# Line graphs and radiometric dating

### Radiometric Dating

based on radiometric dating. • “radioactivity” Examine the graph that plots the abundance of . in a sample. the 4 colored lines represent 4 different isotopes. line-graphs-and-radiometric-dating: line graphs and radiometric dating. Radiometric dating methods give absolute ages ranging from decades to billions of years. Graph the data in your data chart on the graph provided on the back. intervals along axes, data points plotted correctly, line starts with first point and .

As we pointed out in these two articles, radiometric dates are based on known rates of radioactivity, a phenomenon that is rooted in fundamental laws of physics and follows simple mathematical formulas. Dating schemes based on rates of radioactivity have been refined and scrutinized for several decades.

**LINE GRAPH for BANKING EXAMS**

The latest high-tech equipment permits reliable results to be obtained even with microscopic samples. Radiometric dating is self-checking, because the data after certain preliminary calculations are made are fitted to a straight line an "isochron" by means of standard linear regression methods of statistics.

The slope of the line determines the date, and the closeness of fit is a measure of the statistical reliability of the resulting date. Technical details on how these dates are calculated are given in Radiometric dating.

## Graphing Half Life WS

Here is one example of an isochron, based on measurements of basaltic meteorites in this case the resulting date is 4. Reliability of radiometric dating So, are radiometric methods foolproof?

Just how reliable are these dates? As with any experimental procedure in any field of science, these measurements are subject to certain "glitches" and "anomalies," as noted in the literature.

### Decay graphs and half lives article (article) | Khan Academy

Skeptics of old-earth geology make great hay of these examples. For example, creationist writer Henry Morris [ Morrispg. In the particular case that Morris highlighted, the lava flow was unusual because it included numerous xenoliths typically consisting of olivine, an iron-magnesium silicate material that are foreign to the lava, having been carried from deep within the Earth but not completely melted in the lava.

Also, as the authors of the article were careful to explain, xenoliths cannot be dated by the K-Ar method because of excess argon in bubbles trapped inside [ Dalrymple ]. Thus in this case, as in many others that have been raised by skeptics of old-earth geology, the "anomaly" is more imaginary than real. Other objections raised by creationists are addressed in [ Dalrymplea ].

The overall reliability of radiometric dating was addressed in some detail in a recent book by Brent Dalrymple, a premier expert in the field. He wrote [ Dalrymplepg. These methods provide valid age data in most instances, although there is a small percentage of instances in which even these generally reliable methods yield incorrect results. Such failures may be due to laboratory errors mistakes happenunrecognized geologic factors nature sometimes fools usor misapplication of the techniques no one is perfect.

We scientists who measure isotope ages do not rely entirely on the error estimates and the self-checking features of age diagnostic diagrams to evaluate the accuracy of radiometric ages. Whenever possible we design an age study to take advantage of other ways of checking the reliability of the age measurements.

The simplest means is to repeat the analytical measurements in order to check for laboratory errors.

Another method is to make age measurements on several samples from the same rock unit. This technique helps identify post-formation geologic disturbances because different minerals respond differently to heating and chemical changes.

The isochron techniques are partly based on this principle.

The use of different dating methods on the same rock is an excellent way to check the accuracy of age results. If two or more radiometric clocks based on different elements and running at different rates give the same age, that's powerful evidence that the ages are probably correct.

Along this line, Roger Wiens, a scientist at the Los Alamos National Laboratory, asks those who are skeptical of radiometric dating to consider the following quoted in several cases from [ Wiens ]: There are well over forty different radiometric dating methods, and scores of other methods such as tree rings and ice cores.

All of the different dating methods agree--they agree a great majority of the time over millions of years of time. Some [skeptics] make it sound like there is a lot of disagreement, but this is not the case.

The disagreement in values needed to support the position of young-earth proponents would require differences in age measured by orders of magnitude e.

- Radiometric dating
- Line Graphs And Radiometric Dating
- Decay graphs and half lives article

The differences actually found in the scientific literature are usually close to the margin of error, usually a few percent, not orders of magnitude! Vast amounts of data overwhelmingly favor an old Earth. Several hundred laboratories around the world are active in radiometric dating. Their results consistently agree with an old Earth. Over a thousand papers on radiometric dating were published in scientifically recognized journals in the last year, and hundreds of thousands of dates have been published in the last 50 years.

Essentially all of these strongly favor an old Earth. Radioactive decay rates have been measured for over sixty years now for many of the decay clocks without any observed changes.

And it has been close to a hundred years since the uranium decay rate was first determined. A recent survey of the rubidium-strontium method found only about 30 cases, out of tens of thousands of published results, where a date determined using the proper procedures was subsequently found to be in error.

The half-life is plotted as a red point. One funny property of exponential decay is that the total mass of radioactive isotopes never actually reaches zero. The mass just keeps getting closer and closer to zero as the amount of time for the isotope to decay gets larger and larger.

Realistically, there are only a fixed number of atoms in a radioactive sample, and so the mass of an isotope will eventually reach zero as all the nuclei decay into another element. How do you read a decay graph? If a scientist comes across a funky new radioactive rock while exploring an excavation site, she can identify what radioactive isotope is present in it by measuring the the decay constant of the isotopes inside the rock.

An exponential decay graph like the one shown above can be generated by taking a sample of an unknown radioactive isotope and repeatedly measuring the total mass of radioactive material within it. At the start of the experiment, a piece of the sample is run through a mass spectrometer or similar device that can identify the relative mass of various isotopes currently present.

Then, at several later times, the procedure is repeated and the new fraction of various isotopes is recorded. One sample of rock is shown decaying and the level of decay is corresponded to points on a decay graph. The fraction of radioactive isotopes observed in the spectrometer will decrease exponentially in time, while the mass of decay products like boron for carbon will gradually increase. The radioactive carbon dioxide gets into the food chain and the carbon cycle.

All living things contain a constant ratio of Carbon 14 to Carbon At death, Carbon 14 exchange ceases and any Carbon 14 in the tissues of the organism begins to decay to Nitrogen 14, and is not replenished by new C The change in the Carbon 14 to Carbon 12 ratio is the basis for dating. The half-life is so short years that this method can only be used on materials less than 70, years old.

Archaeological dating uses this method. Also useful for dating the Pleistocene Epoch Ice Ages. Assumes that the rate of Carbon 14 production and hence the amount of cosmic rays striking the Earth has been constant through the past 70, years.