Potassium-Argon dating has the advantage that the argon is an inert gas that does not react chemically and would not be expected to be included in the solidification of a rock, so any found inside a rock is very likely the result of radioactive decay of potassium.

What is the difference between potassium-argon dating and carbon-14 dating?

Potassium-argon dating Potassium-40 is a radioactive isotope of potassium that decays into argon-40. The half-life of potassium-40 is 1.3 billion years, far longer than that of carbon-14, allowing much older samples to be dated. K–Ar dating was used to calibrate the geomagnetic polarity time scale.

Why is potassium-argon dating useful?

It is used to determine the ages of formation and thermal histories of potassium-bearing rocks and minerals of igneous, metamorphic and sedimentary origin, as well as extraterrestrial meteorites and lunar rocks.

How accurate is Ar Ar dating?

One problem with argon-argon dating has been a slight discrepancy with other methods of dating. Work by Kuiper et al. reports that a correction of 0.65% is needed.

What is potassium-argon dating used to date?

Potassium-argon dating, method of determining the time of origin of rocks by measuring the ratio of radioactive argon to radioactive potassium in the rock. The potassium-argon dating method has been used to measure a wide variety of ages.