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Frontiers
Unusual Rock Upsets Geology Theory
October 1996
Found: A mysterious
crystal-filled rock. While it hasn't moved from its perch in the Swiss
Alps for millions of years, its presence there is shaking up the geology
community.
Discovered by an NSF-funded team from the University
of California, Riverside, the rock is startling because of its unusual
crystals -- formations that only could have been created in Earth's
inner core, more than 300 miles below the surface. The rock's mountaintop
location suggests the theory of plate tectonics may need some tweaking.
It also opens the possibility that gems exist in areas previously
ignored.
Geologists suspect that the half-mile long,
quarter-mile wide slab has had a long journey. Starting at the surface,
the light crustal material was pushed down when Africa and Europe
collided about 50 million years ago.
Below the surface, extreme pressure and heat
created the crystals. Then, 40 million years ago, the Alps formed.
The moving earth allowed the comparatively light material to pop
up, like a cork. The material then rested on the new mountains as
they were pushed up to their present elevation.
"These are very powerful observations that
will shake up the community," team member Dr. Harry Green told the New
York Times. "They show that anything can go all the way down
and back up, even to the top of the Alps."
The theory of plate tectonics does not currently
account for the possibility of a lighter rock being forced below
the earth's surface. Scientists suggest the collision of continents
could cause enough of a gravitational instability to allow this to
happen.
Finding one crystal may mean there are others,
of the same or different kind, says Green. "It is possible there
are rocks like these in the Himalayas that are full of diamonds," he
told the Times.
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