ALMOST INCONCEIVABLE" CHANGES IN THE GEOMAGNETIC FIELD
A decade ago, a trio of geophysicists published a group of papers based
on their measurements of the remnant magnetism of the 16-million-year-old
layered lava flows at Steens Mountain, Oregon. (SF#45) At that time, they
claimed that these finely bedded lava flows testified that, during a
field reversal, the earth's field swung around at the astonishing rate of
3 degrees per day! This rate is about one thousand times the current rate
of polar drift.
Mainstream geophysicists could not believe the 3 degr/day figure because
it implied incredibly rapid changes in the flow of those molten materials
within the earth that supposedly generate the geomagnetic field. The
Steens Mountain data were "tabled"; that is, dismissed.
The three researchers, though, continued their labors at Steens Mountain
and have now offered additional, even more impressive data. They now
find that the geomagnetic field probably shifted as much as 6 degr in a
single day. Their work has been carried forward so professionally and
meticulously that other scientists are finding their conclusions harder
and harder to dismiss. Instead, the search is on for explanations of
the rapid field changes. Three possibilities have been advanced --
all of them unpalatable to geophysicists:
The Steens Mountain rocks are not faithful recorders of the main
geomagnetic field. Should this be actually so, the whole field of
paleomagnetism, including plate tectonics, is undermined, for it
depends upon similar measurements. The earth's molten core can change
rapidly, at least in some regions, in response to forces still
unrecognized. This, of course, is not really a satisfying "explanation."
The dynamo theory of the origin of the geomagnetic field is incorrect.