What Killed the Mammoths?
A layer of iridium suggests a comet caused the extinction of North America’s megafauna, but skeptics ask "Where is the crater?" and insist that a layer of Clovis points suggest human depredation. When arctic ice sheets reveal a layer of nanodiamonds and models demonstrate that comets could leave no craters, the evidence tilts strongly toward cometary impact. The disc includes a teacher’s guide with discussion ideas and activity handouts. Grades 6 and up. Closed captioned. Described video. Color. 56 minutes. WGBH. ©2009.
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