The theory of continental drift states that Earth's continents moved over time (i.e., they have drifted across the Earth's surface over time). The theory of continental drift was proposed by Wegener in the early 20th century. This theory has been incorporated into the idea of plate tectonics, a theory that describes the movement of seven large plates on Earth's lithosphere three billion years ago. The discovery of an extinct Permian order of seed ferns (i.e., Glossopteridales) in the Antarctic continent is nowadays considered as a proof that continents were once joined and moved over time.
