An ice tongue or glacier tongue exists when there is a narrow floating part of a glacier that extends out into a body of water beyond the glacier's lowest contact with the Earth's crust.
An ice tongue forms when a glacier that is confined by a valley moves very rapidly out into a lake or ocean, relative to other ice along the coastline.
When such ice surges past adjacent coastal ice, the boundary experiences physical forces described as "shearing".
[1] Ice tongues can gain mass from water freezing at their base, by snow falling on top of them, or by additional surges from the main glacier.
Icebergs are often formed when ice tongues break off in part or wholly from the main glacier.