1946-1974
Calm Before
the Storm

The Debate Begins

Wegener Drifts Into Gear

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 The Theory

 The Debate

 The Lecture

 The Evolution

Although American scientists were difficult to convince, it cannot be said that they didn't engage in the debate. AAPG was one of the first scientific organizations in America to provide a forum for discussion of the predecessor of global plate tectonics, which has been called the most profound addition to the science since Hutton introduced the concept of geologic time.

Alfred Wegener, the German meteorologist/geographer who introduced his concept of continental drift in Europe in 1912, traveled in 1926 to New York City, where he presented his case to members of AAPG at the association's annual fall meeting.

His paper must have received lukewarm response, judging from the other papers presented in the same session. The significance of the occasion was not overlooked, however. Wegener's speech was recorded, along with the other papers given, in AAPG's first special publication, Theory of Continental Drift, a volume that today has attained rare book status.

At the meeting, founding member W.A.J.M. van Waterschoot van der Gracht spoke supportively of several aspects of the theory, especially its explanation of mountain ranges resulting from continental collision and its accountance for similarities in stratigraphy and corresponding fossil records in land masses separated by vast oceans.

He urged those present to keep an open mind and not reject the concept simply because the mechanism wasn't obvious.

"The whole controversy reminds me vividly of the discussions during my student days on the problem of sheet overthrusting in the Alps," van der Gracht told the assembly. "Its mere possibility was then as firmly denied, as is now the possibility of continental drift. The facts have since proved beyond any doubt that these sheets exist, not only in the Alps, but universally. Still their detailed mechanism, their 'possibility' remains almost as much a riddle as it was then. The possibility has only been demonstrated by fact, not explained."

Van der Gracht's prescient reference to the debate on Alpine geology speaks even more eloquently today than it did then -- but eloquence apparently wasn't enough to sway the majority away from the conventional wisdom of the era.

Perhaps the most popular structure theory of the time -- first proposed nearly 100 years earlier -- was the contraction theory, which held that surface structures were the result of the Earth's crust buckling and arching on a shrinking globe, "like the skin on a dried apple."

Fantastic Contrivances

Many advocates of the contraction theory favored the idea that the ocean floors were sunken continents that had once formed land bridges between the surviving land masses.

In order to explain why sea fossils could be found almost everywhere on the continents, a hypothesis attributed to Lyell suggested that periodically the land masses that remained behind began to sink faster than those previously below the sea, so that what was dry land could have become sea floor and vice versa, in as many cycles as needed to account for the fossil record.

Although in retrospect such theories seem fantastic contrivances, the Wegener skeptics remained adamant in their opposition to his explanation of continental drift, mainly on the grounds that it lacked a plausible mechanism.

The problem was magnified by Wegener's belief that the ocean floors were composed primarily of basalt. His vision of light-weight continents "sailing" through a foundation of basalt proved to be a hard sell, even though some, like Alexander du Toit in South Africa, found merit in the central concept of continental drift and used it as a basis for their own investigations.

Wegener won few converts in America and he returned to Europe.

There a growing group of interested colleagues, joined by scientists in Japan and throughout the Southern Hemisphere, were taking a healthy interest in the theory and the literature base was expanding dramatically.

Unfortunately, Wegener died four years later while on an expedition in Greenland, 20 years before advances in geophysical techniques would cast new light on the ocean floor and rejuvenate continental drift theory. He left the world's geoscientists in a fractioned state, divided between "fixists" and "mobilists."

In the United States, opposition remained strong.

Despite the unpopularity of the theory, however, AAPG was well-advised in having arranged the special symposium on continental drift. Proceeds from the meeting not only covered costs, but also paid for the publication of the symposium papers. Income from the sale of the volume ($3.50 postpaid) was set aside in a new Revolving Publication Fund, "to become the nucleus for a fund for printing books and papers in addition to the regular BULLETIN."

Thus began AAPG's Special Publications program.