Scientists Say Craters in U.S., Siberia Made 35 Million Years Ago
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NEW YORK — Two huge objects struck Earth about 35.5 million years ago, slamming into Siberia and a site off the Virginia coast, a study concludes.
That raises the question of whether the one-two punch caused a later mass extinction.
Scientists already knew that the 53-mile-wide crater near Virginia was caused by an impact around 35.5 million years ago. But the age of the 60-mile-wide Popigai crater in Siberia, one of the biggest on Earth, has been open to dispute.
Now researchers say the Siberian crater is about as old as the other one, based on analysis of rocks melted by the impact.
Richard Grieve of the Geological Survey of Canada and colleagues report their results in the July 24 issue of the journal Nature.
In an accompanying editorial, Dieter Stoeffler and Philippe Claeys of the Natural Sciences Museum in Berlin suggest that the tremendous energy released by the impacts may have created long-lasting changes in the global environment. That could have caused the mass extinction that happened within about 2 million years, they said.
In any case, Grieve and colleagues wrote that two such impacts within a few hundred thousand years was unusual.
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