Re: OK Nancy, Where Is It?

Almost Inconceivable Changes in the Geomagnetic Field,
Science Frontiers #101 Sep-Oct 1995, by William R. Corliss

    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° per day! This rate is about 
    one thousand times the current rate of polar drift. 
    Mainstream geophysicists could not believe the 
    3°/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° 
    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.

Continental Drift and Plate Tectonics

    During the 1950's, at least partly driven by the 
    military need to understand the ocean as the 
    arena of submarine warfare, intensive studies
    of the ocean floor were carried out. It was found 
    that the center of each major ocean was occupied
    by a ridge at whose center was a valley. On each
    side of this, parallel stripes of rocks magnetized
    in opposite directions were found. The pattern 
    of stripes on one side was the mirror image of 
    the pattern on the other side. The reversal of the
    earth's magnetic field recorded in the rocks was 
    repeated on each side of the ridge. This led 
    H. H. Hess (1960) to propose the idea of sea-floor
    spreading. Molten rock is continuously extruded 
    and cools to form the ridge. As it solidifies, it 
    records the magnetic field at that time. Since it 
    spreads to each side of the ridge, each side has 
    the same record magnetic field record (one is 
    the mirror image of the other). Since new crust 
    is being formed at the ridges, it must be 
    consumed somewhere. Hess proposed that his 
    happens at deep sea trenches, where oceanic 
    crust "dives" under a continent. 

Q: Since lava hardens quickly, how can the core of the Earth be
dictating a different direction for the magnetic field in the hardening
lava unless the crust is shifted between these great volcanic outbursts
and periods when the oceanic rifts are ripped apart?