Geoscience Reference
In-Depth Information
Neither Science nor Scholarship
In America and to a lesser extent in Britain and on the continent, most geologists
had rejected drift even before the AAPG symposium. But two problems remained.
First, was the theory well and truly dead? Might some disciple of Wegener not find
a way resurrect it? Second, and more important, if drift were dead, and if contrac-
tion, permanence, and land bridges were in doubt, what was left to serve as the
unifying theory of geology? Uniformitarianism was not the answer. It described a
method but did not explain any of the larger questions about the Earth. With no
ruling theory and so many fundamental questions unanswered, could geology, as
Rollin Chamberlin had poignantly asked, truly be called a science?
Schuchert and Willis took it upon themselves to save geology, and, not coin-
cidentally, their own long-held views. But this introduced another problem: Wil-
lis insisted on permanence, Schuchert on land bridges, and each was unconvinced
by the other. The two began an extensive private correspondence that reads like a
treaty negotiation between two friendly but wary nations, each prepared to give a
little but not to compromise its core position. Robert Newman and Naomi Oreskes
have done science a great favor by perusing and reporting on the lengthy corres-
pondence between Schuchert and Willis, and also between Schuchert and Arthur
Holmes, who had taken an interest in continental drift and the possibility that con-
vection currents were behind the process.
Schuchert was blunt about the dilemma that confronted geology. In 1927 he
wrote to Holmes: “The South Atlantic land bridge between Brazil and Africa =
Gondwana is a fact for Paleozoic and much of Mesozoic time. We must have a
way of getting rid of it in early Cretaceous time, and I asked Barrell [his Yale col-
of Wegener's ideas with magmatic convection currents inside the earth on a gi-
gantic scale to provide the energy.”
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But the gulf between Schuchert and Willis remained. How to close it? Schuchert
claimed that land bridges were a fact; Willis believed that continents and oceans
werepermanentandthattheless-denselandbridgescouldnotsinkintotheoceanic
crust and mantle. Willis conjured up a solution that preserved the essential features
of both philosophies. Land bridges had existed, he said, but, instead of being made
of lighter continental rock, had been composed of oceanic basalt thrust up from the
ocean floor. Basalt, being dense, would conveniently sink when no longer needed.
These “uptrusions,” as Willis called them, formed long slender connections that
Willis,everfondofaneologism,named“isthmianlinks.”Histheorywasevenuni-
formitarian: basaltic islands are common; Central America is an isthmus that links
