Other radiometric dating techniques are available for earlier periods.
The first practical radiometric dating technique, developed in the middle of the 20th century at the University of Chicago, used the isotope carbon-I4, and is a good example of how this procedure works. References in periodicals archive? Young, Ralph Stearley, Because radiometric dating necessarily entails It is the best known of all radiometric techniques, but because the half-life of carbon 14 is only years, this method can be used only with K—Ar dating was used to calibrate the geomagnetic polarity time scale. The amount of luminescence released is used to calculate the equivalent dose De that the sediment has acquired since deposition, which can be used in combination with the dose rate Dr to calculate the age.