Scientists uncover new evidence of the asteroid that killed off the dinosaurs
Excerpt: 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. [Unfortunately, the Proceedings of the National Academy of Sciences publication of the study isn’t easily available to me. All of this stuff is relatively “new” knowledge. As recently as the early 1970s, no one really had a good idea why the dinosaurs all died out at about the same time. Even after Alvarez, Asaro, and Michel found an iridium-rich layer nearly worldwide, it took another 30 years before most agreed a comet-like body impacted the Earth. A very fine speculative fiction novel about this called “Lucifer’s Hammer” by Niven and Pournelle in 1977 (Hugo Award nominee, 1978) gives a pretty good idea what the physical after effects of even a small such strike would be like. Ron P.]
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