K-Ar dating relies on very long half-lives, and hence should not be used for dating new rocks.
Wikipedia says "the technique is most applicable for dating minerals and rocks more thanyears old. For shorter timescales, it is likely that not enough Argon 40 will have had time to accumulate in order to be accurately measurable.
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As an aside, this article from the Creation Institute admits that K-Ar's effective range starts at aboutyears old. That should refute your creationist friends. Sign up to join this community. The best answers are voted up and rise to the top. Home Questions Tags Users Unanswered. Is K-Ar a reliable method for dating rock ages? Ask Question. Asked 9 years, 1 month ago. Active 4 years, 4 months ago.
K-Ar dating calculation - Life on earth and in the universe - Cosmology & Astronomy - Khan Academy
Viewed 4k times. Motivation for the question to follow: Some of the common mistakes we make in evaluating claims are resisting contrary evidence, looking for confirming evidence, and preferring available evidence. My question: Since the real age of the rocks was around 50 years, does this demonstrate that K-Ar dating is inaccurate?
I'm not an expert, but I remember that all those dating methods have only a certain range where they're accurate. If you're outside the range you won't get reliable results, but you can just use different isotopes that give good results in the desired range.
Fabian: that was kinda what i was getting at with 1. Should be moved to physics? In addition to your 3 possible explanations, I'd add: 4 The conditions under which the magma formed were insufficient to "reset" the K-Ar ratio, or 5 The conditions under which the sample formed led to contamination by mixing with nearby material Wikipedia says this is not uncommonor 6 The samples were somehow contaminated after being collected.
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Drawing inferences from radiometric dating requires at least two basic assumptions: At the time the rock as formed, no daughter product was present. No daughter or parent product has entered the sample since then. SigmaX SigmaX 1, 10 10 silver badges 10 10 bronze badges.
I'm coming in late, but I don't understand this argument. Isn't it the No True Scotsman fallacy?
If the sample gathered by these skeptics cannot be measured accurately allegedly due to assumption violationshow can we trust results given on other samples? Oddthinking: Dismissing claims of anomalous data is a No True Scotsman if it is done in a cavalier fashion.
In the philosophy of science, this danger is described by the Durhem-Quine Thesis en.
Since all data carries the possibility of error, the solution is not to "pick and choose" what data you deem reliable, but to use converging lines of evidence to synthesize all the data and its uncertainty. This is how Bayes filters work to let robots reason about evidence under uncertainty. Unfortunately science is less formal than robotics.
Is potassium-argon dating accurate
The converging lines of evidence for radiometric dating are outside the scope of this question. But basically, it's like seeing a TV image in a noisy signal. Each pixel is somewhat unreliable, but when you piece together the whole picture, the predictions of the hypothesis "that's Mr.
Jan 21, Potassium Argon dating is equally controversial. it is also based upon decaying potassium into argon gas and the rate of decay. Same problems as with carbon dating. Interestingly, dating a substance with both K-AR and C sometimes produces dates that are a hundred million years apart. (So one or both are wrong).
Rogers' face" are met so well that it's unambiguously true that Mr. Rogers is playing on TV.
We may also be able to put bounds on the unreliability of each pixel once we know what Mr. Rogers' face looks like. But it's easier to just sample more pixels: get lots and lots of rocks from that mountain.
SigmaX: Uh, so what I took from that was "K-Ar is a noisy method and can't trusted on individual samples, but with sufficient samples a strong signal can be determined. So there are reasons why their test could came back the way it did. Konrad Rudolph Darwy Darwy 4, 26 26 silver badges 24 24 bronze badges.
(A) The varying mineral composition of the myriads of types of rocks negates the accuracy of the standard potassium-argon dating method. (B) The potassium-argon method should not be used to calculate the ages of rocks. (C) As all new radiometric dating methods are calibrated using dates from existing methods, any based directly or indirectly on. Nov 13, In order to determine how old the Earth is, these scientists use a technique called potassium-argon dating (K-AR). A particular isotope of potassium, K, undergoes a decay process and eventually becomes an argon isotope, Ar It is reasonable to ask if the K-Ar test is accurate before we accept its results as accurate. K-Ar dating relies on very long half-lives, and hence should not be used for dating new rocks. Wikipedia says "the technique is most applicable for dating minerals and rocks more than , years old. For shorter timescales, it is likely that not enough Argon 40 will have had time to accumulate in order to be accurately measurable.".
These flawed studies cite examples of "anomalous" ages from specific lava floes: Their claims: "Volcanic rocks produced by the lava flows which occured in Hawaii in the years were dated by the potassium-argon method. John Lyon The accuracy can be determined mathematically when multiple data sets from multiple samples are obtained. The more samples are collected and analyzed, and the closer they are to each other, the higher the level of certainty is on the resulting data.
Of course, there are religious nutcakes out there who refuse to believe scientific facts for their own agenda, and they desperately grasp at minor flaws to satisfy their own egos.
Those are commonly the same people who don't believe in gravity or a round earth, and they are welcome to believe what they want. Why is it that the rate of radioactive decay is not disputable? What is the fundamental ct of physics which would be violated if the rate were different in the ancient past?
Please help me here. I am engaged in a debate with a creationist and I do not have a science background.
Thank you! You believe what You want my friend. If believing scientific testing rocks your boat, then go for it. Since discovering God I have realized that He is alive and He is able to help me in areas that science cannot.
Science could not cure my cancer, but prayers to God made it go completely. The doctor was really amazed how one week the scans showed a tumor and the next week it had gone completely. Science can't do that. Carbon dating has been calibrated against tree rings and other countable annual deposits, and is very accurate within the limits of the method which is about 60, years.
The potassium-argon dating method has been used to measure a wide variety of ages. The potassium-argon age of some meteorites is as old as 4, years, and volcanic rocks as young as 20, years old have been measured by this method. Argonargon dating. Radiometric dating. Additional Information. External Websites. Jan 31, The potassium-argon (K-Ar) isotopic dating method is especially useful for determining the age of lavas. Developed in the s, it was important in developing the theory of plate tectonics and in calibrating the geologic time simplybeyondexpectations.com: Andrew Alden. Potassium-argon dating is accurate from billion years (the age of the Earth) to about , years before the present. At , years, only of the potassium in a rock would have decayed to argon, pushing the limits of present detection devices. Eventually, potassium-argon dating may be able to provide dates as recent as.
But since dates derived by that method agree well with those from other methods, it's a very useful method in many cases. Usually, it'll be accurate to within a couple of per cent as a rough rule of thumband that's in both cases.
The suggestion that these methods are somehow "controversial" is bilge water. After the recrystallization of magma, more 40 K will decay and 40 Ar will again accumulate, along with the entrained argon atoms, trapped in the mineral crystals.
Measurement of the quantity of 40 Ar atoms is used to compute the amount of time that has passed since a rock sample has solidified.
Despite 40 Ca being the favored daughter nuclide, it is rarely useful in dating because calcium is so common in the crust, with 40 Ca being the most abundant isotope. Thus, the amount of calcium originally present is not known and can vary enough to confound measurements of the small increases produced by radioactive decay. The ratio of the amount of 40 Ar to that of 40 K is directly related to the time elapsed since the rock was cool enough to trap the Ar by the equation.
The scale factor 0. In practice, each of these values may be expressed as a proportion of the total potassium present, as only relative, not absolute, quantities are required. To obtain the content ratio of isotopes 40 Ar to 40 K in a rock or mineral, the amount of Ar is measured by mass spectrometry of the gases released when a rock sample is volatilized in vacuum.
The potassium is quantified by flame photometry or atomic absorption spectroscopy. The amount of 40 K is rarely measured directly. The amount of 40 Ar is also measured to assess how much of the total argon is atmospheric in origin. Both flame photometry and mass spectrometry are destructive tests, so particular care is needed to ensure that the aliquots used are truly representative of the sample.
Ar-Ar dating is a similar technique which compares isotopic ratios from the same portion of the sample to avoid this problem.
Due to the long half-life of 40 Kthe technique is most applicable for dating minerals and rocks more thanyears old. For shorter timescales, it is unlikely that enough 40 Ar will have had time to accumulate in order to be accurately measurable.