Geoscience Reference
In-Depth Information
Isostasy revealed that continents and ocean basins have fundamentally different
densities and therefore must have different chemical compositions. Continents can
no more be changed into ocean basins, or vice versa, than cats into dogs.
The cooling Earth had allowed Kelvin to calculate its age and Suess to explain
its major features. Contraction had supplied the motor for mountain building and
geologic change. But by the teens of the twentieth century, contraction was dead.
As the author Naomi Oreskes put it, “the best geological ideas of the nineteenth
century had been refuted, and geologists found themselves with no viable account
of their most basic and agreed-upon observational phenomena.”
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To understand the state in which geology found itself as Wegener was germinat-
ing the idea of continental drift, let us review two articles from the year 1910, the
first from Bailey Willis (1857-1949). He wrote his first scientific paper in 1884
and his last in 1948, a span of sixty-four years, during which he was a ubiquitous
figure in American geology. In December 1910, Willis published an article with
the waters occupy, have constantly existed or may have been the sites of continents
which have now sunken in.” Willis found “the evidence that the hollows have con-
stantlyexistedisstrong,”sostrongthathecouldstate:“
The great ocean basins are
permanent features of the earth's surface and they have existed, where they now
are, with moderate changes of outline, since the waters first gathered
” (243). Wil-
lis would later restate this principle: “Once a continent, always a continent; once
an ocean, always an ocean.”
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But notice that in the italicized quotation Willis introduced something new: the
seemingly innocuous four words “where they now are.” This had nothing to do
with his topic, permanence. Continents could have always been present but not al-
ways have been in the same geographic location. But that the continents had not
moved became Willis's unshakeable credo.
Taylor's Plan
The second paper came from the American geologist Frank Taylor. Instead of
the continents having always been “where they now are,” Taylor, like Wegener,
viewed the present arrangement of land and ocean as recent. Frank Bursley Taylor
(1860-1938) studied at Harvard and joined first the Michigan Geological Survey
and then the U.S. Geological Survey, where he worked with two giants of geology,
T.C.ChamberlinandG.K.Gilbert.Likethetwoofthem,Taylor'sinterestsranged
from the geology beneath his feet to the heavens above.
