Wilkins Ice Shelf

The Wilkins Ice Shelf is a large body of floating ice covering the greater part of Wilkins Sound off the western coast of the Antarctic Peninsula. Both the ice shelf and the sound were named for Australian-born British explorer Sir George Hubert Wilkins, who first scouted the region by airplane in late December 1928. The Wilkins Ice Shelf spanned the region between Alexander Island, Charcot Island, and Latady Island in the Bellingshausen Sea, an area of about 16,000 square km (6,200 square miles), before its retreat began in the late 1990s. By the early 21st century the ice shelf had substantially diminished because of rising regional air temperatures and the physical stresses of ocean wave activity. In January 2008 the ice shelf covered an area of approximately 13,700 square km (about 5,300 square miles). However, a section measuring 405 square km

(about 160 square miles) collapsed by March of that year, leaving a thin bridge of continuous ice connecting the ice shelf to Charcot Island. This bridge, only about 6 km (3.7 miles) wide at its widest point, acted like a dam to hold back the shelf's partially broken interior from the open sea. In April 2009 the ice bridge lost its connection to Charcot Island, increasing the likelihood of rapid disintegration of the remaining ice shelf.

albedo The fraction of light reflected by a body or surface. anchor ice Ice formed beneath the surface of water and attached to the bottom of a water body or to submerged objects. calving The separation of a volume of ice from its parent glacier. candling Another name for ice deterioration, so-called because of the similarity of deteriorating ice crystals to an assembly of closely packed candles. cirque An amphitheatre-shaped basin characterized by steep walls, at the head of a glacial valley crevasse A fissure or crack in a glacier produced by stress associated with the movement of a glacier. drumlin An oval or elongated hill thought to result from the streamlined movement of glacial ice sheets across rock debris, or till. esker A long, narrow, winding ridge composed of stratified sand and gravel deposited by a subglacial or englacial meltwater stream. felsenmeer Exposed rock surfaces that have been quickly broken up by frost action so that much rock is buried under a cover of angular shattered boulders. fjord A long narrow arm of the sea, commonly extending far inland, that results from marine inundation of a glaciated valley. frazil Ice that forms as small plates drifting in rapidly flowing water where it is too turbulent for pack ice to form.

gelifluction The process by which the active layer of permafrost moves under the influence of gravity hummock A rounded ridge of ice. isothermal Relating to or marked by changes of volume or pressure under conditions of constant temperature. lee The side that is sheltered from the wind. moraine An accumulation of rock debris (till) carried or deposited by a glacier. nucleation The process by which a small number of ions, atoms, or molecules become arranged in a pattern characteristic of a crystalline solid, forming a site upon which additional particles are deposited as the crystal grows. ogive A graph of a cumulative distribution function or a cumulative frequency distribution. percolation zone The area on a glacier or ice sheet characterized by limited surface melting occurs, but the meltwater refreezes in the same snow layer. pingo A dome-shaped hill that rises in permafrost regions as a result of the hydrostatic pressure of freezing ground-water. plucking Glacial action that results in the removal of larger pieces of rock from the glacier bed; also known as quarrying. polynyas Semipermanent areas of open water in sea ice.

relict A relief feature or rock that remains after other parts have disappeared. roches moutonnées Bedrock knobs or hills that have a gently inclined, glacially abraded, and streamlined stoss side and a steep, glacially plucked lee side. sastrugi Jagged erosional features (often cut into snow dunes) caused by strong prevailing winds that occur after snowfall.

shergottites Igneous volcanic rock meteorites. shoal An accumulation of sediment in a river channel or on a continental shelf that is potentially dangerous to ships.

solifluction The flowage of water-saturated soil down a steep slope.

stoss Facing toward the direction from which an overriding glacier impinges. supercooling When water remains liquid below it's normal freezing point of 0 °C (32 °F). talus A slope formed especially by an accumulation of rock debris.

thermokarst Land-surface configuration that results from the melting of ground ice in a region underlain by permafrost. till Material laid down directly or reworked by a glacier.

Samuel C. Colbeck (ed.), Dynamics of Snow and Ice Masses (1980), includes chapters on valley glaciers, ice sheets, snow packs, icebergs, sea ice, and avalanches, emphasizing the basic physics. P.V Hobbs, Ice Physics (1974); and Victor F. Petrenko and Robert W Whitworth, Physics of Ice (1999), treat all aspects of the physics and chemistry of ice. W. Richard Peltier (ed.), Ice in the Climate System (1993), is a modern review of the past, present, and future interactions between ice and climate.

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