Such failures may be due to laboratory errors (mistakes happen), unrecognized geologic factors (nature sometimes fools us), or 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.
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-238 decay rate was first determined.
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 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. As with any experimental procedure in any field of science, these measurements are subject to certain "glitches" and "anomalies," as noted in the literature.147] has highlighted the fact that measurements of specimens from a 1801 lava flow near a volcano in Hualalai, Hawaii gave apparent ages (using the Potassium-Argon method) ranging from 160 million to 2.96 billion years, citing a 1968 study [Funkhouser1968].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 1968 article were careful to explain, xenoliths cannot be dated by the K-Ar method because of excess argon in bubbles trapped inside [Dalrymple2006].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.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.Several hundred laboratories around the world are active in radiometric dating.Their results consistently agree with an old Earth.