Iapetus Ocean

Ocean that existed in the late Neoproterozoic and early Paleozoic eras

The Iapetus Ocean (eye-AP-ih-təs) existed in the late Neoproterozoic and early Paleozoic eras of the geologic timescale (between 600 and 425 million years ago). It was in the Southern Hemisphere, between the paleocontinents of Laurentia, Baltica and Avalonia. The ocean disappeared with the Acadian, Caledonian and Taconic orogenies, when these three continents joined to form one big landmass called Euramerica.

From Wikipedia, under CC BY-SA. More on occurri.