When a large section of a floating glacier breaks off ... An iceberg is born!
Although icebergs float on ocean waters, they are composed of freshwater. An iceberg is simply an extraordinarily large mass of ice that has broken off from an ice cap or glacier where it met the sea. The first stage of iceberg formation occurs when part of a glacier or ice cap that has been pushed into the sea, begins to float on the water. Tides and wave action subsequently cause stress fractures, causing a piece of the glacier to break off and a new iceberg is born! This process is termed calving.
An iceberg’s extraordinary blue and white coloration is a reminder of its glacial origins. Glacial ice appears blue because pure ice absorbs other colors more rapidly than blue. This colour appears in the deepest layers of the ice that are under such high pressure that all of the air bubbles have been forced out of the ice. By contrast the surface layers of the iceberg are white because the air bubbles trapped in the snow layers reflect much of the incident light. These air bubbles also result in iceberg fizz. As an iceberg melts, fizzing results from the release of gases that have been held under pressure, trapped in bubbles for thousands of years!