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.
Motonori Matuyama’s proof generated little interest at
the time; however, it became more significant in the late fifties
when studies of continental drift and sea-floor spreading required
an understanding of geomagnetic reversals. Today, the most recent
reversal is named after him.
Motonori Matuyama’s proof generated little interest at the time; however, it became more significant in the late fifties when studies of continental drift and sea-floor spreading required an understanding of geomagnetic reversals. Today, the most recent reversal is named after him.
See also in The book of science:
Readings on wikipedia: