San Francisco Chronicle, 24 September 2005

http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2005/09/24/BAGG9ET78M1.DTL

Scientists say cosmic debris killed mammoths

Keay Davidson, Chronicle Science Writer

An exploding star might have wiped out one of North America's strangest denizens
from the Ice Age -- wooly mammoths, which resembled hippie elephants --
according to a Berkeley scientist's controversial new idea.

Like a cosmic version of TV's "CSI" team, which analyzes a murder victim's teeth
to learn how he died, nuclear scientist Richard Firestone of Lawrence Berkeley
National Laboratory and an Arizona geologist have examined 34,000-year-old
mammoth tusks to determine the cause of the prehistoric animals' demise.

Inside the tusks, they discovered numerous tiny craters that, they claim, were
formed by the impact of iron-rich grains traveling at the astounding speed of
thousands of miles per second.