Drilling into the seafloor off Mexico, scientists have extracted a unique geologic record of the single worst day in the history of life on Earth, when a city-sized asteroid smashed into the planet 65 million years ago, wiping out the dinosaurs and three-quarters of all other life.
Their analysis of these new rock samples from the Chicxulub crater, made public Monday, reveals a parfait of debris deposited in layers almost minute-by-minute at the heart of the impact during the first day of a global catastrophe. It records traces of the explosive melting, massive earthquakes, tsunamis, landslides and wildfires as the immense asteroid blasted a hole 100 miles wide and 12 miles deep, the scientists said.
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The sediments also offer chemical evidence that the cataclysm blew hundreds of billions of tons of sulfur from pulverized ocean rock into the atmosphere, triggering a global winter in which temperatures world-wide dropped by as much as 30 degrees Fahrenheit for decades, the scientists said.
“It tells us what went on inside the crater on that day of doom that killed the dinosaurs,” said Jay Melosh, a geophysicist at Purdue University who studies impact craters and wasn’t a member of the drilling team. “All of this mayhem is directly recorded in the core.”
The scientists in the drilling consortium, led by geophysicist Sean Gulick at the University of Texas in Austin, who was co-chief of the $10 million project, published their research in the Proceedings of the National Academy of Sciences. The project was sponsored by the International Ocean Discovery Program and the International Continental Scientific Drilling Program.