# Radiometric dating of fossils dating a woman with trust issues

However, although 5730 years is the correct half-life, it is not the one used for most C-14 dating, simply because the original half-life used to determine dates back in the 1950s was wrong, and to be consistent we still tend to use the wrong value (a bit like the direction of current flow in electronics, which is the opposite of that which the electrons take, but was the original and incorrect assumption).The practical range for dating is in the order of a few hundred to about 40,000 years BP.For example, Uranium (U-235 or U-238) runs into the Thorium series then breakdowns into Radium and Radon, and finally, into Lead (the stable isotope).Volcanic tuft containing U-235 also contains (stable) Lead associated directly with it.Here are the half-lives of some other radioactive elements: These are said to be used in dating techniques of gas formation light emission called thermoluminescence).Besides thermoluminescence there is also the measurement of the ratio of the radioactive material to its decay elements.

By matching the proportion of original unstable isotope to stable decay product, and knowing the half-life of that element, one can thus deduce the age of the rock, as shown in the following diagram.With the discovery of radiometric dating, it became possible for the first time to attempt precise figures.Radiometric dating works on the principle that certain atoms and isotopes are unstable.During the 19th century, and even well into the twentieth, geological chronology was very crude.Dates were estimated according to the supposed rate of deposition of rocks, and figures of several hundred million years were bandied out; usually arrived at through inspired guesswork rather than anything else.