Alfred Wegener proposed that around 225 million years ago, all of Earth's land was joined together in a "supercontinent" surrounded by a single vast ocean. This supercontinent was called Pangaea, and the surrounding ocean was Panthalassa. Eventually, Pangaea broke apart into two separate continents divided by an ocean, called Laurasia and Gondwana. Wegener put forward evidence including matching coastlines and fossil distributions to support his theory of continental drift.