Based on historical patterns, when a market «flips» from bullish to bearish
after a long
period of moving in the same
direction, the market will usually remain bearish for an extended
period of time.
After correcting the logs for errors in location, Gubbins compared the
directions of captains» compass needles with the magnetic properties
of rocks from the same
period, allowing him to construct a
time line
of movements in the magnetic field.