Potassium argon and argon argon dating
The geomagnetic polarity time scale was calibrated largely using K-Ar dating.Argon, being a noble gas, is not a major component of most samples of geochronological or archeological interest: it does not bind with other constituents of the material, but normally escapes into the surrounding region.
By comparing the proportion of K-40 to Ar-40 in a sample of volcanic rock, and knowing the decay rate of K-40, the date that the rock formed can be determined.With 18 protons and 22 neutrons, the atom has become Argon-40 (Ar-40), an inert gas.For every 100 K-40 atoms that decay, 11 become Ar-40.Potassium-Argon Dating Potassium-Argon dating is the only viable technique for dating very old archaeological materials.
Geologists have used this method to date rocks as much as 4 billion years old.
The potassium-argon dating method has been used to measure a wide variety of ages.