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Bible History: Real or Fiction? Bible History: Fact or Fiction? Debunking Evolution Video: Radiometric Dating.
Radiometric Dating Summary. Debunking Evolution Video: Uniformitarianism Summary: Uniformitarianism. Bible Questions: Job Bible Questions: 2 Peter For More Reading: Bible History. Debunking Evolution Video: Human Evolution Human Evolution Summary. Debunking Evolution Video: Vestigial Structures Vestigial Structures Summary. We can calculate the half-lives of all of these elements. All the intermediate nuclides between U and Pb are highly unstable, with short half-lives.
Then any excess of Pb must be the result of the decay of U When we know how much excess Pb there is, and we know the current quantity of U, we can calculate how long the U in our sample has been decaying, and therefore how long ago the rock formed.
Th and U also give rise to radioactive series - different series from that of U, containing different nuclides and ending in different nuclides of lead. Chemists can apply similar techniques to all three, resulting in three different dates for the same rock sample.
Other articles where Radiometric dating is discussed: Earth sciences: Radiometric dating: In , shortly after the discovery of radioactivity, the American chemist Bertram Boltwood suggested that lead is one of the disintegration products of uranium, in which case the older a uranium-bearing mineral the greater should be its proportional part of lead. The age of the Earth is estimated to be ± billion years ( ? 10 9 years ± 1%). This age may represent the age of the Earth's accretion, or core formation, or of the material from which the Earth formed. This dating is based on evidence from radiometric age-dating of meteorite material and is consistent with the radiometric ages of the oldest-known terrestrial and lunar samples. V. Independent Checks on Radiometric Dating VI. Summary and Sources. I. Theory of radiometric dating. What is radiometric dating? Simply stated, radiometric dating is a way of determining the age of a sample of material using the decay rates of radio-active nuclides to provide a 'clock.' It relies on three basic rules, plus a couple of.
Uranium and thorium have similar chemical behavior, so all three of these nuclides frequently occur in the same ores. If all three dates agree within the margin of error, the date can be accepted as confirmed beyond a reasonable doubt. Since all three of these nuclides have substantially different half-lives, for all three to agree indicates the technique being used is sound.
But even so, radioactive-series dating could be open to question. The rock being dated must remain a closed system with respect to uranium, thorium, and their daughter nuclides for the method to work properly. Both the uranium and thorium series include nuclides of radon, an inert gas that can migrate through rock fairly easily even in the few days it lasts.
To have a radiometric dating method that is unquestionably accurate, we need a radioactive nuclide for which we can get absolutely reliable measurements of the original quantity and the current quantity. Is there any such nuclide to be found in nature? The answer is yes. Which brings us to the third method of radiometric dating. Method 3: Potassium-Argon Dating. The element potassium has three nuclides, K39, K40, and K Only K40 is radioactive; the other two are stable.
K40 is unusual among radioactive nuclides in that it can break down two different ways. It can emit a beta particle to become Ca40 calciumor it can absorb an electron to become Ar40 argon Argon is a very special element. Argon is a gas at Earth-normal temperatures, and in any state it exists only as single atoms. By contrast, potassium and calcium are two of the most active elements in nature.
Lesson Summary. Let's review. Radiometric dating, also known as radioactive dating, is what we use to determine the age of rocks. To be more specific, it is a method used to date rocks based on. Lesson Summary. Let's review. Radiometric dating is a method used to date rocks and other objects based on the known decay rate of radioactive isotopes. Radiometric dating (often called radioactive dating) is a way to find out how old something butterfishny.com method compares the amount of a naturally occurring radioactive isotope and its decay products, in butterfishny.com method uses known decay rates. It is the most used method of geochronology, the main way to learn the age of rocks and other geological features, including the age of the Earth itself.
They both form compounds readily and hold onto other atoms tenaciously. What does this mean? It means that before a mineral crystallizes, argon can escape from it easily. It also means that when an atom of argon forms from an atom of potassium inside the mineral, the argon is trapped in the mineral. So any Ar40 we find deep inside a rock sample must be there as a result of K40 decay. That and some simple calculations produce a figure for how long the K40 has been decaying in our rock sample.
What happens if our mineral sample has not remained a closed system? What if argon has escaped from the mineral?
What if argon has found its way into the mineral from some other source? If some of the radiogenic argon has escaped, then more K40 must have decayed than we think - enough to produce what we did find plus what escaped.
In other words, a mineral that has lost argon will be older than the result we get says it is. In the other direction, if excess argon has gotten into the mineral, it will be younger than the result we get says it is.
An isochron dating method isochron dating is described in the next section can also be applied to potassium-argon dating under certain very specific circumstances. When isochron dating can be used, the result is a much more accurate date. Method 4: Rubidium-Strontium Dating. Yet a fourth method, rubidium-strontium dating, is even better than potassium-argon dating for old rocks.
The nuclide rubidium Rb87 decays to strontium Sr87 with a half-life of 47 billion years. Strontium occurs naturally as a mixture of several nuclides.
If three minerals form at the same time in different regions of a magma chamber, they will have identical ratios of the different strontium nuclides. The total amount of strontium might be different in the different minerals, but the ratios will be the same.
Now, suppose that one mineral has a lot of Rb87, another has very little, and the third has an in-between amount. That means that when the minerals crystallize there is a fixed ratio of RbSr As time goes on, atoms of Rb87 decay to Sr, resulting in a change in the RbSr87 ratio, and also in a change in the ratio of Sr87 to other nuclides of strontium.
The decrease in the RbSr87 ratio is exactly matched by the gain of Sr87 in the strontium-nuclide ratio. It has to be - the two sides of the equation must balance. If we plot the change in the two ratios for these three minerals, the resulting graph comes out as a straight line with an ascending slope. This line is called an isochron. When every one of four or five different minerals from the same igneous formation matches the isochron perfectly, it can safely be said that the isochron is correct beyond a reasonable doubt.
There are numerous other radiometric dating methods: the samarium-neodymium, lutetium-hafnium, rhenium-osmium, and lead isochron methods just to name a few. A full cite for this book is given in the bibliography. Now, why is all this relevant to the creation-vs. Every method of radiometric dating ever used points to an ancient age for the Earth.
Radiometric dating summary. Certain unstable isotopes. The atom is extremely important radioactive elements. Radiometric dating is a variant of genesis. Independent evidence that rocks formed slowly as rocks formed slowly as mountains eroded and the time order. Using relative dating written by .
For creationists to destroy the old-Earth theory, they must destroy the credibility of radiometric dating. They have two ways to do this. They can criticize the science that radiometric dating is based on, or they can claim sloppy technique and experimental error in the laboratory analyses of radioactivity levels and nuclide ratios.
Radiometric dating, radioactive dating or radioisotope dating is a technique which is used to date materials such as rocks or carbon, in which trace radioactive impurities were selectively incorporated when they were formed. The method compares the abundance of a naturally occurring radioactive isotope within the material to the abundance of its decay products, which form at a known constant. Radiometric Dating Summary Debunking Evolution Video: Uniformitarianism Summary: Uniformitarianism. Summary. In this short paper I have briefly described 4 examples of radiometric dating studies where there is both internal and independent evidence that the .
Option 1: Criticize the Theory. Is there any way to criticize the theory of radiometric dating? Well, look back at the axioms of radiometric dating methods. Are any of those open to question. Answer: yes, two of them are. Or at least, they seem to be. Do we know, for a fact, that half-lives are constant axiom 1? Do we know for a fact that nuclide ratios are constant axiom 2? However, if all we had were theoretical reasons for believing axiom 1, we would be right to be suspicious of it.
Do we have observational evidence? On several occasions, astronomers have been able to analyze the radiation produced by supernovas. In a supernova, the vast amount of energy released creates every known nuclide via atomic fusion and fission.
Some of these nuclides are radioactive. We can also detect the characteristic radiation signatures of radioactive decay in those nuclides. We can use that information to calculate the half-lives of those nuclides. In every case where this has been done, the measured radiation intensity and the calculated half-life of the nuclide from the supernova matches extremely well with measurements of that nuclide made here on Earth. And when we look at a supernova in the Andromeda Galaxy, 2, years old, we see nuclides with the exact same half-lives as we see here on Earth.
Not just one or two nuclides, but many. For these measurements to all be consistently wrong in exactly the same way, most scientists feel, is beyond the realm of possibility. What about nuclide ratios?
Radiometric dating summary
Are they indeed constant? The chemical behavior of an element depends on its size and the number of electrons in its outer shell. This is the foundation of the periodic table of the elements, a basic part of chemistry that has stood without challenge for a hundred and fifty years. The shell structure depends only on the number of electrons the nuclide has, which is the same as the number of protons in its nucleus.
How Does Radiocarbon Dating Work? - Instant Egghead #28
K39 is chemically identical to K40; the only way we can distinguish between them is to use a nonchemical technique like mass spectrometry. Water molecules containing oxygen are lighter and therefore evaporate faster than water molecules with oxygen However, as far as is known such fractionation occurs only with light nuclides: oxygen, hydrogen, carbon. Sr86 atoms and Sr87 atoms behave identically when they bond with other atoms to form a mineral molecule.
If there are ten Sr86 atoms for every Sr87 atom in the original magma melt, there will be ten Sr86 atoms for every Sr87 atom in the minerals that crystallize from that melt. Option 2: Criticize the Techniques.
The only other possible source of error is in laboratory technique. To translate theory into useful measurements, the lab procedures must be accurate.
A contaminated rock sample is useless for dating. A sample that is taken from the surface, where atoms could get in and out easily, is also useless. Measuring the age of this impact event independently of the stratigraphic evidence is an obvious test for radiometric methods, and a number of scientists in laboratories around the world set to work.
Table 2 In addition to shocked quartz grains and high concentrations of iridium, the K-T impact produced tektites, which are small glass spherules that form from rock that is instantaneously melted by a large impact. The K-T tektites were ejected into the atmosphere and deposited some distance away.
Tektites are easily recognizable and form in no other way, so the discovery of a sedimentary bed the Beloc Formation in Haiti that contained tektites and that, from fossil evidence, coincided with the K-T boundary provided an obvious candidate for dating. Scientists from the US Geological Survey were the first to obtain radiometric ages for the tektites and laboratories in Berkeley, Stanford, Canada, and France soon followed suit.
The results from all of the laboratories were remarkably consistent with the measured ages ranging only from Similar tektites were also found in Mexico, and the Berkeley lab found that they were the same age as the Haiti tektites. The K-T boundary is recorded in numerous sedimentary beds around the world.
Numerous thin beds of volcanic ash occur within these coals just centimeters above the K-T boundary, and some of these ash beds contain minerals that can be dated radiometrically. Since both the ash beds and the tektites occur either at or very near the K-T boundary, as determined by diagnostic fossils, the tektites and the ash beds should be very nearly the same age, and they are Table 2.
There are several important things to note about these results. First, the Cretaceous and Tertiary periods were defined by geologists in the early s. The boundary between these periods the K-T boundary is marked by an abrupt change in fossils found in sedimentary rocks worldwide.
Its exact location in the stratigraphic column at any locality has nothing to do with radiometric dating - it is located by careful study of the fossils and the rocks that contain them, and nothing more. Furthermore, the dating was done in 6 different laboratories and the materials were collected from 5 different locations in the Western Hemisphere. And yet the results are the same within analytical error. In the early afternoon of August 24, 79 CE, Mt Vesuvius erupted violently, sending hot ash flows speeding down its flanks.
These flows buried and destroyed Pompeii and other nearby Roman cities. We know the exact day of this eruption because Pliny the Younger carefully recorded the event.
They separated sanidine crystals from a sample of one of the ash flows. Incremental heating experiments on 12 samples of sanidine yielded 46 data points that resulted in an isochron age of 94 years. The actual age of the flow in was years.
Is this just a coincidence? No - it is the result of extremely careful analyses using a technique that works. This is not the only dating study to be done on an historic lava flow. Two extensive studies done more than 25 years ago involved analyzing the isotopic composition of argon in such flows to determine if the source of the argon was atmospheric, as must be assumed in K-Ar dating Dalrymple26 flows; Krummenacher19 flows. Both studies detected, in a few of the flows, deviations from atmospheric isotopic composition, most often in the form of excess 40 Ar.
The majority of flows, however, had no detectable excess 40 Ar and thus gave correct ages as expected. Of the handful of flows that did contain excess 40 Ar, only a few did so in significant amounts. Note, however, that even an error of 0. Austin has documented excess 40 Ar in the dacite flow from Mount St Helens, but the amounts are insufficient to produce significant errors in all but the youngest rocks. Thus any potential error due to excess 40 Ar was eliminated by the use of this technique, which was not available when the studies by Dalrymple and Krummenacher were done.
Thus the large majority of historic lava flows that have been studied either give correct ages, as expected, or have quantities of excess radiogenic 40 Ar that would be insignificant in all but the youngest rocks. In this short paper I have briefly described 4 examples of radiometric dating studies where there is both internal and independent evidence that the results have yielded valid ages for significant geologic events.
It is these studies, and the many more like them documented in the scientific literature, that the creationists need to address before they can discredit radiometric dating. Their odds of success are near zero. Even if against all odds they should succeed, it still would not prove that the Earth is young. Only when young-earth creationists produce convincing quantitative, scientific evidence that the earth is young will they be worth listening to on this important scientific matter.
I thank Chris Stassen and 2 anonymous reviewers for their thoughtful comments, which led to important improvements in the manuscript.
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