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a b c
36
Fig. 5. a: Details of the
5 oscillatTons marked to
the left of the Dye 3 record
in Fig. 3. b: Further
details of some of the
5 shifts. c: Concentration
of insoluble microparticles.
Notice, increasing values
towards the left.
ted with/caused by abrupt shifts of the mean latitude of the oceanic polar
front in the North Atlantic, in analogy with the changing conditions during
the last glacial oscillation (B011ing-Aller0d-Younger Dryas), discribed
in ref. /21/.
The driving mechanism behind the oscillations is not clear. It is probably
connected to the North Atlantic atmosphere-ocean interaction, because
Antarctic ice cores contain no such feature, at least only in a strongly
damped form /8,11,22/, and because the last glacial oscillation (B011ing/
Aller0d-Younger Dryas) was most pronounced, by far, in Europe, Greenland
and the eastern part of maritime Canada /20/.
The abruptness of particularly the cold to warm shifts in 5 appears from
Fig. 5, which shows details of the 5 or 6 oscillations marked to the left
of the Dye 3 record in Fig. 3. The time scale does not allow a direct
estimate of the duration of the 5 shifts, but if a full oscillation lasted
of the order of 2600 yrs (cpo 18 oscillations from 77,000 to 30,000 yrs
B.P.), the shifts to warmer conditions would seem to be completed within
a century or two, perhaps less in view of the diffusive smoothing of the
5 record since the time of deposition. The return to full glacial severity
proceeded slower and stepwise. The less abrupt changes in the dust concen-
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