Excerpts from Icebergs. Christian Kempf.
From Snowflake to Ice Caps to Glaciers*
Snow gathers in hollows called “cirques,” sometimes up to 20 to 30 meters deep, (65 - 98 ft) assisted by wind, rain and avalanches.
Fallen snow packs down and becomes less complex in structure as it releases much of the air that was trapped inside between the individual flakes. This granular snow turns into ice over several years as the crystals bond to each other under high pressure, reaching ever larger sizes, that then bond to each other in turn.
It generally takes five to ten years for snow to turn to ice. In Greenland or Antarctica, this process can take a hundred years, while it takes just three to five years on certain glaciers in Svalbard or the Alps, where there is greater snowfall and the climate is cooler – speeding up the process.
Glaciers are formed from successive layers of snow, though freezing mist or surface meltwater can also cause the ice to build up. These accumulations of ice in the center of continents and polar islands are called ice caps (up to 50,000 km2) or ice sheets (over 50,000 km2) (19,305 sq mi).
The ice is up to 600 meters deep in Svalbard and the Campo do Hielo, Chile, (1968 ft). 3100 meters in Greenland (10,170 ft) and up to 4800 meters in Antarctica (15,748 ft or 3 miles deep).