Pangaea (Greek for “all lands”) is the supercontinent that existed during the Paleozoic and Mesozoic eras, before the process of plate tectonics separated the component continents. The name was coined by Alfred Wegener in 1915. When the continents first came together to form Pangaea about 300 mya, mountains were formed, and some of these ranges still exist although they have become much lower, such as the Appalachians, the Atlas Mountains, and the Urals. The vast ocean that surrounded Pangaea has been named Panthalassa. Pangaea broke up about 180 mya.