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- From 1912, Wegener publicly advocated the existence of "continental drift", arguing that all the continents were once joined together in a single landmass and had since drifted apart. He supposed that the mechanisms causing the drift might be the centrifugal force of the Earth's rotation ("Polflucht") or the astronomical precession. Wegener also speculated on sea-floor spreading and the role of the mid-ocean ridges, stating: the Mid-Atlantic Ridge ... 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, Die Entstehung der Kontinente und Ozeane, written in German (the first English edition was published in 1924 as The Origin of Continents and Oceans, a translation of the 1922 third German edition), Wegener drew together evidence from various fields to advance the theory that there had once been a giant continent which he named "Urkontinent" (German for "primal continent", analogous to the Greek "Pangaea", meaning "All-Lands" or "All-Earth"). Expanded editions during the 1920s presented further evidence. 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.