Large grounded ice-berg
- Antarctica icebergs
Icebergs are made of freshwater ice and not of frozen sea water. They form from the edge of glaciers when the glacier reaches the sea and either break off in pieces to form an iceberg, or in the case of an ice shelf, begin to float on the sea and then break off from the rest of the glacier as a large slab.
Icebergs are made up of snow that has fallen over many hundreds or even thousands of years. The stripes and different coloured layers in icebergs represent different layers of snowfall and the weather conditions under which the snow fell. If it is very cold then a light open layer with much air included will be formed, this gives a paler or white layer. The darker, bluer layers come from snow fall in relatively warm, maybe even wet conditions when little or no air is trapped in the layer.
In addition to this, air is squeezed out of the lower layers of a glacier as more and more snow falls and so the weight of snow builds up.
Photo credit - Paul Ward / coolantarctica.com