Suppose these mix together so that at point 0 we have only A, at point 1 we have only B, and in between we have varying concentrations. Half way between there is a mixture of half A and half B, for example.
Suppose X is a parent substance, Y is its daughter, and Z is a non-radiogenic isotope of the daughter. Suppose A has a little X and lots of Y and not much Z, all uniformly distributed, and B has some mixture of Y and Z, all uniformly distributed. Then this varying mixture of A and B, with all A at 0 and all B at 1, produces a good isochron. There is no way this mixture can be distinguished from a similar case in which A has lots of X and little Y, and B is the same as before, and a lot of time passes.
It is claimed that mixing can often be detected. If this is so, then the question remains, for super isochrons on the geologic column which can be shown not to be caused by mixing, how do they correlate with other methods, and with the expected dates for their geologic period? My understanding is that isochrons measure the time since a rock was last well mixed.
For a lava flow, this could be the time of the flow. Or it could be that several flows all come from the same well-mixed magma, and might yield a joint isochron giving the time of the flow. It seems to me that a single lava flow might not mix well, and thus the age obtained would be that of the magma and not the time of the flow.
So this points out another problem with interpretation of isochrons. I'm also curious to know how much of the geologic column is datable by super isochrons for which no mixing can be shown. Atlantic sea floor dating One often hears about K-Ar dates of the Atlantic Ocean bottom which increase from zero at the mid-Atlantic ridge to about million years at the edges.
This is taken as proof that the continents began separating about million years ago. However, this can be explained by assuming that argon rises to the top of the magma, so magma deeper down looks younger.
The magma deeper down would have come to the surface later, and thus would be nearer to the mid-Atlantic ridge. Or if the continents split quickly, the observed pattern of dates could be explained by a decreasing concentration of Ar40 in the water. In any event, I don't see how the lava in the center of the Atlantic could have a young age in the conventional view, since it would have cooled rapidly under a lot of water, and would have retained its argon, making it look old.
Dating Meteorites We now make some comments about dating the meteorites. Since I have not had as much time to study this, I will just list some points that must be considered. Many parent to daughter ratios for many meteorites give radiometric ages of about 4. This gives support to an ancient age for the meteorites, assuming constant decay rates.
However, in interpreting these results, some facts need to be kept in mind. The first is that these results are not obtained by a simple parent to daughter ratio. Instead, some estimate of the amount of daughter initially present in the meteorite has to be made in order to compute a radiometric age.
Thus one has a "fudge factor," and in fact, a different fudge factor for each method. So one has to be sure that these fudge factors are properly used, and not simply adjusted in order to obtain an agreement among the dates. The importance of this is underlined by the fact that these same fudge factors are used to estimate uranium and thorium dates on earth. Thus the estimate of initial concentrations of lead isotopes could also affect the 4.
We noted above that there also seems to be a fudge-factor built into potassium-argon dating, namely, the branching ratio estimate. This causes the correlation between K-Ar dates and other dates on meteorites to come into question, as well. Now, at least for uranium-lead dating, a kind of isochron has been observed among five meteorites containing uranium and a number which do not, which gives a rational basis for assuming how much daughter product was present initially.
The obvious question to ask in regards to this is how the meteorites were chosen for this isochron, and whether there are other meteorites and other bodies from the solar system that do not fit. If so, this calls this interpretation into question. In addition, there is just one point on this isochron for all of the meteorites that do not contain uranium. Is this obtained by averaging, or do they all have exactly the same ratio of lead isotopes? If the former, then this could indicate that the points of this isochron have considerable scatter, further calling the age computation into question.
A point from the earth is also on this isochron. This is from a sedimentary deposit. But since uranium is much more water soluble than lead, it seems questionable to use this point as reprsenting the ratio of lead isotopes on earth, since it may be impoverished or enriched in uranium. In addition, if other sediments yield different ratios of isotopes, why was only this one chosen? Another question that needs to be asked is whether this isochron could have been produced by some kind of a mixing process, since such processes can produce isochrons not representing a true age.
It also needs to be determined whether the daughter products for methods other than uranium-lead dating also yield isochrons among the different meteorites.
The above discussion concerns dating techniques based on simple parent to daughter ratios. There are other dating techniques such as isochrons and discordia which avoid the need to estimate initial daughter product concentrations. Therefore, it should be determined how many correlations remain in meteorite dating when only such techniques are applied.
Of course, in the traditional view, the matter out of which the solar system was formed would have been very old at the start, in any event, and so the radiometric ages obtained from meteorites or from the earth do not necessarily tell us anything about the age of the solar system or the age of the earth. My point is not to refute the meteorite dating, since it may be sound, assuming a constant decay rate.
However, on seeing the lack of evidence for large-scale evolution, the many problems with radiometric dating on the geologic column, and the many plausible evidences for catastrophe which often seem to be interpreted away by science, I have become somewhat skeptical of any area of science having to do with origins, and so have come to question even the assumptions behind the dating of the meteorites.
This does not answer my question, which referred at least in part to dates obtained by a simple daughter-to-parent ratio. Dalrymple does say that many ages for meteorites are "model ages," which are computed by making assumptions about initial amounts of daughter product.
Such assumptions are also necessary for the Pb-Pb method of dating. For meteorites, there is a good basis for making such assumptions. Also, Dalrymple gives impressive agreements between different isochron methods on meteorites, which support a roughly 4. Henke refers to this in his second reply:.
Dalrymple lists more than just a "small number of meteorites. None of these results are only a few thousand years old. For further details, see Dalrymple , chapter 6. Other than a true age for the meteorites, this could indicate a mixing process, which does not seem likely, or an increase in decay rates, for which a mechanism would need to be found. However, in order to date the earth, one needs an isochron which includes a point from the earth. This is more difficult, and this is the isochron that I saw on the talk.
Also, many of the meteorite dates I saw in the FAQ were apparently simple daughter-to-parent ratio ages. It is also remarkable that so many different isochron-based dating schemes, even on the same meteorite, often yield roughly the same 4.
This is a case where different methods agree without making assumptions about initial amount of daughter product. This either indicates a true age, or a change in the decay constants.
I would like to know how often this is true on the phanerozoic. How often does one have two or three different isochrons on the same system yielding very similar dates? It is also important that the concentrations of parent substances are linearly independent, to preclude mixings.
Such a multiple-isochron agreement is fairly convincing, but the failure to find such isochrons likewise casts doubt on the ages obtained. If radiometric dating is accurate on fossil-bearing rocks, there should be an abundance of such agreements between different isochrons on the same systems, and they should yield the conventionally accepted ages. A change in the decay constants on the phanerozoic seems less likely, since it could radically affect the properties of matter, and be harmful to life.
Another reliable technique mentioned by Dalrymple is the U-Pb concordia-discordia method on zircons, which is valid even for many open systems. This technique requires assumptions about lead and uranium loss, and seems to give good evidence of a reliable date relative to decay constants , especially when there is agreement with other methods such as isochrons on the same system. However, Dickin , pp. Also, zircons can survive transport through magma p. This leaves open the possibility that all of the dates obtained from zircons on the phanerozoic are too old.
Conclusion An evolutionist said his experience is that whenever he looks into a creationist source, it blows up on him. My experience is that whenever I look into an evidence for evolution or now the reliability of radiometric dating on the geologic column, it blows up on me, too.
I don't deny that there is some degree of plausibility to radiometric dating, although I have to wonder if many field geologists secretly have their doubts about it. My concern is instead to know how much stamina the evidence has against other evidence that may call it into question. My conclusion for the geologic column is, not much. Gentry's radiohaloes in coalified wood Here is some more material from my web site bearing on the question of the age of the geologic column:.
It is also of interest in regard to radiometric dating that Robert Gentry claims to have found "squashed" polonium haloes as well as embryonic uranium radiohaloes in coal deposits from many geological layers claimed to be hundreds of millions of years old.
These haloes represent particles of polonium and uranium which penetrated into the coal at some point and produced a halo by radioactive decay. The fact that they are squashed indicates that part of the decay process began before the material was compressed, so the polonium had to be present before compression. Since coal is relatively incompressible, Gentry concludes that these particles of uranium and polonium must have entered the deposit before it turned to coal.
However, there is a very small amount of lead with the uranium; if the uranium had entered hundreds of millions of years ago, then there should be much more lead. The amount of lead present is consistent with an age of thousands rather than millions of years. It's hard to believe, according to conventional geological time scales, that this coal was compressed any time within the past several thousand or even hundred million years.
No presently available experimental evidence would exclude the possibility that essentially all the lead in the halo centers was introduced together with the uranium either directly or as parent polonium or lead and thus did not accumulate from uranium. Thus the amount of lead with the uranium is consistent with an age in the hundreds of thousands to millions of years range, much too small for conventional geologic time.
And it is reasonable to assume that almost all of this lead came with the uranium, rather than being a result of decay, suggesting that the true age could be much younger than this. Note that this phenomenon of squashed haloes appears in different coal deposits in different geologic formations, and all give about the same U-Pb ages.
The squashing is in the vertical direction, and I can't think of any way this could happen at a time later than the burial of the logs or whatever under a lot of sediment. Coal is not water soluble at least, coal cars aren't covered, and no one seems to worry about thunderstorms dissolving the coal away , and wood is waterproof, so one would expect that coalified wood would also be waterproof.
Coal has small pores. If it had cracks, they would have to be small, since the cell structure is still visible. And if there was a flow of water, it would be more likely to remove soluble uranium than insoluble lead, making the date older. But it is possible that small cracks exist and that uranium could be deposited by a flow of water at some more recent date. If there were such cracks, we would expect uranium to be entering at regular intervals, and to give a range of ages up to about million years or even higher due to lead being introduced with the uranium.
But note that all of the haloes give young ages. The fact that all the ages are so young suggests that the coal is young, too. It seems most likely that the uranium entered at the same time as the polonium. The fact that so many of the polonium haloes are squashed indicates that the polonium entered before the wood was covered with sediement. I think the most reasonable explanation is that this coal has an age at most a few millions of years old, possibly much younger, and that the geologic time scale is in error.
Some of the haloes have ages of , or , years, so the true age would have to be this or younger. This applies to several geologic periods. In fact, a couple of the haloes have such low ratios as to imply an age in the thousands of years.
Another possible objection made by an evolutionist is that the radon that results from uranium decay is an inert gas and may have escaped, resulting in little lead being deposited.
This would make the observed haloes consistent with an old age for the coal. However, the fact that these uranium haloes are embryonic very faint also argues for a young age. In addition, not all of the radon would be on the surface of the particles of uranium. That which was inside or bordering on coal would likely not be able to escape. Since radon has a half-life of about 4 days, it would not have much time to escape, in any event. Libby, the discoverer of the C14 method, which won for him a Nobel prize, expressed his shock that human artifacts extended back only years, a finding totally in conflict with any evolutionary concept.
Older dates were found to be very unreliable CRSQ , , 9: By this time tens of thousands of C14 dates have been published from tests performed by various laboratories around the world. As we had noted earlier, radiocarbon 14 C is produced via the cosmogenic process and this happens at stratospheric altitudes of 9 to 15 km above the surface of the Earth.
In general, the cosmic rays flux remains constant and observed fluctuations in production rate of 14 C are controlled by geomagnetic field strength and solar activity. Thus seasonal changes and presence of moisture on the surface of the Earth have no effect on the production rate of 14 C. What about the variation of decay of radiocarbon 14 C due to the chemical environment around the atom?
Thus, the variation of just a percentage or so, is much too small to affect Earth's overall time scale and consequently the radiocarbon dating itself. If one were to instead use the data from the southern hemisphere and we are talking about Arabia here , I am told by those more expert in this procedure than me that very different datings would result. To begin with, Arabia is not in the Southern Hemisphere. It is situated in the Northern Hemisphere between the latitudes The Tropic of Cancer at As for the global atmospheric radiocarbon content, it is controlled by several factors such as climatic changes, oceanic circulation, solar output and geomagnetic variability.
It has been demonstrated that Southern Hemisphere samples have lower 14 C contents. The question now is how much older are the radiocarbon samples from the Southern Hemisphere compared to the Northern Hemisphere? Furthermore, it is not surprising that the calibration data set for the Northern Hemisphere IntCal series  is different from that of the Sourthern Hemisphere SHCal series ,  and that these are frequently updated to fine tune the respective calibration curves.
That is, these manuscripts are from 1st century of hijra. Shoemaker's argument against radiocarbon dating shifts from raising the inter-hemispheric offset to intra-hemispheric changes in radiocarbon content. The problem, it would seem, is that radiocarbon dating in the medieval period is only accurate when it can be calibrated by tree ring data, particularly from oak trees.
Such data is wanting for the medieval Mediterranean or Near East, and the data from the northern hemisphere that has been used to calibrate these tests was taken from Ireland and North America. There are several inaccuracies in the above set of statements. The work of the Aegean Dendrochronology Project started in s and since then it has continued since to build the long tree-ring chronologies for the eastern half of the Mediterranean.
Its aim was to make scientific sense of the Aegean and Near Eastern chronology from the Neolithic Age to the present. The most recent state as of late of the Aegean tree-ring chronology is shown in Figure 23 which also appeared in a slightly expanded form in The state of Aegean tree-ring chronologies as of late This is an update of the bar graph published in Less common species such as boxwood and yew are removed in this plot.
Now that we have established the fact that the dendrochronological data from oak trees among others already exist, let us now look into the issue of calibration. Shoemaker says that since the calibration is done using the tree-ring data from Ireland and North America, it can't be trusted for dating medieval Mediterranean and Near East samples.
The tacit assumption of his claim is that the chronology derived from the tree-ring data from Ireland and North America is very different from what is obtained from the Mediterranean and Near East samples. One of the fundamental tenets of radiocarbon dating is that within each hemisphere there was sufficient mixing of the pre-industrial atmosphere to allow the use of a universal 14 C calibration dataset.
On the issue of calibration, it must be mentioned that the dendrochronological database for the IntCal04 curve is largely similar to the dataset of the IntCal98 curve, but also includes new measurements for the Iron Age period, for example, German Oak samples run for the East Mediterranean Radiocarbon Comparison Project.
A trial run of the model against the IntCal04 calibration curve gave essentially similar results, albeit that the dates become slightly older. Reynolds, on the other hand, claimed that the dating of Dead Sea Scrolls may be considered more accurate than the dating of manuscripts of Qur'an.
His reasoning is as follows:. This allows scientists to calibrate their measurements more precisely. This is entirely erroneous. The tree ring atmospheric radiocarbon calibration data set spanning 0 to 12, years BP is used Figure It is superior to all other atmospheric radiocarbon calibration data due to the number and quality of the radiocarbon measurements and the accuracy and precision of the tree dendrochronology. Schematic diagram of IntCal04 and Marine04 calibration data set construction.
The IntCal09 uses a similar data set. Said scraps of linen and piece of leather are dated using the standard calibration data set. It appears that Reynolds does not properly comprehend how radiocarbon calibration curves are constructed. Strained, arbitrary and impossible interpretations of science, in our case of the science of radiocarbon dating, can lead to endless possibilities, i.
We have already seen specific examples in the above sub-sections. Here we are going to deal with historical constructions or possibilities that have been put forth which are a result of interpretations of radiocarbon dating, more specifically of the Mingana folios at Birmingham. Parchment was an expensive material the skin of the entire animal was used to produce the big folio.
These stocks became part of the loot captured by the Arabs in the first years of the conquest. To test this hypothesis, it is necessary to reread the existing historical sources dedicated to the first years of the Arab conquests. In essence, one is asked to believe in the fantastic hypothesis that the people of Greater Syria among other places stocked already prepared blank parchment and were eagerly awaiting the advent of Islam and Arab conquests in order to hand them willingly this valuable possession.
In essence one is to believe unused parchment had been left for years! Why would the seller s expend an enormous amount of time, money and effort to prepare a multitude of blank parchment with no customer or no prospect of a customer? This in itself is self-contradictory and it assumes a thriving market. Additionally, if a client could afford to have such a codex constructed, why would one rely on parchment that is years old? Rich patrons presumably could afford brand new parchment, given the likely deterioration of prepared stocked parchment that is years old.
Did the new rulers and their subjects need recourse to stocked parchment? We are not aware of any example in early Islamic history where the Muslims were unable to execute a writing project because of the lack of prepared stocked parchment.
Common sense dictates if the Muslims desperately needed parchment to write on, they could have simply requested already used parchment, religious or otherwise, scraped it clean and started writing. All of the preceding assumes the existence and logical necessity of prepared stocked parchment that is years old. Rezvan cites no historical sources supportive of his hypothesis, and, as far as we are aware, there is no recorded instance around the time of late antiquity of prepared blank parchment being stored for years.
Unfortunately, his misunderstanding of the radiocarbon date range has resulted in him adopting an ad hoc randomly generated number range to satisfy his hypothesis retrospectively. Reynolds has expended a not inconsiderate amount of effort explaining, identifying and at times advocating John Wansbrough's theories,  including Wansbrough's now abandoned theory of a late compilation of the Qur'an.
There is not the slightest hint of historical context that necessitates the wholesale re-writing of the Late Antiquity, including nascent religious movements, inter-religious dynamics, Arabic palaeography, codicology, scribal culture and book culture. This kind of irresponsible flip-flopping is unlikely to benefit the field of Qur'anic studies and leaves the author's stated position on this most important issue confused and uncertain. There is an important methodological principle to be observed here.
Arabe a and Ms. With the benefit of further examination and additional evidence, he has since revised his views and now considers them as emanating from the same manuscript. One must be very careful not to make assumptions and generalisations on the basis of a few tests.
As described in the previous section, sample pretreatment is absolutely critical if one wants to obtain the most accurate measurements. Who then should have the final say in matters relating to dating? It may seem what is at stake here is the historian's craft. Spending decades honing skills learnt from masters in the field, it is only natural to encounter some pushback against a recently developed detached scientific method, especially when it appears to undermine commonly accepted historical paradigms.
However, there need not be any confrontation. One of the great benefits and advantages of radiocarbon dating is that scholarly prejudice and pre-suppositions about the genesis of Arabic scripts and Qur'anic manuscripts are not factored into the calculation. It cannot, however, be seen as disadvantageous or faulty when it appears to clash with one's own chronological reconstruction.
A collaborative approach that makes full use of scientific tests whilst remaining anchored in time tested traditional historical methods is more likely to provide the most fruitful results. The invention of radiocarbon dating has been revolutionary for the humanities. One of the great benefits and advantages of this method of dating is that scholarly prejudice and pre-suppositions regarding the genesis of Arabic scripts and Qur'anic manuscripts are not factored into the calculation.
Nevertheless, one of the downsides are the potential large time intervals which do not prove very useful in dating manuscripts very precisely, though this has been mitigated somewhat by the year on year improvement in accuracy and precision. At the outset when this technique was being considered for application to the Qur'an, specialists were rightly cautious and skeptical regarding the usefulness of the expected results. Writing in , Gerd-R. Puin pointed out radiocarbon dating had results scattered over a large time period, sometimes spanning a few hundred years.
He suggested the "traditional" methods of Arabic palaeography were more precise and offered a smaller range for dating Qur'anic manuscripts. Since then much progress has been made in the intervening thirty years. One can take a positive view of the science and see in the interpretation of its results an avenue of further enquiry into the examination of Islamic Origins. Of course, radiocarbon dating was not developed as a tool to advance the traditional account of the compilation and transmission of the Qur'an, though this is the impression one may be left with reading certain scholarly articles and popular level works written by scholars.
Faulty understanding of the scientific principles underpinning this radiometric dating technique have caused some modern scholars working in Islamic Studies to imagine improbable and sometimes absurd hypotheses.
Some seem to suggest the wholesale dismissal of this technique. Others that this technique doesn't work for the Qur'an. Flowing from this are a series of misunderstandings resulting in false assertions and scientific inaccuracies. Key terms such as probability, accuracy and precision are found to be poorly understood. A common feature of all of these criticisms, at present without exception, is that not a single scientific study is cited in support of such views.
Instead we are treated to a mish-mash of pseudo-scientific discussions occasionally referencing unnamed and unknown persons who apparently provided certain scientific information. Some of the discussion is strained to coincide with the authors preferred historical reconstruction. Our discussion points to the fact that even though the palaeographic and radiocarbon results usually match each other, the scientific method of radiocarbon dating can assist in generating and informing the debate regarding the chronology of Qur'anic manuscripts.
In fact, more than twenty years ago similar conclusions were reached for the Dead Sea Scrolls using radiocarbon and palaeographic datings. The radiocarbon method can only supplement, and at times complement, the "traditional" palaeography and is gaining prominence in dating.
As the accuracy and precision of radiocarbon dating improves with every passing year, one would be wise to take heed of Blair's insistence on utilising a more comprehensive approach than is currently the case, insisting that the adoption of multi-disciplinary sophistication will help to solve the disputes on dating early Qur'anic manuscripts.
Orlando FL , pp. Libby for development of the 14 C dating technique is given on p. An Archaeological Perspective , , op. Petersburg ", Manuscripta Orientalia , , Volume 6, No.
This leaf immediately precedes the leaf described in the previous Sotheby's auction containing the verses 2: Including this folio, several other folios of this manuscript have been carbon tested at a total of five different laboratories worldwide. With the exception of an impossibly early date given by one lab, they are in general agreement.
A further carbon test is given by Corpus Coranicum here. It would be prudent to treat these results with caution until further investigations are made. Accessed on 5th April Weisweiler gives the starting verse as According to the verse numbering system adopted by the well-known modern printed editions, it is Accessed on 25th December Hans-Casper Graf von Bothmer says:.
Ist damit die Datierung mittels kunsthistorischer Methoden in Frage gestellt? Furthermore, she complains that the testing facility and standard deviations confidence levels are absent.
Edinburgh Scotland , p. Any judgements as to the soundness and completeness of the results reported above should be resolved by the publication of this volume. Heavenly Art And Earthly Beauty , , op. Whelan, " Writing the Word of God: Beirut Lebanon , p. Kwiatkowski, Ink And Gold: Islamic Calligraphy , , Sam Fogg: A First Overview , , op. We made further investigation, identifying the manuscript and its constituent parts located at various collections around the world, publishing the results in the update of our article, Concise List of Arabic Manuscripts of the Quran Attributable to the First Century Hijra.
A First Overview , , Koninklijke Brill nv: Leiden The Netherlands , p. Petersburg ", Manuscripta Orientalia , , op. Emergence Of A Canon: Also see " Oudste Leidse Koranfragmenten ruim een eeuw ouder dan gedacht ".
Both the links accessed on 29th December Shebunin, " Kuficheskii Koran Imp. Pissareff, Coran Coufique de Samarcand: Petersbourg , , St. New Haven and London, p. London , Tuesday, 20 October at 10 a. Sam Fogg's catalogue contains a typographical error here. The carbon dating reads CE instead of CE. For dating, see Corpus Coranicum website. All the links accessed on 10th August Noseda's history of the manuscript and its description of the script have been summarised above.
Accessed 8th March Januarius Justus Witkam , , Archetype: Geburtstag , , op. Manuscrits Musulmans - Tome I, 1: Les Manuscrits Du Coran: Januarius Justus Witkam , , op. Link accessed on 2nd May , time slice [ Leiden The Netherlands , pp. R 38 has been carbon dated with The issue of uncertainty and imprecision has been long recognized as an issue in palaeography. For example, citing Eric Turner, Nongbri says p. Similarly, in geology, if distinctive granitic pebbles can be found in the sediment beside a similar granitic body, it can be inferred that the granite, after cooling, had been uplifted and eroded and therefore was not injected into the adjacent rock sequence.
Although with clever detective work many complex time sequences or relative ages can be deduced, the ability to show that objects at two separated sites were formed at the same time requires additional information. A coin, vessel, or other common artifact could link two archaeological sites, but the possibility of recycling would have to be considered.
It should be emphasized that linking sites together is essential if the nature of an ancient society is to be understood, as the information at a single location may be relatively insignificant by itself.
Similarly, in geologic studies, vast quantities of information from widely spaced outcrops have to be integrated. Some method of correlating rock units must be found. In the ideal case, the geologist will discover a single rock unit with a unique collection of easily observed attributes called a marker horizon that can be found at widely spaced localities. Any feature, including colour variations, textures, fossil content, mineralogy , or any unusual combinations of these can be used.
It is only by correlations that the conditions on different parts of Earth at any particular stage in its history can be deduced. In addition, because sediment deposition is not continuous and much rock material has been removed by erosion , the fossil record from many localities has to be integrated before a complete picture of the evolution of life on Earth can be assembled.
Using this established record, geologists have been able to piece together events over the past million years, or about one-eighth of Earth history, during which time useful fossils have been abundant. The need to correlate over the rest of geologic time, to correlate nonfossiliferous units, and to calibrate the fossil time scale has led to the development of a specialized field that makes use of natural radioactive isotopes in order to calculate absolute ages.
The precise measure of geologic time has proven to be the essential tool for correlating the global tectonic processes that have taken place in the past. Precise isotopic ages are called absolute ages, since they date the timing of events not relative to each other but as the time elapsed between a rock-forming event and the present. The same margin of error applies for younger fossiliferous rocks, making absolute dating comparable in precision to that attained using fossils.
To achieve this precision, geochronologists have had to develop the ability to isolate certain high-quality minerals that can be shown to have remained closed to migration of the radioactive parent atoms they contain and the daughter atoms formed by radioactive decay over billions of years of geologic time. In addition, they have had to develop special techniques with which to dissolve these highly refractory minerals without contaminating the small amount about one-billionth of a gram of contained lead and uranium on which the age must be calculated.
Since parent uranium atoms change into daughter atoms with time at a known rate, their relative abundance leads directly to the absolute age of the host mineral. In fact, even in younger rocks, absolute dating is the only way that the fossil record can be calibrated. Without absolute ages, investigators could only determine which fossil organisms lived at the same time and the relative order of their appearance in the correlated sedimentary rock record. Unlike ages derived from fossils, which occur only in sedimentary rocks, absolute ages are obtained from minerals that grow as liquid rock bodies cool at or below the surface.
When rocks are subjected to high temperatures and pressures in mountain roots formed where continents collide, certain datable minerals grow and even regrow to record the timing of such geologic events.
When these regions are later exposed in uptilted portions of ancient continents, a history of terrestrial rock-forming events can be deduced. Episodes of global volcanic activity , rifting of continents, folding, and metamorphism are defined by absolute ages. The results suggest that the present-day global tectonic scheme was operative in the distant past as well. Continents move, carried on huge slabs, or plates, of dense rock about km 62 miles thick over a low-friction, partially melted zone the asthenosphere below.
In the oceans , new seafloor, created at the globe-circling oceanic ridges , moves away, cools, and sinks back into the mantle in what are known as subduction zones i. Where this occurs at the edge of a continent, as along the west coast of North and South America, large mountain chains develop with abundant volcanoes and their subvolcanic equivalents.
These units, called igneous rock , or magma in their molten form, constitute major crustal additions. By contrast, crustal destruction occurs at the margins of two colliding continents, as, for example, where the subcontinent of India is moving north over Asia. Great uplift, accompanied by rapid erosion, is taking place and large sediment fans are being deposited in the Indian Ocean to the south.
Rocks of this kind in the ancient record may very well have resulted from rapid uplift and continent collision. When continental plates collide, the edge of one plate is thrust onto that of the other.
The rocks in the lower slab undergo changes in their mineral content in response to heat and pressure and will probably become exposed at the surface again some time later. Rocks converted to new mineral assemblages because of changing temperatures and pressures are called metamorphic. Virtually any rock now seen forming at the surface can be found in exposed deep crustal sections in a form that reveals through its mineral content the temperature and pressure of burial.
Such regions of the crust may even undergo melting and subsequent extrusion of melt magma, which may appear at the surface as volcanic rocks or may solidify as it rises to form granites at high crustal levels.
Magmas produced in this way are regarded as recycled crust, whereas others extracted by partial melting of the mantle below are considered primary. Even the oceans and atmosphere are involved in this great cycle because minerals formed at high temperatures are unstable at surface conditions and eventually break down or weather, in many cases taking up water and carbon dioxide to make new minerals.
If such minerals were deposited on a downgoing i. These components would then rise and be fixed in the upper crust or perhaps reemerge at the surface. Such hot circulating fluids can dissolve metals and eventually deposit them as economic mineral deposits on their way to the surface. Geochronological studies have provided documentary evidence that these rock-forming and rock-re-forming processes were active in the past. Seafloor spreading has been traced, by dating minerals found in a unique grouping of rock units thought to have been formed at the oceanic ridges, to million years ago, with rare occurrences as early as 2 billion years ago.
Other ancient volcanic units document various cycles of mountain building. The source of ancient sediment packages like those presently forming off India can be identified by dating single detrital grains of zircon found in sandstone.
Magmas produced by the melting of older crust can be identified because their zircons commonly contain inherited older cores.
Episodes of continental collision can be dated by isolating new zircons formed as the buried rocks underwent local melting. Periods of deformation associated with major collisions cannot be directly dated if no new minerals have formed. The time of deformation can be bracketed, however, if datable units, which both predate and postdate it, can be identified. The timing of cycles involving the expulsion of fluids from deep within the crust can be ascertained by dating new minerals formed at high pressures in exposed deep crustal sections.
In some cases, it is possible to prove that gold deposits may have come from specific fluids if the deposition time of the deposits can be determined and the time of fluid expulsion is known. Where the crust is under tension, as in Iceland, great fissures develop. These fissures serve as conduits that allow black lava , called basalt , to reach the surface.
The portion that remains in a fissure below the surface usually forms a vertical black tubular body known as a dike or dyke. Precise dating of such dikes can reveal times of crustal rifting in the past.
Images: why is radiocarbon dating limited
But isochrons might be able to account for pre-existing daughter elements. Dickin Radiogenic Isotope Geology, , p.
Magmas produced by the melting of older crust can be identified because their zircons commonly contain inherited older cores.
On the other hand, palaeography is a relative dating method radiocarobn gives why is radiocarbon dating limited order of events without giving an exact age. Some of top 10 free android dating apps discussion is strained to coincide with the authors preferred historical reconstruction. Since Cambrian and later rocks are largely sedimentary and igneous volcanic rocks are found in Cambrian and later strata, if these rocks are really million years old, whyy life must also be at least million years old. This manuscript has been subject to radiocarbon analysis under the auspices of the Corpus Coranicum project and has been dated to — CE with In other words, the probability of decay for an atom of 14 C in a sample os constant, thus making it amenable to the application of statistical methods for the analysis of counting data. Local melting may occur, and certain minerals suitable for precise isotopic dating may form both in the melt and in why is radiocarbon dating limited host rock.
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