Moreover, of the 240-page volume, published in 1928 by the American Association of Petroleum Geologists (in both the United States and England), pages 1–76 are an extensive introduction by van der Gracht to the problem of continental drift in general, including a detailed summary of Wegener’s theory, but also summarizing the views of Frank B. Taylor; Reginald A. Daly (1871–1957), a Canadian geologist and author of Our Mobile Earth (1926); and John Joly, as expressed in his Surface History of the Earth (1925). These last two authors had theories of intracontinental mobility and the creation of mountain ranges by heating, asymmetric uplift of continents, and “continental sliding.” At the end of the volume, between pages 197 and 226, van der Gracht published a summary of the major criticisms of Wegener presented in the papers, refuting them one after another.
Taken altogether, the published volume, in spite of the vigorous criticisms it contains of Wegener’s hypothesis, had much more material defending and expounding Wegener than attacking him, given that van der Gracht was an outspoken proponent of continental drift. It was not really a North American response, since the convener and four of the authors were Europeans. Most importantly, as van der Gracht pointed out in his concluding remarks, “an outstanding feature of this symposium is that the majority of those contributors who attack Wegener’s theory express themselves as not fundamentally opposed to the conception of such a thing as intra-and inter- continental drift, even on a considerable scale. This is a very important step forward.”86 It was indeed a step forward, and a large one; Wegener, had he attended, would have been as pleased at the outcome as he had been in Berlin in 1921. They were agreeing on displacement and disagreeing about the details.
Turning away from the misleadingly titled “symposium” to the more general and longer-lived North American debate over Wegener’s theory, Naomi Oreskes has shown that this debate was quite different from the open consideration Wegener’s theory clearly enjoyed in Germany as early as 1921; in Denmark, Holland, and England by 1922; and in Austria by 1924. Rather, it was a concerted and deliberate attempt to reject Wegener and his work as the kind of German “pseudo-science” of which Yale geologist Joseph Barrell, back in 1914, had warned his American colleagues to be wary.87 The rejection of Wegener’s theory in North America was the result of a crusade to forestall not just its acceptance but even its discussion. This crusade, led by Charles Schuchert and Bailey Willis, is amply documented by Naomi Oreskes through their correspondence—hence the apposite title of her book, The Rejection of Continental Drift.88
More recently, philosopher-historian Henry Frankel has completed a massive four-volume study, The Continental Drift Controversy (2012), covering from the beginnings until the 1980s. This is, by the way, an indispensable work for anyone interested in the relationship of Wegener’s career to the emergence and acceptance of the theory of plate tectonics. Frankel devoted the first volume entirely to the debate about Wegener’s hypothesis and its aftermath—a debate, we have often noted, in which Wegener took a very small part. Frankel’s broad and deep analysis of the many hundreds of publications concerning Wegener’s hypothesis demonstrates very convincingly (if one knows the European background) that the same arguments used against Wegener in the first decade of the theory’s life, principally in Germany, were mobilized again and again by Wegener’s opponents, who sought to discredit his expertise as well as dismiss his ideas. This is not to say that all the debates were like this; far from it—there was much good science in play, the issues were real, and the flaws in Wegener’s arguments were apparent. What Frankel documents (as a side issue to his own deeper discussions) is the peculiar lag time from debate to debate.89
It appears that the consideration of this hypothesis, everywhere it went, followed the same trajectory on roughly the same timescale as the original German debates. In the middle 1920s, when Wegener’s book was already in a third edition, many English and most North American opponents were still depending heavily on criticisms offered of the first edition of 1915, though we have seen that the hypothesis, in the form that Wegener was propounding it in 1920 and in 1922 (and after), was quite different from the hypothesis that brought about the initial criticism. Finally, the Klimate der geologischen Vorzeit, already out for two years before the New York “symposium,” amounted to yet another major revision of Wegener’s displacement theory, both in the timing and extent of continental motions and in the timing and amount of movement of the pole of rotation.
One of Frankel’s most important claims is that, beginning in the middle of the 1920s, the debate over continental drift began to divide up into subcontroversies argued by subdisciplinary specialists. Frankel counts four such controversies as being of special significance: floral and faunal (biotic) disjunctions, the Permo-Carboniferous glaciation, the measurement controversy, and a controversy over the mechanism of drift.90
If this is so, and it appears to be so, this was not good news for Wegener’s theory. Theories of great scope must, in consequence of their scope, lack precision. The more you explain in general, the less you explain in detail. This is true not only of theories of Earth but of the theory of gravity, the theory of electromagnetism, and the principle of conservation of energy. Wegener had been quite explicit in 1912 that he was proposing a unifying theory of Earth based less on the full ensemble of details of each component discipline than on solving evidentiary conflicts by an appeal to Earth’s bulk (thermodynamic) properties. It was only later, as he refined his own theory, that he went more and more into the details of the various classes of evidence he had assembled. Still, compared to his geologist counterparts, there was a distinct lower bound to his curiosity about anomalies, and this shows clearly in Frankel’s fine-grained analysis.
All this notwithstanding, van der Gracht did a great service to Wegener in organizing the symposium and ensuring its much-amplified publication. This is perhaps most notably so for a reason that van der Gracht never mentioned: he chose to illustrate his long introduction to “continental drift” not with the well-known maps from Wegener’s 1922 edition or its 1924 English translation, but with almost every single map from Die Klimate der geologischen Vorzeit. He did not integrate these maps in any particular way with the discussion in his text; he simply reproduced and identified them. This was the only publication of these maps in an English-language book for some decades to come, providing the opportunity for Wegener’s critics, had they wished to take advantage of it, to study Wegener’s continental reconstructions, his pole positions, and his latitude-based climate zones from the standpoint of the most recent and complete version of his theory.
This was important for Wegener, as the core of the theory was in the maps, and Die Klimate der geologischen Vorzeit has never been translated into any language from the original German. This alone tells us a good deal about the status of the debate over Wegener’s full theory in the later 1920s, considering that (by 1926) Wegener’s book on continental displacements was already in English, French, Spanish, Russian, and Swedish. It also tells us that Wegener and Köppen may have played an unwitting role in the move toward subcontroversies, by minimizing the extent to which their joint work of 1924 contained yet another version of Wegener’s displacement theory, differing in crucial respects from all previous versions, and yet presenting the work as a strictly paleoclimatic book based on a theory (displacements) already complete and independently published.
Well before the November 1926 symposium in New York, Köppen and Wegener’s work was already thoroughly integrated into climatology in Europe. In the fall of 1926, Charles Brooks (1888–1957), the librarian of the British Meteorological Office and editor of the Meteorological Magazine, published a large book entitled Climate through the Ages: A Study of the Climatic Factors and Their Variations.91 Brooks was a respected climatologist and the author of the previous study The Evolution of Climate (1922).92 The latter was mostly a book about the Quaternary ice ages and the postglacial periods, and Brooks had planned a companion volume dealing with the mechanism of
climate change and drawing on this book for illustrations, but “then came the work of Wegener on the theory of continental drift, and of Köppen and Wegener on the interpretation of the climatic record in terms of the travels of the continents across the parallels of latitude and this stimulated me to complete the investigation in order to examine Wegener’s theory from the climate side.”93
The first part of Climate through the Ages was, as Brooks said, “essentially a text-book of meteorology, in which, however, some of the constants of the ordinary meteorological text-book are treated as variables. Various theories of climatic change are discussed in successive chapters as they arise, but no attempt has been made to include all the theories which have been put forward from time to time.”94
The second part of Climate through the Ages, nearly 100 pages in length, was titled “Geological Climates and Their Causes,” and it was an extensive and detailed examination of Wegener’s theory of continental displacements and Köppen and Wegener’s work on climates of the past. Brooks said, in his preface, “I may, I hope, be excused for the length to which the discussion of continental drift has run. The theory is at present on its trial before the tribunal of the world’s scientists, and the verdict appears to be wavering in the balance. Geology, naturally will be the final arbiter, but the voices of other sciences are not without some weight.”95
Brooks’s judgments are quite interesting. He accepted almost without question that stretching and compression of the crust, in conjunction with tidal forces, had led to the gradual drifting apart of the continents in an east-west direction. On the other hand, he found Wegener’s latitude shifts to be much more problematic, arguing that “the only real evidence adduced in support of this view is climatological and, practically speaking, the climate of the Upper Carboniferous; the geological evidence is quite inadequate.… Wegener’s explanation, though not probable, is possible.”96
When, in chapter 13, Brooks undertook his detailed examination of the theory of continental drift, his framing shows the extent to which Wegener’s thinking seemed unproblematic in its general outlines (if not proven in its details) from the standpoint of paleoclimatology as practiced in Great Britain. Brooks accepted the work of Theodor Arldt and of Edgar Dacqué (both deeply influential to Wegener) as showing the way paleoclimatology ought to be done from the standpoint of paleontology and biogeography.97
Brooks’s approach also seems to demonstrate that Wegener’s formulation of the problem of continents and oceans, his restriction of the alternatives to either displacement or permanence (no sunken land bridges), and his argument that the results of geology, paleontology, geophysics, geodesy, and paleoclimatology were all required to solve the problem of ancient climate had carried the day in how the question of past climate should be resolved. Wegener’s work was not just a serious part of this discussion in Brooks’s work; it was altogether the impetus for his book. Brooks had questions about mechanism, timing, and other issues concerning displacements, but the substance and tone of his treatment of Wegener show that of the forty-eight climate change theories Brooks listed, in eleven different categories, Wegener’s theory was for him the most serious and important intellectual event in paleoclimatology in many years, and that no further progress was likely until it had been thoroughly evaluated and mastered by climatologists and put to a rigorous test.
As pleasant as this must have been for Wegener to read, it was also frustrating. What, for instance, could Brooks mean by “putting the theory to the test?” Did this mean an indefinite postponement of commitment on the geological model, or a certain span of time in which to compare Wegener’s ideas with other ideas of similar scope? Brooks seemed to be waiting for the “community” to make up its mind, but there lay the problem: if every investigator is waiting for the “community” to make up its mind, this event will never happen, as everyone postpones commitment until everyone else is committed.
This was not just a geological problem: Wegener had once quoted Rudzki as saying that if climatologists found evidence of a shift of the pole, the geophysicist must surrender to their judgment. Harold Jeffreys had said in London in 1923 that the decision about Wegener’s theory was a matter for geologists to decide. Brooks in 1926 had said of Wegener’s theory, “Geology, naturally, will be the final arbiter, but the voices of other sciences are not without some weight.”98
In Wegener’s view, this was quite wrongheaded. In the Innsbruck symposium in 1924, when challenged by Schweydar, Wegener said that he stood by his geological reconstructions but that he had to defer on the question of the motion of the pole to the expertise of mathematical geophysicists more competent than he. In order to get out his views about the order of the sciences, and of who should be deferring to whom, he accepted an invitation from Eugenio Rignano (1870–1930), the editor of the multilingual popular science journal Scientia, published in Milan. Rignano was a well-known philosopher and author of the book Psychology of Reasoning, and he was interested in the phenomenon of selective attention. He published articles on all aspects of science in his journal, and he always had an eye toward vital (currently active) controversies, soliciting articles from major participants in such debates.
Wegener wrote an article based on his Graz lecture on the significance of the theory of displacements for the systematic and the exact sciences. Now, however, he came to have a somewhat different conclusion. Where before he expressed the need for all these sciences to collaborate, he now asserted that while collecting information from many fields was necessary, which he indeed had done, “nevertheless, I believe that the ultimate resolution of this question must come via geophysics, because only geophysics has sufficiently exact methods.”99 If geophysics were to decide that the displacement theory was false, then all the systematic sciences would have to go along with that judgment and would then have to find another explanation for their own facts.100 He then went on to sketch how modern results in the measurement of gravity, in seismology, and in the study of rigidity and viscosity in solid mechanics all pointed unambiguously toward the impossibility of the sinking of continents, while they underlined the likelihood that floating continents might also displace laterally.
This can hardly be surprising; Wegener was, after all, a physicist, trained in physics and astronomy, and once again doing work of the most definitive kind in optics and acoustics at the time of this writing. He was trying to find a way out of the impasse created by the decision of the proponents of continental permanence to continue to assert their geological ideas in the face of their geophysical implausibility.
Looking Far North
The life of a theorist and the life of his theory do not necessarily run in tandem. While Wegener’s theory was being debated in New York and treated in Great Britain by Brooks, Wegener the theorist was teaching (in the winter semester 1926/1927) “Introduction to Geophysics,” which had less to do with his theory of displacements and past climates than with his editorial work on the Lehrbuch der Physik. Wegener had not yet begun to catch up on work bearing on his theory going back as far as 1924.101
As his editorial work pulled him away from continental displacements and climates of the past, a variety of independent events were also turning his mind back to the Arctic. The phenomenon of Haupthalos (parhelia), on which he had just spent so much time—studying the refraction of sunlight by ice crystals in the upper atmosphere—was something that was visible most frequently in high latitudes. He was, at this time, in correspondence with Carl Störmer (1874–1957), a Norwegian mathematician and investigator of the auroras who had found Wegener’s work on the auroras essential reading and had solicited offprints of Wegener’s work as part of a major study of the aurora which Störmer was pursuing in 1926.102 Additionally, the Royal Danish Geographical Society had named Wegener an honorary member in November 1926. In December, Eduard Brückner wrote to Wegener to inform him that he had been named Austria’s representative to the International Society for the Exploration of the Arctic by Airship (AEROARCTIC), whose presi
dent was Fridtjof Nansen.103
More powerful than all of these Arctic stimuli, however, was an appeal he received from Koch in the late fall of 1926. Koch’s health was deteriorating rapidly, and he proposed that Wegener should take over the writing up of the glaciology from 1912–1913; Koch said he no longer had the strength or the powers of concentration to see it through.104 Wegener wrote back with another suggestion: they would work on the glaciology together; Wegener would work up a draft from Koch’s notes, and then they would meet and go over it extensively, to clear up disputed points. Koch agreed.105
Nothing could happen immediately with this project; Wegener was too deeply involved with his teaching and with the meteorological problems with which he had started to engage again. As we have seen, in his search for information about the “outer zone of audibility” he had come across data indicating a variation in altitude (with the seasons) of the reflecting layer in the stratosphere and had written a paper on this in 1925 for Meteorologische Zeitschrift.106 He had also been working on the temperature profile of the atmosphere above 80 kilometers and its connection with his theory of elemental segregation of oxygen, nitrogen, and hydrogen at successive altitudes.
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