A glacier terminus, toe, or snout, is the end of 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 over many years, often centuries. It acquires distinguishing features, such as ...
at any given point in time. Although glaciers seem motionless to the observer, in reality glaciers are in endless
motion
In physics, motion is the phenomenon in which an object changes its position with respect to time. Motion is mathematically described in terms of displacement, distance, velocity, acceleration, speed and frame of reference to an observer and m ...
and the glacier terminus is always either advancing or retreating. The location of the terminus is often directly related to
glacier mass balance
Crucial to the survival of a glacier is its mass balance or surface mass balance (SMB), the difference between accumulation and ablation (sublimation and melting). Climate change may cause variations in both temperature and snowfall, causing c ...
, 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 z ...
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 due to melting, sublimation, evaporation, ice calving, aeolian processes like blowing snow, avalanche, and any ...
. 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 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.
See also
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Terminal moraine
A terminal moraine, also called 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 edge ...
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Boulder Glacier
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Mendenhall Glacier
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Perito Moreno Glacier
The Perito Moreno Glacier () is a glacier located in Los Glaciares National Park in southwest Santa Cruz Province, Argentina. It is one of the most important tourist attractions in the Argentine Patagonia.
The ice formation, in length, is one ...
Notes
External links
Types of GlaciersIceland Glacier Recession 1973 to 2000, Glacier Terminus contrast emphasized
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Glaciers
Bodies of ice