Continental rift refers to the movement of the Earth's continents relative to each other. The hypothesis that continents 'drift' was first put forward by Abraham Ortelius in 1596 and was fully developed by Alfred Wegener in 1912. However, only with the development of the theory of plate tectonics in the 1960s a sufficient geological explanation of the cause of their movement could be found. (This article gives an overview about the development of the continental drift hypothesis before 1950. For the contemporary theory, see the article plate tectonics.)