The Fourth Revolt / Der Spiegel Article (English)
Researcher reveals secret of the northerly drift
By Axel Bojanowski / Spiegel Online
Researchers have overlooked it for many decades: The crowding of the continents in the
northern hemisphere can be explained with simple global geometry - and with a tectonic
spreading ring around Antarctic. The insight comes so late because scientists look so
rarely at the bottom of the earth.
Some questions are so good and so simple that only children ask them. Thus, for
example, no scientist was surprised at the fact that almost all continents lay on the north
hemisphere of the earth, while the southern hemisphere is covered predominantly by
oceans -- although this really jumps at the eye of everyone who looks at a globe.
Up to now, however, geo-researchers had explained it with silly plausibility-answers: The
drift of the earth's plates has created this pattern just by chance. This sounds
unsatisfactory as an explanation, and the real reason has been a long time coming.
Now a researcher of a natural history museum provides a better answer: The unequal
distribution lies in the shape of the earth – and in a powerful, all too evident motive force
that other geo-researchers had overlooked like the proverbial forest for the trees. Dennis
McCarthy, at the museum of Science in Buffalo, New York discovered the answer by
regarding the globe from an unusual perspective: from below.
Antarctica lies on the South Pole of the planet, thousands of kilometers away from other dry
little spots --- a special case below all the other land masses. Because a three kilometer
high spreading ridge in the seafloor surrounds the south continent, lava perpetually pours
from this so-called mid-oceanic ridge and hardens to form new earth crust. This pushing
lava continually forces the plates apart.
THE NORTHWARD PUSH
But around the submarine spreading ridge the tectonic plates all push mutually, hence,
Antarctica remains relatively stationary. And the pressure must be released northwards.
There the new seafloor and the circum-Antactic ridge moves. Consequently, all the plates
all around the south continent are pressed toward the equator.
The northern drift and the shape of the earth cause the differences between the northern
hemisphere and southern hemisphere, McCarthy has found out: Just as degree of
longitudes lie further apart at the equator than near the Pole, the northward moving plates
have also diverged. Therefore, the seafloor of southern hemisphere rips apart. There new
seafloor continuously forms - [and] the oceans of the south become larger, writes
McCarthy now in the renowned specialist journal "Journal of Geophysical Research".
2. Part: Humans have distorted, mutilated, and ignored the Antarctic Stepchild -- thus
they also overlooked the obvious engine for the northern drift of the continents.
The spherical shape? How trivial! However, maps shape world views, and the troubles that
humans have had in modeling the three-dimensional world adequately on a level surface
have stretched throughout the history of the modern age. Antarctica always became the first
victim of cartographers: absurdly distorted as disproportionate strips in the lower map
edge - or completely left out. So as a fulcrum and pivot of plate tectonics, Antarctica and her
undersea spreading ridges did not attract attention.
That is the problem of perspective, says the geologist Helmut Echtler of the geo research
center potsdam (GFZ) to MIRROR ON-LINE ONE: Due to its peripheral location on the
maps, one considers the south continent too infrequently.
THE GREATER ROOM AT THE EQUATOR
All the necessary data were present. McCarthy used a standard geological map ("Nuvel-1")
with motion and velocity of the plates as determined by GPS measurements, and are
available to every researcher. The plates move in all directions. However, McCarthy put
down the vectors precisely into tables - and found out: In general, the earth plates move
northward more than in any other direction.
The earth plates [move] away from Antarctica to the north, McCarthy has calculated. The
cause is the spherical shape of the earth: In the southern hemisphere, the pushing
seafloor has a lot of room and can move nearly without braking [toward the equator],
Over the course of the last 200 million years, most continents were pushed thus in the
northern hemisphere. Now large crowding thus prevails there, and the plates collide in
many places: A collision front stretches, for instance, from Europe to Eastern Asia, along
which mountains tower up like the Alps and the Himalayas. As the spur land masses –
like Africa and India - push into the Eurasian continent from the south, collisions slow the
plates in the northern hemisphere, McCarthy has calculated.
"ELEGANT GEOMETRICAL EXPLANATION"
The study surprises the professional world. The work shows that the movement of the
tectonic plates can be explained elegantly with geometry, says Onno Oncken, GFZ expert
for Plattentektonik, to SPIEGEL ONLINE. Up to now plate movements were reconstructed
only with the help of measured motions.
Now McCarthy's geometry law possibly explains even [past and future configurations of] the
continents. Since in the course of the history of the earth the land masses united several
times to a supercontinent. Why this happened appeared puzzling for a long time.
According to the new study, the plates conglomerate possibly systematically : The last
supercontinent Pangea – before 225 million years ago -- comprised almost all of the land
mass of the earth and partially lay on the south hemisphere -- disintegrated before about
200 million years ago. The break-up originated [at least in part] as a result of that exact
same undersea spreading ridge around today's Antarctica, which has driven the tectonic
plates to the north since that time.
In the distant future today's continents will presumably join in the north, says the geologist
Wolfgang Frisch of the University of Tübingen to SPIEGEL ONLINE. He is the author of the
standard work "Plattentektonik". The next continent cycle would possibly begin when
another huge lava ring opened near the North Pole. Following McCarthys geometry rule,
Frisch speculates: Then the continental plates could drift again toward the south - and in
the north an enormous new ocean would develop.
Slide show for article
Bojanowski's article on the JGR paper has also appeared in
SonntagsZeitung, a nationwide Sunday paper of Switzerland.