The ocean that split worlds and then braided them again
The Atlantic, second largest of Earth's five oceans, covers about 85 million square kilometres, some 17 per cent of the planet's surface. Its S-shaped basin long divided the Americas from Afro-Eurasia, and after Columbus crossed in 1492 it became the highway of European colonisation, though Norse sailors had crossed first.
The name reaches back to Stesichorus in the mid-sixth century BC and Herodotus around 450 BC, both calling it the Sea of Atlas, the water beyond the Pillars of Hercules. Early Greek sailors thought it part of Oceanus, the great river circling all land, and its southern reaches were long called the Aethiopian Ocean. English mapmakers of the Age of Discovery knew it as the Great Western Ocean, and British and American speakers still joke about crossing the pond, a phrase dating to 1640.
Counting marginal seas such as the Mediterranean, Caribbean, Baltic and Gulf of Mexico, it covers 106,460,000 square kilometres, 23.5 per cent of the global ocean, with a coastline of 111,866 kilometres. It meets the Arctic through seas around Iceland and Svalbard, and the Indian Ocean along the 20° East meridian south of Cape Agulhas. Between the 60th parallels north and south the average depth is 3,730 metres, while the Puerto Rico Trench plunges to 8,376.
Down the middle runs the Mid-Atlantic Ridge, from about 300 kilometres south of the North Pole to Bouvet Island at 54°S, standing 2–3 kilometres above the surrounding floor. Its rift valley marks where the North American and Eurasian plates, and farther south the South American and African plates, pull apart, producing volcanoes like Iceland's Eyjafjallajökull. The Challenger expedition found parts of it in the 1870s, the German Meteor expedition traced the rest by echo sounding in the 1920s, and in 1922 USS Stewart drew a continuous sonar profile across the ocean bed.
Surface temperatures range from below −2 °C to above 30 °C, peaking north of the equator; the South Atlantic stays warm year-round while the North Atlantic swings through sharp seasons. From October to June sea ice usually covers the Labrador Sea, the Denmark Strait and the Baltic.
Source: Atlantic Ocean
