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The following are some of the more interesting ones: • Destruction of the earth's
ozone layer. Since the late Cretaceous was a time of widespread volcanic activity
, M. L. Keith, professor emeritus of geochemistry at Pennsylvania State University
Within two years, geologists found the same iridium- rich boundary layer at more
than two dozen widely scattered sites around the world. The Glomar Challenger
drilled into the sea floor off South Africa and brought up a core containing the ...
Clemens and his team, to be sure, found the iridium-enriched layer at four sites in
the Hell Creek area. The layer, no more than a few centimeters thick, is always
just below or in the lower Z coal. This made a good benchmark for further ...
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The riddle of the dinosaurUser Review - Not Available - Book Verdict
Unlike many other dinosaur books, this is not a picture book (although it is illustrated) or a review of specific types of dinosaurs. Rather, it is a sophisticated overview of how dinosaurs have been ... Read full review