A trim line, also written as trimline, is a clear line on the side of a valley formed by a

glacier A glacier (; ) is a persistent body of dense ice that is constantly moving under its own weight. A glacier forms where the accumulation of snow exceeds its Ablation#Glaciology, ablation over many years, often Century, centuries. It acquires dis ...

. The line marks the most recent highest extent of the glacier. The line may be visible due to changes in color to the rock or to changes in vegetation on either side of the line. The term "trim line" is also used for similar looking phenomena caused by floods, volcanic activity, or

tsunamis A tsunami ( ; from ja, 津波, lit=harbour wave, ) is a series of waves in a water body caused by the displacement of a large volume of water, generally in an ocean or a large lake. Earthquakes, volcanic eruptions and other underwater expl ...

.Steven Dutch
Giant Waves in Lituya Bay, Alaska
USGS PP 354-C

References

{{Glaciology-stub Glaciers