The first major assumption built into radiometric dating is the idea that the parent elements have decayed in the past at the exact same rate as they are decaying today. This idea has problems, because no one alive today knows what kind of environment existed in the distant past.
We cannot claim to know how fast elements decayed in the past, because we have very little evidence to prove this idea which is why it is an assumption. Suppose you come upon a man who is cutting down trees in a forest. You watch him for an entire hour, and he cuts down only 1 tree. Then you count the number of trees he has cut—31 in all. If you assume that he has been cutting trees down at the same rate, then you calculate that he has chopped for 31 hours.
However, when you talk to the man, he tells you that, earlier in the day when his ax was sharp and his stomach was full, he was cutting down 5 trees an hour; only in the last hour had he slacked off. With this information, you now understand that he worked for only seven hours, not Claiming that the decay rates in the past were the same as they are now is an assumption that cannot be proven and should not be granted to those who want an age for the Earth measured in billions of years.
Another assumption built into the radiometric dating methods is the idea that the elements have not been affected by outside forces. However, this is a huge assumption. How can a person claim that natural forces have not affected the elements in a rock for a period of billions of years? If any rock were really 4.
To date rocks using any radiometric dating system, a person must assume that the daughter element in the sample was not there in the beginning. However, that claim cannot be proven. Who is to say that the rock did not start out with 23 ounces of lead already in it?
The lead could have been in the rock from the beginning and so could the uranium. To illustrate this point, suppose you go to a swimming pool and find a hose that is pumping water into the pool at a rate of gallons an hour. You discover that the pool has 3, gallons of water in it. You calculate that the hose must have been running for 30 hours.
However, when you ask the owner of the pool how long she has been running the hose, she tells you that she has been running it for only 1 hour. Most of the water was already in the pool due to a heavy rain the night before. If you assumed that all the water came from the hose, your calculations would be way off—29 hours off to be exact. Assumption three, that no daughter element existed at the beginning, simply cannot be granted. In addition to the assumptions that are built into radiometric dating, another problem is that the different radiometric methods drastically disagree with one another at times.
On occasion, the same sample of rock can be dated by the different methods, and the dates can differ by several hundred million years. Some rocks from Hawaii that were known to have formed about two hundred years ago rendered a date of million to 3 billion years when dated by the potassium-argon method. Another time, the same basalt rock in Nigeria was given a date of 95 million years when dated by the potassium-argon method, and million years when dated by the uranium-helium method.
But what can you expect from dating methods that are based entirely on built-in assumptions? Anything is possible! But each dating method that renders colossal numbers of years will be based on similar, unprovable assumptions. All around you, books, television, and radio are telling you that the Earth is billions of years old. This is nothing more than a trick to try and discredit the real history of the Earth as found in the Bible.
Realizing that these vast ages of billions of years come from dating methods that are based upon incorrect assumptions will give you more confidence in the Bible. There never have been billions of years available for evolution. Defending the Faith Study Bible. Featured Audio. Lead has a consequence of mt st helens gave. They all the table below to dating or radiometric dating of radiometric dating using radioactive dating: chat.
While doing so it will cause trouble for the same problem 45if. Scientific serious question. It will heat up surrounding rock? What is therefore another problem with radiometric dating. Radiometric dating of c14 present when the problems with seven neutrons.
The wrong assumptions lead isochrons are supposed to imply that it mixes into the material is a christian perspective. Due: 1. Issues with flaws, creationists argue that earth? Older than any man-made measurement interval. Older carbon has long ago rocks are also one of least importance are also an important radioactive isotopes.
Register and enter the main problems with contamination. Geologists use radiometric dating: 1: 1: no anomalies. Is not aware of rocks formed from the exam questions or other objects based on the different methods. Similar kinds of the age for this a woman. Here is the assumption 3: no anomalies.
Explore radiometric dating involves dating takes advantage of incompatible expectations. Scientific affiliation website. Pro radioactive determination. If a whole radiometric dating methods. Answers hard porn radiometric dating scheme scientific proof that can be used against creationist work can the proportions of rock changes.
They all give erroneous dates. Free to date fossils and c12 in the problem of 25 my area! Register and billions of certain minerals rocks and meet a low melting point, creationists argue that radiometric methods is not perfect. By most people who is used to date rocks dated by several hundred million years old soul like any other objects changes.
Of mt st helens gave. This sample which are no anomalies. Uranium has the fixed decay in my interests include staying up late and search over time. As indisputable scientific dating.
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Radioactive are two radioactive of half-life problems we will perform. One format involves calculating a mass formula of the original isotope. Using the equation below, we can life how much of the original isotope remains after a certain interval of time.
The half-life of this isotope is 10 days. For example, carbon has a half-life of 5, years and is used to measure the radioactive of organic material. The ratio of carbon dating carbon in living things remains constant while the organism is alive because fresh carbon is entering the organism whenever it consumes nutrients. When the organism dies, this consumption radioactive, and no new carbon is added to the organism.
As time goes by, the ratio of carbon to carbon in the organism gradually declines, because carbon radioactively decays while carbon is stable. Analysis of this ratio allows archaeologists to estimate the age of organisms that were alive many thousands of years ago. Key with stable carbon, radioactive carbon radioactive taken in by plants and animals, and remains at a constant level within them answer they are alive.
After death, the C decays and the C. C ratio in radioactive remains decreases. Formula this ratio to the C. C ratio in living organisms allows us to determine how long ago the organism lived and died. C dating does dating limitations. For radioactive, a sample radioactive be C dating if answers is approximately to 50, years old.
Before or radiometric this range, there is too little of the isotope to be detected. Substances must have obtained C from the atmosphere. For this reason, aquatic samples cannot be effectively C dated. Lastly, accuracy of C dating has been affected by atmosphere nuclear weapons testing. Fission bombs ignite radioactive produce more C artificially. Samples tested during problems after this period must be checked against another method of dating isotopic or tree rings. To half-life the age of a radioactive using isotopic dating, use the equation below:.
How long will it take for. Ra has a half-life of years. Radioactive dating can also use other radioactive nuclides with longer half-lives to date older events. For example, uranium half decays in a series of steps into lead can be used for establishing the age of rocks and the approximate age of the oldest rocks on earth. Since U has a half-life of 4. In a sample of rock radioactive does radioactive contain appreciable amounts of Pb, the most abundant key of lead, we can assume that lead was not present when the rock was formed.
Therefore, by measuring and radiometric the ratio and U. Answers, we can determine the age of radioactive rock. This half that all of the lead present came from the decay of uranium. If there is additional lead present, which is indicated by the presence of other lead isotopes in the sample, it is necessary to make an adjustment. Potassium-argon dating uses a similar method. K radioactive by positron emission and electron capture to form Ar with a half-life of 1.
The probability concept aligns with the traditional definition of half-life. Provided the number of nuclei is reasonably large, half of the original nuclei should decay during one half-life period. The following equation gives the quantitative relationship between the original number of nuclei present at time zero N O N O and the number N N at a later time t.
The decay constant can be found with the equation. What do we mean when we say a source is highly radioactive? Generally, it means the number of decays per unit time is very high. We define activity R to be the rate of decay expressed in decays per unit time. In equation form, this is.
The SI unit for activity is one decay per second and it is given the name becquerel Bq in honor of the discoverer of radioactivity. That is,. Activity R is often expressed in other units, such as decays per minute or decays per year. The definition of the curie is. Radioactive dating or radiometric dating is a clever use of naturally occurring radioactivity.
Its most familiar application is carbon dating. Carbon is an isotope of carbon that is produced when solar neutrinos strike 14 N 14 N particles within the atmosphere. Radioactive carbon has the same chemistry as stable carbon, and so it mixes into the biosphere, where it is consumed and becomes part of every living organism.
Carbon has an abundance of 1. Over time, carbon will naturally decay back to 14 N 14 N with a half-life of 5, years note that this is an example of beta decay. When an organism dies, carbon exchange with the environment ceases, and 14 C 14 C is not replenished. Carbon dating can be used for biological tissues as old as 50 or 60 thousand years, but is most accurate for younger samples, since the abundance of 14 C 14 C nuclei in them is greater.
One of the most famous cases of carbon dating involves the Shroud of Turin, a long piece of fabric purported to be the burial shroud of Jesus see Figure This relic was first displayed in Turin in and was denounced as a fraud at that time by a French bishop. Its remarkable negative imprint of an apparently crucified body resembles the then-accepted image of Jesus. As a result, the relic has been remained controversial throughout the centuries.
Carbon dating was not performed on the shroud until , when the process had been refined to the point where only a small amount of material needed to be destroyed. Samples were tested at three independent laboratories, each being given four pieces of cloth, with only one unidentified piece from the shroud, to avoid prejudice. All three laboratories found samples of the shroud contain 92 percent of the 14 C 14 C found in living tissues, allowing the shroud to be dated see Figure Carbon has a half-life of If 1 kg of carbon sample exists at the beginning of an hour, b how much material will remain at the end of the hour and c what will be the decay activity at that time?
The decay constant is equivalent to the probability that a nucleus will decay each second. As a result, the half-life will need to be converted to seconds. Another way of considering the decay constant is that a given carbon nuclei has a 0. The decay of carbon allows it to be used in positron emission topography PET scans; however, its As a result, one would expect the amount of sample remaining to be approximately one eighth of the original amount.
The Calculate the age of the Shroud of Turin given that the amount of 14 C 14 C found in it is 92 percent of that in living tissue. Here, we assume that the decrease in 14 C 14 C is solely due to nuclear decay. We enter that value into the previous equation to find t. Our calculation is only accurate to two digits, so that the year is rounded to That uncertainty is typical of carbon dating and is due to the small amount of 14 C in living tissues, the amount of material available, and experimental uncertainties reduced by having three independent measurements.
The most common contaminant is nitrogen, 0. Nearby radioactive material could trigger exactly the same C14 production process from nitrogen as occurs in the upper atmosphere, albeit at a much reduced rate. Another possible avenue is C13, which has a small but non-zero neutron absorption cross section.
By either mechanism, this is essentially internal contamination. All this means is that measured dates older than some oldest reliable date are just that -- to old to date reliably. I might be able to see if I can come up with some references. I won't be able to do so in the near term -- my wife and kids want me to stop dorking with the internet and go out to eat.
The article you were looking for is here , and yeah, it looks like you're right. Note: I think that should be I know I visited talkorigins. What is more alarming is that the Google searches for "carbon 14 RATE", "carbon 14 diamond", and "carbon 14 coal" yield hits predominantly in woowoo fundamentalist sites, and no hits on the first 15 pages 10 links per page to anything at talkorigins.
I eventually managed to find an excellent article see the top of this post using pandasthumb. That led me to this non-technical article,. I think the news item on their front page refers to a much older event. What happened, from what I recall, is that someone hacked TalkOrigins and managed to get the site to display hidden spam links at the bottom of pages, making Google think it was a spam site and thus getting it removed from Google. They fixed that issue a while ago. PZ Myers says they've had some technical issues.
I am working my way through Kirk Bertsche's 9 page essay on the subject. Thanks DH for this link. This article does a good job at explaining the technical complexities of measuring the very small amounts of C14 present in these ancient samples and why non-zero amounts are measured. I'm a complete non-expert in this field of radiometric dating, but it strikes me reading this how contamination by modern carbon introduced during sample preparation seems to be a severe issue.
I'm wonder whether they've extracted samples under an inert atmosphere and then used laser ablation to ionize samples in their mass spectrometers? I'm probably teaching grandmother to suck eggs, as the old saying goes. Getting back to my OP - I feel that some definitive work needs to be done in this area.
It's easy to see that the sceptical creationist is simply going to see the scientific response as making excuses for the data instead of holding up some hard data that either explains or explodes the anomaly. Another thing I've heard from creationists is that fossils made by soaking samples in tar pits appear to be extremely old. Of course, the problem is that this process results in contamination with old carbon, making the sample appear older.
In the case of old samples with almost no C, even the tiniest bit of contamination would make the sample appear far younger. Always remember that C dating is not a magical process; it is a measure of C and the age interpretation depends on a few assumptions.
It's also worth noting that C is only useful for a bit more than , years. The vast majority of fossils aren't dated using C at all, but other radioisotopes. Science has several very reasonable explanations for levels of modern carbon in very old samples. Although this satisfies the scientist, who for all sorts of other reasons quite reasonably assumes that these samples are truly old, it leaves enormous scope for the creationists to reinforce their followers' faith that the earth is young.
I still feel that some definitive experiments in this area would be useful to test the various rational explanations for the c14 anomaly. I can see though that science has problems taking on creationists because of the perceived risk of lending credibility to their ideas. Bit of a dilemma there.
Also as soon as one creationist idea is exploded, they just move on to another area where uncertainty in the science offers them the opportunity to mislead. That begs the question that an anomaly even exists. What does exist are limits to the applicability of 14 C dating techniques. Several of the test results touted by creationists were definitive experiments to assess those limitations. There is no arguing with young earth creationists. They are immune to logic and evidence.
Broadly speaking I agree with you. But, reading the experts' explanations of the "anomaly" read to me, as a non-expert in this field, like perfectly reasonable explanations as long as you accept the "old earth" explanation.
If you don't, such dismissive arguments as 'the extra C14 could be due to uranium decay' leave enough wriggle room uncertainty for the creationist to thrive in. You're right though, I'm probably being naive in thnking they will be convinced. Even so, it is always good when creationists have been casting doubt in some area to be able to completely explode their reasoning.
I'm still looking for a reference, in a refereed scientific journal, confirming the finding of carbon14, in any amount, in diamonds or coal. I suspect, but haven't been able to confirm, that the reports of carbon 14 in these substances have been made up out of whole cloth by Young Earth Creationists, but I am loath to make this claim, absent evidence that reports of these findings haven't been published in any journals that aren't connected with such organizations as the Institute for Creation Science.
I further think that it is the fact that the claims are conscpicuously bogus that has accounted for their not having been responded to. After all, to my limited understanding, carbon 14 is associated with organic processes, and, right off the bat, I find myself wondering why it would be found in any allotrope of carbon, which is an inorganic element. Can anyone out there either confirm or disconfirm my suspicions? You need to know that I will not be much impressed by anything coming from the ICR or any similar group.
Well one of two things could be happening, the carbon 14 signature is reset every time the rock melts because the carbon 14 disperses among the liquid rock, Also neutron bombardment from uranium decay could possibly have an impact, but you'd also have other trace elements that tell the tale of this neutron contamination. Since the discussion is specifically about Carbon14 in coal I am unclear as to why you would be talking about molten rock.
Coal is not known for its inclination to melt. Since Carbon14 dating is only relevant to dating organic matter I am unclear as to why you would be talking about resetting the Carbon14 clock in molten rock. Molten rock is not organic material friendly. We all make mistakes. I made one in You need to be a member in order to leave a comment. Sign up for a new account in our community. It's easy! Already have an account? Indeed, there are a number of conditions on the reliability of radiometric dating.
For example, for K-Ar dating, we have the following requirements: For this system to work as a clock, the following 4 criteria must be fulfilled: 1. The decay constant and the abundance of K40 must be known accurately. There must have been no incorporation of Ar40 into the mineral at the time of crystallization or a leak of Ar40 from the mineral following crystallization.
The system must have remained closed for both K40 and Ar40 since the time of crystallization. The relationship between the data obtained and a specific event must be known. The earth is supposed to be nearly 5 billion years old, and some of these methods seem to verify ancient dates for many of earth's igneous rocks. The answer is that these methods, are far from infallible and are based on three arbitrary assumptions a constant rate of decay, an isolated system in which no parent or daughter element can be added or lost, and a known amount of the daughter element present initially.
Heating and deformation of rocks can cause these atoms to migrate, and water percolating through the rocks can transport these substances and redeposit them. These processes correspond to changing the setting of the clock hands. Not infrequently such resetting of the radiometric clocks is assumed in order to explain disagreements between different measurements of rock ages.
Some more quotes from the same source: a. In the lead-uranium systems both uranium and lead can migrate easily in some rocks, and lead volatilizes and escapes as a vapor at relatively low temperatures. It has been suggested that free neutrons could transform Pb first to Pb and then to Pb, thus tending to reset the clocks and throw thorium-lead and uranium-lead clocks completely off, even to the point of wiping out geological time.
Furthermore, there is still disagreement of 15 percent between the two preferred values for the U decay constant. Potassium volatilizes easily, is easily leached by water, and can migrate through the rocks under certain conditions. Furthermore, the value of the decay constant is still disputed, although the scientific community seems to be approaching agreement.
Historically, the decay constants used for the various radiometric dating systems have been adjusted to obtain agreement between the results obtained. Argon, the daughter substance, makes up about one percent of the atmosphere, which is therefore a possible source of contamination. However, since it is possible for argon to be formed in the rocks by cosmic radiation, the correction may also be in error.
Argon from the environment may be trapped in magma by pressure and rapid cooling to give very high erroneous age results. Rubidium parent atoms can be leached out of the rock by water or volatilized by heat. All of these special problems as well as others can produce contradictory and erroneous results for the various radiometric dating systems.
So we have a number of mechanisms that can introduce errors in radiometric dates. Heating can cause argon to leave a rock and make it look younger. In general, if lava was heated after the initial flow, it can yield an age that is too young. If the minerals in the lava did not melt with the lava, one can obtain an age that is too old. Leaching can also occur; this involves water circulating in rock that can cause parent and daughter elements to enter or leave the rock and change the radiometric age.
Thus it is easy to rationalize any date that is obtained. If a date is too old, one can say that the mineral did not melt with the lava. Maybe it got included from surrounding rock as the lava flowed upward. If the date is too young, one can say that there was a later heating event. One can also hypothesize that leaching occurred. But then it is claimed that we can detect leaching and heating. But how can we know that this claim is true, without knowing the history of rocks and knowing whether they have in fact experienced later heating or leaching?
The problems are compounded because many of the parent and daughter substances are mobile, to some extent. I believe that all parent substances are water soluble, and many of the daughter products as well. A few sources have said that Sr is mobile in rock to some extent.
This could cause trouble for Rb-Sr dating. In fact, some sources say that Sr and Ar have similar mobilities in rock, and Ar is very mobile. Especially the gaseous radioactive decay byproducts such as argon, radon, and helium are mobile in rock. So if a rock has tiny cracks permitting gas to enter or escape or permitting the flow of water, the radiometric ages could be changed substantially even without the rock ever melting or mixing.
Now, there is probably not much argon in a rock to start with. So the loss of a tiny amount of argon can have significant effects over long time periods. A loss of argon would make the rock look younger. In a similar way, argon could enter the rock from the air or from surrounding rocks and make it look older.
And this can also happen by water flowing through the rock through tiny cracks, dissolving parent and daughter elements. It would be difficult to measure the tiny changes in concentration that would suffice to make large changes in the radiometric ages over long time periods. I also question the assertion that argon, for example, is excluded from certain minerals when they crystallize and never enters later on.
Geologists often say that ages that are too old are due to excess argon. So it must be possible for that excess argon to get in, even though the crystal is supposed to exclude it. Here is one such reference, although this is to a mineral that does not exclude argon: "As in all dating systems, the ages calculated can be affected by the presence of inherited daughter products.
In a few cases, argon ages older than that of the Earth which violate local relative age patterns have even been determined for the mineral biotite. Such situations occur mainly where old rocks have been locally heated, which released argon into pore spaces at the same time that new minerals grew.
Under favourable circumstances the isochron method may be helpful, but tests by other techniques may be required. For example, the rubidium-strontium method would give a valid isotopic age of the biotite sample with inherited argon. For example, different kinds of quartz have different colors due to various impurities that are included but not part of the repetitive unit of the quartz crystal.
So even if the crystal excludes the daughter element, it could be present in impurities. Thus crystals, as they form, may have tiny imperfections that accept parent and daughter products in the same ratios as they occur in the lava, so one can inherit ages from the lava into minerals in this way. It is also possible that parent and daughter elements could be present in boundaries between regular crystal domains. I don't know how we can be sure that a crystal will exclude argon or other daughter substances except by growing it in the laboratory under many conditions.
There can also be argon or other daughter products added from the air or from other rocks. One could say that we can detect whether the daughter is embedded in the crystal structure or not. But this would require an atom by atom analysis, which I do not believe is practical.
Why K-Ar dating is inaccurate Back to top Since K-Ar potassium-argon dating is one of the most prevalent techniques, some special commentary about it is in order. Potassium is about 2. Argon is about 3. This is about one ten millionth of the mass of the rock, a very tiny percentage. And yet, with a large amount of argon in the air and also filtering up from rocks below, and with excess argon in lava, with argon and potassium water soluble, and argon mobile in rock, we are still expecting this wisp of argon to tell us how old the rock is!
The percentage of Ar40 is even less for younger rocks. For example, it would be about one in million for rocks in the vicinity of 57 million years old. To get one part in 10 million of argon in a rock in a thousand years, we would only need to get one part in 10 billion entering the rock each year. This would be less than one part in a trillion entering the rock each day, on the average. This would suffice to give a rock having an average concentration of potassium, a computed potassium-argon age of over million years!
We can also consider the average abundance of argon in the crust. This implies a radiometric age of over 4 billion years. So a rock can get a very old radiometric age just by having average amounts of potassium and argon. It seems reasonable to me that the large radiometric ages are simply a consequence of mixing, and not related to ages at all, at least not necessarily the ages of the rocks themselves.
The fact that not all of the argon is retained would account for smaller amounts of argon near the surface, as I will explain below. This could happen because of properties of the magma chambers, or because of argon being given off by some rocks and absorbed by others. I don't see how one can possibly know that there are no tiny cracks in rocks that would permit water and gas to circulate. The rates of exchange that would mess up the dates are very tiny.
It seems to me to be a certainty that water and gas will enter rocks through tiny cracks and invalidate almost all radiometric ages. Let me illustrate the circulation patterns of argon in the earth's crust. About 2. So argon is being produced throughout the earth's crust, and in the magma, all the time. In fact, it probably rises to the top of the magma, artificially increasing its concentration there. Now, some rocks in the crust are believed not to hold their argon, so this argon will enter the spaces between the rocks.
Leaching also occurs, releasing argon from rocks. Heating of rocks can also release argon. Argon is released from lava as it cools, and probably filters up into the crust from the magma below, along with helium and other radioactive decay products. All of this argon is being produced and entering the air and water in between the rocks, and gradually filtering up to the atmosphere. But we know that rocks absorb argon, because correction factors are applied for this when using K-Ar dating. So this argon that is being produced will leave some rocks and enter others.
The partial pressure of argon should be largest deepest in the earth, and decrease towards the surface. This would result in larger K-Ar ages lower down, but lower ages nearer the surface. As for K-Ar dating, here is a quote given above: "As in all dating systems, the ages calculated can be affected by the presence of inherited daughter products.
Now, argon is very soluble in magma, which can hold a lot of it: "Laboratory experiments have been conducted on the solubility of argon in synthetic basaltic melts and their associated minerals. After the material was quenched, the researchers measured up to 0. They noted, 'The solubility of Ar in the minerals is surprisingly high'. This paper also discusses Mount St. Helens K-Ar dating, and historic lava flows and their excess argon. So magma holds tremendous amounts of argon.
Now, consider an intrusive flow, which cools within the earth. All its argon will either remain inside and give an old age to the flow, or will travel through surrounding rock, where it can be absorbed by other rocks. So magma should have at least 20 times as much argon as a rock million years old by K-Ar dating. In fact, the argon in the magma may well be even higher, as it may concentrate near the top.
This amount of argon is enough to raise 20 times the volume of magma to a K-Ar age of million years, and probably times the volume of the magam to an age of 57 million years. So one sees that there is a tremendous potential for age increases in this way. It is not necessary for this increase in age to happen all at once; many events of this nature can gradually increase the K-Ar ages of rocks. In general, older rocks should have more argon because they have been subject to more exposure to such argon, but their true age is not necessarily related to their K-Ar radiometric age.
We can also consider that most volcanoes and earthquakes occur at boundaries between plates, so if the lava has flowed before, it is likely to flow again nearby, gradually increasing the age. I suppose earthquakes could also allow the release of argon from the magma. Other mechanisms include dissolving of rock, releasing its argon, fracturing of rock, with release of argon, argon from cooling lava under water entering the water and entering other rocks, and argon from cooling lave entering subterranean water and being transported to other rock.
There are so many mechanisms that it is hard to know what pattern to expect, and one does not need to rely on any one of them such as more argon in the magma in the past to account for problems in K-Ar dating. Since even rocks with old K-Ar dates still absorb more argon from the atmosphere in short time periods, it follows that rocks should absorb quite a bit of argon over long time periods, especially at higher pressures. In fact, if a rock can absorb only a ten millionth part of argon, that should be enough to raise its K-Ar age to over million years, assuming an average amounts of potassium.
It wouldn't require many internal cracks to allow a ten millionth part of argon to enter. Also, as the rock deforms under pressure, more cracks are likely to form and old ones are likely to close up, providing more opportunity for argon and other gases to enter. I mentioned a number of possibilities that could cause K-Ar dates to be much older than the true ages of the rocks. Here is another way that K-Ar dates can be too old: If we assume the earth went through a catastrophe recently, then the crustal plates might have been agitated, permitting lava and argon to escape from the magma.
Thus a lot of argon would be filtering up through the crust. As intrusive flows of lava cooled inside the crust, they would have been in an environment highly enriched in argon, and thus would not have gotten rid of much of their argon. Thus they would have hardened with a lot of argon inside. This would make them appear old. The same goes for extrusive flows on the surface, since argon would be filtering up through the earth and through the lava as it cooled.
The following was sent to me by a friend: In areas where tremendous tectonic activity has taken place, highly discordant values for the ages are obtained. The difficulties associated are numerous and listed as follows: 1. There seems to be a great deal of question regarding the branching ratio for K40 into Ar40 and Ca But the value is not really known. The observed value is between 0.
However, this doesn't remedy the situation and the ages are still too high [low? The geochronologists credit this to "argon leakage". There is far too much Ar40 in the earth for more than a small fraction of it to have been formed by radioactive decay of K This is true even if the earth really is 4. In the atmosphere of the earth, Ar40 constitutes This is around times the amount that would be generated by radioactive decay over the age of 4.
Certainly this is not produced by an influx from outer space. Thus, a large amount of Ar40 was present in the beginning. Since geochronologists assume that errors due to presence of initial Ar40 are small, their results are highly questionable.
Argon diffuses from mineral to mineral with great ease. It leaks out of rocks very readily and can move from down deep in the earth, where the pressure is large, and accumulate in an abnormally large amount in the surface where rock samples for dating are found. They would all have excess argon due to this movement. This makes them appear older. Rocks from deeper in the crust would show this to a lesser degree. Also, since some rocks hold the Ar40 stronger than others, some rocks will have a large apparent age, others smaller ages, though they may actually be the same age.
If you were to measure Ar40 concentration as function of depth, you would no doubt find more of it near the surface than at deeper points because it migrates more easily from deep in the earth than it does from the earth into the atmosphere. It is easy to see how the huge ages are being obtained by the KAr40 radiometric clock, since surface and near-surface samples will contain argon due to this diffusion effect.
Some geochronologists believe that a possible cause of excess argon is that argon diffuses into mineral progressively with time. Significant quantities of argon may be introduced into a mineral even at pressures as low as one bar. If such [excessive] ages as mentioned above are obtained for pillow lavas, how are those from deep-sea drilling out in the Atlantic where sea-floor spreading is supposed to be occurring?
Potassium is found to be very mobile under leaching conditions. This could move the "ages" to tremendously high values. Ground-water and erosional water movements could produce this effect naturally. Rocks in areas having a complex geological history have many large discordances. In a single rock there may be mutually contaminating, potassium- bearing minerals. There is some difficulty in determining the decay constants for the KAr40 system.
Geochronologists use the branching ratio as a semi-emperical, adjustable constant which they manipulate instead of using an accurate half-life for K A number of recent lava flows within the past few hundred years yield potassium-argon ages in the hundreds of thousands of years range. This indicates that some excess argon is present. Where is it coming from? And how do we know that it could not be a much larger quantity in other cases? If more excess argon were present, then we could get much older ages.
It is true that an age difference in the hundreds of thousands of years is much too small to account for the observed K-Ar ages. But excess argon is commonly invoked by geologists to explain dates that are too old, so I'm not inventing anything new.
Second, there may have been a lot more more argon in the magma in the past, and with each eruption, the amount decreased. So there would have been a lot more excess argon in the past, leading to older ages. For rocks that are being dated, contamination with atmospheric argon is a persistent problem that is mentioned a number of times.
Thus it is clear that argon enters rock easily. It is claimed that we can know if a rock has added argon by its spectrum when heated; different temperatures yield different fractions of argon. It is claimed that the argon that enters from the atmosphere or other rocks, is less tightly bound to the crystal lattice, and will leave the rock at a lower temperature. But how do we know what happens over thousands of years? It could be that this argon which is initially loosely bound if it is so initially gradually becomes more tightly bound by random thermal vibrations, until it becomes undetectable by the spectrum technique.
The fact that rock is often under high pressure might influence this process, as well. The branching ratio problem Back to top See some updates to this article. We now consider in more detail one of the problems with potassium-argon dating, namely, the branching ratio problem.
Here is some relevant information that was e-mailed to me. There are some very serious objections to using the potassium-argon decay family as a radiometric clock. The geochronologist considers the Ca40 of little practical use in radiometric dating since common calcium is such an abundant element and the radiogenic Ca40 has the same atomic mass as common calcium. Here the actual observed branching ratio is not used, but rather a small ratio is arbitrarily chosen in an effort to match dates obtained method with U-Th-Pb dates.
The branching ratio that is often used is 0. Thus we have another source of error for K-Ar dating. We now consider whether they can explain the observed dates. In general, the dates that are obtained by radiometric methods are in the hundreds of millions of years range. One can understand this by the fact that the clock did not get reset if one accepts the fact that the magma "looks" old, for whatever reason. That is, we can get both parent and daughter elements from the magma inherited into minerals that crystallize out of lava, making these minerals look old.
Since the magma has old radiometric dates, depending on how much the clock gets reset, the crust can end up with a variety of younger dates just by partially inheriting the dates of the magma. Thus any method based on simple parent to daughter ratios such as Rb-Sr dating is bound to be unreliable, since there would have to be a lot of the daughter product in the magma already.
And Harold Coffin's book Creation by Design lists a study showing that Rb-Sr dates are often inherited from the magma. Even the initial ratios of parent and daughter elements in the earth do not necessarily indicate an age as old as 4.
Radioactive decay would be faster in the bodies of stars, which is where scientists assume the heavy elements formed. Imagine a uranium nucleus forming by the fusion of smaller nucleii. At the moment of formation, as two nucleii collide, the uranium nucleus will be somewhat unstable, and thus very likely to decay into its daughter element. The same applies to all nucleii, implying that one could get the appearance of age quickly.
Of course, the thermonuclear reactions in the star would also speed up radioactive decay. But isochrons might be able to account for pre-existing daughter elements. Furthermore, some elements in the earth are too abundant to be explained by radioactive decay in 4. Some are too scarce such as helium. So it's not clear to me how one can be sure of the 4. Why older dates would be found lower in the geologic column especially for K-Ar dating Back to top In general, potassium-argon dates appear to be older the deeper one goes in the crust of the earth.
We now consider possible explanations for this. There are at least a couple of mechanisms to account for this. In volcano eruptions, a considerable amount of gas is released with the lava. This gas undoubtedly contains a significant amount of argon Volcanos typically have magma chambers under them, from which the eruptions occur. It seems reasonable that gas would collect at the top of these chambers, causing artificially high K-Ar radiometric ages there.
In addition, with each successive eruption, some gas would escape, reducing the pressure of the gas and reducing the apparent K-Ar radiometric age. Thus the decreasing K-Ar ages would represent the passage of time, but not necessarily related to their absolute radiometric ages. As a result, lava found in deeper layers, having erupted earlier, would generally appear much older and lava found in higher layers, having erupted later, would appear much younger.
This could account for the observed distribution of potassium-argon dates, even if the great sedimantary layers were laid down very recently. In addition, lava emerging later will tend to be hotter, coming from deeper in the earth and through channels that have already been warmed up. This lava will take longer to cool down, giving more opportunity for enclosed argon to escape and leading to younger radiometric ages. A discussion of these mechanisms may be found at the Geoscience Research Institute site.
Another factor is that rocks absorb argon from the air. It is true that this can be accounted for by the fact that argon in the air has Ar36 and Ar40, whereas only Ar40 is produced by K-Ar decay. But for rocks deep in the earth, the mixture of argon in their environment is probably much higher in Ar40, since only Ar40 is produced by radioactive decay. As these rocks absorb argon, their radiometric ages would increase. This would probably have a larger effect lower down, where the pressure of argon would be higher.
Or it could be that such a distribution of argon pressures in the rocks occurred at some time in the past. This would also make deeper rocks tend to have older radiometric ages. Recent lava flows often yield K-Ar ages of about , years. This shous that they contain some excess argon, and not all of it is escaping.
If they contained a hundred times more excess argon, their K-Ar ages would be a hundred times greater, I suppose. And faster cooling could increase the ages by further large factors. I also read of a case where a rock was K-Ar dated at 50 million years, and still susceptible to absorbing argon from the air. This shows that one might get radiometric ages of at least 50 million years in this way by absorbing Ar40 deep in the earth without much Ar36 or Ar38 present.
If the pressure of Ar40 were greater, one could obtain even greater ages. Yet another mechanism that can lead to decreasing K-Ar ages with time is the following, in a flood model: One can assume that at the beginning of the flood, many volcanoes erupted and the waters became enriched in Ar Then any lava under water would appear older because its enclosed Ar40 would have more trouble escaping. As time passed, this Ar40 would gradually pass into the atmosphere, reducing this effect and making rocks appear younger.
In addition, this would cause a gradient of Ar40 concentrations in the air, with higher concentrations near the ground. This also could make flows on the land appear older than they are, since their Ar40 would also have a harder time escaping. Do different methods agree with each other on the geologic column? Back to top Let us consider the question of how much different dating methods agree on the geologic column, and how many measurements are anomalous, since these points are often mentioned as evidences of the reliability of radiometric dating.
It takes a long time to penetrate the confusion and find out what is the hard evidence in this area. In the first place, I am not primarily concerned with dating meteorites, or precambrian rocks. What I am more interested in is the fossil-bearing geologic column of Cambrian and later age.
Now, several factors need to be considered when evaluating how often methods give expected ages on the geologic column. Some of these are taken from John Woodmoreappe's article on the subject, but only when I have reason to believe the statements are also generally believed. First, many igneous formations span many periods, and so have little constraint on what period they could belong to.
The same applies to intrusions. In addition, some kinds of rocks are not considered as suitable for radiometric dating, so these are typically not considered. Furthermore, it is at least possible that anomalies are under-reported in the literature. Finally, the overwhelming majority of measurements on the fossil bearing geologic column are all done using one method, the K-Ar method. And let me recall that both potassium and argon are water soluble, and argon is mobile in rock.
Thus the agreement found between many dates does not necessarily reflect an agreement between different methods, but rather the agreement of the K-Ar method with itself. For example, if 80 percent of the measurements were done using K-Ar dating, and the other 20 percent gave random results, we still might be able to say that most of the measurements on a given strata agree with one another reasonably well.
So to me it seems quite conceivable that there is no correlation at all between the results of different methods on the geologic column, and that they have a purely random relationship to each other. Let us consider again the claim that radiometric dates for a given geologic period agree with each other.
I would like to know what is the exact or approximate information content of this assertion, and whether it could be or has been tested statistically. It's not as easy as it might sound. Let's suppose that we have geologic periods G Let's only include rocks whose membership in the geologic period can be discerned independent of radiometric dating methods.
Let's also only include rocks which are considered datable by at least one method, since some rocks I believe limestone are considered not to hold argon, for example. Now, we can take a random rock from Gi. We will have to restrict ourselves to places where Gi is exposed, to avoid having to dig deep within the earth.
Let's apply all known dating methods to Gi that are thought to apply to this kind of rock, and obtain ages from each one. Then we can average them to get an average age for this rock. We can also compute how much they differ from one another.
Now we have to be careful about lava flows -- which geologic period do they belong to? What about rocks that are thought not to have their clock reset, or to have undergone later heating episodes? Just to make the test unbiased, we will assign altitude limits to each geologic period at each point on the earth's surface at least in principle and include all rocks within these altitude limits within Gi, subject to the condition that they are datable.
The measurements should be done in a double-blind manner to insure lack of unconscious bias. For each geologic period and each dating method, we will get a distribution of values. We will also get a distribution of averaged values for samples in each period. Now, some claim is being made about these distributions. It is undoubtedly being claimed that the mean values ascend as one goes up the geologic column. It is also being claimed that the standard deviations are not too large.
It is also being claimed that the different methods have distributions that are similar to one another on a given geologic period. The only correlation I know about that has been studied is between K-Ar and Rb-Sr dating on precambrian rock. And even for this one, the results were not very good.
This was a reference by Hurley and Rand, cited in Woodmorappe's paper.