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ALFRED-WEGENER-INSTITUT
HELMHOLTZ-ZENTRUM FÜR POLARUND MEERESFORSCHUNG
Seafloor spreading
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The Archiv für deutsche Polarforschung
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Mid-Atlantic Ridge on the globe (Photo: Sina Löschke)
It wasn’t until the mid-1960s, around third years after Wegener’s death, that his ideas received
recognition in science. Seismological investigations showed that the Earth merely has a thin solid
crust that floats on a plastic mantle. Deep inside our planet there’s a very hot core. The Earth’s
crust, which contains the continents and seafloor, is geologically divided into seven large and
numerous small plates. The plates move, driven by the heat convection in the Earth’s mantle, at a
speed of several millimetres to centimetres per year (plate tectonics).
So-called mid-oceanic ridges run through the oceans. In these zones magma rises from the Earth’s
interior to the surface, cools down there and constantly forms new seafloor. At the same time the
existing seafloor spreads (seafloor spreading) and presses the Earth’s surface, including the
continents, apart. In so-called subduction zones old seafloor is, in turn, pressed down, melts and in
this way becomes magma again. A region in which new seafloor continuously forms is, for
instance, Gakkel Ridge in the Arctic. This is a submarine mountain range whose northern foothills
extend from the northeast tip of Greenland to Laptev Sea in Siberia. At this point the Eurasian
and the North American plate drift apart by a few millimetres every year.
Using the research icebreaker “POLARSTERN” scientists study this system of ridges and
investigate the effects of the mechanisms involved in the spreading process: volcanism, Black
Smokers and lava flow.
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Geophysics 
Bathymetrie 
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Seafloor spreading
Alfred Wegener