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Chesapeake and Popigai

Double whammy 35 million years ago

(ASTRONOMY NOW, Sep 97, News Update, p. 5):

According to a report in Nature, a mass extinction of life 34 million
years ago may have been caused by two major asteroid impacts occurring
one after the other. The Chesapeake Bay crater on the eastern seaboard
of the United States has already been dated to around 35.5 - 35.2
million years old. Now the Popigai impact structure in Siberia, one of
the largest impact craters on Earth, has been given an age of 35.7 -
35.3 million years.
Richard Grieve and colleagues from the Geological Survey of Canada argue
that the tremendous energy released by these two successive huge impacts
may have led to a long-lasting disruption of the global environment
which led to the extinction of many early forms of mammals. Not everyone
agrees. ‘The effects of an impact would be much the same as a very large
volcanic explosion,’ said Norman MacLeod of the Natural History Museum
in London. ‘The effect would last five, 10 or 15 years at the utmost.’
The late Eocene extinction was the most disastrous since the extinction
of the dinosaurs 65 million years ago. (Peter Bond)


Best regards and good night
everywhere around the globe,

Bernd

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