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Drift’s other greatest defender was South African geologist Alexander du Toit (1878–1948), whom Reginald Daly called “the world’s greatest field geologist.” Du Toit was an expert on the rocks of his native country, including the Karoo formation, whose similarities to rocks of the same age in other parts of the world had made Eduard Suess think of the protocontinent Gondwanaland. Wegener cited these similarities as a major support for his theory in later editions of his book.

After seeing the Karoo formation and meeting du Toit in 1922, Reginald Daly and Frederick E. Wright (1877–1953), a geologist at the Carnegie Institution of Washington, proposed that the institu- tion send du Toit to South America to examine the formations that Wegener had claimed were so much like the South African ones. Du

Toit spent five months in Brazil, Uruguay, and Argentina in 1923 and found the similarities just as great as Wegener had said. He described his South American trip in a 1927 book called A Geological

Comparison of South America with South Africa. In this book, he

wrote of rocks he had seen in Brazil

Anyone who knows southern Africa will find the geology of this landscape startling. At every step I was reminded of the formations of Namaland and the Transvaal [parts of South Africa]. The Brazilian strata [layers of sedimentary rock] correspond perfectly in every detail to the strata series of the southern African shield.

Du Toit was one of the most outspoken supporters of the con- tinental drift theory after Wegener’s death, although he did not describe it in quite the same way that Wegener had. For instance, instead of a single protocontinent, Pangaea, du Toit proposed two: Laurasia in the Northern Hemisphere and Gondwanaland in the Southern. Du Toit described his version of drift most fully in Our Wandering Continents: An Hypothesis of Continental

Drifting, which appeared in 1937. Like Holmes, du Toit believed

that convection currents in the mantle, produced by the heat that radioactive decay generated, moved the slabs of crust on which the continents rode.

In A Revolution in the Earth Sciences, an account of the conti- nental drift controversy, science historian Anthony Hallam wrote, “Du Toit unquestionably made a substantial contribution to the drift hypothesis, partly by eliminating some of Wegener’s errors and partly by integrating a vast amount of evidence, much of it new, into a plausible story whereby a wide array of disparate facts was given a coherent, simple interpretation.” Unfortunately for drift theory, however, du Toit, like Wegener, did not pretend to be an objective reporter. He defended the theory in a writing style even more pas- sionate than Wegener’s and just as full of sarcasm as those of the critical scientists at the 1926 symposium. Even though du Toit’s col- leagues respected his geological fieldwork, many of them thought his writings about drift were too emotional to be truly scientific.

9  Alfred Wegener

Comic Relief

The writings of Daly, Holmes, and du Toit improved some Earth scientists’ opinions of continental drift in the 1930s and beyond, but many of those who had criticized the theory in the 1920s still rejected it. In 1944, for instance, Bailey Willis, who had objected to Wegener’s ideas at the 1926 New York meeting, called the drift theory a “fairy tale.”

Willis proposed a new version of the land-bridge idea in 1932 as an alternative to drift. He suggested that mountain-building forces beneath the ocean basins deform not only continental borders but the basins themselves, producing the mid-ocean ridges. These undersea mountain ranges continue onto the continents, from time to time forming what Willis called “isthmian links” between them. Ursula Marvin writes in Continental Drift: The Evolution of a

Concept, “To many scientists Willis’ isthmian links were the perfect

compromise between the doctrine of permanence and the Suessian idea of submerged continents. . . . They seemed to remove all need for continental drift.” Willis’s theory became very popular in the 1930s, 1940s, and 1950s, especially in the United States.

Interest in the drift theory also remained low because evidence against it continued to emerge. For instance, new measurements by a group of British and Danish scientists in 1936 showed that the ear- lier determinations of longitude in Greenland, which had impressed Wegener so much, were in error. The revised figures showed no sign that the island was moving west, as Wegener had claimed.

Continental drift was not completely forgotten during this period. Most geology textbooks described it, at least briefly, as one of a number of theories about what might have happened to the Earth’s crust during past geological eras. Professors mentioned it in their college classes, too, but often only as comic relief. For instance, Percy E. Raymond, a professor of paleontology at Harvard, liked to tell his students that half of a fossil sea creature had been found in Newfoundland and another half in Ireland. The two parts matched so perfectly, Raymond said, that they had to belong to the same animal, which had been “wrenched apart by Wegener’s hypothesis in the late Pleistocene.” When scientists considered drift at all, they thought of

it in the revised versions offered by researchers like Holmes, not in the form in which Wegener had originally presented it.