The Isotope appears to form rapidly and constantly making it apart of the carbon dioxide in the air and in life.
By comparing the activity of the Carbon-14 and the equilibrium levels of living organism a time can be found for this method to work.
Potassium (K) is one of the most abundant elements in the Earth's crust (2.4% by mass).
On the other hand, the abundance of argon in the is relatively small because of its escape to the atmosphere during processes associated with volcanism.
The potassium-argon dating method has been used to measure a wide variety of ages.
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.
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.
Thus, the ratio of argon-40 and potassium-40 and radiogenic calcium-40 to potassium-40 in a mineral or rock is a measure of the age of the sample.