[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Did a Comet Swarm Kill the Dinosaurs?

FYI, something more to debate:


Did a Comet Swarm Kill the Dinosaurs?
By David Tytell
Sky & Telescope
September 13, 2002

In 1991 a modern scientific 'whodunit' was solved when
geologists identified a deeply buried, 180-kilometer-wide crater in the
Yucatán peninsula. Now known as Chicxulub, the scar resulted from the impact
of a 10-km asteroid or comet nucleus 65 million years ago that triggered
global tidal waves, worldwide firestorms, and massive earthquakes. When the
planet finally returned to normal, the dinosaurs and the majority of all
then-living species had gone extinct, paving the way for mammals to evolve
and dominate Earth.

Now a new study suggests that Chicxulub might not have been an isolated
event. Rather, it seems the dinosaurs may have been the victims of a one-two
impact punch.

Simon P. Kelley (Open University, United Kingdom) and Eugene Gurov (National
Academy of Ukraine) reexamined the age of a buried 24-km-wide Ukrainian
crater known as Boltysh. As recently as 1993, scientists had determined this
impact to be 73 million years old. However, through a number of isotopic
experiments, Kelley and Gurov refined that date to 65.2 ± 0.6 million years.
By comparison, Chixculub's age is 65.5 ± 0.6 million years.

The overlapping uncertainties strongly suggest, (but don't prove) that these
two impacts occurred simultaneously or nearly so.
It's "highly probable" the two craters are linked.

Full story here:


Patricia Kane-Vanni, Esq.
pkv1@erols.com  or  pkvanni@sas.upenn.edu