Note that time is expressed in millions of years on this graph, as opposed to thousands of years in the C graph. Click on the "Show Movie" button below to view this animation. How are Samples Processed? Clicking on the "Show Movie" button below will bring up an animation that illustrates how a K-Ar sample is processed and the calculations involved in arriving at a date. This is actually a mini-simulator, in that it processes a different sample each time and generates different dates.
Limitations on K-Ar Dating The Potassium-Argon dating method is an invaluable tool for those archaeologists and paleoanthropologists studying the earliest evidence for human evolution.
As with any dating technique, there are some significant limitations. Potassium Argon Dating Obsidian Hydration Dating The claim shows one sample that dated to 3. While other answers are correct that the half-life of Potassium is very large, the 0. The claim "the real ratio of elements would indicate a 50 year old sample" lies more than 17 standard deviations away from the mean measurement, so it is very unlikely that the sample matched that prediction.
But here's a problem. The same flow yielded samples that dated to 1. These are also significant numbers.
One sample also dated to less than , years ago, which appears to be the minimum measurable value, so is not a significant aberration. Radiometric dating would predict that, if the assumptions 1 and 2 hold, samples from the same flow would have the same age. Therefore, radiometric dating does not predict that the rocks would date accurately. Therefore this data cannot be used to falsify K-Ar dating, because it does not violate a prediction of radiometric dating.
Other methods, such as Isochron dating could potentially be used to show that the data are still consistent with current geological theory.
Lies of Evolution: K-Ar Dating
This answer has been completely rewritten. I wrote the first draft thinking the entire range of reported dates represented the error bars on one sample, implying that the perceived dating error was not statistically significant. I later realized that this was not the case.
The hydration level of the basalt. There might also be a case for ' Argon inheritance '. The rock that came out of the volcano isn't magically reformed into brand new material: A Reply to "Scientific" Creationism by G. Geological Survey Open file report Your exact question is on page These flawed studies cite examples of "anomalous" ages from specific lava floes:. Excess argon produced apparent ages ranging from million to 2.
These authors cite a study by Funkhouser and Naughton on xenolithic inclusions in the flow from Hualalei Volcano on the Island of Hawaii. The flow is an unusual flow because it carries very abundant inclusions of rocks foreign to the lava. These inclusions, called xenoliths meaning foreign rocks , consist primarily of olivine, a pale-green, iron-magnesium silicate mineral.
They come from deep within the mantle and were carried upward to the surface by the lava. In the field, they look like large raisins in a pudding, and even occur in beds piled one on top of the other, glued together by the lava.
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The study by Funkhouser and Naughton was on the xenoliths, not on the lava. The xenoliths, which vary in composition and range in size from single mineral grains to rocks the size of basketballs, do indeed carry excess argon in large amounts.
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Funkhouser and Naughton were quite careful to point out that the apparent "ages" they measured were not geologically meaningful. Quite simply, xenoliths are one of the types of rocks that cannot be dated by K-Ar techniques. Funkhouser and Naughton were able to determine that the excess gas resides primarily in fluid bubbles in the minerals of the xenoliths, where it cannot escape upon reaching the surface. Studies such as the one by Funkhouser and Naughton are done to determine which materials are suitable for dating and which are not, and to determine the cause of sometimes strange results.
They are part of the continuing effort to learn. There have been two extensive K-Ar studies on historic lava flows Dalrymple, ; Krummenacher, that showed that excess argon is not a serious problem for dating lava flows. An exception is the lava from the Hualalei flow, which is so badly contaminated by the xenoliths that it is not possible to obtain a completely inclusion-free sample.
K-Ar dating is sometimes tricky, but if you understand what you are doing, the results are generally reliable.
Geologists avoid dating glassy, polydeformed or very altered rocks with K-Ar, because these are known to sometimes be problematic. Here are the original claims behind the Ngauruhoe volcanic rocks from the Institute for Creation Research. The rest is assumed to be atmospheric; the atmospheric 40Ar is subtracted from the total 40Ar: However for very young rocks like these it is a problem.
Modern methods of analysis allow individual regions of crystals to be investigated.
This method is important as it allows crystals forming and cooling during different events to be identified. One problem with argon-argon dating has been a slight discrepancy with other methods of dating. Thus the Cretaceous—Paleogene extinction when the dinosaurs died out - previously dated at Similarly, the Permian-Triassic extinction is now dated at From Wikipedia, the free encyclopedia. Retrieved from " https: Views Read Edit View history.