How reliable is geologic dating?
Radiometric dating is rooted in the rates of radioactive decay of various isotopes, which the formula for graph of a straight line with slope m and with y-intercept b : here y . refuted come forward to publicly identify these weaknesses or flaws?. There is a refinement of the radiometric dating method known as on the graph, the samples at time 2 all fall on the time 2 isochron line (see. 2 days ago Citing and more! Add citations directly into your paper, Check for unintentional plagiarism and check for writing mistakes.
Surely, if some daughter nuclei left the rock or parent nuclei entered the rock, the dates would come out all wrong!
While this is technically true, there are several mini-industries dedicated developing methods and techniques to make sure that there is no contamination and check to see if the rocks where disturbed between forming and being tested by scientists. How is this done? Follow Debunking Denialism on Facebook or Twitter for new updates. Radiometric dating and testing for contamination and disturbances On of the great things about many forms of radiometric dating is that they are self-checking.
That is, you can see if the sample comes from rocks that have been disturbed or contaminated or not just by looking at the results. Now, creationists will claim that scientists are just somehow assuming that if samples show an age that does not fit their preconceptions, the sample must be contaminated or leaky. To see why, we need to look deeper into radiometric dating methods.
A very important tool in radiometric dating is the so called isochron diagram and it holds the key to refuting the central creationist claims about radiometric dating. One of the most beneficial things about it is that it can check itself for accuracy; the method tells you how well the rocks have been closed systems. An isochron diagram is obtained by looking at many minerals from the same rock or from rocks forming from the same parent mineral.
Data is plotted on a simple two dimensional graph; the parent isotope on the x-axis and the daughter isotope on the y-axis. Both of these are divided or normalized by a stable isotope of the same elements as the daughter element. If the samples have been undisturbed closed systems since formation, the data will fall on the same line the isochron from which the diagram is named.
The slope of this line is a function of the age of the rock.
If the rock is older, the slope is higher. The reason scientists normalize with another stable isotope of the same element as the daughter is because most chemical or physical processes that occurs normally in nature does not differentiate between different isotopes of the same element when the difference in mass is as small as it is between isotopes of the same element that is used in radiometric dating.
This means that the while different rocks contain different absolute amounts of the two isotopes, the ratio is same.
At the time of formation for a rock, the isotopes for an element are homogenized and so the composition of a certain isotope is the same in all the minerals in the rock. But what happens when the rocks have been disturbed? If so, the data will not fall on an isochron line, but will be all over the place. This tells scientists that the sample has been disturbed and cannot be dated with this particular method. So far from rejecting samples because they do not fit a preconceived notion of what the age should be, scientists reject samples because there is ample evidence that it has been disturbed: Scientists do not assume that rocks have been closed systems; it is a well-supported conclusion from experiments.
Graphing Half Life WS
But what about assuming that initial amounts are known? Radiometric dating and initial conditions A second property of isochron diagrams is that it actually gives the initial amount of daughter isotope as a result of the method.
It is just the y-intercept of the isochron line. The initial conditions are just read off the graph; it is not just assumed. Radiometric dating and decay rates In a last ditch effort, young earth creationists exclaim that scientists just assume, without warrant, that decay rate are constant. However, this is not the case. Decay rates have been shown to be constant, despite very high pressure and temperature. These lines are called "isochrons".
The steeper the slope of the isochron, the more half lives it represents. When the fraction of rubidium is plotted against the fraction of strontium for a number of different minerals from the same magma an isochron is obtained. If the points lie on a straight line, this indicates that the data is consistent and probably accurate. An example of this can be found in Strahler, Fig If the strontium isotope was not present in the mineral at the time it was formed from the molten magma, then the geometry of the plotted isochron lines requires that they all intersect the origin, as shown in figure However, if strontium 87 was present in the mineral when it was first formed from molten magma, that amount will be shown by an intercept of the isochron lines on the y-axis, as shown in Fig Thus it is possible to correct for strontium initially present.
- Refuting “Radiometric Dating Methods Makes Untenable Assumptions!”
The age of the sample can be obtained by choosing the origin at the y intercept. Note that the amounts of rubidium 87 and strontium 87 are given as ratios to an inert isotope, strontium However, in calculating the ratio of Rb87 to Sr87, we can use a simple analytical geometry solution to the plotted data.
Again referring to Fig. Since the half-life of Rb87 is When properly carried out, radioactive dating test procedures have shown consistent and close agreement among the various methods. If the same result is obtained sample after sample, using different test procedures based on different decay sequences, and carried out by different laboratories, that is a pretty good indication that the age determinations are accurate. Of course, test procedures, like anything else, can be screwed up.
Mistakes can be made at the time a procedure is first being developed. Creationists seize upon any isolated reports of improperly run tests and try to categorize them as representing general shortcomings of the test procedure.
Refuting "Radiometric Dating Methods Makes Untenable Assumptions!" | Debunking Denialism
This like saying if my watch isn't running, then all watches are useless for keeping time. Creationists also attack radioactive dating with the argument that half-lives were different in the past than they are at present.
There is no more reason to believe that than to believe that at some time in the past iron did not rust and wood did not burn. Furthermore, astronomical data show that radioactive half-lives in elements in stars billions of light years away is the same as presently measured. On pages and of The Genesis Flood, creationist authors Whitcomb and Morris present an argument to try to convince the reader that ages of mineral specimens determined by radioactivity measurements are much greater than the "true" i.
The mathematical procedures employed are totally inconsistent with reality. Henry Morris has a PhD in Hydraulic Engineering, so it would seem that he would know better than to author such nonsense. Apparently, he did know better, because he qualifies the exposition in a footnote stating: This discussion is not meant to be an exact exposition of radiogenic age computation; the relation is mathematically more complicated than the direct proportion assumed for the illustration.
Nevertheless, the principles described are substantially applicable to the actual relationship. Morris states that the production rate of an element formed by radioactive decay is constant with time. This is not true, although for a short period of time compared to the length of the half life the change in production rate may be very small.
Radioactive elements decay by half-lives.
At the end of the first half life, only half of the radioactive element remains, and therefore the production rate of the element formed by radioactive decay will be only half of what it was at the beginning. The authors state on p.Carbon Dating Flaws
If these elements existed also as the result of direct creation, it is reasonable to assume that they existed in these same proportions. Say, then, that their initial amounts are represented by quantities of A and cA respectively.
Morris makes a number of unsupported assumptions: This is not correct; radioactive elements decay by half lives, as explained in the first paragraphs of this post. There is absolutely no evidence to support this assumption, and a great deal of evidence that electromagnetic radiation does not affect the rate of decay of terrestrial radioactive elements. He sums it up with the equations: He then calculates an "age" for the first element by dividing its quantity by its decay rate, R; and an "age" for the second element by dividing its quantity by its decay rate, cR.
It's obvious from the above two equations that the result shows the same age for both elements, which is: Of course, the mathematics are completely wrong. The correct relation can obtained by rearranging the equation given at the beginning of this post: For a half life of years, the following table shows the fraction remaining for various time periods: In all his mathematics, R is taken as a constant value.
We may therefore set R as equal to the initial rate in the above table: Click on the web site of Dr.