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Precisely Dating The KT Boundary
August 23, 2006
The mass extinction of dinosaurs occurred about 66 million years ago, at
the end of the Cretaceous Period (K) and the beginning of the Tertiary
Period, known as the K-T boundary. A massive asteroid slammed into what is
now the Gulf of Mexico about that time.
"About" is the key word here. The correlation is close, but not close
enough for Samuel A. Bowring, a professor of geology in MIT's Department
of Earth, Atmospheric and Planetary Sciences.
"With the K-T boundary and the death of the dinosaurs, everyone is happy
with it being caused by an impact. To me, that's a reason not to be
happy," said Bowring.
Bowring thinks there is a correlation between the two events. But he
firmly believes that it may be possible to more precisely date the
sequence of events before, during and after the extinction.
In 2003 Bowring launched the Earthtime initiative to bring together
scientists from all over the world to work together to calibrate and
sequence Earth history through the integration of high-precision
geochronology and quantitative chronostratigraphy.
Now, Earthtime (http://www.earth-time.org) has more than 200 members,
hailing from a variety of disciplines. ...
Earthtime's official goal is to bring dating accuracy to better than 0.1
percent. That means in dating a 250-million-year-old fossil, results would
be plus or minus 250,000 years. Bowring thinks it is possible to improve
precision to 0.05 percent.
"We are working on the age of the K-T boundary right now using zircon and
we think we can constrain it to within about 50,000 years," Bowring said.