The geomagnetic polarity time scale had been calibrated mainly making use of K—Ar dating. Potassium obviously does occur in 3 isotopes: Conversion to stable 40 Ca happens via electron emission beta decay in Conversion to stable 40 Ar does occur via electron capture within the staying Argon, being truly a noble fuel , is a small part of rock samples that are most of geochronological interest: whenever 40 K decays to 40 Ar argon , the atom typically continues to be caught in the lattice since it is bigger than the areas involving the other atoms in a mineral crystal. Continue reading →