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THE END OF THE DINOSAURS by Charles Frankel

THE END OF THE DINOSAURS

Chicxulub Crater and Mass Extinction

by Charles Frankel

Pub Date: Sept. 1st, 1999
ISBN: 0-521-47447-7
Publisher: Cambridge Univ.

Every schoolchild now knows that the dinosaurs were killed off by a meteor, but it took a while for scientists to accept the idea. Here’s the story of how they changed their minds, by science writer Frankel (Volcanoes of the Solar System, not reviewed, etc.). The discovery of Chicxulub crater in Mexico was the crucial clue in one of the great scientific detective stories of modern times. For more than a century, paleontologists had spun theories to explain the sudden disappearance of the dinosaurs at the end of the Cretaceous era, some 65 million years ago. The first clear indication that the extinction was sudden, rather than evolutionary, was the famous paper by Luis Alvarez and others, showing an increase in the rare element iridium in strata associated with the end of the Cretaceous, and suggesting a meteor impact as the cause. The geological community, not used to the notion of extraterrestrial causes for earthly events, at first resisted the suggestion. But other scientists documented additional signs of meteoric activity: shocked quartz crystals, caused only by significant meteor impacts, and tektites, droplets of ejected material that cool into glass spheres. By this point, some scientists had begun to search for the impact crater—no sure thing, since there were two chances out of three that the meteor had landed in the ocean. Nonetheless, scientists were largely convinced by the discovery of the Chicxulub crater, which matched all the criteria for the “smoking gun” in this mystery. Frankel devotes a chapter to describing the probable aftereffects of the impact, from shock waves to burning ejecta to poisonous chemicals. He then expands his scope to look at the possibility that other mass extinctions were caused by impacts and at the possible implications of these discoveries for human civilization. A workmanlike job, covering the main events and key players of one of the great stories in modern science. (67 photos, 9 ilustrations)