Potassium-argon dating, method of determining the time of origin of rocks by measuring the ratio of radioactive argon to radioactive potassium in the rock. This dating method is based upon the decay of radioactive potassium-40 to radioactive argon-40 in minerals and rocks; potassium-40 also decays to calcium-40.

What is K Ar used for?

allows the method to be used to calculate the absolute age of samples older than a few thousand years.

What is K Ar dating and how is it used in archeology?

fossils, including hominids, as well as archaeological material that has been found in the sequence. The potassium-argon (K-Ar) isotopie dating method is widely used for numerical age measurement of rocks, especially igneous rocks, which are formed by cooling of magmas after emplacement or after eruption as lava flows.