Continental drift is a hypothesis that explains how the Earths continents have moved over geologic time relative to each other, thus appearing to have "drifted" across the ocean bed. The idea of continental drift was first introduced by Alfred Wegener in 1912, who proposed that the continents were once united into a single supercontinent named Pangaea, meaning "all lands" in ancient Greek. Over millions of years, Pangaea broke into several fragments, which began moving away from each other, slowly drifting to their current positions on Earths surface/05%3A_Plate_Tectonics/5.05%3A_Continental_Drift).

Wegener supported his theory by demonstrating the biological and geological similarities between continents. For example, South America and Africa contain fossils of animals that are not found anywhere else in the world, suggesting that the two continents were once connected. Other evidence for continental drift includes the fit of the continents, the distribution of ancient fossils, rocks, and mountain ranges, and the locations of ancient climate zones/05%3A_Plate_Tectonics/5.05%3A_Continental_Drift).

Although Wegener presented much evidence for continental drift, he was unable to provide a convincing explanation for the physical processes that might have caused this drift. It was not until the 1960s that the theory of plate tectonics was developed, which provided a mechanism for how the continents move. According to this theory, the Earths crust is fractured into plates that move over a rocky inner layer called the mantle.

In summary, the idea of continental drift describes how the Earths continents have moved over time, and it was first introduced by Alfred Wegener in 1912. Wegener proposed that the continents were once united into a single supercontinent named Pangaea, which broke into several fragments that drifted to their current positions on Earths surface. Although Wegeners evidence was sound, most geologists at the time rejected his hypothesis of continental drift. It was not until the development of the theory of plate tectonics in the 1960s that the mechanism for how the continents move was explained.