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78-647: Plunket Point, at the northern tip of the Meyer Desert, is the northernmost point of the range, where the Mill Glacier to the east of the range converges with the Beardmore Glacier to the west. The Rutkowski Glacier forms to the west of the Meyer Desert and flows south past Mount mills. The Koski Glacier flows east past the Kane Rocks to the south and Browns Butte to the north into Mill Glacier. The Vandament Glacier

156-424: A cirque landform (alternatively known as a corrie or as a cwm ) – a typically armchair-shaped geological feature (such as a depression between mountains enclosed by arêtes ) – which collects and compresses through gravity the snow that falls into it. This snow accumulates and the weight of the snow falling above compacts it, forming névé (granular snow). Further crushing of the individual snowflakes and squeezing

234-511: A glacier is usually assessed by determining the glacier mass balance or observing terminus behavior. Healthy glaciers have large accumulation zones, more than 60% of their area is snow-covered at the end of the melt season, and they have a terminus with a vigorous flow. Following the Little Ice Age 's end around 1850, glaciers around the Earth have retreated substantially . A slight cooling led to

312-595: A glacier may flow into a body of water, it forms only on land and is distinct from the much thinner sea ice and lake ice that form on the surface of bodies of water. On Earth, 99% of glacial ice is contained within vast ice sheets (also known as "continental glaciers") in the polar regions , but glaciers may be found in mountain ranges on every continent other than the Australian mainland, including Oceania's high-latitude oceanic island countries such as New Zealand . Between latitudes 35°N and 35°S, glaciers occur only in

390-411: A glacier via moulins . Streams within or beneath a glacier flow in englacial or sub-glacial tunnels. These tunnels sometimes reemerge at the glacier's surface. Most of the important processes controlling glacial motion occur in the ice-bed contact—even though it is only a few meters thick. The bed's temperature, roughness and softness define basal shear stress, which in turn defines whether movement of

468-408: A kilometer per year. Eventually, the ice will be surging fast enough that it begins to thin, as accumulation cannot keep up with the transport. This thinning will increase the conductive heat loss, slowing the glacier and causing freezing. This freezing will slow the glacier further, often until it is stationary, whence the cycle can begin again. The flow of water under the glacial surface can have

546-404: A large effect on the motion of the glacier itself. Subglacial lakes contain significant amounts of water, which can move fast: cubic kilometers can be transported between lakes over the course of a couple of years. This motion is thought to occur in two main modes: pipe flow involves liquid water moving through pipe-like conduits, like a sub-glacial river; sheet flow involves motion of water in

624-460: A lower heat conductance, meaning that the basal temperature is also likely to be higher. Bed temperature tends to vary in a cyclic fashion. A cool bed has a high strength, reducing the speed of the glacier. This increases the rate of accumulation, since newly fallen snow is not transported away. Consequently, the glacier thickens, with three consequences: firstly, the bed is better insulated, allowing greater retention of geothermal heat. Secondly,

702-676: A part of the west escarpment of the Dominion Range, 4.5 nautical miles (8.3 km; 5.2 mi) north-northwest of Mount Nimrod. Discovered by the British Antarctic Expedition (1907–09) and named for Edward Saunders, secretary to Shackleton, who assisted in preparing the narrative of the expedition. 85°25′S 165°45′E  /  85.417°S 165.750°E  / -85.417; 165.750 . A mountain, 2,835 metres (9,301 ft) high, standing 4 nautical miles (7.4 km; 4.6 mi) south-southeast of Mount Saunders in

780-485: A rock median between the upper reaches of Koski Glacier and Vandament Glacier in the Dominion Range. Named by US-ACAN for Henry Scott Kane, USARP cosmic rays scientist at South Pole Station, winter 1964; a member of the South Pole-Queen Maud Land Traverse, 1964–65 and 1965-66. 85°15′S 167°30′E  /  85.250°S 167.500°E  / -85.250; 167.500 . A bare rock butte at

858-484: A thin layer. A switch between the two flow conditions may be associated with surging behavior. Indeed, the loss of sub-glacial water supply has been linked with the shut-down of ice movement in the Kamb ice stream. The subglacial motion of water is expressed in the surface topography of ice sheets, which slump down into vacated subglacial lakes. The speed of glacial displacement is partly determined by friction . Friction makes

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936-410: A tremendous impact as the iceberg strikes the water. Tidewater glaciers undergo centuries-long cycles of advance and retreat that are much less affected by climate change than other glaciers. Thermally, a temperate glacier is at a melting point throughout the year, from its surface to its base. The ice of a polar glacier is always below the freezing threshold from the surface to its base, although

1014-468: Is a persistent body of dense ice 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 distinguishing features, such as crevasses and seracs , as it slowly flows and deforms under stresses induced by its weight. As it moves, it abrades rock and debris from its substrate to create landforms such as cirques , moraines , or fjords . Although

1092-456: Is above or at freezing at the interface and is able to slide at this contact. This contrast is thought to a large extent to govern the ability of a glacier to effectively erode its bed , as sliding ice promotes plucking at rock from the surface below. Glaciers which are partly cold-based and partly warm-based are known as polythermal . Glaciers form where the accumulation of snow and ice exceeds ablation . A glacier usually originates from

1170-407: Is affected by factors such as slope, ice thickness, snowfall, longitudinal confinement, basal temperature, meltwater production, and bed hardness. A few glaciers have periods of very rapid advancement called surges . These glaciers exhibit normal movement until suddenly they accelerate, then return to their previous movement state. These surges may be caused by the failure of the underlying bedrock,

1248-478: Is an area of smooth and level blue ice over 7 kilometres (4.3 mi) long in a NNW-SSE direction that is suitable for an airfield. The ice thickness seems to be about 650 metres (2,130 ft). The runway faces directly into the wind. It appears to be a useful alternative to Mount Howe in an emergency. During the Shackleton Glacier Project, 1995-1996, Lockheed LC-130 aircraft placed fuel caches on

1326-411: Is because these peaks are located near or in the hyperarid Atacama Desert . Glaciers erode terrain through two principal processes: plucking and abrasion . As glaciers flow over bedrock, they soften and lift blocks of rock into the ice. This process, called plucking, is caused by subglacial water that penetrates fractures in the bedrock and subsequently freezes and expands. This expansion causes

1404-406: Is by basal sliding, where meltwater forms between the ice and the bed itself. Whether a bed is hard or soft depends on the porosity and pore pressure; higher porosity decreases the sediment strength (thus increases the shear stress τ B ). Porosity may vary through a range of methods. Bed softness may vary in space or time, and changes dramatically from glacier to glacier. An important factor

1482-434: Is called glaciology . Glaciers are important components of the global cryosphere . Glaciers are categorized by their morphology, thermal characteristics, and behavior. Alpine glaciers form on the crests and slopes of mountains. A glacier that fills a valley is called a valley glacier , or alternatively, an alpine glacier or mountain glacier . A large body of glacial ice astride a mountain, mountain range, or volcano

1560-416: Is called rock flour and is made up of rock grains between 0.002 and 0.00625 mm in size. Abrasion leads to steeper valley walls and mountain slopes in alpine settings, which can cause avalanches and rock slides, which add even more material to the glacier. Glacial abrasion is commonly characterized by glacial striations . Glaciers produce these when they contain large boulders that carve long scratches in

1638-628: Is higher, and the mountains above 5,000 m (16,400 ft) usually have permanent snow. Even at high latitudes, glacier formation is not inevitable. Areas of the Arctic , such as Banks Island , and the McMurdo Dry Valleys in Antarctica are considered polar deserts where glaciers cannot form because they receive little snowfall despite the bitter cold. Cold air, unlike warm air, is unable to transport much water vapor. Even during glacial periods of

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1716-586: Is south of the Kane Rocks and west of Safety Spur. The south of the range includes Mount Saunders, Mount Nimrod and Mount Tennent. The Davis Nunataks and Mount Ward are to the south of the range. The Polar Subglacial Basin lies between the Gamburtsev Subglacial Mountains and the Dominion Range. Download coordinates as: Features, from north to south, include: 85°05′S 167°06′E  /  85.083°S 167.100°E  / -85.083; 167.100 . A conspicuous rock point marking

1794-897: Is termed an ice cap or ice field . Ice caps have an area less than 50,000 km (19,000 sq mi) by definition. Glacial bodies larger than 50,000 km (19,000 sq mi) are called ice sheets or continental glaciers . Several kilometers deep, they obscure the underlying topography. Only nunataks protrude from their surfaces. The only extant ice sheets are the two that cover most of Antarctica and Greenland. They contain vast quantities of freshwater, enough that if both melted, global sea levels would rise by over 70 m (230 ft). Portions of an ice sheet or cap that extend into water are called ice shelves ; they tend to be thin with limited slopes and reduced velocities. Narrow, fast-moving sections of an ice sheet are called ice streams . In Antarctica, many ice streams drain into large ice shelves . Some drain directly into

1872-413: Is the region where there is a net loss in glacier mass. The upper part of a glacier, where accumulation exceeds ablation, is called the accumulation zone . The equilibrium line separates the ablation zone and the accumulation zone; it is the contour where the amount of new snow gained by accumulation is equal to the amount of ice lost through ablation. In general, the accumulation zone accounts for 60–70% of

1950-402: Is the underlying geology; glacial speeds tend to differ more when they change bedrock than when the gradient changes. Further, bed roughness can also act to slow glacial motion. The roughness of the bed is a measure of how many boulders and obstacles protrude into the overlying ice. Ice flows around these obstacles by melting under the high pressure on their stoss side ; the resultant meltwater

2028-552: Is then forced into the cavity arising in their lee side , where it re-freezes. As well as affecting the sediment stress, fluid pressure (p w ) can affect the friction between the glacier and the bed. High fluid pressure provides a buoyancy force upwards on the glacier, reducing the friction at its base. The fluid pressure is compared to the ice overburden pressure, p i , given by ρgh. Under fast-flowing ice streams, these two pressures will be approximately equal, with an effective pressure (p i – p w ) of 30 kPa; i.e. all of

2106-952: The Andes , the Himalayas , the Rocky Mountains , the Caucasus , Scandinavian Mountains , and the Alps . Snezhnika glacier in Pirin Mountain, Bulgaria with a latitude of 41°46′09″ N is the southernmost glacial mass in Europe. Mainland Australia currently contains no glaciers, although a small glacier on Mount Kosciuszko was present in the last glacial period . In New Guinea, small, rapidly diminishing, glaciers are located on Puncak Jaya . Africa has glaciers on Mount Kilimanjaro in Tanzania, on Mount Kenya , and in

2184-622: The Dominion Range and the Supporters Range into Beardmore Glacier , Antarctica. It was discovered by the British Antarctic Expedition, 1907–09 , and named for Hugh Robert Mill , a British geographer and Antarctic historian. The Grosvenor Mountains , a group of widely scattered mountains and nunataks, rises above the polar plateau east of the head of Mill Glacier. The Mill Glacier is a valley glacier that flows down from

2262-636: The Faroe and Crozet Islands were completely glaciated. The permanent snow cover necessary for glacier formation is affected by factors such as the degree of slope on the land, amount of snowfall and the winds. Glaciers can be found in all latitudes except from 20° to 27° north and south of the equator where the presence of the descending limb of the Hadley circulation lowers precipitation so much that with high insolation snow lines reach above 6,500 m (21,330 ft). Between 19˚N and 19˚S, however, precipitation

2340-750: The Himalayas , Andes , and a few high mountains in East Africa, Mexico, New Guinea and on Zard-Kuh in Iran. With more than 7,000 known glaciers, Pakistan has more glacial ice than any other country outside the polar regions. Glaciers cover about 10% of Earth's land surface. Continental glaciers cover nearly 13 million km (5 million sq mi) or about 98% of Antarctica 's 13.2 million km (5.1 million sq mi), with an average thickness of ice 2,100 m (7,000 ft). Greenland and Patagonia also have huge expanses of continental glaciers. The volume of glaciers, not including

2418-551: The Quaternary , Manchuria , lowland Siberia , and central and northern Alaska , though extraordinarily cold, had such light snowfall that glaciers could not form. In addition to the dry, unglaciated polar regions, some mountains and volcanoes in Bolivia, Chile and Argentina are high (4,500 to 6,900 m or 14,800 to 22,600 ft) and cold, but the relative lack of precipitation prevents snow from accumulating into glaciers. This

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2496-521: The Rwenzori Mountains . Oceanic islands with glaciers include Iceland, several of the islands off the coast of Norway including Svalbard and Jan Mayen to the far north, New Zealand and the subantarctic islands of Marion , Heard , Grande Terre (Kerguelen) and Bouvet . During glacial periods of the Quaternary, Taiwan , Hawaii on Mauna Kea and Tenerife also had large alpine glaciers, while

2574-448: The 1990s and 2000s. In a study using data from January 1993 through October 2005, more events were detected every year since 2002, and twice as many events were recorded in 2005 as there were in any other year. Ogives or Forbes bands are alternating wave crests and valleys that appear as dark and light bands of ice on glacier surfaces. They are linked to seasonal motion of glaciers; the width of one dark and one light band generally equals

2652-637: The Dominion Range, extending southeast from a broad isolated prominence between the mouth of Vandament Glacier and the west side of Mill Glacier. So named by the Southern Party of the NZGSAE (1961–62) because it was at this landfall that the party arrived after their first crossing of Mill Glacier in November 1961. 85°21′S 165°26′E  /  85.350°S 165.433°E  / -85.350; 165.433 . A mountain, 2,895 metres (9,498 ft) high, forming

2730-750: The Dominion Range. Discovered by the British Antarctic Expedition (1907–09) and named after the expedition ship Nimrod. 85°22′S 166°45′E  /  85.367°S 166.750°E  / -85.367; 166.750 . A rocky peak, 2,895 metres (9,498 ft) high, in the Dominion Range, 2 nautical miles (3.7 km; 2.3 mi) south of Vandament Glacier. Named by the NZGSAE (1961–62) for W.B. Tennent, Minister in Charge of Scientific and Industrial Research, New Zealand. 85°37′S 166°36′E  /  85.617°S 166.600°E  / -85.617; 166.600 . A small cluster of rock nunataks 3 nautical miles (5.6 km; 3.5 mi) northwest of Mount Ward,

2808-754: The Grosvenor Mountains past Otway Massif , then between the Dominion Range and Supporters Range before joining the Beardmore Glacier. The head of the glacier is crossed by the Scott Icefalls. From there it flows northwest between the Dominion Range to the west and the Otway Massif to the east. The Mill Stream Glacier, which is fed from the south by the Burgess Glacier, joins the Mill Glacier from

2886-682: The Mill Glacier. 85°32′S 170°15′E  /  85.533°S 170.250°E  / -85.533; 170.250 . Extensive icefalls near the head of Mill Glacier, between Otway Massif and the south part of Dominion Range. Named by the NZGSAE (1961-62) for Captain Robert Falcon Scott . 85°20′S 171°00′E  /  85.333°S 171.000°E  / -85.333; 171.000 . A tributary glacier, about 10 nautical miles (19 km; 12 mi) wide, flowing west between Supporters Range and Otway Massif to enter Mill Glacier. Named by

2964-726: The NZGSAE (1961-62) in association with Mill Glacier. 85°26′S 171°55′E  /  85.433°S 171.917°E  / -85.433; 171.917 . A glacier, 7 nautical miles (13 km; 8.1 mi) long, flowing northwest through Otway Massif to enter Mill Stream Glacier. Named by the Advisory Committee on Antarctic Names (US-ACAN) for Robert W. Burgess, United States Antarctic Program (USARP) ionospheric physicist at South Pole Station in 1963. 85°19′S 167°10′E  /  85.317°S 167.167°E  / -85.317; 167.167 . An east-flowing glacier, 6 nautical miles (11 km; 6.9 mi) long, draining

3042-412: The advance of many alpine glaciers between 1950 and 1985, but since 1985 glacier retreat and mass loss has become larger and increasingly ubiquitous. Glaciers move downhill by the force of gravity and the internal deformation of ice. At the molecular level, ice consists of stacked layers of molecules with relatively weak bonds between layers. When the amount of strain (deformation) is proportional to

3120-520: The air from the snow turns it into "glacial ice". This glacial ice will fill the cirque until it "overflows" through a geological weakness or vacancy, such as a gap between two mountains. When the mass of snow and ice reaches sufficient thickness, it begins to move by a combination of surface slope, gravity, and pressure. On steeper slopes, this can occur with as little as 15 m (49 ft) of snow-ice. In temperate glaciers, snow repeatedly freezes and thaws, changing into granular ice called firn . Under

3198-430: The amount of melting at surface of the glacier, the faster the ice will flow. Basal sliding is dominant in temperate or warm-based glaciers. The presence of basal meltwater depends on both bed temperature and other factors. For instance, the melting point of water decreases under pressure, meaning that water melts at a lower temperature under thicker glaciers. This acts as a "double whammy", because thicker glaciers have

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3276-713: The annual movement of the glacier. Ogives are formed when ice from an icefall is severely broken up, increasing ablation surface area during summer. This creates a swale and space for snow accumulation in the winter, which in turn creates a ridge. Sometimes ogives consist only of undulations or color bands and are described as wave ogives or band ogives. Glaciers are present on every continent and in approximately fifty countries, excluding those (Australia, South Africa) that have glaciers only on distant subantarctic island territories. Extensive glaciers are found in Antarctica, Argentina, Chile, Canada, Pakistan, Alaska, Greenland and Iceland. Mountain glaciers are widespread, especially in

3354-432: The bedrock has frequent fractures on the surface, glacial erosion rates tend to increase as plucking is the main erosive force on the surface; when the bedrock has wide gaps between sporadic fractures, however, abrasion tends to be the dominant erosive form and glacial erosion rates become slow. Glaciers in lower latitudes tend to be much more erosive than glaciers in higher latitudes, because they have more meltwater reaching

3432-445: The bedrock. By mapping the direction of the striations, researchers can determine the direction of the glacier's movement. Similar to striations are chatter marks , lines of crescent-shape depressions in the rock underlying a glacier. They are formed by abrasion when boulders in the glacier are repeatedly caught and released as they are dragged along the bedrock. The rate of glacier erosion varies. Six factors control erosion rate: When

3510-559: The created ice's density. The word glacier is a loanword from French and goes back, via Franco-Provençal , to the Vulgar Latin glaciārium , derived from the Late Latin glacia , and ultimately Latin glaciēs , meaning "ice". The processes and features caused by or related to glaciers are referred to as glacial. The process of glacier establishment, growth and flow is called glaciation . The corresponding area of study

3588-467: The deep profile of fjords , which can reach a kilometer in depth as ice is topographically steered into them. The extension of fjords inland increases the rate of ice sheet thinning since they are the principal conduits for draining ice sheets. It also makes the ice sheets more sensitive to changes in climate and the ocean. Although evidence in favor of glacial flow was known by the early 19th century, other theories of glacial motion were advanced, such as

3666-483: The deformation to become a plastic flow rather than elastic. Then, the glacier will begin to deform under its own weight and flow across the landscape. According to the Glen–Nye flow law , the relationship between stress and strain, and thus the rate of internal flow, can be modeled as follows: where: The lowest velocities are near the base of the glacier and along valley sides where friction acts against flow, causing

3744-630: The east to the north of the Otway Massif. The Vandement Glacier and the Koski Glacier enter from the Dominion Range to the west. The Mill Glacier flows past the Supporters Range to the east to join the Beardmore Glacier from the southeast at Plunket Point . Over large areas the Mill Glacier has very smooth ice, free of crevasses. Just upstream of Plunket Point , where it joins the Beardmore, there

3822-541: The east-central portion of the Dominion Range icecap. The glacier lies close north of Vandament Glacier, whose flow it parallels, and terminates at Mill Glacier just southeast of Browns Butte. Named by US-ACAN for Raymond J. Koski, USARP engineer on several traverses originating at the South Pole Station 1962-63, 1963–64 and 1964–65. Glacier A glacier ( US : / ˈ ɡ l eɪ ʃ ər / ; UK : / ˈ ɡ l æ s i ər , ˈ ɡ l eɪ s i ər / )

3900-508: The east-central portion of the Dominion Range icecap. The glacier lies close south of Koski Glacier, whose flow it parallels, and terminates 2 nautical miles (3.7 km; 2.3 mi) northwest of Safety Spur . Named by US-ACAN for Charles H. Vandament, USARP ionospheric physicist at South Pole Station in 1962. 85°17′S 167°15′E  /  85.283°S 167.250°E  / -85.283; 167.250 . An east-flowing glacier, 7 nautical miles (13 km; 8.1 mi) long, draining

3978-418: The essentially correct explanation in the 1840s, although it was several decades before it was fully accepted. The top 50 m (160 ft) of a glacier are rigid because they are under low pressure . This upper section is known as the fracture zone and moves mostly as a single unit over the plastic-flowing lower section. When a glacier moves through irregular terrain, cracks called crevasses develop in

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4056-415: The feature being a southern outlier of the main body of the Dominion Range. Named by US-ACAN for Ronald N. Davis, USARP geomagnetist-seismologist at South Pole Station, winter 1963. 85°40′S 167°10′E  /  85.667°S 167.167°E  / -85.667; 167.167 . A rock peak 3 nautical miles (5.6 km; 3.5 mi) southeast of Davis Nunataks, the feature being a southern outlier of

4134-475: The fracture zone. Crevasses form because of differences in glacier velocity. If two rigid sections of a glacier move at different speeds or directions, shear forces cause them to break apart, opening a crevasse. Crevasses are seldom more than 46 m (150 ft) deep but, in some cases, can be at least 300 m (1,000 ft) deep. Beneath this point, the plasticity of the ice prevents the formation of cracks. Intersecting crevasses can create isolated peaks in

4212-453: The glacier to melt, creating a water source that is especially important for plants, animals and human uses when other sources may be scant. However, within high-altitude and Antarctic environments, the seasonal temperature difference is often not sufficient to release meltwater. Since glacial mass is affected by long-term climatic changes, e.g., precipitation , mean temperature , and cloud cover , glacial mass changes are considered among

4290-428: The glacier will be accommodated by motion in the sediments, or if it'll be able to slide. A soft bed, with high porosity and low pore fluid pressure, allows the glacier to move by sediment sliding: the base of the glacier may even remain frozen to the bed, where the underlying sediment slips underneath it like a tube of toothpaste. A hard bed cannot deform in this way; therefore the only way for hard-based glaciers to move

4368-504: The glacier's surface area, more if the glacier calves icebergs. Ice in the accumulation zone is deep enough to exert a downward force that erodes underlying rock. After a glacier melts, it often leaves behind a bowl- or amphitheater-shaped depression that ranges in size from large basins like the Great Lakes to smaller mountain depressions known as cirques . The accumulation zone can be subdivided based on its melt conditions. The health of

4446-614: The ice at the bottom of the glacier move more slowly than ice at the top. In alpine glaciers, friction is also generated at the valley's sidewalls, which slows the edges relative to the center. Mean glacial speed varies greatly but is typically around 1 m (3 ft) per day. There may be no motion in stagnant areas; for example, in parts of Alaska, trees can establish themselves on surface sediment deposits. In other cases, glaciers can move as fast as 20–30 m (70–100 ft) per day, such as in Greenland's Jakobshavn Isbræ . Glacial speed

4524-420: The ice sheets of Antarctica and Greenland, has been estimated at 170,000 km . Glacial ice is the largest reservoir of fresh water on Earth, holding with ice sheets about 69 percent of the world's freshwater. Many glaciers from temperate , alpine and seasonal polar climates store water as ice during the colder seasons and release it later in the form of meltwater as warmer summer temperatures cause

4602-544: The ice to act as a lever that loosens the rock by lifting it. Thus, sediments of all sizes become part of the glacier's load. If a retreating glacier gains enough debris, it may become a rock glacier , like the Timpanogos Glacier in Utah. Abrasion occurs when the ice and its load of rock fragments slide over bedrock and function as sandpaper, smoothing and polishing the bedrock below. The pulverized rock this process produces

4680-488: The ice, called seracs . Crevasses can form in several different ways. Transverse crevasses are transverse to flow and form where steeper slopes cause a glacier to accelerate. Longitudinal crevasses form semi-parallel to flow where a glacier expands laterally. Marginal crevasses form near the edge of the glacier, caused by the reduction in speed caused by friction of the valley walls. Marginal crevasses are largely transverse to flow. Moving glacier ice can sometimes separate from

4758-411: The idea that meltwater, refreezing inside glaciers, caused the glacier to dilate and extend its length. As it became clear that glaciers behaved to some degree as if the ice were a viscous fluid, it was argued that "regelation", or the melting and refreezing of ice at a temperature lowered by the pressure on the ice inside the glacier, was what allowed the ice to deform and flow. James Forbes came up with

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4836-418: The increased pressure can facilitate melting. Most importantly, τ D is increased. These factors will combine to accelerate the glacier. As friction increases with the square of velocity, faster motion will greatly increase frictional heating, with ensuing melting – which causes a positive feedback, increasing ice speed to a faster flow rate still: west Antarctic glaciers are known to reach velocities of up to

4914-423: The infrared OH stretching mode of the water molecule. (Liquid water appears blue for the same reason. The blue of glacier ice is sometimes misattributed to Rayleigh scattering of bubbles in the ice.) A glacier originates at a location called its glacier head and terminates at its glacier foot, snout, or terminus . Glaciers are broken into zones based on surface snowpack and melt conditions. The ablation zone

4992-447: The main body of the Dominion Range. Discovered by the British Antarctic Expedition (1907–09) and named for Sir Joseph George Ward, then Prime Minister of New Zealand, who gave the expedition considerable support. Mill Glacier Mill Glacier ( 85°10′S 168°30′E  /  85.167°S 168.500°E  / -85.167; 168.500 ) is a tributary glacier , 10 nautical miles (19 km) wide, flowing northwest between

5070-679: The most deformation. Velocity increases inward toward the center line and upward, as the amount of deformation decreases. The highest flow velocities are found at the surface, representing the sum of the velocities of all the layers below. Because ice can flow faster where it is thicker, the rate of glacier-induced erosion is directly proportional to the thickness of overlying ice. Consequently, pre-glacial low hollows will be deepened and pre-existing topography will be amplified by glacial action, while nunataks , which protrude above ice sheets, barely erode at all – erosion has been estimated as 5 m per 1.2 million years. This explains, for example,

5148-445: The most sensitive indicators of climate change and are a major source of variations in sea level . A large piece of compressed ice, or a glacier, appears blue , as large quantities of water appear blue , because water molecules absorb other colors more efficiently than blue. The other reason for the blue color of glaciers is the lack of air bubbles. Air bubbles, which give a white color to ice, are squeezed out by pressure increasing

5226-568: The north end of the Dominion Range, near the confluence of the Beardmore and Mill Glaciers. Named by New Zealand Geological Survey Antarctic Expedition (NZGSAE) (1961–62) for George Meyer of the United States Antarctic Research Program (USARP), who was scientific leader at McMurdo Station, 1961, and led a field party into this area, summer 1961-62. 85°11′S 166°21′E  /  85.183°S 166.350°E  / -85.183; 166.350 . A glacier which drains

5304-544: The north escarpment of the Dominion Range, overlooking the Beardmore Glacier 8 nautical miles (15 km; 9.2 mi) north of Mount Saunders. Discovered by the British Antarctic Expedition (1907–09) and named for Sir James Mills who, with the government of New Zealand, paid the cost of towing the expedition ship Nimrod to Antarctica in 1908. 85°18′S 166°45′E  /  85.300°S 166.750°E  / -85.300; 166.750 . An east–west trending ridge, 3 nautical miles (5.6 km; 3.5 mi) long, forming

5382-781: The north side of the mouth of Koski Glacier in the Dominion Range. Named by US-ACAN for Craig W. Brown, USARP meteorologist at South Pole Station, 1963. 85°19′S 167°10′E  /  85.317°S 167.167°E  / -85.317; 167.167 . An east-flowing glacier, 6 nautical miles (11 km; 6.9 mi) long, draining the east-central portion of the Dominion Range icecap. The glacier lies close south of Koski Glacier, whose flow it parallels, and terminates 2 nautical miles (3.7 km; 2.3 mi) NW of Safety Spur. Named by US-ACAN for Charles H. Vandament, USARP ionospheric physicist at South Pole Station, 1962. 85°19′S 168°00′E  /  85.317°S 168.000°E  / -85.317; 168.000 . A small rock spur from

5460-422: The northern end of the Dominion Range and the confluence of the Beardmore and Mill Glaciers. Discovered by the British Antarctic Expedition (1907–09) and named for Lord Plunket, at that time Governor of New Zealand. 85°08′S 166°45′E  /  85.133°S 166.750°E  / -85.133; 166.750 . A triangular ice-free area of about 50 square nautical miles (170 km; 66 sq mi) at

5538-495: The northern part of the Dominion Range icecap eastward of Mount Mills. It descends northeastward into Meyer Desert where it terminates without reaching Beardmore Glacier. Named by United States Advisory Committee on Antarctic Names (US-ACAN) for Richard L. Rutkowski, USARP meteorologist at the South Pole Station, 1962. 85°12′S 165°17′E  /  85.200°S 165.283°E  / -85.200; 165.283 . A mountain, 2,955 metres (9,695 ft) high, forming part of

5616-721: The pooling of meltwater at the base of the glacier  — perhaps delivered from a supraglacial lake  — or the simple accumulation of mass beyond a critical "tipping point". Temporary rates up to 90 m (300 ft) per day have occurred when increased temperature or overlying pressure caused bottom ice to melt and water to accumulate beneath a glacier. In glaciated areas where the glacier moves faster than one km per year, glacial earthquakes occur. These are large scale earthquakes that have seismic magnitudes as high as 6.1. The number of glacial earthquakes in Greenland peaks every year in July, August, and September and increased rapidly in

5694-410: The pressure of the layers of ice and snow above it, this granular ice fuses into denser firn. Over a period of years, layers of firn undergo further compaction and become glacial ice. Glacier ice is slightly more dense than ice formed from frozen water because glacier ice contains fewer trapped air bubbles. Glacial ice has a distinctive blue tint because it absorbs some red light due to an overtone of

5772-558: The sea, often with an ice tongue , like Mertz Glacier . Tidewater glaciers are glaciers that terminate in the sea, including most glaciers flowing from Greenland, Antarctica, Baffin , Devon , and Ellesmere Islands in Canada, Southeast Alaska , and the Northern and Southern Patagonian Ice Fields . As the ice reaches the sea, pieces break off or calve, forming icebergs . Most tidewater glaciers calve above sea level, which often results in

5850-409: The stagnant ice above, forming a bergschrund . Bergschrunds resemble crevasses but are singular features at a glacier's margins. Crevasses make travel over glaciers hazardous, especially when they are hidden by fragile snow bridges . Below the equilibrium line, glacial meltwater is concentrated in stream channels. Meltwater can pool in proglacial lakes on top of a glacier or descend into the depths of

5928-423: The stress being applied, ice will act as an elastic solid. Ice needs to be at least 30 m (98 ft) thick to even start flowing, but once its thickness exceeds about 50 m (160 ft) (160 ft), stress on the layer above will exceeds the inter-layer binding strength, and then it'll move faster than the layer below. This means that small amounts of stress can result in a large amount of strain, causing

6006-438: The surface snowpack may experience seasonal melting. A subpolar glacier includes both temperate and polar ice, depending on the depth beneath the surface and position along the length of the glacier. In a similar way, the thermal regime of a glacier is often described by its basal temperature. A cold-based glacier is below freezing at the ice-ground interface and is thus frozen to the underlying substrate. A warm-based glacier

6084-417: The weight of the ice is supported by the underlying water, and the glacier is afloat. Glaciers may also move by basal sliding , where the base of the glacier is lubricated by the presence of liquid water, reducing basal shear stress and allowing the glacier to slide over the terrain on which it sits. Meltwater may be produced by pressure-induced melting, friction or geothermal heat . The more variable

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