What is a sheet of ice on the ocean called?
Icebergs.The icebergs that break off do so because the glacier of which they are a part flows toward the sea, like a river, only much slower.When a fracture or a vulnerable sheer exists in the glacier, and the glacier tongue drifts far enough into open water, and the sea currents or waves exert enough pressure on the tongue, the tongue splits off from the glacier and becomes an iceberg.