From Smokey God:
About three-fourth of the "inner" surface of the earth is land and about one-fourth water. There are numerous rivers of tremendous size, some flowing in a northerly direction and others southerly. Some of these rivers are thirty miles in width, and it is out of these vast waterways, at the extreme northern and southern parts of the "inside" surface of the earth, in regions where low temperatures are experienced, that freshwater iceberg are formed. They are then pushed out to sea like huge tongues of ice, by the abnormal freshets of turbulent waters that, twice every year, sweep everything before them.
Members,
Maybe this is why Arctic icebergs are comprised of fresh water.