Glaciers are the ice machines producing icebergs, churning away primarily in Greenland and Antarctica. A very small number of icebergs originate in Alaska and in Siberia or south of Franz Joseph Land in the Barents Sea. Since icebergs come from glaciers, they are composed of freshwater. Glaciers are formed by thousands of years of snowfall accumulation that is eventually compressed into ice. The bergs are then at the mercy of the currents.
Icebergs are serious hazards in shipping lanes.
At the time of the Titanic disaster, there were no systems in place to track icebergs and forewarn ship captains. Also, when an iceberg's original size was 10 nm or greater before the iceberg split into two or more pieces, NIC will continue to track the iceberg until it breaks up below the resolution of satellite imagery. Two icebergs, A38 and B10A, recently grabbed quite a bit of media attention. Iceberg B10A, measuring 24 by 48 miles, amazed scientists not because of its size but because it managed to get so far north without breaking up. Iceberg A38 was originally almost twice the size of B10A. Data Exercise Print a map of Antarctica from National Geographic's Map Machine, and track the path of Antarctic icebergs using data from the NIC .