Supercontinent: Ten Billion Years in the Life of Our Planet (16 page)

Wegener was walking into a tough room.

Not all US geologists were opposed to drift. Today (and indeed also in older literature, when American pro-drifters were trying to make it seem less un-American) continental drift is often referred to as the Taylor-Wegener hypothesis to recognize US Geological Survey
geologist
Frank Bursley Taylor (1860–1938), who proposed a form of drift in 1910. There were also others. But despite converts (many highly respected), it was slow going. As the Wegener theory’s huge explanatory power won new adherents elsewhere, by and large, and for a wide variety of reasons (some spoken, others not), American geologists stood out against it almost to a man. Just how unanimous this opposition was became evident at a landmark scientific meeting in 1926 organized by Dr Willem Anton Joseph Maria van Waterschoot van der Gracht (1873–1943).

Three years earlier Royal Dutch Shell had fired this brilliant, Amsterdam-born geologist. Van der Gracht was by no means the last geologist to find that being sacked by a multinational was the making of him, and a distinguished career in the United States as a pioneer in prospecting by seismic interpretation lay before him. He was also destined to play a pivotal role in the history of continental drift theory. In 1917 he had co-founded the American Association of Petroleum Geologists (AAPG), today the world’s largest Earth-
science
society, and in 1926 convened one of that body’s meetings. The conference, in New York City, had a single purpose: to discuss
theories
of continental drift.

For the AAPG, which was then still a fledgling organization, this was a decisive moment. Its co-founder had chosen a controversial topic because it was, he believed, the biggest scientific game in town, with massive implications for oil prospecting. What better launch for a prestigious series of published symposium proceedings than to treat such a revolutionary subject?

In the mythology of the subject this meeting has often been
portrayed
in something of the manner of the famous confrontation at the British Association in Oxford in 1860 between Darwin’s defender and champion, Thomas Henry Huxley, and Bishop Samuel Wilberforce. Although the earlier debate is always held up as a triumphant rout of the forces of fundamentalism, the New York meeting on drift is
portrayed
as one man’s lonely defence of Wegener’s theory against seemingly insuperable opposition. Neither of these histories is really accurate.

Wegener was not present in New York, and it should not be
forgotten
that his theory was by no means the only drift theory in town. Other theories about how continents might have drifted were also on the agenda; it’s just that Wegener’s happened to be the main target. Frank Bursley Taylor, for example, also presented his theory. The American survey geologist suggested that two supercontinents,
formerly
at or near the Earth’s poles, gradually drifted towards the Equator, pushing up mountains along their leading edges and
splitting
under tension along their poleward, trailing edges. However, although Taylor’s theory had been around for about two years longer than Wegener’s, only Wegener had written so persuasively and at such length about it, and almost none of the other speakers addressed themselves to Taylor.

In fact, with Taylor concentrating on his own ideas, the only person present who was at all in favour of Wegener was the convener himself. Almost without exception, Wegener was condemned, and even those
who did not join in the condemnation merely urged further research. Reservation of judgement, however, was not to be the order of the day.

The interesting thing about discussion meetings is, of course,
discussion
. If unanimity should unexpectedly break out, people reading the resulting proceedings will wonder why the meeting took place at all. So, in order to save his publication, and introduce at least a
semblance
of balance, van der Gracht solicited a number of supporting contributions from people who had not been present in New York. He commissioned contributions from Alfred Wegener himself, from the Irishman John Joly of Trinity College, Dublin, his fellow Dutchman Gustaaf Molengraaf, of Delft’s Institute of Technology, and Glasgow University’s professor John W. Gregory.

These men were known to be broadly open to drift theory. Joly (1857–1933) was a highly original thinker with his own theory. His contribution, though, barely covered two sides, and concentrated on generalities. Molengraaf pronounced himself a drift enthusiast, but quibbled about Wegener’s insistence that Pangaea’s fragmentation had all been westerly. Gregory was also lukewarm. He was not opposed to drift
per se
, but saw no reason why the present distribution of land and sea could not equally well be attributed,
à la
Suess, to vertical rather than horizontal movements.

These endorsements, though hardly ringing, did help, but not very much. So the convener decided to exert his privilege not only to have the first word, reproducing a seventy-five-page set of opening remarks, but also the last, book-ending the proceedings with a twenty-nine-page summing-up, in which he critically examined (and often demolished) various objections. In the end van der Gracht himself wrote 43 per cent of the entire volume. The proceedings were saved (and are now a sought-after collector’s item); but in its list of contributors the transatlantic divide over continental drift theory
was made flesh. The supercontinent of science had undergone a geological rift.

In the pragmatic, fieldwork-obsessed world of early-twentieth-century American geology, where hard work and first-hand familiarity with the rocks were the only justification for any excursion into
theoretical
territory, the accusation of being an ‘armchair geologist’ was a grave one. It was levelled at, for example, Suess, whose great insights were indeed the product of much book learning and relatively little fieldwork (at least in his mature years). Both Suess and Wegener, in pointing to the geological correlations between the modern fragments of Gondwanaland, were generalizing from observations made by others about the congruence of facing Atlantic coastlines, Wegener doing little more than taking Suess’s data and interpreting them differently.

American scientists might not have liked the method, but, some asked, what was the truth of this assertion? How alike
were
these sequences of rocks? Would it not be scientific to go there and check it out? The logic seemed faultless, but there was a snag. Proceeding in this way would be engaging in
deductive
research – setting out explicitly to test a ruling theory – and that was not the American way. Given that, who in the States would be prepared to put up the funds needed to send someone halfway across the globe to test a theory that most geologists in America had already dismissed?

By good fortune, Reginald Daly, Harvard University’s Sturgis Hooper Professor of Geology, had been on a nine-month fact-
finding
mission to Africa in 1922, the year Wegener’s book was published for the first time in America. The main focus of the expedition had been South Africa’s massive Bushveld Igneous Province, and during
the trip Daly had met Alex du Toit. The party had also included Molengraaf and Frederick Wright (1877–1953), a geologist from the Carnegie Institution of Washington, which funded the trip.

Returning that autumn a convinced ‘drifter’, Daly began to hatch a plan with his friend in that well-endowed institution. The result was an illuminating exchange of letters between Wright and the Carnegie’s Director, John Merriam. In the first, Wright told Merriam about how the geological world was now in the thrall of an amazing new theory. He told his boss about the British Association for the Advancement of Science, and how its meeting in Hull had listed some crucial tests that should be done to verify the claims made for the geology of facing shores. The correlation of the Karoo rocks of South Africa with their South American equivalents particularly cried out for attention. There was only one man for the job, Alex du Toit. The Institution should pay for him to go to Brazil and verify it. In high hopes he sent off the proposal.

Merriam turned it down. After the initial shock of disappointment, however, Wright found that the boss had not closed the door
completely
. Merriam was not about to put to his Trustees a request to spend the Carnegie Institution’s money on any overtly deductive search after facts. No, the proposal had to be more circumspect, more pluralistic, more American. To judge by Wright’s second (successful) attempt, it also had to be less exciting.

Where version one had begun, like a piece of contemporary
journalism
, ‘The hypothesis of continental drift … is arousing the keen interest of geologists the world over’, version two opened: ‘In
accordance
with your request for information I take pleasure in presenting, herewith, an outline of some of the results that may be expected from a comparative study by A L du Toit of the Karoo, Gondwana and other equivalent formations of the southern hemisphere …’

When Merriam finally gave the project the green light, Wright
copied both versions to du Toit and explained the situation. Sure,
they
all knew why he was going to Brazil: to test Wegener’s hypothesis. They just couldn’t say so. This was important information for du Toit because, whatever his own intentions, he would now have to write up his results the American way, using multiple working hypotheses. This thoroughly deductive expedition had to be turned on its head and made to look like induction in action. The stated main purpose of the trip would be to gather facts: to add these good, solid bricks to the great edifice of science, and then to offer many different explanations of them, drift being merely one theory among equals. Wright’s letter arrived in Pretoria the very day du Toit set off on the Trans-Karoo railway for Cape Town, where he would catch a boat for Brazil.

It would take du Toit two years to complete his monograph, and it would be four years before it finally appeared in print, in 1927. It is a curious document, and the tension between the dictates of American-style induction and du Toit’s own pro-drift convictions shows in almost every line. Du Toit succeeded in confirming the transatlantic correlations of Suess, expanded by Wegener, and he added some more of his own; yet to his dismay, all his work hardly seemed to help the cause of drift. In fact, he often found his
painstaking
fieldwork dismissed as irrelevant or inconclusive; he was even tarred with the same brush as Suess and branded an armchair
geologist
for his pains – he, a man who had mapped 50,000 square miles!  

The reason for du Toit’s failure lay in the nature of the evidence itself, of the ‘proofs’, as Skerl would have translated it. Both du Toit and Wegener were aware of this problem, which was that by their nature, geological correlations did not
compel
drift. In fact, du Toit
committed
a PR blunder of his own by admitting in his monograph that the
similarities between the fossils of Africa and South America ‘can
generally
be explained equally well, even if less neatly, by the orthodox view that assumes the existence of extended land bridges …’. This was putting weapons in the hands of his enemies; but his point was that fossils
on their
own
could not decide anything because fossils are remains of living things and living things can move. Instead, he
concentrated
on the rocks themselves.

Sedimentary rocks change their character from place to place, depending on the environment that lays them down. Beach sediments change as the bay merges with, say, a river estuary. What du Toit showed was that sediments of the same age in South America and Africa often showed greater changes
within their outcrops in those
continents
than they did across the wide expanse of the South Atlantic. This, for him, was far more compelling evidence than the fossil
similarities
that the two continents were once close together and hence probably joined along their now distant coastlines.

But this evidence was also circumstantial. Geophysicists persisted with their
non posse
, ‘it’s impossible’, line of argument (it is a
well-known
fact that a scientist always finds evidence from his own field most convincing). If you wanted to win over physicists, it was little use drawing their attention to fossils and sediments. For that group, drift didn’t happen because it
couldn’t
happen.

Writers of popular science are often accused of ‘hardening up’ stories to make them simpler, clearer or more exciting. This sometimes gets them into trouble with scientists, who tend to favour caution. Charles Ray was writing
The World of Wonder
, my father’s unwieldy science encyclopaedia, in the early 1930s. Wegener, referred to throughout as ‘the late Professor Wegener’, had not long perished on the Greenland icecap. Continental drift theory had been around for eighteen years but was still highly controversial. Yet undaunted, after an excellent summary of the theory, Ray writes: ‘It seems a startling
theory to think of the continents sliding or drifting over their
foundations
; but distinguished geologists say there is
nothing at all impossible in the theory from a mechanical point of view
…’

When I first read this as a boy, of course I believed it. When I came across it again later, having by then read the conventional textbook histories of plate tectonics, it made me laugh. Surely, the situation was quite the reverse? Was it not precisely the ‘mechanical point of view’ (the mechanism) that gave even the most eminent geologists the
greatest
difficulty of all? No amount of evidence based on animal or fossil distributions, or similarities in sequences of strata, or matching up of mountain ranges across oceans would convince anyone about
continents
doing this unthinkable thing until a
mechanism
had been found; and I remembered the observation ‘To see a thing, you must first believe it possible’.