Narrator: This is Science Today. A method called argon-argon dating has been used by geologists since the sixties to determine the age of old fossils and meteorites. But University of California, Berkeley geology professor Paul Renne says reliability was questioned, so he and his colleagues put the method to test by using it to date samples from the eruption of Mt. Vesuvius in 79 A.D.
Renne: We wanted to find something that was younger than say 5 or 10 thousand years old, yet had volcanism of high potassium content associated and had an historically accurate age tied to it and this particular situation was met perfectly by Vesuvius.
Narrator: The argon-argon technique was just 7 years off, giving validity to future endeavors.
Renne: It means that we can date a lot of important archeological things, including the record of inhabitation of the Americas, which is long been a big challenge. And we can check when periods of glaciation occurred or exceptionally warm spells occurred.
Narrator: For Science Today, I'm Larissa Branin.