Icebergs are large floating pieces of ice that have broken off from a snow formed glacier or ice shelf. They consist of freshwater rather than saltwater even though they are found in the ocean. For an iceberg to be classified as an iceberg it needs to have a height of greater than 16 feet (five meters) above sea level and the thickness must be 98-164 feet (30-50 meters). It also needs to cover an area of at least 5,382 square feet (500 square meters). Floating pieces of ice that are smaller than this are called bergy bits or growlers.
The Formation of Icebergs
Most icebergs come from glaciers that break off into the sea. Glaciers are formed in the polar regions where snow falls almost constantly. This snow does not get the chance to melt completely and the water that does melt turns into compacted ice. Most icebergs in the North Atlantic Sea are formed by the tidewater glaciers of Greenland. As the tide rises and falls it wears through the ice close to the sea and large chucks of ice break free and become icebergs. Some glaciers do not reach the ocean, but rather end in deep sided valleys known as fiords. Large pieces of ice break off the glacier into the fiords and travel down steam into the ocean. The largest icebergs on earth are found around Antarctica where huge chunks of ice as big as Rhode Island have been observed floating in the ocean around the continent.