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Figure 3.4. Illustration in map view of the way seafloor spreading and magnetic
field reversals combine to yield strips of sea floor that are alternately normally
and reversely magnetised. The resulting pattern is symmetric about the crest of
the ridge if the spreading itself is symmetric (meaning that equal amounts of new
sea floor are added to each plate).
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Figure 3.5. The pattern of magnetic anomalies across the Mid-Atlantic Ridge
south of Iceland, where it is known as the Reykjanes Ridge. Black indicates a
positive anomaly, inferred to be due to normally magnetised crust, and white
indicates a negative anomaly, inferred to be due to reversely magnetised crust.
The short lines mark the location of the ridge crest, along which there is a positive
anomaly. Despite the irregularities, the pattern shows a striking symmetry about
the ridge crest. From Heirtzler et al. [30]. Copyright by Elsevier Science. Reprinted
with permission.
consolidated sediment ([7], p. 220). Morley submitted a paper about the beginning
of 1963, which was rejected by two journals in succession, the second with unflat-
tering comments. Vine and Matthews submitted a paper in about July 1963, which
was published in September. Morley's story emerged later [7].
Subsequent exploration revealed extensive patterns of magnetic stripes on the
sea floor, with an astonishing degree of symmetry about ridge crests (Figure 3.5),
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