What are pieces of a glacier that have broken off and float in the sea?

• A. Icebergs
• B. Ice floes
• C. Ice sheets
• D. Sea ice

Answer: (A)

The phenomenon being tested is calving, where a glacier ends its journey at the ocean and pieces break off to float away. When chunks of the glacier crack and separate, they become icebergs, which drift in the sea and can melt as they move into warmer waters. Icebergs are formed specifically from glacial ice breaking off a land-based glacier, so they are distinct from other icy forms.

Ice floes are blocks of sea ice that form from seawater freezing, not from a glacier breaking apart. Ice sheets are vast expanses of land-based ice, not floating in the ocean as individual pieces. Sea ice refers to frozen ocean water at the surface, again not derived from calving of a glacier.