(1) Ice that is part of a glacier, as opposed to other forms of frozen water such as ground ice and sea ice. (2) Ice that is part of a glacier, having formed by the compaction and recrystallization of
snow to a point at which few of the remaining voids are connected, and having survived at least one ablation season. In this more restricted sense, the term refers to the body of the glacier, excluding not only snow and firn but also superimposed ice, accreted ice and marine ice. See zone. The density at which voids cease to form a connected network, that is, the density at which firn becomes glacier ice, is conventionally taken to be near to 830 kg m-3. Ice in, or originating from, a glacier, whether on land or floating on the sea as icebergs, bergy bits, or growlers. Snowflakes are compressed under the weight of the overlying snowpack. Individual crystal near the melting point have slick liquid edges allowing them to glide along other crystal planes and to readjust the space between them. Where the crystals touch they bond together, squeezing the air between them to the surface or into bubbles. During summer we might see the crystal metamorphosis occur more rapidly because of water percolation between the crystals. By summer's end the result is firn -- a compacted snow with the appearance of wet sugar, but with a hardness that makes it resistant to all but the most dedicated snow shovelers! Several years are usually required for the snow to settle and to season into the substance we call glacier ice. Above the firnline, snow that falls each year packs down and changes into glacier ice as air is slowly forced out of it. Ice in, or originating from, a glacier, whether on land or floating on the sea as icebergs, bergy bits or growlers.
Sea ice terminology that describes ice in or originating from a glacier, whether on land or floating on the sea as icebergs, bergy bits, growlers or ice islands.
The covering of a land area by glacier ice. This term was coined by G. Taylor in the Antarctic and introduced by Wright and Priestly (1922) to distinguish the act of glacial inundation from its geolog
ic consequences (glaciation). It is growing in use in Great Britain but still is considered unnecessary by some American geologists, who use "glacier covering."
A nearly vertical channel in ice that is formed by flowing water; usually found after a relatively flat section of glacier in a region of transverse crevasses.
As glaciers melt, their remaining load of rocks is distributed in several ways. Rocks may be dropped in place by the melting ice; they may be rolled to the ice margins, or they may be deposited by mel
twater streams. Collectively, these deposits are called 'glacial drift'. 'Till' refers to the debris deposited directly by the glacier. Rock debris rolls off the glacier edges and builds piles of loose unconsolidated rocks called 'glacier moraine'. 'Lateral moraines' form along the side of a glacier and curl into a 'terminal moraine' at the glacier's downvalley end. Drift and moraines are valuable to geologists because they outline the boundaries of past glaciations.