Definition: A depression caused by erosion by water or ice. Low-lying land bordered by higher ground; especially elongate, relatively large gently sloping depressions of the Earth's surface, commonly situated between two mountains or between ranges of hills or mountains, and often containing a stream with an outlet.
Definition: A long and narrow sheet of ice projecting out from the coastline. An ice tongue forms when a valley glacier moves very rapidly out into the ocean or a lake.