February
8, 2002
MHC
Student Rocks!
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FRED LEBLANC
Katharine
Sayre '02 is pleased to count herself among the nation's
"rock squeezers," scientists who study rock deformation.
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Scientists know a
lot about rocks, from their age, to their makeup, to how they
form. But they still have a lot to learn, such as how certain
rocks react under certain conditions. Among the scientists trying
to answer such questions are geologists who study rock deformation.
They are known as "rock squeezers," and Mount Holyoke
student Katharine Sayre '02 now counts herself among them. Last
summer, the geology major studied rock friction at Brown University
with Terry Tullis, professor of geological sciences, and Brian
Titone, a student at the State University of New York, New Paltz.
Sayre sought the experience in a university lab to prepare herself
for graduate school, but she left with a new research passion
and a discovery that may have implications for understanding earthquake-causing
fault lines around the world. She presented her work at the December
meeting of the American Geophysical Union (AGU) in San Fracisco,
an undergraduate achievement that Associate Professor of Geology
Al Werner calls "nothing short of amazing."
Sayre's first experiments
at Brown looked at the friction caused by quartz rocks sliding
against each other. As expected, this sliding action created high
friction. When she added water to the rocks, however, Sayre saw
the formation of a gel substance that lubricated the rocks, thereby
decreasing the friction on the sliding surface between them and
keeping the temperature of the surface relatively low.
The discovery might
help explain why there are no melted quartz rocks in nature, says
Sayre. Because of the pressure of moving slabs of rocks along
fault lines, she explains, "melted fault rocks" called
pseudotachylites form in all kinds of rock—all kinds except
quartz, that is. Sayre wonders whether circulating underground
water creates silica gel on quartz rocks in nature, just as it
did in the lab, resulting in less friction, a lower temperature,
and no melting.
Sayre's experiments
might also help to explain the "heat flow paradox" that
geophysicists have observed at fault lines such as the San Andreas
Fault in California. The paradox, says Sayre, is that the temperature
of the fault surface at the San Andreas Fault is much lower than
is expected at a place of friction created by rock sliding against
rock. Sayre hopes that her findings will help explain that discrepancy.
Although disappointed
that she can't participate in friction experiments now being continued
by her lab group at Brown, Sayre is excited about the possibility
of publishing her findings in Geophysical Research Letters. She
also looks forward to future graduate study in rock friction,
earthquake mechanics, and neotectonics (modern movement of the
earth's crust), a program of study that she hopes will lead her
to helping the world's communities plan for earthquake hazards.
As one of a rare few undergraduates invited to present at a professional
conference, Sayre is well on her way toward becoming just such
a leader among "rock squeezers."
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