The potassium-argon age of some meteorites is as old as 4,500,000,000 years, and volcanic rocks as young as 20,000 years old have been measured by this method.was published, the earth was "scientifically" determined to be 100 million years old. In 1947, science firmly established that the earth was 3.4 billion years old.
For every 100 K-40 atoms that decay, 11 become Ar-40.
Potassium–argon dating, abbreviated K–Ar dating, is a radiometric dating method used in geochronology and archaeology.
Developed in the 1950s, it was important in developing the theory of plate tectonics and in calibrating the geologic time scale.
Potassium occurs in two stable isotopes (Ar atoms trapped inside minerals.
The geomagnetic polarity time scale was calibrated largely using K–Ar dating.