Atlantic Ocean

THE NAME OF THE Atlantic Ocean is derived from the Greek god Atlas and means “Sea of Atlas.” Its area is approximately 41 million square mi (106 million square km) including its adjacent seas; volume is approximately 85 million cubic mi (354 million cubic km), including adjacent areas. The average depth of the ocean with adjacent seas is 10,932 ft (3,332 m). The greatest depth is in the North Atlantic at 28,232 ft (8,605 m) in the Milwaukee Deep of the Puerto Rico Trench just north of PUERTO RICO; in the South Atlantic, the greatest depth is 27,651 ft (8,428 m) at the South Sandwich Trench east of the Falkland Islands. The width of the Atlantic varies from 1,769 mi (2,848 km) between Brazil and Liberia to about 3,000 mi (4,830 km) between the United States and northern Africa.

The ocean has a coastline of 69,357 mi (111,866 km). Adjacent areas include the CARIBBEAN SEA, Gulf of Mexico, Gulf of St. Lawrence, Hudson Bay, Baffin Bay, MEDITERRANEAN SEA, BLACK SEA, North Sea, Baltic Sea, Barents Sea, Norwegian-Greenland Sea, and Weddell Sea.

The Atlantic Ocean is the second-largest of the Earth’s oceans. Covering approximately 20 percent of globe’s surface, the Atlantic is second only to the PACIFIC OCEAN in size. Because the continents bordering its waters in the north are offset to the west of those in the south, the Atlantic appears as an elongated northsouth S-shaped channel. In the north, the Atlantic is bounded by North America on the west and Europe on the east, while in the south it is bounded by South America on the west and Africa on the east. It is also linked to the Pacific Ocean by the ARCTIC OCEAN in the north and by the Drake Passage in the south.

The dividing line between the Atlantic and the INDIAN OCEAN to the east has been arbitrarily set at the 20 degrees E meridian, while the dividing line with the Pacific Ocean on the west follows the line of shallowest depth between Cape Horn and the Antarctic Peninsula. In the north, the boundary between the North Atlantic and the Arctic Ocean lies along a system of submarine ridges that extend between Baffin Island, GREENLAND, and Scotland. There is also a boundary between the Atlantic’s northern and southern zones, formed by the equatorial counter currents that circulate just north of the equator (8 degrees north latitude) in an area known as the Intertropical Convergence Zone (ITCZ). The Atlantic Ocean appears to be the youngest of the world’s oceans. It began to form during the Jurassic period, about 150 million years ago, when a rift opened up in the supercontinent of Gondwanaland, resulting in the separation of South America and Africa.

The separation continues today at the rate of several centimeters a year along the Mid-Atlantic Ridge, a great submarine mountain range that extends from ICELAND in the north to approximately 60 degrees south latitude, dividing the Atlantic into a series of somewhat equal basins (also known as ABYSSAL PLAINS). Roughly 930 mi (1500 km) wide, the ridge has a more rugged topography than any mountain range on land and ranges from about 0.6 to 2 mi (about 1 to 3 km) above the ocean bottom. The ridge is a continuous feature of the Atlantic floor with one exception, the Romanche Furrow near the equator where the crest of the ridge drops significantly (15,000 ft or 4,573m) below the surface, allowing deep waters to flow freely between the Atlantic’s eastern and western basins. Other transverse ridges running between the continents and the Mid-Atlantic Ridge divide the ocean floor into numerous other sub-basins including the Guiana, North American, Cape Verde, and Canaries basins in the North Atlantic and the Angola, Cape, Argentina, and Brazil basins in the South Atlantic. The large Atlantic-Antarctic Basin lies between the southernmost extension of the Mid-Atlantic Ridge and the Antarctic continent