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hypothesis is a fantastic one,” confessed Holmes. “But this is not science,” he went
on, “and in reaction I have been deliberately careful not to ignore the very formid-
able body of evidence that has seemed to make continental drift an inescapable in-
ference.” 30
Understandably, the lack of support for his convection theory may have sapped
Holmes's self-confidence, as it had likely sapped Wegener's as he prepared the
fourth edition of his topic. Holmes went so far as to think the previously un-
thinkable: “This symposium has left me with the general impression that a few
land bridges or linkages by island stepping-stones would probably suffice for the
biogeographical problems” (671). But by the end of the review, Holmes had re-
gained his balance: “While so many contradictory voices confuse judgment, one
cannot do better than commend [Carl] Dunbar's [who participated in the symposi-
um] wise dictum that 'it is unsafe to reject, a priori, either continental drift or
foundering of broad land bridges'” (671).
One reason why Holmes may have thought that many generations would be re-
quired to test convection and continental drift was that hardly anyone seemed to
be interested. In the years since Wegener first proposed drift, almost all of the new
information had come from Du Toit. In his magnum opus, Our Wandering Contin-
ents , he had laid out a mass of convincing geological evidence showing that south-
ern Africa and South America had once been connected. But no matter, it was still
the same kind of “newsprint” evidence that Wegener had offered but which geolo-
gists had declined to accept. To rescue drift from oblivion would require not just
more evidence but evidence of a new and wholly different type.
As Arthur Holmes transformed his lecture notes into his monumental Principles
of Physical Geology , isolated as he was by a world war and military secrecy, he
could not have known that on and under the world's oceans, scientists were laying
a foundation that in less than one generation would prove Alfred Wegener right
and his myriad opponents wrong.
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