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Globe may rift into soccer-ball pattern
MISSOULA, Mont., April 23 (UPI) -- The continents may
periodically split apart to form giant hexagons and pentagons across the
globe in a pattern similar to that found on soccer balls, says a Montana
scientist. If these controversial new findings prove valid, they may yield
insight into the planet's structure and into the evolution of life on
Earth. Evidence of this pattern lies in what James Sears, professor
of geology at the University of Montana, believes was the largest geometric
figure ever to appear on the face of the Earth -- a hexagon whose sides
are continental rifts roughly 2,600 kilometers (1,615 miles) long. These
giant cracks opened up some 500 million years ago during the breakup of
the ancient continent Laurentia. "The rifts appear to arrange exactly to the size
and shape of one of the hexagonal faces you find in the pattern on a soccer
ball," Sears said. "The closer I measured all of the angles
and the lengths and so forth, the more precise the fit was." This pattern, known as a truncated icosahedron, makes
up a soccer ball's 12 black pentagons and 20 white hexagons. "It
was first discovered by the ancient Greeks -- by Archimedes, in fact --
so all of its parameters are very well-defined," Sears said. "The
pattern's found everywhere, from carbon buckyballs to the herpes and wart
viruses." The six continental rifts that made up this hexagon pattern
have drifted apart over hundreds of millions and can now be seen as mountain
ranges, Sears said. The Rocky Mountains would have made up the western
side, while a mountain belt running through Scotland formed the original
eastern border. The hexagon's northwest and northeast sides are now ranges
across the Arctic and Greenland, while the southeast and southwest borders
are now the Appalachians and a mountain belt passing through Alabama and
Arkansas. Sears thinks this pattern, formed over the millennia,
was an energy-efficient fracture mechanism. "The continent Laurentia
was under very uniform stress about 1.5 billion years ago," Sears
said. "I think it alleviated the most stress for the least work by
taking on this fracture pattern. What may have happened is that the continent
fractured, but the pieces didn't really go anywhere. Then, much later
-- about a billion years later -- fragments may have broken off on these
dotted lines." Hexagonal patterns are found everywhere in geology, from
lava flows to rock outcroppings. "Geology is fractal -- we find the same kind of patterns
on all scales," Sears explained. "You see these hexagonal patterns
in mud cracks. It's just that if you scale up to the size of the Earth,
they can't get a hexagon any larger than this one, because then they would
start interfering with their neighbors. This is as big as it gets."
This continental rifting theory could help reconstruct
very ancient supercontinents such as Rodinia, which formed roughly 1.1
billion years ago and lasted about 350 million years. Rodinia was one
of several supercontinents in Earth's history, where all land mass was
concentrated in one place. "There's a lot of controversy over what was where
in Rodinia," Sears explained. "If there is a very regular pattern,
then it limits the arrangements of the continental fragments. It's kind
of like you have a grid to go by." The rifts Sears studied may have also played a key part
in the incredible proliferation of marine life that exploded across the
planet during the Cambrian period. Scientists posit that the rifts helped
form "shelves" at continental margins, where warm, shallow seas
allowed for a vast range of ecological niches and diversity of life. "Any rift producing continental shelves would have
helped produce diversity of life," Sears said. "All I'm adding
to what's been proposed is that there's a very large scale pattern and
organization that might help reconstruct this event." Sears' proposed intersection of geology and geometry has
sparked controversy among scientists. Ian Dalziel, a tectonics expert
at the University of Texas at Austin, finds that the Scottish and Appalachian
sides of Sears' hexagon especially appear "very much forced."
"I don't believe this story for a moment," Dalziel
said. "Four of the six sides are real, but if you take away these
two sides, the pattern goes away." Dalziel added that continents would not have fractured
into hexagons like mud would. Mud is homogeneous, in that its ingredients
are evenly distributed throughout, like those found in a melting pot.
Continents, on the other hand, are heterogeneous and made up more like
the contents of salad bowls, with many different types of complex structures.
"When you look at the breakup of the supercontinent
Pangea, there's no pattern like this," Dalziel said. "And we
have more evidence for the Pangean breakup compared to the Laurentian
breakup." Geologist David Fastovsky, the editor for the journal
Geology that reported Sears' findings, maintained that this sort of controversy
was good for science. "It's a really unusual idea, and there are people
who would argue that it's just plain crazy," Fastovsky said. "One
person literally said, 'Why not?' Other reviews were quite a bit more
negative. I just felt that the idea was not completely half-baked, not
hare-brained -- there was some limited data to support it, and I felt
that if it was true, then it deserved an airing and had some real potential
significance. What's relevant here is that scientists hash things out."
Sears will present new findings connecting hexagonal patterns to the breakup of Pangea at an annual Earth System Processes meeting in Edinburgh, Scotland, in June. |