zone in which the floor of the Atlantic, as it keeps spreading, is continuously tearing open and making space for fresh, relatively fluid and hot sima [rising] from depth." However, he did not pursue these ideas in his later works. In 1915, in the first edition of his book, , written in German, Wegener drew together evidence from various fields to advance the theory that there had once been a giant continent, which he named "" (German for "primal continent", analogous to the Greek "Pangaea", meaning "All-Lands" or "All-Earth"). Expanded editions during the 1920s presented further evidence. (The first English edition was published in 1924 as The Origin of Continents and Oceans, a translation of the 1922 third German edition.) The last German edition, published in 1929, revealed the significant observation that shallower oceans were geologically younger. It was, however, not translated into English until 1962. Reaction In his work, Wegener presented a large amount of observational evidence in support of continental drift, but the mechanism remained a problem, partly because Wegener's estimate of the velocity of continental motion, 250 cm/year, was too high. (The currently accepted rate for the separation of the Americas from Europe and Africa is about 2.5 cm/year.) While his ideas attracted a few early supporters such as Alexander Du Toit from South Africa, Arthur Holmes in England and Milutin Milanković in Serbia, for whom continental drift theory was the premise for investigating polar wandering, the hypothesis was initially met with scepticism from geologists, who viewed Wegener as an outsider and were resistant to change. Nevertheless, the eminent Swiss geologist Émile Argand advocated Wegener's theory in his inaugural address to the 1922 International Geological Congress. The one American edition of Wegener's work, published in 1925, was written in "a dogmatic style that often results from German translations". In 1926, at the initiative of Willem van der Gracht, the American Association of Petroleum Geologists organised a symposium on the continental drift hypothesis. The opponents argued, as did the Leipziger geologist Franz Kossmat, that the oceanic crust was too firm for the continents to "simply plough through". From at least 1910, Wegener imagined the continents once fitting together not at the current shore line, but 200 m below this, at the level of the continental shelves, where they match well. Part of the reason Wegener's ideas were not initially accepted was the misapprehension that he was suggesting the