Potassium argon dating is a method used in determining the origin of a rock. I is done by comparing the ratio of radioactive argon to radioactive potassium in the rock. This method is used to date rocks that are thousands of million years old.
the assumptions made when using the Potassium argon dating include :
no argon was left after formation of the rock
no argon has either entered or escaped the sample since it was formed.
