K–Ar dating was used to calibrate the geomagnetic polarity time scale.
Thermoluminescence testing also dates items to the last time they were heated.
One of the most widely used is potassium–argon dating (K–Ar dating).
Potassium-40 is a radioactive isotope of potassium that decays into argon-40.
Absolute dating is the process of determining an age on a specified chronology in archaeology and geology.