Are Icebergs Made of Salt Water?
Icebergs do not consist of salt water, but are made of fresh-water ice. They do float in salt water. Icebergs begin as snow, high in the mountains. The snow never completely melts. It piles up year after year, gradually turning into solid ice. The ice then starts to slide slowly down the mountainside. This moving river of ice is a glacier.
Icebergs form when huge chunks of glaciers break off and fall into the sea. “Berg” means mountain in German. So “iceberg” means Ice Mountain. Icebergs have been used by sailors as an emergency supply of water.
When a piece of iceberg ice melts, it makes a fizzing sound called “Bergie Seltzer”. This sound is made when the water-ice interface reaches compressed air bubbles trapped in the ice. As this happens, each bubble bursts, making a ‘popping’ sound. The bubbles contain air trapped in snow layers very early in the history of the ice, that eventually got buried to a given depth (up to several kilometers) and pressurized as it transformed into firn then to glacial ice.
An iceberg or ice mountain is a large piece of freshwater ice that has broken off a glacier or an ice shelf and is floating freely in open water. It may subsequently become frozen into pack ice (one form of sea ice). As it drifts into shallower waters, it may come into contact with the seabed, a process referred to as seabed gouging by ice.
Because the density of pure ice is about 920 kg/m³, and that of seawater about 1025 kg/m³, typically only one-tenth of the volume of an iceberg is above water (due to Archimedes’s Principle).
The shape of the underwater portion can be difficult to judge by looking at the portion above the surface. This has led to the expression “tip of the iceberg”, for a problem or difficulty that is only a small manifestation of a larger problem.