(NPL: Teddington, Middlesex, UK) -- New research by the United Kingdom’s National Physical Laboratory (NPL), and the Scottish Universities Environmental Research Centre (SUERC) will improve the accuracy of estimates of the time of geological events. The work centers on the calibration of one of the world’s slowest clocks, known as the “argon-argon clock.”

The argon-argon clock works by measuring the ratio of the amount of radioactive potassium in a sample of rock to the amount of its decay product, argon. Because scientists already know the half-life of this radioactive decay (1.25 billion years), it can be used to date rocks back to the time of the formation of the Earth, 4.5 billion years ago. The older a rock is, the more potassium has decayed and the more argon is found in the rock.

The effect of the new research varies from one rock type to another, but could mean up to a 1.2-percent difference in a rock’s age from the original calculation.

“One-percent change in the accuracy of an age doesn’t sound like a lot, but when aiming for 0.1-percent precision through geological time, it is a very significant breakthrough,” says Darren Mark at the SUERC, who worked with NPL on the research.

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