Did Ancient Earth-Chilling Meteor Crash Near Canada?
Scientists have traced the geochemical signature of the BB-sized
spherules that rained down back to their source, the
1.5-billion-year-old Quebecia terrane in northeastern Canada
near the Gulf of Saint Lawrence. At the time of the impact, the
region was covered by a continental ice sheet, like Antarctica
and Greenland are today.   Top 10 Ways to Stop an Asteroid
Asteroids reach Earth's atmosphere every day -- but only the
biggest make it to the ground.  Younger Dryas?  The new research
shakes up a controversial theory about a big climate shift
called the Younger Dryas, when Earth abruptly swung into a
glacial period 12,900 years ago. The cooling has been attributed
to a sudden shutdown in Northern Atlantic Ocean currents, caused
by a big glacial lake flood out the St. Lawrence or Mackenzie
Rivers. But in 2007, scientists suggested that comet or meteor
impacts or atmospheric fireballs triggered the Younger Dryas,
though no crater of the right age has eve