A glacier terminus, toe, or snout, is the end of a
glacier
A glacier (; or ) is a persistent body of dense ice, a form of rock, that is constantly moving downhill under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires ...
at any given point in time. Although glaciers seem motionless to the observer, in reality they are in endless
motion
In physics, motion is when an object changes its position with respect to a reference point in a given time. Motion is mathematically described in terms of displacement, distance, velocity, acceleration, speed, and frame of reference to an o ...
and the glacier terminus is always either advancing or retreating. The location of the terminus is often directly related to
glacier mass balance, which is based on the amount of snowfall which occurs in the
accumulation zone
On a glacier, the accumulation zone is the area above the firn line, where snowfall accumulates and exceeds the losses from ablation, ( melting, evaporation, and sublimation). The annual equilibrium line separates the accumulation and ablation ...
of a glacier, as compared to the amount that is melted in the
ablation zone
Ablation zone or ''ablation area'' refers to the low-altitude area of a glacier or ice sheet below firn with a net loss in ice mass. This loss can result from melting, sublimation, evaporation, ice calving, aeolian processes like blowing snow, ...
. The position of a glacier terminus is also impacted by localized or regional temperature change over time.
Tracking
Tracking the change in location of a glacier terminus is a method of monitoring a glacier's movement. The end of the glacier terminus is measured from a fixed position in neighboring
bedrock
In geology, bedrock is solid rock that lies under loose material ( regolith) within the crust of Earth or another terrestrial planet.
Definition
Bedrock is the solid rock that underlies looser surface material. An exposed portion of bed ...
periodically over time. The difference in location of a glacier terminus as measured from this fixed position at different time intervals provides a record of the glacier's change. A similar way of tracking glacier change is comparing photographs of the glacier's position at different times.
The form of a glacier terminus is determined by many factors. If the glacier is retreating, it is usually mildly sloping in form because a melting glacier tends to assume this shape. But there are many conditions that alter this typical shape, including the presence of thermal fields and various stresses that cause cracking and melting feedback resulting in glacial calving and other diverse forms.
Antarctic Peninsula
The Antarctic Peninsula, known as O'Higgins Land in Chile and Tierra de San Martin in Argentina, and originally as Graham Land in the United Kingdom and the Palmer Peninsula in the United States, is the northernmost part of mainland Antarctica.
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glacier's terminus
See also
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Terminal moraine
A terminal moraine, also called an end moraine, is a type of moraine that forms at the terminal (edge) of a glacier, marking its maximum advance. At this point, debris that has accumulated by plucking and abrasion, has been pushed by the front e ...
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Boulder Glacier
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Mendenhall Glacier
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Perito Moreno Glacier
Notes
External links
Types of GlaciersIceland Glacier Recession 1973 to 2000, Glacier Terminus contrast emphasized
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Glaciers
Bodies of ice