ice island

An ice island is a large mass of floating ice that resembles an island. Specifically, it is a piece of ice discharged from arctic shelf ice, which can be hundreds of square miles in area and hundreds of feet thick, floating with subsurface currents.1

Arctic ice islands primarily originate from glaciers descending from the Greenland Ice Sheet. A notable source used to be the Ward Hunt Ice Shelf on Canada's Ellesmere Island. These ice islands can be up to 30 km long but are only about 60 meters thick. They calve into ocean currents and can travel extensively before exiting the Arctic Ocean.2

When ice islands run aground, they can create deep furrows in the seabed, known as iceberg scour marks. These marks can be found at significant depths, indicating past iceberg activity. Ice islands transport sediment, including rocks and finer materials, from their source areas, which can be identified in seabed sediment cores as ice-rafted debris.3