A meteorite struck what is now Ames, Oklahoma, about 370 million years ago, not 467.5 million years ago as geologists had thought. A team led by the University of Texas at Austin reports the new date in the journal Meteoritics & Planetary Science.
The old age tied the crater to the Ordovician Meteor Event, a time of many impacts on Earth. The new age moves it to the Late Devonian, nearly 100 million years later. That changes the list of craters scientists use to study that cluster.
Clocks inside crystals
The crater is buried, so the team worked with rock from below the surface. They dated zircon, a hard mineral that holds small amounts of uranium. Uranium slowly turns into lead at a known rate, so the ratio between the two works as a clock.
The researchers checked the result with two kinds of crystal imaging, done together with NASA. Every method pointed the same way.
"No matter what technique we used, it was coming back to this younger signal," says Elizabeth Catlos, the study's lead author and an associate professor at UT Austin.
The crater did not move. Its place in Earth's history did.
