Argon is gas that gradually builds up within rocks from the decay of radioactive potassium.
It is initially formed in the molten rock that lies beneath the Earth’s crust.
Where excess argon is a problem, accurate, reliable dates typically can be obtained using harlequin2, 2001.
Geochronology and Thermochronology by the 40Ar/39Ar Method.
The heat from a volcanic eruption releases all the argon from the molten rock and disperses it into the atmosphere.
Argon then starts to re-accumulate at a constant rate in the newly formed rock that is created after the eruption.
Different methods have their own limitations, especially with regard to the age range they can measure and the substances they can date.
Another useful chemical analysis technique involves calculating the amount of nitrogen within a bone.
Morris cited other examples of anomalous dates produced by excess argon and falsely claimed that it is a universal problem for K-Ar dating.
The problem is not universal, as the majority of minerals and rocks dated by K-Ar do not contain the excess argon.
This newer method converts a stable form of potassium (potassium-39) into argon-39.
Measuring the proportions of argon-39 and argon-40 within a sample allows the age of the sample to be determined.
The age of volcanic rocks and ash can be determined by measuring the proportions of argon (in the form of argon-40) and radioactive potassium within them.