Editorial Reviews - Impact Events From the Publisher Chapters: Permian-triassic Extinction Event, Cretaceous-tertiary Extinction Event, Impact Event, Tunguska Event, Comet Shoemaker-Levy 9, Giant Impact Hypothesis, Carancas Impact Event, Tollmann's Hypothetical Bolide, Late Heavy Bombardment, Younger Dryas Event, 2009 Jupiter Impact Event, Thwing, Sikhote-Alin Meteorite, Vitim Event, Impact Winter, Eastern Mediterranean Event, Tenham Meteorites, Shiva Hypothesis, Sulawesi 2009 Superbolide, Karoonda Meteorite. Excerpt: The PermianTriassic (PTr) extinction event, informally known as the Great Dying, was an extinction event that occurred , forming the boundary between the Permian and Triassic geologic periods. It was the Earth's most severe extinction event, with up to 96 percent of all marine species and 70 percent of terrestrial vertebrate species becoming extinct; it is the only known mass extinction of insects. Fifty-seven percent of all families and 83% of all genera were killed. Because so much biodiversity was lost, the recovery of life on earth took significantly longer than after other extinction events. This event has been described as the "mother of all mass extinctions". Researchers have variously suggested that there were from one to three distinct pulses, or phases, of extinction. There are several proposed mechanisms for the extinctions; the earlier phase was likely due to gradualistic environmental change, while the latter phase has been argued to be due to a catastrophic event. Suggested mechanisms for the latter include large or multiple bolide impact events, increased volcanism, and sudden release of methane hydrates from the sea floor; gradual changes include sea-level change, anoxia, increasing aridity, and a shift in ocean circulation driven by climate change. Until about the year 2000... More: http://booksllc.net/?id=24749 Synopsis Chapters: Permian-triassic Extinction Event, Cretaceous-tertiary Extinction Event, Impact E