No. 48: Nov-Dec 1986
In studying the minute electrochemical cells responsible for metal corrosion, J.G. Bellingham and M.L.A. MacVicar, at MIT, discovered a remarkable effect:
"One interesting and surprising property of electrochemical cells was discovered by accident. Normally, the magnetometer scans each cell as the cell moves horizontally beneath the magnetometer. During one run, the researchers left the cell in a single position for a long time while the magnetometer was still on. After 20 minutes or so, the magnetic field strength began to drop. 'It was very dramatic to watch this field collapse,' says MacVicar. After about a minute at zero, the magnetic field grew larger again but in the opposite direction."
These reversals occurred over and over again at regular intervals.
(Peterson, I.; "Tracing Corrosion's Magnetic Field," Science News, 130:132, 1986.)
Comment. The self-reversal of magnetic specimens has been observed before under some conditions, but here is a periodic reversal of an electrochemical system. Why place it under the heading of Geology? Because the earth's field seems to reverse on a fairly regular basis. Catastrophists have invoked as teroid or cometary collions to account for these flip-flops, but it might be that the earth contains giant electrochemical cells that spontaneously reverse on a million-year timescale rather than minutes. We know the earth's crust is filled with brines and other conducting fluids. Who knows what electrochemical activity transpires down there?