Continental drift is the theory that the Earth’s continents have shifted relative to one another during geologic time, giving the impression that they have “drifted” over the ocean floor. Abraham Ortelius proposed the theory that continents ‘drifted’ in 1596. Alfred Wegener separately and more extensively established the notion in 1912, but his hypothesis was dismissed by many due to the lack of any motivating mechanism. Mantle convection was later hypothesized by Arthur Holmes as a mechanism for this. The concept of continental drift has subsequently been absorbed into the discipline of plate tectonics, which analyzes the movement of continents as they ride on plates of the Earth’s lithosphere.