So there would have been a lot more excess argon in the past, leading to older ages. Using science, there are at least three hypotheses that may be purposed to explain why Austin obtained 'dates' of , to 2. 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. Although Austin failed to properly fractionate and date the minerals and glass in Mt. In general, if lava was heated after the initial flow, it can yield an age that is too young. Finally, the fact that the great majority of dates are from one method means that the general but not universal agreement of K-Ar dating with itself is sufficient to explain the small percentange of anomalies if it is small. 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.
Need for a double-blind test. On another point, if we can detect minerals that were not molten with the lava, as has been claimed, then this is one more reason why there should be no anomalies, and radiometric dating should be a completely solved problem. Galunggung status raised to alert" , The Jakarta Post , archived from the original on February 14, 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. 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. For older samples, which contain more 40Ar, the contamination is diluted and has insignificant effects.
On the basis of the glass and mineral textures and elementary melt chemistry, we know that the zoned plagioclases and other relatively large and well-developed minerals in Austin's dacite must have taken more time to grow than the surrounding glass matrix.
By using high-temperature ovens in undergraduate university laboratories or even crystal-growing kits and kitchen chemicals, a normally intelligent person can verify that coarse crystals take more time to grow than finer-grained materials. Clearly, basic crystal chemistry and physics dictates that zoned and other relatively large phenocrysts grew deep within the Earth and existed before the glass matrix that rapidly formed during the eruption.
Nevertheless, it is clear from Austin's essay that he has failed to incorporate the obviously diverse ages of the phenocrysts and the volcanic glass into his explanation for the origin of the dacite.
Similarly, Swenson also fails to comprehend the indisputable history that is associated with the plagioclase zoning and to properly recognize the important age differences between the coarsest phenocrysts and the volcanic glass. Obviously, if Austin wanted a sample that only represented the material that solidified during the eruption, he would have had to remove ALL of the plagioclase and other phenocrysts from the glass component. Even when phenocrysts as in Austin's Figure 4 and xenocrysts can be seen with an optical microscope, they can be extremely difficult, if not impossible, to effectively separate from the glass.
I've attempted to separate very fined-grained minerals from glass in coal ashes by using magnetic separation and hydrofluoric and other acids. Specifically, Austin admits that most of his fractions are impure when he includes the term 'etc. Furthermore, Austin's descriptions in the following statements clearly indicate that he FAILED to adequately separate the phenocrysts and possible xenocrysts from the volcanic glass.
Because Austin did NOT separate the plagioclase from the glass, we would expect this sample to contain a mixture of young glass, plagioclases with relatively old calcium-rich cores and moderately old sodium-rich rims. Because Austin clearly understands the heterogeneous composition of this 'fraction', he should have known that a K-Ar date on this mess would be meaningless.
Again, the mineral textures, as well as the laws of chemistry and physics, dictate that the calcium-rich plagioclase cores grew at higher temperatures before the sodium-rich rims and that glasses only formed once the melt erupted at the surface. Mafic microphenocrysts within these glassy particles were probably dominated by the strongly magnetic Fe-Ti oxide minerals.
The microscopic examination of the 'heavy-magnetic concentrate' also revealed a trace quantity of iron fragments, obviously the magnetic contaminant unavoidably introduced from the milling of the dacite in the iron mortar. No attempt was made to separate the hornblende from the Fe-Ti oxides, but further finer milling and use of heavy liquids should be considered. At this point Austin admits that the iron mortar probably contaminated his sample.
Although the contamination might have seriously affected any iron analyses, K and Ar analyses may not have been affected.
The description of another one of Austin's 'fractions' indicates that it is also highly impure: These mafic microphenocrysts and fragments of mafic phenocrysts evidently increased the density of the attached glass particles above the critical density of 2.
This sample also had recognizable hornblende, evidently not completely isolated by magnetic separation. Because it was composed of finer particles mesh , it contained far fewer mafic particles with attached glass fragments than DOME-IH. This preparation is the purest mineral concentrate. Therefore, instead of dating the ages of the pyroxenes, he probably dated a mixture of mostly pyroxenes along with other minerals and volcanic glass.
Again, a K-Ar date on such an impure 'fraction' would be meaningless and a waste of time and money. That is, Austin is not dating the volcanic glass or the pyroxenes in the dacite, but artificial mixtures, which result from incomplete separations.
However, because Austin ignores the analytical inadequacies of Geochron's mass spectrometer hypothesis 2 , except for possibly the pyroxenes, there is no evidence that excess argon is present in any of the other mineral or glass components in this sample. Because Austin admits that his separations were impure, how can he, Swenson and other YECs justify their claims that these dacite samples were a fair test of the validity of the K-Ar method?
Why did Austin waste precious time and money analyzing samples that were known to contain mineral and glass impurities?
As a geologist, Austin should have known that minerals, especially zoned minerals, take more time to crystallize than quenched disorder glass. How could he expect the relatively large and sometimes zoned minerals to be as young as the glass?!!
The following additional comments by Swenson demonstrate that he does not understand the mineralogy and chemistry of the dacite: However, Dalrymple  found that even volcanic glass can give wrong ages and rationalized that it can be contaminated by argon from older rock material. I should state that Swenson did not have the courtesy to name this critic it's me or cite even one of my sources that criticize Austin's efforts.
In any debate, the debaters should provide the references or Internet links for their opponents so that the readers can evaluate both sides and really understand what's going on. Clearly, Swenson simply assumes that the volcanic glass contains 'excess argon.
In his essay, Austin even admits that the glass still needs to be separated and analyzed for argon. Furthermore, many studies for example, the Haulalai basalt; Funkhouser and Naughton, demonstrate that Swenson and other YECs cannot automatically assume that modern volcanic glass contains excess argon. Although hypothesis 1 is plausible, until the argon isotope concentrations of the PURE glass are accurately measured for Austin's dacite if this is even possible we cannot properly evaluate this hypothesis.
Because Swenson does not provide a page number for his citation of Dalrymple , the identity of the volcanic glass with excess argon is uncertain. Perhaps, Swenson was referring to the following statement from Dalrymple , p. If Swenson is referring to this section, it's nothing more than an irrelevant red herring. Although high-pressure ocean water may prevent argon gas from escaping from the rims of a lava flow on the ocean floor, the centers of modern submarine flows typically provide K-Ar dates of 'zero years' Young, , p.
Because the centers of the flows cool more slowly, any excess 40Ar and other gases can disperse out of the remaining melt before solidification. While YECs explain geology by invoking talking snakes, magical fruit, and a mythical 'Flood', Dalrymple discusses legitimate chemistry and fluid physics, which is hardly relying on flimsy 'rationalizations' or implausible excuses. Furthermore, contrary to Swenson's claims, nothing in Dalrymple excuses Austin's sloppy approach to K-Ar dating.
In particular, YECs have no justification for automatically assuming that the dacite glass contains excess argon. Even if the dacite glass does contain excess argon, Dalrymple , p.
That is, as the volcanics age, the excess argon would be diluted into insignificance by the developing radiogenic 40Ar. Furthermore, if abundant excess argon is present in older rocks, Ar-Ar dating and K-Ar isochron dating can detect and eliminate its effects as examples, McDougall and Harrison, , p.
Austin clearly believes that the ancient dates for his samples entirely resulted from excess argon hypothesis 1: Orthopyroxene retains the most argon, followed by hornblende, and finally, plagioclase.
It's certainly plausible that some excess argon could accumulate in small fractures or defects within the crystalline structures of pyroxenes, amphiboles, feldspars and other minerals Dickin, , p. While Austin claims that orthopyroxenes should retain the most argon followed by hornblende an amphibole and finally plagioclase, he provides no references to support this claim.
In reality, the crystalline structures of amphiboles, unlike feldspars and pyroxenes, contain open channels, which can hold argon gas and other fluids Klein and Hurlbut, , p. I'm skeptical that the defects and fractures in the orthopyroxenes and feldspars of Austin's dacites could hold more excess argon per mineral volume than the relatively large open structures within the hornblendes Dickin, , p.
Therefore, IF hypothesis 1 was the only factor influencing the dates of Austin's samples, I would expect the hornblende-rich 'fraction' to provide an older date than the pyroxene- and feldspar-rich 'fractions.
From the above discussions, we already know that hypothesis 2 is a likely explanation for Austin's old dates. To evaluate hypothesis 3, we should look at the crystallization order of the phenocrysts as suggested by Bowen's Reaction Series. The series states that certain minerals will crystallize in a melt at higher temperatures than other minerals. That is, different minerals have different freezing points. Mafic magnesium and iron-rich volcanic rocks, such as basalts, form from relatively hot melts C and hotter, Hall, , p.
Felsic silica-rich rocks, such as granites, form at cooler temperatures perhaps as cool as C , Hall, , p. The most common minerals in rocks of intermediate chemistry, such as dacites, are located towards the middle of the series.
Bowen's Reaction Series is a very important concept that undergraduate students learn in their introductory physical geology courses. To be exact, Bowen's Reaction Series was the one diagram that I was required to memorize when I took my first geology course in college. Although Bowen's Reaction Series was established long ago by field and laboratory studies, Swenson, Austin and other YECs repeatedly fail to comprehend its importance and how it can produce ancient phenocrysts, which may affect the radiometric dating of very young samples.
In a young volcanic rock, such as the Mt. Helen's dacite, the calcium-rich plagioclases may have formed thousands or even a few million years ago. Again, as a rock ages and 40Ar accumulates in both the glass and any 40K-bearing minerals, the differences in the ages of the materials becomes less significant. That is, if the glass quenched in an eruption , years after the formation of the calcium-rich plagioclases, after Bowen's Reaction Series also predicts that pyroxenes will crystallize at higher temperatures before amphiboles.
Assuming that any argon contamination from Geochron's equipment hypothesis 2 is negligible, we see that the dates in Austin's table are consistent with the crystallization order in Bowen's Reaction Series. As expected, the purest pyroxene fraction provides an older date 2. That is, IF the dates are real, the pyroxenes formed in the melt before the amphiboles as predicted by the series. Because the pyroxenes solidify before most other minerals, it's also not surprising that the 'pyroxene, etc.
Depending upon the amount of zoned feldspars which consist of older calcium-rich cores and younger sodium-rich rims and the quantity of glass, amphibole and pyroxene impurities, the 'feldspar etc. On the basis of the following statements by Swenson, his gross misinterpretations of Dalrymple , and his unwillingness to respond to my earlier statements on Bowen's Reaction Series and its possible relevance to Austin's results, it is clear that Swenson does not know what Bowen's Reaction Series is and how it can affect the age distributions of minerals in very young volcanic rocks: They said that Dr Austin should have known they were old because the crystals were large and zoned.
However, Dr Austin's results Table 1 show that the wrong ages were not confined to one particular mineral. The idea that the age of a mineral can be anticipated by its size or colour is incorrect. Dalrymple , for example, found that the wrong ages in his samples were unrelated to crystal size, or any other observable characteristic of the crystal. Contrary to Swenson's implications, mineral zoning is much more than a color property. As discussed earlier, zoning and crystal growth are extremely important in understanding phenocryst ages.
Based on the statements in his essays, Swenson simply assumes that excess argon is present in all of the components of the dacite and that any statements on the lack of a relationship between excess argon and crystal size in Dalrymple automatically apply to Austin's dacite. Again, because Swenson does not provide any page numbers when referring to Dalrymple , we can only guess which sections of Dalrymple's article he is citing.
The results for the Mt. Lassen plagioclase and the Mt. Etna flow, which contains a HIGH percentage of large phenocrysts, appear to support their contention. Thus, for THESE experiments there does not appear to be any correlation of excess 40Ar with large phenocrysts or with any other petrological or petrographic parameter. Clearly, whether amphibole, pyroxene, plagioclase or other phenocrysts are effectively degassed or not during eruptions is a complex and, perhaps, unpredictable issue.
Nevertheless, as discussed in Dalrymple , p. Furthermore, if excess argon is relatively abundant in older samples, Ar-Ar dating and K-Ar isochron dating can detect and eliminate its effects as examples, McDougall and Harrison, , p.
They claim that these pieces of old rock xenoliths contaminated the sample and gave the very old age. In his report, Austin refers to the presence of 'lithic inclusions' in his samples.
Helens lava dome is 'lithic inclusions': Although the mineral concentrates are not pure, and all contain some glass, an argument can be made that both mafic and non-mafic minerals of the dacite contain significant 40 Ar. The lithic inclusions in the lava dome might be thought to be the contaminant, in which case they might add "old" mafic and non-mafic minerals to the young magma.
It could be argued that gabbroic clumps in the magma disaggregated as the fluidity of the magma decreased with time, thereby adding an assortment of 'old' mineral grains. These inclusions are, therefore, regarded as a unique association within the recent magmatic system. Even IF 1 Austin's summation of Heliker is absolutely accurate and no gabbro xenoliths or xenoliths of any other lithologies were present in the dacite, 2 Austin succeeded in removing all of the 'lithic inclusions' from his samples as Swenson claims, 3 no microscopic xenocrysts were hiding in this messy dacite, and 4 hypothesis 2 was not a factor, Austin would still need to specify the lifespan of the 'recent magmatic system.
Sarfati's Support of Flood Geology. Again, Figure 4 by itself illustrates that ancient phenocrysts were present in the dacite, which would invalidate Austin's dates. Although Austin failed to properly fractionate and date the minerals and glass in Mt.
Helens dacite, many scientists have been able to isolate specific minerals from older volcanics and successfully date them. Although xenocrysts and xenoliths are very common in the Peach Springs Tuff, Nielson et al. Unlike Austin, Nielson et al. Because Nielson et al. When confronted by Nielson et al. Even if excess argon is present in a sample, YECs must still explain the ultimate origin of 40Ar.
The Earth's atmosphere currently contains relatively abundant concentrations of argon 0. Where did all of this argon come from if the Earth is only a few thousand years old? In nature, 40Ar is only known to originate from the radioactive decay of 40K. Do different methods agree with each other on the geologic column? Possible other sources of correlation. Anomalies of radiometric dating. Why a low anomaly percentage is meaningless. The biostrategraphic limits issue.
Preponderance of K-Ar dating. Need for a double-blind test. Possible changes in the decay rate. Atlantic sea floor dating. Gentry's radiohaloes in coalified wood. Evidence for catastrophe in the geologic column. Reliability of creationist sources. Radiometric dating methods estimate the age of rocks using calculations based on the decay rates of radioactive elements such as uranium, strontium, and potassium.
On the surface, radiometric dating methods appear to give powerful support to the statement that life has existed on the earth for hundreds of millions, even billions, of years. We are told that these methods are accurate to a few percent, and that there are many different methods. We are told that of all the radiometric dates that are measured, only a few percent are anomalous. This gives us the impression that all but a small percentage of the dates computed by radiometric methods agree with the assumed ages of the rocks in which they are found, and that all of these various methods almost always give ages that agree with each other to within a few percentage points.
Since there doesn't seem to be any systematic error that could cause so many methods to agree with each other so often, it seems that there is no other rational conclusion than to accept these dates as accurate. However, this causes a problem for those who believe based on the Bible that life has only existed on the earth for a few thousand years, since fossils are found in rocks that are dated to be over million years old by radiometric methods, and some fossils are found in rocks that are dated to be billions of years old.
If these dates are correct, this calls the Biblical account of a recent creation of life into question. After study and discussion of this question, I now believe that the claimed accuracy of radiometric dating methods is a result of a great misunderstanding of the data, and that the various methods hardly ever agree with each other, and often do not agree with the assumed ages of the rocks in which they are found.
I believe that there is a great need for this information to be made known, so I am making this article available in the hopes that it will enlighten others who are considering these questions. Even the creationist accounts that I have read do not adequately treat these issues. At the start, let me clarify that my main concern is not the age of the earth, the moon, or the solar system, but rather the age of life, that is, how long has life existed on earth.
Many dating methods seem to give about the same ages on meteorites. Thus radiometric dating methods appear to give evidence that the earth and meteorites are old, if one accepts the fact that decay rates have been constant. However, there may be other explanations for this apparent age. Perhaps the earth was made from older pre-existing matter, or perhaps decay rates were briefly faster for some reason. When one considers the power of God, one sees that any such conclusions are to some extent tentative.
I believe that life was recently created. I also believe that the evidence indicates that the earth has recently undergone a violent catastrophe. Geologic time is divided up into periods, beginning with the Precambrian, followed by the Cambrian and a number of others, leading up to the present.
Some fossils are found in Precambrian rocks, but most of them are found in Cambrian and later periods. We can assume that the Precambrian rocks already existed when life began, and so the ages of the Precambrian rocks are not necessarily related to the question of how long life has existed on earth. The Cambrian period is conventionally assumed to have begun about million years ago.
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, then life must also be at least million years old.
Therefore, my main concern is with rocks of the Cambrian periods and later. How radiometric dating works in general Radioactive elements decay gradually into other elements. The original element is called the parent, and the result of the decay process is called the daughter element.
Assuming we start out with pure parent, as time passes, more and more daughter will be produced. By measuring the ratio of daughter to parent, we can measure how old the sample is. A ratio of zero means an age of zero.
A higher ratio means an older age. A ratio of infinity that is, all daughter and no parent means an age of essentially infinity. Each radioactive element has a half-life, which tells how long it takes for half of the element to decay. For potassium 40, the half-life is about 1. In general, in one half-life, half of the parent will have decayed. Potassium 40 K40 decays to argon 40, which is an inert gas, and to calcium. Potassium is present in most geological materials, making potassium-argon dating highly useful if it really works.
Uranium decays to lead by a complex series of steps. Rubidium decays to strontium. When it is stated that these methods are accurate to one or two percent, it does not mean that the computed age is within one or two percent of the correct age. It just means that there is enough accuracy in the measurements to compute t to one or two percentage points of accuracy, where t is the time required to obtain the observed ratio of daughter to parent, assuming no initial daughter product was present at the beginning, and no daughter or parent entered or left the system.
For isochrons, which we will discuss later, the conditions are different. If these conditions are not satisfied, the error can be arbitrarily large. In order to use these methods, we have to start out with a system in which no daughter element is present, or else know how much daugher element was present initially so that it can be subtracted out. We also need to know that no parent or daughter has entered or left the system in the meantime. Radiometric dating is commonly used on igneous rocks lava , and on some sedimentary minerals.
But fossils can generally not be dated directly. When lava is hot, argon escapes, so it is generally assumed that no argon is present when lava cools. Thus we can date lava by K-Ar dating to determine its age. As for the other methods, some minerals when they form exclude daughter products. Zircons exclude lead, for example, so U-Pb dating can be applied to zircon to determine the time since lava cooled.
Micas exclude strontium, so Rb-Sr dating can be used on micas to determine the length of time since the mica formed. In rubidium-strontium dating, micas exclude strontium when they form, but accept much rubidium. In uranium-lead U-Pb dating of zircon, the zircon is found to exclude initial lead almost completely. The Interpretation and Dating of the Geologic Record. Thus one would know that any strontium that is present had to come from the parent rubidium, so by computing the ratio and knowing the half life, one can compute the age.
In general, when lava cools, various minerals crystallize out at different temperatures, and these minerals preferentially include and exclude various elements in their crystal structures.
So one obtains a series of minerals crystallizing out of the lava. Thus the composition of the lava continues to change, and later minerals can form having significantly different compositions than earlier ones.
Lava that cools on the surface of the earth is called extrusive. This type of lava cools quickly, leaving little time for crystals to form, and forms basalt. Lava that cools underground cools much more slowly, and can form large crystals. This type of lava typically forms granite or quartz. Why methods in general are inaccurate I admit this is a very beautiful theory.
This would seem to imply that the problem of radiometric dating has been solved, and that there are no anomalies. So if we take a lava flow and date several minerals for which one knows the daughter element is excluded, we should always get the exact same date, and it should agree with the accepted age of the geological period.
I doubt it very much. If the radiometric dating problem has been solved in this manner, then why do we need isochrons, which are claimed to be more accurate? The same question could be asked in general of minerals that are thought to yield good dates. Mica is thought to exclude Sr, so it should yield good Rb-Sr dates. But are dates from mica always accepted, and do they always agree with the age of their geologic period? Indeed, there are a number of conditions on the reliability of radiometric dating.
For example, for K-Ar dating, we have the following requirements:. 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 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.
It is known that neutrinos interact with atomic nucleii, so a larger density of neutrinos could have sped up radioactive decay and made matter look old in a hurry. Some more quotes from the same source:. 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:. 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.
Another problem is that the crystal structure typically has imperfections and impurities. 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 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.
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.
So this confirms that argon can travel from rock to rock when one rock is heated. Now, argon is very soluble in magma, which can hold a lot of it:. After the material was quenched, the researchers measured up to 0. They noted, 'The solubility of Ar in the minerals is surprisingly high'. I note that this concentration of argon, if it were retained in the rock, would suffice to give it a geological age well over nillion years, assuming an average concentration of potassium.
This is from a paper by Austin available at ICR. 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. 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:. 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 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. Henke criticized some statements in my article taken from Slusher about the branching ratio for potassium. Slusher asserted that the best known value of the branching ratio was not always used in computing K-Ar radiometric ages. Unfortunately, Dalrymple says nothing about the calculation of the branching ratio.
He simply gives the correct value for the K-Ar system. The issue is not just how well this was known in the past, but which value was actually used, and whether dates published in the past have been computed with the most recent value.
Often values for constants are standardized, so that the values actually used may not be the most accurate known. All that Dalrymple says is that his ages were all recomputed using the most accurate values of the constants. This implies that some of them were originally computed using less accurate values, which is similar to Slusher's point.
He admits that Slusher's statements about it would have been true in the 's and early 's, but are no longer true.
But he didn't say when the correct value for the branching ratio began to be used. Even some figures from Faure, Principles of Isotope Geology, are based on another constant that is 2 or 3 percent too low, according to Dalrymple, and so there may be many ages in the literature that need revision by small amounts.
However, Harland et al imply that nearly the correct value for the branching ratio has been known and used since the mid-fifties. 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 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. 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 shows 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. Plaisted wants to give his readers the impression that argon can readily move in and out of minerals and, therefore, the gas is too volatile for radiometric dating. Specifically, he quotes one of his anonymous friends that claims that argon easily diffuses from minerals p.
Of course, these statements are inaccurate generalizations. Geochronologists are aware that excess argon may accumulate on mineral surfaces and the surface argon would be removed before analysis. However, Henke admits that this can happen in some cases. He states that geologists are aware of this problem, and make allowances for it.
But it is more difficult to remove argon that has deposited on cracks in the mineral, which can be difficult to see. Henke referenced Davis A. Young frequently, but I was not able to find Young referenced in any of the other sources I examined except Dalrymple Henke states that hornblendes retain argon very well, but then later says that they can easily absorb excess argon. Geologists also recognize that heating causes argon to leave minerals, and that dissolved argon in a mineral that does not escape will become incorporated into it, artificially increasing its K-Ar age.
I will comment more on this below, but a few comments now are appropriate. For a temperature of K 27 degrees C , there is no significant argon loss from biotite. At K degrees C , there is a slow but significant diffusion rate.
At K degrees C , loss of argon is quite rapid. To lose one percent in one year requires a temperature of nearly degrees centigrade. Thus the temperature does not have to be very high for argon to move through rock.
This also justifies Slusher's statements about argon moving in and out of rocks with ease. However, it does not seem likely that sedimentary rocks would be this hot very often, except near lava or magma flows.
But argon does not need to move through all rock in order to influence radiometric dates, it only has to reach ancient lava flows. This it can do by following the path of the ancient lava flow itself, coming up along the path of the magma. As the magma or lava cools, this path will consist entirely of hot magma or lava, and so the argon will have a free path, and will continue to enter the magma as it cools.
Thus in many cases, the lava or magma will never completely degas, and extra argon will end up trapped in the cooled rock. This will result in artificially increased K-Ar ages. Many ancient lava flows are relatively flat, in contrast to modern ones. Also, they appear to have been covered over quickly.
The flatness means that the lava is a contiguous mass, and can still be reached from the hot magma by a continuous path of hot rock.
The fact that they soon are covered over means that the argon has a hard time escaping vertically from the lava, so argon coming up from the mantle will tend to enter the cooling rock. Both facts will tend to produce artificially high K-Ar ages in these flows which will not be seen in modern lava flows in the same manner. Modern lava flows often come down the sides of volcanoes, and thus become separated from their source by large distances.
Also, they do not get quickly buried by additional sediment. Thus modern lava flows are not subject to the same mechanism of artificial increases in their K-Ar ages as are ancient ones. Also, it is reasonable to assume that as argon leaves the mantle in successive eruptions, the amount of argon remaining is reduced, so that later lava flows are less susceptible to such artificial increases in age. The path of magma also becomes longer for later flows, and the magma probably also is a little cooler, inhibiting argon flow.
Thus later lava flows give younger K-Ar ages. Another point to note is that even after it cools, the lava or magma may still have many cracks in it, permitting argon to flow.
This argon will tend to deposit on the surface of minerals, but with the passage of time it will tend to diffuse into the interior, even if only a very small distance. This is especially true as the lava is cooling. This will make it more difficult to detect this added argon by the spectrum test described below.
Also, the diffusion of argon in cracks and channels of a mineral is likely much less temperature-dependent than diffusion through unbroken regions of the mineral, since diffusion through cracks and channels simply involves jumps through the air. By a combination of diffusion through cracks and channels, and short passages through unbroken regions of the mineral, argon may be able to reach a considerable distance into the mineral.
At low temperatures, this may become the dominant means by which argon diffuses into a mineral, but the effect of this kind of diffusion at low temperatures may not be evident until many years have passed. Thus it may take experiments lasting 50 or years at low temperatures to detect the effects of this kind of diffusion of argon, which however could be significantly increasing the K-Ar ages of minerals over long time periods. Dickin Radiogenic Isotope Geology, , p.
It has been claimed that this can be accomplished by preheating samples under vacuum or by leaching them briefly with hydroflouric acid, or both However Armstrong has questioned whether atmospheric argon, that has been acquired by minerals over a long interval of time, can be removed by this method. Thus there is some means by which argon from outside can become very firmly embedded within a rock, and one would expect that the quantity of this argon would continue to increase over time, giving anomalously old K-Ar ages.
Added atmospheric argon can be detected, because the ratio of argon 40 to argon 36 for atmospheric argon is But argon 40 coming up from the mantle and diffusing into a mineral would not be detectable in this way, because it has a higher ratio of argon 40 to argon This shows that rocks can adsorb a large amount of argon relative to the argon needed to give them old K-Ar ages, and also suggests that old K-Ar ages can be produced by external argon from the mantle.
Over a long period of time, adsorbed argon will tend to diffuse into the rock, and thus it will be possible for even more argon to be deposited on the surface, increasing K-Ar ages even more. Generally, excess 40Ar is observed in minerals that have been exposed to a high partial pressure of argon during regional metamorphism, in pegmatites The argon that may either diffuse into the minerals or may be occluded within them is derived by outgassing of K-bearing minerals in the crust and mantle of the Earth.
The presence of excess 40Ar increases K-Ar dates and may lead to overestimates of the ages of minerals dated by this method. 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.
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. As far as I know, no study has been done to determine how different methods correlate on the geologic column excluding precambrian rock. The reason for my request is that a correlation is not implied by the fact that there are only 10 percent anomalies, or whatever.
I showed that the fact that the great majority of dates come from one method K-Ar and the fact that many igneous bodies have very wide biostratigraphic limits, where many dates are acceptable, makes the percentage of anomalies irrelevant to the question I am asking. And since this agreement is the strongest argument for the reliability of radiometric dating, such an assumption of agreement appears to be without support so far.
The question of whether different methods correlate on the geologic column is not an easy one to answer for additional reasons. Since the bulk of K-Ar dates are generally accepted as correct, one may say that certain minerals are reliable if they tend to give similar dates, and unreliable otherwise.
We can also say that certain formations tend to give reliable dates and others do not, depending on whether the dates agree with K-Ar dates. Thus we can get an apparent correlation of different methods without much of a real correlation in nature. It's also possible for other matter to be incorporated into lava as it rises, without being thoroughly melted, and this matter may inherit all of its old correlated radiometric dates.
Coffin mentions that fission tracks can survive transport through lava, for example. It may also be that lava is produced by melting the bottom of continents and successively different layers are melted with time, or there could be a tendency for lighter isotopes to come to the top of magma chambers, making the lava there appear older.
But anyway, I think it is important really to know what patterns appear in the data to try to understand if there is a correlation and what could be causing it. Not knowing if anomalies are always published makes this harder.
It is often mentioned that different methods agree on the K-T boundary, dated at about 65 million years ago. This is when the dinosaurs are assumed to have become extinct. This agreement of different methods is taken as evidence for a correlation between methods on the geologic column.
One study found some correlated dates from bentonite that are used to estimate the date of the K-T boundary. I looked up some information on bentonite. It is composed of little glass beads that come from volcanic ash. This is formed when lava is sticky and bubbles of gas in it explode.
So these small particles of lava cool very fast. The rapid cooling might mean that any enclosed argon is retained, but if not, the fact that this cooling occurs near the volcano, with a lot of argon coming out, should guarantee that these beads would have excess argon. As the gas bubble explodes, its enclosed argon will be rushing outward along with these tiny bubbles as they cool.
Iamges: dating rocks from mt st helens
It is composed of little glass beads that come from volcanic ash.
In areas where tremendous tectonic activity has taken place, highly discordant values for the ages are obtained.
The Interpretation and Dating of the Geologic Record. For example, dating rocks from mt st helens kinds of quartz have different colors due to various impurities that are included but not part of jt repetitive unit of gay dating app spain quartz crystal. For older samples, which contain more 40Ar, the contamination is diluted and has insignificant effects. Thus the composition of the lava continues to change, and later minerals can form having significantly different compositions than earlier ones. I mentioned a number of possibilities that could cause K-Ar dates to be much older than the true ages of the rocks. It is also possible that parent and daughter elements could be present in boundaries between regular crystal domains.
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