Iapetus Ocean

Reconstruction of how the Iapetus Ocean and surrounding continents might have been arranged during the late Ediacaran period The Iapetus Ocean (/aɪˈæpɪtəs/; 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. The "southern" Iapetus Ocean has been proposed to have closed with the Famatinian and Taconic orogenies, meaning a collision between western Gondwana and Laurentia.

Because the Iapetus Ocean was positioned between continental masses that would at a much later time roughly form the opposite shores of the Atlantic Ocean, it can be seen as a sort of precursor of the Atlantic, and the process by which it opened shares many similarities with that of the Atlantic's initial opening in the Jurassic. The Iapetus Ocean was therefore named for the titan Iapetus, who in Greek mythology was the father of Atlas, after whom the Atlantic Ocean was named.