<P> Continental drift is the movement of the Earth's continents relative to each other, thus appearing to "drift" across the ocean bed . The speculation that continents might have' drifted' was first put forward by Abraham Ortelius in 1596 . The concept was independently and more fully developed by Alfred Wegener in 1912, but his theory was rejected by some for lack of a mechanism (though this was supplied later by Arthur Holmes). The idea of continental drift has been subsumed by the theory of plate tectonics, which explains how the continents move . </P> <P> Abraham Ortelius (Ortelius 1596), Theodor Christoph Lilienthal (1756), Alexander von Humboldt (1801 and 1845), Antonio Snider - Pellegrini (Snider - Pellegrini 1858), and others had noted earlier that the shapes of continents on opposite sides of the Atlantic Ocean (most notably, Africa and South America) seem to fit together . W.J. Kious described Ortelius' thoughts in this way: </P>

Who proposed the first comprehensive theory of continental drift