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A glacier is a large body of ice, persisting year-round, which flows, under its own mass, slowly outward from its center of accumulation of ice and snow.
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- ... As hydrological reservoirs, glaciers are seen by the public mainly for their contribution to sea-level rise, which they provide through their melting. This is admittedly of global interest and may change our planet in the long term, especially if the two ice sheets in Greenland and Antarctica are included.
Somewhat less well known is the fact that glaciers are active landscape shapers and have in the past shaped not only high mountain relief but also large areas of North American and Central and Northern European lowlands. Anyone wishing to understand the formation of these glacial land surfaces cannot avoid considering the processes and effects of glacier erosion and deposition.
- Glaciers record climate changes in two ways: the deposits left during successive advances and retreat provide a coarse record of climatic change which, with careful study, a little luck, and a good deal of skill, can be placed in correct chronological order and dated. A more detailed record is contained in ice cores from polar glaciers such as the Antarctic and Greenland ice sheets. Isotopic and other chemical variations in these cores reflect past atmospheric circulation patterns, changes in temperature, and changes in the composition of the atmosphere. Changes during the past several centuries to several millennia can be quite precisely dated using core stratigraphy. Those further back in time are dated less precisely using flow models and proxy measures of other well-dated phenomena such as Earth's orbital variations.
- ... sitting on a cold glacier, at night, in winter, with a stranger, in Iceland ... it was dark one minute, and then the next minute it wasn't. The northern lights, the aurora borealis, started to blaze. ... And this glacier we were sitting on — this bowl of ice — it started to pick up those lights. The whole glacier I was sitting on started to light up like a disco ball — like a chandelier. I felt like I was inside light.
- Jerilynn "M" Jackson, (October 30, 2019)"Landmark College Presents: Dr. M Jackson - the Secret Lives of Glaciers". Brattleboro Community TV, YouTube. (quote at 5:32 of 1:04:25 in video)
- ... A glacier foreland is the area of a newly-formed landscape in front of a glacier, which was recently ice covered but has since been exposed by glacier retreat ...
There are several fundamental advantages of using glacier forelands as field laboratories for ecological purposes. First, their restricted physical size facilitates comprehensive investigation. Second, with a relatively severe climatic environment, they support relatively simple ecosystems. Third, recently-deglaciated terrain has experienced only a short history of modification by changing natural environmental processes. Last, but by no means least, with increasing distance from a retreating glacier, a longer time period has been available for ecosystem development: hence the pattern of ecosystems on the glacier foreland is commonly interpreted as a spatial representation of temperate changed as a vast natural experiment.
- John A. Matthews, The Ecology of Recently-deglaciated Terrain: A Geoecological Approach to Glacier Forelands. Cambridge University Press. 30 April 1992. pp. 1–2. ISBN 9780521361095.
- ... Glaciers are formed on any portion of the earth’s surface that is permanently above the snow-line. This line varies locally in the same latitudes, being in some places higher than in others, but in the main it may be described as an elliptical shell surrounding the earth with its longest diameter in the tropics and its shortest in the polar regions, where it touches sea-level. From the extreme regions of the Arctic and Antarctic circles this cold shell swells upwards into a broad dome, from 15,000 to 18,000 ft. high over the tropics, truncating, as it rises, a number of peaks and mountain ranges whose upper portions like all regions above this thermal shell receive all their moisture in the form of snow. Since the temperature above the snow-line is below freezing point evaporation is very slight, and as the snow is solid it tends to accumulate in snow-fields, where the snow of one year is covered by that of the next, and these are wrapped over many deeper layers that have fallen in previous years. If these piles of snow were rigid and immovable they would increase in height until the whole field rose above the zone of ordinary atmospheric precipitation, and the polar ice-caps would add a load to these regions that would produce far-reaching results. The mountain regions also would rise some miles in height, and all their features would be buried in domes of snow some miles in thickness. When, however, there is sufficient weight the mass yields to pressure and flows outwards and downwards. Thus a balance of weight and height is established, and the ice-field is disintegrated principally at the edges, the surplus in polar regions being carried off in the form of icebergs, and in mountain regions by streams that flow from the melting ends of the glaciers.
- Edward Clarke Spicer, Glacier. 1911 Encyclopædia Britannica.