ahar...@earthlink.net Really fascinating! Study links mammoth extinction, comets
> URL to an interesting article in USAToday > _http://www.usatoday.com/tech/science/2009-01-01-mammothimpact_N.htm_ > (http://www.usatoday.com/tech/science/2009-01-01-mammothimpact_N.htm) > > This reinforces > how vulnerable we are. (I sure mis those Irish elk and cave bears.) > > First few paragraphs > > > > By _Dan Vergano_ > (http://www.usatoday.com/community/tags/reporter.aspx?id=133) , USA TODAY > A swarm of comets that smacked North America 12,900 years ago wiped out > the > wooly mammoth and early Native American cultures, according to a soil > study > released Thursday. > The report in the journal Science focuses on tiny "nanodiamonds," > crystals > tied to past comet impacts, at six sites across the continent in a soil > layer > dated to the start of a 1,300-year-long ice age. > Geologists and archaeologists have long argued about what caused the > extinction of dozens of large North American "megafauna" species, such as > saber-toothed cats and mammoths. > "What we're reporting is consistent with a major cosmic impact that had > major consequences for the environment and Earth's climate," says study > leader > Douglas Kennett of the University of Oregon in Eugene. > "A swarm of comets" or carbon-rich meteorites either delivered or created > the nanodiamonds in a fiery impact, the study suggests. The report relies > on > photomicrograph analyses of soil samples from Arizona, Minnesota, > Oklahoma, > South Carolina and two Canadian sites. Photomicrography captures images > seen > through a microscope. > "This is the 'smoking gun' evidence for a massive impact event 12,900 > years > ago that triggered the (ice age) and the extinction of the megafauna," > says > nuclear scientist Richard Firestone of the Lawrence Berkeley (Calif.) > National > Laboratory, who was not part of the study. > If true, the impact date coincides with the abrupt halting of deposits of > "Clovis" Native American artifacts, distinctively fluted tools and > arrowheads. > Dozens of large animal species vanished then in North America. Kennett > and > other impact researchers have suggested a continent-wide wildfire may > have > contributed to the extinction of large North American creatures. In > Europe, there > were disruptions to the prehistoric culture and the demise there of > species > such as the cave bear and Irish elk. "
