Iceberg

Iceberg, large floating mass of ice. In the Southern Hemisphere, the Antarctic ice sheet overflows its land support to form shelves of ice on the sea; huge pieces, as much as 150 mi (240 km) across, break off to form icebergs. In the Northern Hemisphere, icebergs are generally not over 175 yds (160 m) across. Most are “calved” from some 20 glaciers on Greenland's west coast. Small icebergs (growlers) may calve from larger ones. Some 75% of the height and over 85% of the mass of an iceberg lies below water. Northern icebergs usually float for some months to the Grand Banks, off Newfoundland, there melting in a few days. They endanger shipping, the most famous tragedy being the sinking of the Titanic (1912). The International Ice Patrol now keeps a constant watch on the area.

See also: Ice.