79-683: The Rimo Muztagh is one of the most remote subranges of the Karakoram range . The southern part of Rimo Muztagh is in the Ladakh portion of far northwestern India , also claimed by Pakistan . The northern half, including the Rimo massif, is in the Siachen area (territory controlled by India). It is far from major towns, and close to the militarily sensitive Siachen Glacier, so it has seen little exploration or climbing activity compared to, for example,
158-424: 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
237-823: A French expedition to the range in 1936. The film won the Silver Lion at the Venice Film Festival of 1937. Greg Mortenson details the Karakoram, and specifically K2 and the Balti , extensively in his book Three Cups of Tea , about his quest to build schools for children in the region. K2 Kahani (The K2 Story) by Mustansar Hussain Tarar describes his experiences at K2 base camp. 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 / )
316-522: 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
395-601: 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
474-411: 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
553-408: 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
632-404: 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
711-460: 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,
790-488: 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
869-410: 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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#1732773407292948-605: Is a mountain range in the Kashmir region spanning the border of Pakistan , China , and India , with the northwestern extremity of the range extending to Afghanistan and Tajikistan . Most of the Karakoram mountain range falls under the jurisdiction of Gilgit-Baltistan , which is located in Pakistan. Its highest (and the world's second-highest ) peak, K2 , is located in Gilgit-Baltistan, Pakistan . It begins in
1027-517: Is a list for the highest peaks of the Karakoram. Included are some of the mountains named with a K code, the most famous of which is the K2 (mountain) . The majority of the highest peaks are in the Gilgit–Baltistan region administered by Pakistan. Baltistan has more than 100 mountain peaks exceeding 6,100 metres (20,000 ft) height from sea level. The naming and division of the various subranges of
1106-468: 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
1185-542: Is about 500 km (311 mi) in length and is the most glaciated place on Earth outside the polar regions . The Siachen Glacier (76 km (47 mi) long) and Biafo Glacier (63 km (39 mi) long) are the second- and third-longest glaciers outside the polar regions. The Karakoram is bounded on the east by the Aksai Chin plateau, on the northeast by the edge of the Tibetan Plateau and on
1264-456: 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
1343-407: 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,
1422-411: 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
1501-406: 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
1580-434: 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
1659-416: 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
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#17327734072921738-647: 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
1817-897: 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
1896-415: Is the only motorable pass across the range. The Shimshal Pass (which does not cross an international border) is the only other pass still in regular use. The Karakoram mountain range has been referred to in a number of novels and movies. Rudyard Kipling refers to the Karakoram mountain range in his novel Kim , which was first published in 1900. Marcel Ichac made a film titled Karakoram , chronicling
1975-413: 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
2054-402: 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
2133-552: 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
2212-993: 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
2291-644: 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
2370-760: 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
2449-562: 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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2528-535: 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
2607-729: The Saltoro Mountains and the Kailas Mountains . The following is a table of the peaks in the Rimo Muztagh which are over 7,200 meters (23,622 feet) in elevation and have over 500 meters (1,524 feet) of topographic prominence . (This is a common criterion for peaks of this stature to be independent.) Other notable peaks include the following: This Indian location article is a stub . You can help Misplaced Pages by expanding it . Karakoram The Karakoram ( / ˌ k ɑːr ə ˈ k ɔːr əm , ˌ k ær -/ )
2686-826: The Wakhan Corridor (Afghanistan) in the west, encompasses the majority of Gilgit-Baltistan, Pakistan and extends into Ladakh (controlled by India) and Aksai Chin (controlled by China). It is part of the larger Trans-Himalayan mountain ranges. The Karakoram is the second-highest mountain range on Earth and part of a complex of ranges that includes the Pamir Mountains , Hindu Kush , and Himalayas . The range contains 18 summits higher than 7,500 m (24,600 ft) in elevation , with four above 8,000 m (26,000 ft): K2 (8,611 m (28,251 ft) AMSL ) (the second-highest peak on Earth), Gasherbrum I , Broad Peak , and Gasherbrum II . The range
2765-665: The 1910s and 1920s established most of the geography of the region. The name Karakoram was used in the early 20th century, for example by Kenneth Mason , for the range now known as the Baltoro Muztagh . The term is now used to refer to the entire range from the Batura Muztagh above Hunza in the west to the Saser Muztagh in the bend of the Shyok River in the east. Floral surveys were carried out in
2844-448: 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
2923-521: The Himalaya and 2.2 percent of the Alps . Mountain glaciers may serve as an indicator of climate change, advancing and receding with long-term changes in temperature and precipitation. The Karakoram glaciers are slightly retreating, unlike the Himalayas where glaciers are losing mass at significantly higher rate, many Karakoram glaciers are covered in a layer of rubble which insulates the ice from
3002-461: The Karakoram is much less inhabited than parts of the Himalayas further east. European explorers first visited early in the 19th century, followed by British surveyors starting in 1856. The Muztagh Pass was crossed in 1887 by the expedition of Colonel Francis Younghusband and the valleys above the Hunza River were explored by General Sir George K. Cockerill in 1892. Explorations in
3081-918: The Karakoram is not universally agreed upon. However, the following is a list of the most important subranges, following Jerzy Wala. The ranges are listed roughly west to east. [REDACTED] 1 : Sia La , [REDACTED] 2 : Bilafond La , [REDACTED] 3 : Gyong La , [REDACTED] 4 : Sasser Pass , [REDACTED] 5 : Burji La , [REDACTED] 6 : Machulo La , [REDACTED] 7 : Naltar Pass , [REDACTED] 8 : Hispar Pass , [REDACTED] 9 : Shimshal Pass , [REDACTED] 10 : Karakoram Pass , [REDACTED] 11 : Turkistan La Pass , [REDACTED] 12 : Windy Gap , [REDACTED] 13 : Mustagh Pass , [REDACTED] 14 : Sarpo Laggo Pass , [REDACTED] 15 : Khunjerab Pass , [REDACTED] 16 : Mutsjliga Pass , [REDACTED] 17 : Mintaka Pass , [REDACTED] 18 : Kilik Pass Passes from west to east are: The Khunjerab Pass
3160-562: The People's Republic of China for UNESCO and have been tentatively added to the list. Karakoram is a Turkic term meaning black gravel . The Central Asian traders originally applied the name to the Karakoram Pass . Early European travellers, including William Moorcroft and George Hayward , started using the term for the range of mountains west of the pass, although they also used the term Muztagh (meaning, "Ice Mountain") for
3239-724: The Shyok River catchment and from Panamik to Turtuk village by Chandra Prakash Kala during 1999 and 2000. The Karakoram is in one of the world's most geologically active areas, at the plate boundary between the Indo-Australian plate and the Eurasian plate . A significant part, somewhere between 28 and 50 percent, of the Karakoram Range is glaciated covering an area of more than 15,000 square kilometres or 5,800 square miles, compared to between 8 and 12 percent of
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3318-412: 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
3397-520: 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
3476-430: 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
3555-713: 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
3634-432: 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
3713-445: 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
3792-571: 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
3871-467: 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
3950-483: 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
4029-418: 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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#17327734072924108-475: 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
4187-453: 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
4266-428: 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
4345-510: 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
4424-619: 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
4503-420: 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
4582-556: 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
4661-488: 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
4740-411: 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
4819-418: 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
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#17327734072924898-423: 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
4977-679: 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,
5056-445: 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
5135-721: The nearby Baltoro Muztagh . The highest peak is Mamostong Kangri , 7,516 metres (24,659 feet). The Rimo Muztagh is bordered on the north by the Rimo Glacier , which drains to the east into the upper Shyok River , and by the Teram Shehr Glacier , a tributary of the Siachen Glacier . To the northeast lie the Northeast Rimo Mountains and the Karakoram Pass , a pass on one of the historically important trade routes into Central Asia . To
5214-659: The north by the river valleys of the Yarkand and Karakash rivers beyond which lie the Kunlun Mountains . At the northwest corner are the Pamir Mountains . The southern boundary of the Karakoram is formed, west to east, by the Gilgit , Indus and Shyok rivers , which separate the range from the northwestern end of the Himalaya range proper. These rivers flow northwest before making an abrupt turn southwestward towards
5293-673: The north lies the eastern end of the Siachen Muztagh . On the east side of the range, the upper Shyok River divides it from the Depsang Plains , part of the Tibetan Plateau . On the southeast, the pass known as the Sasser Pass (Saser La) separates the Rimo Muztagh from the Saser Muztagh . The western border of the range is formed by the lower Siachen Glacier and its outflow, the Nubra River . Across this boundary lie
5372-520: The north, the Karakoram glaciers joined those from the Kunlun Mountains and flowed down to 2,000 metres (6,600 ft) in the Tarim basin. While the current valley glaciers in the Karakoram reach a maximum length of 76 kilometres (47 mi), several of the ice-age valley glacier branches and main valley glaciers, had lengths up to 700 kilometres (430 mi). During the Ice Age, the glacier snowline
5451-678: The plains of Pakistan . Roughly in the middle of the Karakoram range is the Karakoram Pass , which was part of a historic trade route between Ladakh and Yarkand that is now inactive. The Tashkurghan National Nature Reserve and the Pamir Wetlands National Nature Reserve in the Karalorun and Pamir mountains have been nominated for inclusion in UNESCO in 2010 by the National Commission of
5530-725: 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
5609-410: 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
5688-597: The range now known as Karakoram. Later terminology was influenced by the Survey of India , whose surveyor Thomas Montgomerie in the 1850s gave the labels K1 to K6 (K for Karakoram) to six high mountains visible from his station at Mount Haramukh in Kashmir Valley , codes extended further up to more than thirty. In traditional Indian geography the mountains were known as Krishnagiri (black mountains), Kanhagiri and Kanheri . Due to its altitude and ruggedness,
5767-567: 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
5846-409: 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
5925-423: 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
6004-438: 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
6083-601: The warmth of the sun. Where there is no such insulation, the rate of retreat is high. In the last ice age , a connected series of glaciers stretched from western Tibet to Nanga Parbat , and from the Tarim basin to the Gilgit District . To the south, the Indus glacier was the main valley glacier, which flowed 120 kilometres (75 mi) down from Nanga Parbat massif to 870 metres (2,850 ft) elevation. In
6162-417: 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
6241-1511: Was about 1,300 metres (4,300 ft) lower than today. Legend: 1: K2 , 2: Gasherbrum I, K5 , 3: Broad Peak , 4: Gasherbrum II, K4 , 5: Gasherbrum III, K3a , 6: Gasherbrum IV, K3 , 7: Distaghil Sar , 8: Kunyang Chhish , 9: Masherbrum, K1 , 10: Batura Sar, Batura I , 11: Rakaposhi , 12: Batura II , 13: Kanjut Sar , 14: Saltoro Kangri, K10 , 15: Batura III , 16: Saser Kangri I, K22 , 17: Chogolisa , 18: Shispare , 19: Trivor Sar , 20: Skyang Kangri , 21: Mamostong Kangri, K35 , 22: Saser Kangri II , 23: Saser Kangri III , 24: Pumari Chhish , 25: Passu Sar , 26: Yukshin Gardan Sar , 27: Teram Kangri I , 28: Malubiting , 29: K12 , 30: Sia Kangri , 31: Momhil Sar , 32: Skil Brum , 33: Haramosh Peak , 34: Ghent Kangri , 35: Ultar Sar , 36: Rimo massif , 37: Sherpi Kangri , 38: Yazghil Dome South , 39: Baltoro Kangri , 40: Crown Peak , 41: Baintha Brakk , 42: Yutmaru Sar , 43: K6 , 44: Muztagh Tower , 45: Diran , 46: Apsarasas Kangri I , 47: Rimo III , 48: Gasherbrum V Here
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