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A glacier 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 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.
The Karakoram 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 falls within the Kashmir region administered by Pakistan
Glaciology is the scientific study of glaciers, or, more generally, ice and natural phenomena that involve ice.
In glaciology, an ice sheet, also known as a continental glacier, is a mass of glacial ice that covers surrounding terrain and is greater than 50,000 km2 (19,000 sq mi). The only current ice sheets are the Antarctic ice sheet and the Greenland ice sheet. Ice sheets are bigger than ice shelves or alpine glaciers. Masses of ice covering less than 50,000 km2 are termed an ice cap. An ice cap will typically feed a series of glaciers around its periphery.
Ablation is the removal or destruction of something from an object by vaporization, chipping, erosive processes, or by other means. Examples of ablative materials are described below, including spacecraft material for ascent and atmospheric reentry, ice and snow in glaciology, biological tissues in medicine and passive fire protection materials.
Scree is a collection of broken rock fragments at the base of a cliff or other steep rocky mass that has accumulated through periodic rockfall. Landforms associated with these materials are often called talus deposits.
Ruth Glacier is a glacier in Denali National Park and Preserve in the U.S. state of Alaska. Its upper reaches are approximately 3 vertical miles below the summit of Denali. The glacier's "Great Gorge" is one mile wide, and drops almost 2,000 feet (610 m) over 10 miles (16 km), with crevasses along the surface. Above the surface on both sides are 4,900 feet (1,500 m) granite cliffs. From the top of the cliffs to the bottom of the glacier is a height exceeding that of the Grand Canyon. Ruth Glacier moves at a rate of 3 feet (0.91 m) per day and was measured to be 4,000 feet (1,200 m) thick in 1983.
Rock glaciers are distinctive geomorphological landforms, consisting either of angular rock debris frozen in interstitial ice, former "true" glaciers overlain by a layer of talus, or something in-between. Rock glaciers are normally found at high latitudes and/or elevations, and may extend outward and downslope from talus cones, glaciers or terminal moraines of glaciers.
Thwaites Glacier is an unusually broad and vast Antarctic glacier located east of Mount Murphy, on the Walgreen Coast of Marie Byrd Land. It was initially sighted by polar researchers in 1940, mapped in 1959–1966 and officially named in 1967, after the late American glaciologist Fredrik T. Thwaites. The glacier flows into Pine Island Bay, part of the Amundsen Sea, at surface speeds which exceed 2 kilometres (1.2 mi) per year near its grounding line. Its fastest-flowing grounded ice is centered between 50 and 100 kilometres east of Mount Murphy. Like many other parts of the cryosphere, it has been adversely affected by climate change, and provides one of the more notable examples of the retreat of glaciers since 1850.
Glacial surges are short-lived events where the flow velocity on a portion of a glacier can increase up to 100 times faster than normal during a few months or years. It is associated with an important transportation of ice mass down-glacier, often but not always causing the advance of the glacier front. Surge events are likely an extreme case of the continuous spectra of glacier instabilities. Surging glaciers cluster around a few areas. High concentrations of surging glaciers occur in the Karakoram, Pamir Mountains, Svalbard, the Canadian Arctic islands, Alaska and Iceland, although overall it is estimated that only one percent of all the world's glaciers ever surge. In some glaciers, surges can occur in fairly regular cycles, with cycle periods commonly ranging from 15 to 100 years or more. In other glaciers, surging remains unpredictable. The period of stagnation and build-up between two surges typically lasts 10 to 200 years and is called the quiescent phase. During this period the velocities of the glacier are significantly lower, and the glaciers can retreat substantially.
The retreat of glaciers since 1850 is a well-documented effect of climate change. The retreat of mountain glaciers provide evidence for the rise in global temperatures since the late 19th century. Examples include mountain glaciers in western North America, Asia, the Alps in central Europe, and tropical and subtropical regions of South America and Africa. Since glacial mass is affected by long-term climatic changes, e.g. precipitation, mean temperature, and cloud cover, glacial mass changes are one of the most sensitive indicators of climate change. The retreat of glaciers is also a major reason for sea level rise. Excluding peripheral glaciers of ice sheets, the total cumulated global glacial losses over the 26 years from 1993 to 2018 were likely 5500 gigatons, or 210 gigatons per year.
The Siachen Muztagh is a remote subrange of the eastern Karakoram Range. Close to 60% is in area controlled by China, 40% in area controlled by India. Pakistan claims the Indian-controlled portion as part of the Siachen Conflict. India claims the Chinese-controlled portion. India administers its portion as part of the Union Territory of Ladakh. China administers its portion as part of Xinjiang province.
Skyang Kangri, or Staircase Peak, is a high mountain peak of the Baltoro Muztagh, a subrange of the Karakoram range. It lies on the Pakistan–China border, about 7 kilometres (4.3 mi) northeast of K2, the world's second-highest mountain. The name "Staircase Peak" refers to the East Ridge, which resembles a giant staircase with five steps.
Batura Glacier, 57 km (35 mi) long, is one of the largest and longest glaciers outside of the polar regions. It lies in the upper Hunza (Gojal) region of Hunza District, in Gilgit-Baltistan, Pakistan. It is just north of the massifs of Batura, at 7,795 metres (25,574 ft), and Passu, at 7,500 metres (24,600 ft). The glacier flows west to east. The lower portions can be described as a grey sea of rocks and gravelly moraine, bordered by a few summer villages and pastures with herds of sheep, goats, cows and yaks and where roses and juniper trees are common.
Totten Glacier is a large glacier draining a major portion of the East Antarctic Ice Sheet, through the Budd Coast of Wilkes Land in the Australian Antarctic Territory. The catchment drained by the glacier is estimated at 538,000 km2 (208,000 sq mi), extending approximately 1,100 km (680 mi) into the interior and holds the potential to raise sea level by at least 3.5 m (11 ft). Totten drains northeastward from the continental ice but turns northwestward at the coast where it terminates in a prominent tongue close east of Cape Waldron. It was first delineated from aerial photographs taken by USN Operation Highjump (1946–47), and named by Advisory Committee on Antarctic Names (US-ACAN) for George M. Totten, midshipman on USS Vincennes of the United States Exploring Expedition (1838–42), who assisted Lieutenant Charles Wilkes with correction of the survey data obtained by the expedition.
Radioglaciology is the study of glaciers, ice sheets, ice caps and icy moons using ice penetrating radar. It employs a geophysical method similar to ground-penetrating radar and typically operates at frequencies in the MF, HF, VHF and UHF portions of the radio spectrum. This technique is also commonly referred to as "Ice Penetrating Radar (IPR)" or "Radio Echo Sounding (RES)".
Lobate debris aprons (LDAs) are geological features on Mars, first seen by the Viking Orbiters, consisting of piles of rock debris below cliffs. These features have a convex topography and a gentle slope from cliffs or escarpments, which suggest flow away from the steep source cliff. In addition, lobate debris aprons can show surface lineations as do rock glaciers on the Earth.
Bara Shigri is a glacier located in Lahaul & Spiti, Himachal Pradesh, India. It is currently extending to 27.7 kilometres and covers over 126.45 square kilometres. It is the largest glacier in Himachal Pradesh.
Indira Col West is a mountain pass at 5,988 metres (19,646 ft)) altitude on the Indira Ridge of Siachen Muztagh in Karakoram Range. It is on the border between Indian-controlled Siachen Glacier and the Chinese-controlled Trans-Karakoram Tract, close to the tripoint of India, Pakistan, and China. The India-Pakistan Actual Ground Position Line (AGPL) in the Siachen area ends near the pass. It is possible to ascend the pass from both the north and south sides controlled by China and India respectively.
Storstrømmen, is one of the major glaciers in northeastern Greenland. The North-East Greenland Ice Stream (NEGIS) discharges into 3 main marine-terminating outlets: 79N Glacier, Zachariae Isstrøm and Storstrømmen – as arranged North to South.
References
- ↑ Thompson, Sarah; Benn, Douglas I.; Mertes, Jordan; Luckman, Adrian (June 2016). "Stagnation and mass loss on a Himalayan debris-covered glacier: processes, patterns and rates". Journal of Glaciology. 62 (233): 467–485. doi:10.1017/jog.2016.37. hdl: 10023/9312 . ISSN 0022-1430.
- ↑ Kneib, M.; Miles, E. S.; Buri, P.; Molnar, P.; McCarthy, M.; Fugger, S.; Pellicciotti, F. (October 2021). "Interannual Dynamics of Ice Cliff Populations on Debris‐Covered Glaciers From Remote Sensing Observations and Stochastic Modeling". Journal of Geophysical Research: Earth Surface. 126 (10). doi:10.1029/2021JF006179. ISSN 2169-9003. PMC 9285626 . PMID 35860443.
- ↑ Bhambri, R.; Hewitt, K.; Kawishwar, P.; Pratap, B. (2017-11-13). "Surge-type and surge-modified glaciers in the Karakoram". Scientific Reports. 7 (1): 15391. doi:10.1038/s41598-017-15473-8. ISSN 2045-2322. PMC 5684366 . PMID 29133812.
- ↑ Glaciers of Asia—Glaciers of Pakistan Satellite Image Atlas of Glaciers of the World By John F. Shroder, Jr., and Michael P. Bishop. Edited by Richard S. Williams, Jr. and Jane G. Ferrigno. U. S. Geological Survey Professional Paper 1386-F-4
- ↑ Raup, Bruce H. "GLIMS: Global Land Ice Measurements from Space". doi:10.7265/n5-rgi-60.
{{cite journal}}: Cite journal requires|journal=(help) - ↑ Evatt, Geoffrey William (November 2017). "The secret life of ice sails". Journal of Glaciology. 63 (242): 1–14.
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