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99-459: The Mariner Glacier ( 73°15′S 167°30′E  /  73.250°S 167.500°E  / -73.250; 167.500 ) is a major glacier over 60 nautical miles (110 km; 69 mi) long, descending southeast from the plateau of Victoria Land , Antarctica, between Mountaineer Range and Malta Plateau , and terminating at Lady Newnes Bay , Ross Sea , where it forms the floating Mariner Glacier Tongue. The lower reaches and entrance to

198-424: 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

297-522: 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

396-601: 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

495-411: 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

594-408: 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

693-404: 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

792-460: 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,

891-582: A possible C-130 landing place. 73°09′S 165°41′E  /  73.150°S 165.683°E  / -73.150; 165.683 . A bold ridge that projects from the middle of the head of Meander Glacier, 5 nautical miles (9.3 km; 5.8 mi) south of Mount Supernal . Mapped by USGS from surveys and United States Navy air photos, 1960–64. Named by US-ACAN for John E. Hobbie, biologist at McMurdo Station 1962–63. 73°04′S 166°40′E  /  73.067°S 166.667°E  / -73.067; 166.667 . A notable bluff that stands just south of

990-488: 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

1089-410: 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

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1188-899: A tribute to the work of mariners in Antarctic research and exploration. The Mariner Glacier forms in the Victory Mountains between The Pleiades to the east and the Barker Range to the west. It is below the Evans Névé to the northwest and the Webb Névé to the east. To the south of the Lawrence Peaks it is fed from the east by the Seafarer Glacier, which in turn is fed by the Wilhelm Glacier and

1287-456: 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

1386-407: 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,

1485-411: 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

1584-406: 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

1683-434: 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

1782-416: 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

1881-647: 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

1980-557: Is included within Antarctic Specially Protected Area 175 High Altitude Geothermal Sites of the Ross Sea Region. The base of the volcano outcrops on the almost vertical cliffs of Pilot Glacier . Fumaroles and geothermally heated ground occur within a single outcrop at the summit of Mount Rittmann in a minor caldera rim at approximately 2,000 metres (6,600 ft) above sea level. Mount Rittmann

2079-897: 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

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2178-413: 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

2277-402: 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

2376-552: 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

2475-684: The Mountaineer Range of Victoria Land, Antarctica. It surmounts Aviator Glacier to the west and the large cirque of Parker Glacier to the east. It was discovered in January 1841 by Sir James Clark Ross who named this peak for Thomas Spring Rice, 1st Baron Monteagle of Brandon , Chancellor of the Exchequer from 1835 to 1839. 73°34′S 165°24′E  /  73.567°S 165.400°E  / -73.567; 165.400 . A mountain 2,460 metres (8,070 ft) high surmounting

2574-993: 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

2673-644: 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

2772-700: The Gair Glacier and Meander Glacier . The feature has at times been mistaken for Mount Murchison. Named by the northern party of NZGSAE, 1962-63, because of its prominent and lofty appearance. 73°04′S 166°11′E  /  73.067°S 166.183°E  / -73.067; 166.183 . A mountain 2,680 metres (8,790 ft) high along the north side of Gair Glacier 8.5 nautical miles (15.7 km; 9.8 mi) east of Mount Supernal. Mapped by USGS from surveys and United States Navy air photos, 1960-64. Named by US-ACAN for Paul L. Montreuil, biologist at McMurdo Station, 1964-65. The western plateau of

2871-760: 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

2970-688: The Mountaineer Range and flowing east-northeast to enter Mariner Glacier just north of Bunker Bluff. Named by the New Zealand Geological Survey Antarctic Expedition (NZGSAE) 1962–63, for Harry Gair, geologist and leader that season of the NZGSAE northern field party. 73°13′S 166°42′E  /  73.217°S 166.700°E  / -73.217; 166.700 . A tributary glacier about 10 nautical miles (19 km; 12 mi) long in

3069-562: 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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3168-535: 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

3267-593: The United States Geological Survey (USGS) from surveys and United States Navy air photos, 1960-64. Named by the United States Advisory Committee on Antarctic Names (US-ACAN) for Lieutenant Gary E. Noice, United States Navy, navigator with Squadron VX-6 at McMurdo Station, 1966. 73°22′S 164°56′E  /  73.367°S 164.933°E  / -73.367; 164.933 . A very steep bluff forming

3366-646: The United States Geological Survey . 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 / ) 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

3465-542: The Victory Mountains . Mapped by USGS from surveys and United States Navy air photos, 1960–62. Named by US-ACAN for Richard D. Olson of the Office of Antarctic Programs, National Science Foundation, who participated in research administration activities at McMurdo Station, 1967–68. 72°58′S 166°50′E  /  72.967°S 166.833°E  / -72.967; 166.833 . A steep glacier draining from

3564-448: 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

3663-507: The Lawrence Peaks and Malta Plateau , to enter Mariner Glacier. So named by the Mariner Glacier party of NZGSAE, 1966–67, in association with the name Mariner. Named after The Seafarer , an Anglo Saxon poem celebrating early harsh navigation. 72°46′S 166°37′E  /  72.767°S 166.617°E  / -72.767; 166.617 . A glacier 2 nautical miles (3.7 km; 2.3 mi) north of Olson Glacier, draining

3762-599: The Mariner Glacier recies the small Boyer Glacier from the south. At its mouth, past Emerging Island, the glacier forms the Mariner Glacier Tongue, which abuts the Borchgrevink Glacier Tongue flowing into Lady Newnes Bay . Tributaries from the left (northeast) include, 72°54′S 166°34′E  /  72.900°S 166.567°E  / -72.900; 166.567 . A tributary glacier draining southward from Webb Névé between

3861-540: The Mariner Glacier valley were reconnoitered in December 1958 by Captain John Cadwalader , United States Navy , and two members of New Zealand Geological Survey Antarctic Expedition (NZGSAE), in a flight from the icebreakers USS Glacier and USS Staten Island which were lying close off the south end of Coulman Island , in an attempt to land expedition members on the mainland. Named by NZGSAE, 1958–59, as

3960-784: The Mountaineer Range to join Mariner Glacier just east of Engberg Bluff. The descriptive name was given by the NZGSAE, 1962–63. 73°18′S 167°21′E  /  73.300°S 167.350°E  / -73.300; 167.350 . Short tributary glacier situated 10 nautical miles (19 km; 12 mi) west of Index Point in the east part of Mountaineer Range. It flows north into lower Mariner Glacier, Victoria Land. Mapped by USGS from surveys and United States Navy air photos, 1960–64. Named by US-ACAN for Jack W. Boyer, United States Navy, radioman at Hallett Station, 1962. 72°42′S 166°18′E  /  72.700°S 166.300°E  / -72.700; 166.300 . The névé at

4059-521: The Mountaineer Range. It flows east to enter Mariner Glacier just north of Engberg Bluff. Named by NZGSAE, 1962–63, in association with Aeronaut Glacier , Cosmonaut Glacier and Cosmonette Glacier . 73°16′S 166°55′E  /  73.267°S 166.917°E  / -73.267; 166.917 . A large meandering tributary to the Mariner Glacier. The glacier emerges in the vicinity of Mount Supernal and Hobbie Ridge and drains generally eastward for 30 nautical miles (56 km; 35 mi) through

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4158-626: The NZARP Northern Party to upper Mariner Glacier, 1966–67. 72°42′S 166°00′E  /  72.700°S 166.000°E  / -72.700; 166.000 . Several rock spurs exposed along the east side of the head of Mariner Glacier, 8 nautical miles (15 km; 9.2 mi) southwest of Mount McCarthy, in Victoria Land. So named by the VUWAE field party to Evans Névé, 1971–72, on the occasion of fossil discoveries made in

4257-635: The Olson Glacier. Flowing southeast, below Mount Heg it is fed from the north by the Potts Glacier. Gair Glacier enters from the west to the north of Bunker Bluff, and Argonaut Glacier enters from the southwest before Engberg Bluff. The Meander Glacier enters from the south after Engberg Bluff. The Meander Glacier forms below the Hercules Névé, forming on both sides of Hobbie Ridge. Before its mouth between Cape Crossfire and Index Point

4356-412: 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

4455-520: 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

4554-430: 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

4653-713: 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

4752-496: The area. 72°50′S 166°20′E  /  72.833°S 166.333°E  / -72.833; 166.333 . A mountain complex of high peaks separating the Seafarer Glacier from the head of the Mariner Glacier. Named by the Northern Party of NZGSAE, 1966–67, for the leader of the party, J.E.S. Lawrence. 73°04′S 165°15′E  /  73.067°S 165.250°E  / -73.067; 165.250 . A névé at

4851-432: 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

4950-445: 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

5049-655: The coast of Victoria Land. The feature lies at the terminus of Mariner Glacier, 1.5 nautical miles (2.8 km; 1.7 mi) west of Emerging Island. So named in 1966 by the New Zealand Antarctic Place-Names Committee (NZ-APC) because the shape is suggestive of an index finger. 73°23′S 168°02′E  /  73.383°S 168.033°E  / -73.383; 168.033 . An ice-covered island 2 nautical miles (3.7 km; 2.3 mi) long, lying 1.5 nautical miles (2.8 km; 1.7 mi) east of Index Point, Victoria Land, in

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5148-571: 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

5247-467: 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

5346-483: 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

5445-577: The east wall of Aviator Glacier 10 nautical miles (19 km; 12 mi) north of Mount Monteagle. Mapped by the United States Geological Survey (USGS) from surveys and United States Navy air photos, 1960-64. Named by the United States Advisory Committee on Antarctic Names (US-ACAN) for Lieutenant Commander Richard C. Brabec, United States Navy, Hercules aircraft commander on United States Navy OpDFrz, 1966. 73°43′S 165°47′E  /  73.717°S 165.783°E  / -73.717; 165.783 . A mountain 2,100 metres (6,900 ft) high at

5544-789: The eastern part include Bunker Bluff , Engberg Bluff , Index Point , Gauntlet Ridge , Spatulate Ridge , Apostrophe Island , Caliper Cove and Cape King . Download coordinates as: 73°25′S 166°37′E  /  73.417°S 166.617°E  / -73.417; 166.617 A mountainous, ice-covered ridge situated 5 miles (8.0 km) east of Mount Murchison. The ridge trends north–south for 10 nautical miles (19 km; 12 mi). Mapped by USGS from surveys and U.S. Navy air photos, 1960-64. Named by US-ACAN for Joseph E. Dessent, meteorologist at Hallett Station, 1961. 73°25′S 166°18′E  /  73.417°S 166.300°E  / -73.417; 166.300 . A very prominent mountain, 3,500 metres (11,500 ft) high, marking

5643-418: 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

5742-475: 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

5841-514: The glacial base and facilitate sediment production and transport under the same moving speed and amount of ice. Material that becomes incorporated in a glacier is typically carried as far as the zone of ablation before being deposited. Glacial deposits are of two distinct types: Mount Supernal The seaward parts of the Mountaineer Range were first viewed by James Clark Ross in 1841, and subsequently by several British and later American expeditions. The precise mapping of its overall features

5940-453: 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

6039-428: 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

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6138-510: 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

6237-578: The head of Seafarer Glacier in Victoria Land. Named by the Northern Party of NZGSAE, 1966–67, after the appointed Public Relations Officer Dexter Webb, who was killed before taking up the appointment. 72°36′S 166°03′E  /  72.600°S 166.050°E  / -72.600; 166.050 . An isolated nunatak of red-brown color at the east side of the head of Mariner Glacier, 3 nautical miles (5.6 km; 3.5 mi) west-southwest of Mount McCarthy, Barker Range. A descriptive name apparently applied by B.W. Riddolls and G.T. Hancox, geologists with

6336-554: The high point on the rugged divide between Fitzgerald Glacier and Wylde Glacier }. Discovered in January 1841 by Sir James Clark Ross who named this feature for Sir Roderick Impey Murchison , then general secretary of the British Association. 73°27′S 165°30′E  /  73.450°S 165.500°E  / -73.450; 165.500 . A large active volcano predominantly buried in ice, with several peaks reaching an estimated 2,600 metres (8,500 ft), It

6435-619: 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

6534-420: 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

6633-556: 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

6732-488: 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

6831-411: 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

6930-418: 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

7029-423: 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

7128-424: The latter's summit, in the Mountaineer Range. Given this descriptive name by the northern party of NZGSAE, 1962-63. 73°10′S 164°36′E  /  73.167°S 164.600°E  / -73.167; 164.600 . A very large mountain 3,395 metres (11,138 ft) high which is an extinct volcano, situated at the northwest limit of Deception Plateau and just east of the head of Aviator Glacier. So named by

7227-679: 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,

7326-445: 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

7425-477: The mouth of Gair Glacier and forms a part of the west wall of Mariner Glacier. Mapped by USGS from surveys and United States Navy air photos, 1960–64. Named by US-ACAN for William H. Bunker, meteorologist at Hallett Station, 1962. 73°13′S 166°48′E  /  73.217°S 166.800°E  / -73.217; 166.800 . Bold ice-covered bluff between the mouths of the Argonaut and Meander Glaciers at

7524-401: The north margin of Mountaineer Range. It is bounded by Deception Plateau , Astronaut Glacier , Retreat Hills , and by such western tributaries to the Mariner Glacier as Meander Glacier and Gair Glacier. Named by the northern party of NZGSAE, 1966–67, in appreciation of the party's transport into the field by United States Navy C-130 Hercules aircraft, also as an indication to future parties of

7623-710: The north part of Lady Newnes Bay. The feature appears to be barely emerging above the ice at the terminus of Mariner Glacier. Named in 1966 by the NZ-APC. 73°27′S 168°20′E  /  73.450°S 168.333°E  / -73.450; 168.333 . The broad seaward extension of the Mariner Glacier. The feature is just west of and abuts the Borchgrevink Glacier Tongue where it discharges into Lady Newnes Bay. Named in association with Mariner Glacier. [REDACTED]  This article incorporates public domain material from websites or documents of

7722-718: The north part of the west slopes of Malta Plateau and flowing west into Seafarer Glacier. Mapped by the United States Geological Survey (USGS) from surveys and United States Navy air photos, 1960–64. Named by the United States Advisory Committee on Antarctic Names (US-ACAN) for Robert C. Wilhelm, a member of the United States Antarctic Research Program (USARP) glaciological party at Roosevelt Island in 1967–68. 72°49′S 166°41′E  /  72.817°S 166.683°E  / -72.817; 166.683 . A tributary glacier descending westward from Malta Plateau to enter Seafarer Glacier in

7821-895: The north side of the head of Oakley Glacier, 5 nautical miles (9.3 km; 5.8 mi) east-northeast of Mount Monteagle. Mapped by USGS from surveys and United States Navy air photos, 1960-64. Named by US-ACAN for Lieutenant Dennis Casey, United States Navy Reserve, Catholic chaplain with the winter party at McMurdo Station, 1967. 73°40′S 165°58′E  /  73.667°S 165.967°E  / -73.667; 165.967 . A mountain 1,700 metres (5,600 ft) high located 4 nautical miles (7.4 km; 4.6 mi) northeast of Mount Casey. Mapped by USGS from surveys and United States Navy air photos, 1960-64. Named by US-ACAN after Lieutenant Commander Jack O. Moriarty, United States Navy, air operations officer at McMurdo Station, winter party 1966. [REDACTED]  This article incorporates public domain material from websites or documents of

7920-452: The northern party of NZGSAE, 1962-63, because it "overlords" lesser peaks in the area. 73°15′S 164°50′E  /  73.250°S 164.833°E  / -73.250; 164.833  ( Deception Plateau ) . A high, ice-covered plateau, 11 nautical miles (20 km; 13 mi) long and 6 nautical miles (11 km; 6.9 mi) wide, which is bounded by Aviator Glacier , Pilot Glacier and Mount Overlord . Deception Plateau

8019-485: The northern party of the New Zealand Geological Survey Antarctic Expedition (NZGSAE), 1966-67, after the Cobham Outward Bound School, Anakiwa , New Zealand. 73°04′S 165°42′E  /  73.067°S 165.700°E  / -73.067; 165.700 . A large double summit mountain 3,655 metres (11,991 ft) high surmounting the southeast corner of Hercules Névé and the heads of

8118-417: The point where these tributaries enter the south part of Mariner Glacier. Mapped by USGS from surveys and United States Navy air photos, 1960–64. Named by US-ACAN for Larry W. Engberg, meteorologist at Hallett Station, 1961. 73°21′S 167°55′E  /  73.350°S 167.917°E  / -73.350; 167.917 . A low, ice-covered point that forms the east extremity of the Mountaineer Range on

8217-725: 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

8316-410: 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

8415-690: The range is near the head of the Aviator Glacier to the west, where it flows round Navigator Nunatak . To the north are the Astronaut Glacier , and Hercules Névé . The Pilot Glacier flows past the southeast side of the plateau into the Aviator Glacier. 73°06′S 164°18′E  /  73.100°S 164.300°E  / -73.100; 164.300 . A small parasite cone on the northwest flank of Mount Overlord, 6.5 nautical miles (12.0 km; 7.5 mi) distant from

8514-567: 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

8613-520: The south end of Deception Plateau, overlooking the point where Pilot Glacier joins the larger Aviator Glacier. Mapped by USGS from surveys and United States Navy air photos, 1960-64. Named by US-ACAN for Lieutenant Commander William E. Shockley, United States Navy, officer in charge of the Squadron VX-6 winter detachment at McMurdo Station, 1966. The southwest of the Mountaineer Range is a triangular block of mountains between Aviator Glacier to

8712-602: The south of the Victory Mountains and northeast of the Southern Cross Mountains . It is bounded by the Aviator Glacier which forms below the Half-ration Névé to the west, and flows south-southeast to Lady Newnes Bay . The bay forms the eastern boundary of the range. To the north it is bound by the Hercules Névé and Mariner Glacier , which flows southeast to Lady Newnes Bay. Features of

8811-586: The south side of the head of Gair Glacier , standing 6 nautical miles (11 km; 6.9 mi) southeast of Mount Supernal. It was mapped by the United States Geological Survey (USGS) from surveys and United States Navy air photos in 1960–64. It was named by the United States Advisory Committee on Antarctic Names (US-ACAN) for Jean P. Whitcomb, radio scientist at McMurdo Station , 1965–66 and 1966–67. 73°14′S 165°54′E  /  73.233°S 165.900°E  / -73.233; 165.900 . A large, rounded mountain 2,180 metres (7,150 ft) high on

8910-510: The south side of upper Meander Glacier, 5 nautical miles (9.3 km; 5.8 mi) southeast of Hobbie Ridge. Mapped by USGS from surveys and United States Navy air photos, 1960-64. Named by US-ACAN for Urbain J. Kinet, biologist at McMurdo Station, 1965-66. 73°00′S 165°43′E  /  73.000°S 165.717°E  / -73.000; 165.717 . A small mountain 2,640 metres (8,660 ft) high situated 3 nautical miles (5.6 km; 3.5 mi) north of Mount Supernal. Named by

9009-409: 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

9108-423: 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

9207-438: 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

9306-417: 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

9405-500: The west slopes of Malta Plateau and flowing south to enter Mariner Glacier. Mapped by USGS from surveys and United States Navy air photos, 1960–64. Named by US-ACAN for Donald C. Potts, biologist at McMurdo Station, 1966–67. Tributaries from the left (southwest ) include, 73°03′S 166°32′E  /  73.050°S 166.533°E  / -73.050; 166.533 . A tributary glacier, 10 nautical miles (19 km; 12 mi) long, rising close southeast of Mount Supernal in

9504-742: The west, Aviator Glacier Tongue and Lady Newnes Bay to the south east and Icebreaker Glacier to the northeast. The Southern Cross Mountains are to the west and south. Features include Mount Monteagle, Cape Sibbald , the Parker Glacier and Andrus Point to the south, Mount Brabec, Finley Glacier , Dunn Glacier to the north, and Mount Casey, Mount Moriarty and Oakley Glacier to the east. 73°43′S 165°28′E  /  73.717°S 165.467°E  / -73.717; 165.467  ( Mount Monteagle ) . A high, sharp peak, 2,780 metres (9,120 ft) high, standing 10 nautical miles (19 km; 12 mi) north of Cape Sibbald in

9603-452: Was accomplished from United States Navy air photographs and surveys by New Zealand and American parties in the 1950s and 1960s. The range was named by the New Zealand Geological Survey Antarctic Expedition (NZGSAE), 1958–59, in keeping with the backgrounds of members of the 1957–58 and 1958–59 field parties who made a reconnaissance of the area, and also in association with the names "Aviator" and "Mariner". The Mountaineer Range lies to

9702-523: Was identified as a volcano by the 4th Italian Antarctic Expedition in the 1988/89 field season, and named by them in 1991 for the volcanologist Alfred Rittmann (1893-1980). Features in the north of the range include Whitcomb Ridge, Hobbie Ridge to the west, Mount Kinet to the south, Mount Anakiwa, Mount Supernal and Mount Montreuil to the north. 73°7′S 166°0′E  /  73.117°S 166.000°E  / -73.117; 166.000  ( Whitcomb Ridge ) . A high, ice-covered ridge along

9801-471: Was so named by the southern party of the New Zealand Geological Survey Antarctic Expedition (NZGSAE), 1966–67, because of its deceptively small appearance when viewed from a distance. 73°17′S 164°40′E  /  73.283°S 164.667°E  / -73.283; 164.667 . A mountain 2,780 metres (9,120 ft) high surmounting the southwest edge of Deception Plateau, 8 nautical miles (15 km; 9.2 mi) south of Mount Overlord. Mapped by

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