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Radiometric dating

A (very) Brief History of Radioactivity

Radiometric dating is a means of determining the "age" of a mineral specimen by determining the relative amounts present of certain radioactive elements. By "age" we mean the elapsed time from when the mineral specimen was formed. Radioactive elements "decay" that is, change into other elements by "half lives. The formula for the fraction remaining is one-half raised to the power given by the number of years divided by the half-life in other words raised to a power equal to the number of half-lives. If we knew the fraction of a radioactive element still remaining in a mineral, it would be a simple matter to calculate its age by the formula. To determine the fraction still remaining, we must know both the amount now present and also the amount present when the mineral was formed. Contrary to creationist claims, it is possible to make that determination, as the following will explain:.
In , Rutherford began calculating the rate of radioactive decay of uranium. Carbon dating has opened the gates to the history of plants on earth and their. Debunking the creationist radioactive dating argument. The age of the sample can be obtained by choosing the origin at the y intercept. In Fig the. The technique of comparing the abundance ratio of a radioactive isotope to a reference isotope to determine the age of a material is called radioactive dating.

Atomic nuclei of a radioactive element decay spontaneously, producing other elements and isotopes until a stable species is formed. The life span of a single atom may have any value, but a statistical quantity, the half-life of a macroscopic sample, can be measured;…. Inshortly 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 history of radioactive dating

Analyzing specimens…. Radiometric dating has provided not only a means of numerically quantifying geologic time but also a tool for determining the…. Radiometric dating of granitic intrusions associated with the Caledonian orogeny yields ages between about million and million years.

The igneous activity that produced such intrusions constituted the final stages of subduction and obduction that is, overthrusting of the edge of one lithospheric plate…. As a result of this and other findings, notably that of Ernest Rutherford see….

Radioactive Dating

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 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.

Comparing figures The age of the sample can be obtained by choosing the origin at the y intercept.

Radiometric dating

In Fig 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 Therefore: log. 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.

Dating Rocks and Fossils Using Geologic Methods

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. 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.

Biblical ages. 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.

Radiometric dating, radioactive dating or radioisotope dating is a technique which is used to .. °C the technique has limitations as well as benefits. The technique has potential applications for detailing the thermal history of a deposit. Radiometric Dating Segment from A Science Odyssey: "Origins." Using fossils as guides, they began to piece together a crude history of Earth, but it was an. The History of Evolutionary Thought. Radiometric Dating: Clair Patterson particles and energy, Radioactive elements decay, releasing particles and energy.

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. Scientists date igneous rock using elements that are slow to decay, such as uranium and potassium.

Radioactive dating and how it works, how carbon is used to date the of more than billion years of geological history in this region. Using relative and radiometric dating methods, geologists are able to answer the fossil primates and that this evolutionary history took tens of millions of years. Geologists use radiometric dating to estimate how long ago rocks formed, and to infer When molten rock cools, forming what are called igneous rocks, radioactive atoms Read more about how radiometric dating factored into the history of.

By dating these surrounding layers, they can figure out the youngest and oldest that the fossil might be; this is known as "bracketing" the age of the sedimentary layer in which the fossils occur. Search Glossary Home. Support this project. Read more about how radiometric dating factored into the history of evolutionary thought.

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