Geomagnetic reversals Sea-floor record Disorder Commentary

Motonori Matuyama plate tectonics

Geomagnetic reversals

• Compass needles point north
• although they wouldn’t have always.
• Fixed in molten rock, the magnetic orientations
• of basalts was confusing; people had found rocks
• with the opposite polarity; so scientists supposed
• that the magnetic field of the earth had once reversed.
• Motonori Matuyama gathered basalt samples
• in Manchuria and Japan and was able to show
• a correlation between the magnetic orientations
• and the position of the rocks in the strata.
• It turns out the magnetic polarity has flipped
• many times in the distant, distant past.

Sea-floor record

• Symmetrical parallel stripes on each side
• of the mid-ocean ridges
• oriented magnetically north, then south
• show that the sea floor has spread
• and that the polarity of the earth’s magnetic field
• has reversed at random many times
• written in the sea floor as on a scroll.

Disorder

• The earth’s magnetic field
• is not as simple
• as a bar magnet’s.
• During a reversal, temporary
• knots of alignments turn
• about at different times.
• Like a creative
• process, characterized by
• disorder and confusion,
• one can not predict
• the progress or conclusion
• of the transforming process
• only after which
• it might seem that
• reason has prevailed.