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Alexandra Witze, Earth in action

Earth scientists think it’s time to sync their geological clocks

SN Prime | July 23, 2012 | Vol. 2, No. 28

For some scientists, measuring time is harder than clocking Olympic sprinters.

To date big events in Earth history, geologists need a clock that stretches back accurately far into the past. In fact, they do have two such clocks — one based on the steady radioactive decay of minerals, the other on the rhythmic swoops of Earth’s orbit.

But recently researchers have found that these timekeepers are out of sync, in ways that would horrify any Swiss watchmaker. It’s like having the clock on your coffeemaker 45 seconds or so ahead of your kitchen clock. Not the end of days, but annoying enough to demand a fix.

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