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Glacier morphology

March 10, 2023

Glacier morphology, or the form a glacier takes, is influenced by temperature, precipitation, topography, and other factors.[1] The goal of glacial morphology is to gain a better understanding of glaciated landscapes and the way they are shaped.[2] Types of glaciers can range from massive ice sheets, such as the Greenland ice sheet, to small cirque glaciers found perched on mountain tops.[3] Glaciers can be grouped into two main categories:

  • Ice flow is constrained by the underlying bedrock topography
  • Ice flow is unrestricted by surrounding topography
Features of a glacial landscape

Unconstrained Glaciers

 
Vatnajökull ice cap in Iceland

Ice sheets and ice caps

Ice sheets and ice caps cover the largest areas of land in comparison to other glaciers, and their ice is unconstrained by the underlying topography. They are the largest glacial ice formations and hold the vast majority of the world's fresh water.[4]

Ice sheets

Ice sheets are the largest form of glacial formation. They are continent sized ice masses that span areas over 50,000 square kilometers (19,000 square miles).[5] They are dome shaped, and similarly to ice caps, exhibit radial flow.[4][5][6] As ice sheets expand over the ocean, they become ice shelves.[6] Ice sheets contain 99% of all the freshwater ice found on Earth, and form as layers of snow fall accumulate and slowly start to compact into ice.[5] There are only two ice sheets present on Earth today, and they are the Antarctic ice sheet, and the Greenland ice sheet. Although only a tenth of modern Earth is covered by ice sheets, the Pleistocene epoch was characterized by ice sheets that covered a third of our land. This was also known as the Last Glacial Maximum.[6][7]

Ice caps

An ice cap can be defined as a dome shaped mass of ice that exhibits a radial flow.[5] They are often easily confused with ice sheets, but these ice structures are smaller in size. They are smaller than 50,000 km2, and obscure the entirety of the topography they span.[5] They mainly form in polar and sub-polar regions that can be characterized by having particularly high elevation but flat ground.[4] Ice caps come in a variety of shapes; they can be round, circular, or irregular in shape.[5] Oftentimes, ice caps gradually merge into ice sheets making them difficult to track and document.[5] Some examples of ice caps include:

Ice domes

An ice dome is a part of an ice cap or ice sheet that is characterized by upstanding ice surface located in the accumulation zone.[5] Ice domes are nearly symmetrical, with a convex or parabolic surface shape.[5] They tend to develop evenly over a land mass that may be either a topographic height or a depression—often reflecting the sub-glacial topography.[5] In ice sheets, domes may reach a thickness that may exceed 3,000 meters (9,800 feet). However, in ice caps, the thickness of the dome is much smaller; measuring roughly up to several hundred metres in comparison.[5] In glaciated islands, ice domes are usually the highest point of the ice cap.[5] An example of an ice dome is Kupol Vostok Pervyy in Alger Island, Franz Josef Land, Russia.

Ice streams

Ice streams rapidly channel ice flow out to the sea, ocean, or an ice shelf. For this reason, they are commonly referred to as the "arteries" of an ice sheet.[8][9] Ice from continental sheets is drained into the ocean by a complex network of ice streams, and their activity is greatly affected by oceanic and atmospheric processes.[8] They feature a higher velocity in the centre of the stream, and are bounded by slow moving ice on either side.[10] Periods of greater ice stream flow result in more ice transfer from ice sheets to the ocean; subsequently impacting sea level by raising it.[10] At the margin between glacial ice and water, ice calving takes place as glaciers begin to fracture, and icebergs break off from the large masses of ice.[11][9] Iceberg calving is a major contributor to sea level rise, but the ocean is not the only place that can experience ice calving.[11] Calving can also take place in lakes, fjords, and continental ice cliffs.[11]

Constrained Glaciers

Icefields

 
Southern Patagonia Ice Field from ISS, astronaut photo. North is to the right.

An icefield is an example of glacier structure that covers a relatively large area, and is usually located in areas characterized by mountain terrain.[4] Icefields are quite similar to ice caps; however, their morphology is much more influenced by the underlying mountainous topography.[4]

The rock formations found under the icefields are variable, and rocky mountain peaks known as nunataks tend to jut out from under the surface of icefields.[12][13] Some examples of icefields include:

Outlet glaciers

Outlet glaciers are often found in valleys, and they originate from major ice sheets and ice caps.[4] They move in a singular direction that is determined by the underlying landscape.[12] Outlet glaciers drain inland glaciers through gaps found in the surrounding topography.[4] A higher amount of inland glacial melt ultimately increases the amount of outlet glacier output.[14] Studies predict that outlet glaciers found in Greenland can increase the global sea level considerably following an increase in global temperature, and a subsequently higher drainage output.[15] Some examples of outlet glaciers include:[14]

Valley glaciers

 

Valley glaciers are outlet glaciers that provide drainage for ice fields, icecaps or ice sheets.[15] The flow of these glaciers is confined by the walls of the valley they are found in; but they may also form in mountain ranges as gathering snow turns to ice.[4][16] The formation of valley glaciers is restricted by formations such as terminal moraines, which are collections of unconsolidated rock material, or till deposited by the terminus of the glacier. Ice-free exposed bedrock and slopes often surround valley glaciers,[17] providing a route for snow and ice to accumulate on the glacier via avalanches. Some examples of valley glaciers include:

Valley-head glaciers

Valley head glaciers are types of valley glaciers that are only limited to the valley head.[16] An example of this type of valley glacier is Bægisárjökull, found in Iceland.[12]

Fjords

True fjords are formed when valley glaciers retreat and seawater fills the now empty valley. They can be found in mountainous, glaciation affected terrain.[18] Some examples of fjords include:

Piedmont glaciers

 
Elephant Foot Glacier, a well-known Piedmont glacier in Romer Lake, northeastern Greenland.[19]

 

Piedmont glaciers are a sub-type of valley glaciers which have flowed out onto lowland plains, where they spread out into a fan-like shape.[12][16] Some examples of Piedmont glaciers include:

Cirque glaciers

 
Lower Curtis Glacier is a cirque glacier in the North Cascades in the State of Washington.

 

Cirque glaciers are glaciers that appear in bowl shaped valley hollows.[4][12] Snow easily settles in the topographic structure; it is turned to ice as more snow falls and is subsequently compressed.[12] When the glacier melts, a cirque structure is left in its place.[4] Some examples of cirque glaciers include:

Hanging glacier

A hanging glacier is a form of glacier that appears in a hanging valley, and has the potential to break off from the side of the mountain it is attached to.[12][20] As bits and pieces of hanging glaciers break off and begin to fall, avalanches can be triggered.[20] Examples of hanging glaciers include:

References

  1. ^ . National Park Service. Archived from the original on 2006-09-03.
  2. ^ Treatise on geomorphology. Shroder, John F., 1939-. London: Academic Press. 2013. ISBN 9780080885223. OCLC 831139698.{{cite book}}: CS1 maint: others (link)
  3. ^ National Snow and Ice Data Center (NSIDC). 2006-06-01.
  4. ^ a b c d e f g h i j "Glacier Types: Ice caps | National Snow and Ice Data Center". nsidc.org. Retrieved 2019-04-05.
  5. ^ a b c d e f g h i j k l Paul, Frank; Ramanathan, A.L.; Mandal, Arindan (2017-03-06), "Ice Caps", International Encyclopedia of Geography: People, the Earth, Environment and Technology, John Wiley & Sons, Ltd, pp. 1–10, doi:10.1002/9781118786352.wbieg0210, ISBN 9780470659632
  6. ^ a b c Society, National Geographic (2012-08-16). "ice sheet". National Geographic Society. Retrieved 2019-04-05.
  7. ^ Clark, P. U.; Dyke, A. S.; Shakun, J. D.; Carlson, A. E.; Clark, J.; Wohlfarth, B.; Mitrovica, J. X.; Hostetler, S. W.; McCabe, A. M. (2009-08-06). "The Last Glacial Maximum". Science. 325 (5941): 710–714. Bibcode:2009Sci...325..710C. doi:10.1126/science.1172873. ISSN 0036-8075. PMID 19661421. S2CID 1324559.
  8. ^ a b Spagnolo, Matteo; Phillips, Emrys; Piotrowski, Jan A.; Rea, Brice R.; Clark, Chris D.; Stokes, Chris R.; Carr, Simon J.; Ely, Jeremy C.; Ribolini, Adriano (2016-02-22). "Ice stream motion facilitated by a shallow-deforming and accreting bed". Nature Communications. 7 (1): 10723. Bibcode:2016NatCo...710723S. doi:10.1038/ncomms10723. ISSN 2041-1723. PMC 4764869. PMID 26898399.
  9. ^ a b Mcintyre, N. F. (1985). "The Dynamics of Ice-Sheet Outlets". Journal of Glaciology. 31 (108): 99–107. Bibcode:1985JGlac..31...99M. doi:10.1017/S0022143000006328. ISSN 0022-1430.
  10. ^ a b Stokes, C. R.; Margold, M.; Clark, C. D.; Tarasov, L. (2016-02-17). "Ice stream activity scaled to ice sheet volume during Laurentide Ice Sheet deglaciation" (PDF). Nature. 530 (7590): 322–326. Bibcode:2016Natur.530..322S. doi:10.1038/nature16947. ISSN 0028-0836. PMID 26887494. S2CID 205247646.
  11. ^ a b c Benn, Douglas I.; Åström, Jan A. (2018). "Calving glaciers and ice shelves". Advances in Physics: X. 3 (1): 1513819. Bibcode:2018AdPhX...313819B. doi:10.1080/23746149.2018.1513819. ISSN 2374-6149.
  12. ^ a b c d e f g Björnsson, Helgi (2016-10-05), "Origins and Nature of Glaciers", The Glaciers of Iceland, Atlantis Press, pp. 3–37, doi:10.2991/978-94-6239-207-6_1, ISBN 9789462392069
  13. ^ Dixon, John C.; Thorn, Colin E.; Darmody, Robert G. (1984). "Chemical Weathering Processes on the Vantage Peak Nunatak, Juneau Icefield, Southern Alaska". Physical Geography. 5 (2): 111–131. doi:10.1080/02723646.1984.10642247. ISSN 0272-3646.
  14. ^ a b Howat, I. M.; Joughin, I.; Scambos, T. A. (2007-03-16). "Rapid Changes in Ice Discharge from Greenland Outlet Glaciers". Science. 315 (5818): 1559–1561. Bibcode:2007Sci...315.1559H. doi:10.1126/science.1138478. ISSN 0036-8075. PMID 17289940. S2CID 27719836.
  15. ^ a b Nick, Faezeh M.; Vieli, Andreas; Andersen, Morten Langer; Joughin, Ian; Payne, Antony; Edwards, Tamsin L.; Pattyn, Frank; van de Wal, Roderik S. W. (2013-05-08). "Future sea-level rise from Greenland's main outlet glaciers in a warming climate". Nature. 497 (7448): 235–238. Bibcode:2013Natur.497..235N. doi:10.1038/nature12068. ISSN 0028-0836. PMID 23657350. S2CID 4400824.
  16. ^ a b c "Valley and Piedmont Glaciers (U.S. National Park Service)". www.nps.gov. Retrieved 2019-04-05.
  17. ^ "Glacier".
  18. ^ Dowdeswell, J. A.; Batchelor, C. L.; Hogan, K. A.; Schenke, H.-W. (2016). "Nordvestfjord: a major East Greenland fjord system". Geological Society, London, Memoirs. 46 (1): 43–44. doi:10.1144/m46.40. ISSN 0435-4052. S2CID 133397966.
  19. ^ Elephant Foot Glacier at NASA Earth Observatory
  20. ^ a b Margreth, Stefan; Funk, Martin; Tobler, Daniel; Dalban, Pierre; Meier, Lorenz; Lauper, Juerg (2017). "Analysis of the hazard caused by ice avalanches from the hanging glacier on the Eiger west face". Cold Regions Science and Technology. 144: 63–72. doi:10.1016/j.coldregions.2017.05.012. ISSN 0165-232X.

Sources

  • Benn, Douglas I.; Evans, David J.A. (2010). Glaciers & Glaciation (2nd ed.). Abingdon, UK: Hodder. ISBN 978-0-340-905791.

External links

  Media related to Glacial geomorphology at Wikimedia Commons

March 10, 2023
glacier, morphology, form, glacier, takes, influenced, temperature, precipitation, topography, other, factors, goal, glacial, morphology, gain, better, understanding, glaciated, landscapes, they, shaped, types, glaciers, range, from, massive, sheets, such, gre. Glacier morphology or the form a glacier takes is influenced by temperature precipitation topography and other factors 1 The goal of glacial morphology is to gain a better understanding of glaciated landscapes and the way they are shaped 2 Types of glaciers can range from massive ice sheets such as the Greenland ice sheet to small cirque glaciers found perched on mountain tops 3 Glaciers can be grouped into two main categories Ice flow is constrained by the underlying bedrock topography Ice flow is unrestricted by surrounding topographyFranz Josef Glacier in New Zealand Features of a glacial landscape Contents 1 Unconstrained Glaciers 1 1 Ice sheets and ice caps 1 1 1 Ice sheets 1 1 2 Ice caps 1 2 Ice domes 1 3 Ice streams 2 Constrained Glaciers 2 1 Icefields 2 2 Outlet glaciers 2 3 Valley glaciers 2 3 1 Valley head glaciers 2 3 2 Fjords 2 3 3 Piedmont glaciers 2 3 4 Cirque glaciers 2 3 5 Hanging glacier 3 References 4 Sources 5 External linksUnconstrained Glaciers Edit Vatnajokull ice cap in Iceland Ice sheets and ice caps Edit Ice sheets and ice caps cover the largest areas of land in comparison to other glaciers and their ice is unconstrained by the underlying topography They are the largest glacial ice formations and hold the vast majority of the world s fresh water 4 Ice sheets Edit Ice sheets are the largest form of glacial formation They are continent sized ice masses that span areas over 50 000 square kilometers 19 000 square miles 5 They are dome shaped and similarly to ice caps exhibit radial flow 4 5 6 As ice sheets expand over the ocean they become ice shelves 6 Ice sheets contain 99 of all the freshwater ice found on Earth and form as layers of snow fall accumulate and slowly start to compact into ice 5 There are only two ice sheets present on Earth today and they are the Antarctic ice sheet and the Greenland ice sheet Although only a tenth of modern Earth is covered by ice sheets the Pleistocene epoch was characterized by ice sheets that covered a third of our land This was also known as the Last Glacial Maximum 6 7 Ice caps Edit An ice cap can be defined as a dome shaped mass of ice that exhibits a radial flow 5 They are often easily confused with ice sheets but these ice structures are smaller in size They are smaller than 50 000 km2 and obscure the entirety of the topography they span 5 They mainly form in polar and sub polar regions that can be characterized by having particularly high elevation but flat ground 4 Ice caps come in a variety of shapes they can be round circular or irregular in shape 5 Oftentimes ice caps gradually merge into ice sheets making them difficult to track and document 5 Some examples of ice caps include Jostedal Glacier Norway Devon Ice Cap Canada Barnes Ice Cap Canada Vatnajokull Iceland Flade Isblink GreenlandIce domes Edit An ice dome is a part of an ice cap or ice sheet that is characterized by upstanding ice surface located in the accumulation zone 5 Ice domes are nearly symmetrical with a convex or parabolic surface shape 5 They tend to develop evenly over a land mass that may be either a topographic height or a depression often reflecting the sub glacial topography 5 In ice sheets domes may reach a thickness that may exceed 3 000 meters 9 800 feet However in ice caps the thickness of the dome is much smaller measuring roughly up to several hundred metres in comparison 5 In glaciated islands ice domes are usually the highest point of the ice cap 5 An example of an ice dome is Kupol Vostok Pervyy in Alger Island Franz Josef Land Russia Ice streams Edit Ice streams rapidly channel ice flow out to the sea ocean or an ice shelf For this reason they are commonly referred to as the arteries of an ice sheet 8 9 Ice from continental sheets is drained into the ocean by a complex network of ice streams and their activity is greatly affected by oceanic and atmospheric processes 8 They feature a higher velocity in the centre of the stream and are bounded by slow moving ice on either side 10 Periods of greater ice stream flow result in more ice transfer from ice sheets to the ocean subsequently impacting sea level by raising it 10 At the margin between glacial ice and water ice calving takes place as glaciers begin to fracture and icebergs break off from the large masses of ice 11 9 Iceberg calving is a major contributor to sea level rise but the ocean is not the only place that can experience ice calving 11 Calving can also take place in lakes fjords and continental ice cliffs 11 Constrained Glaciers EditIcefields Edit Southern Patagonia Ice Field from ISS astronaut photo North is to the right An icefield is an example of glacier structure that covers a relatively large area and is usually located in areas characterized by mountain terrain 4 Icefields are quite similar to ice caps however their morphology is much more influenced by the underlying mountainous topography 4 The rock formations found under the icefields are variable and rocky mountain peaks known as nunataks tend to jut out from under the surface of icefields 12 13 Some examples of icefields include Columbia Icefield Canada Juneau Icefield Canada Southern Patagonian Ice Field Chile amp Argentina Harding Icefield USAOutlet glaciers Edit Outlet glaciers are often found in valleys and they originate from major ice sheets and ice caps 4 They move in a singular direction that is determined by the underlying landscape 12 Outlet glaciers drain inland glaciers through gaps found in the surrounding topography 4 A higher amount of inland glacial melt ultimately increases the amount of outlet glacier output 14 Studies predict that outlet glaciers found in Greenland can increase the global sea level considerably following an increase in global temperature and a subsequently higher drainage output 15 Some examples of outlet glaciers include 14 Helheim Glacier Greenland Kangerlussuaq Glacier Greenland Jakobshavn Glacier Greenland Petermann Glacier GreenlandValley glaciers Edit Grosser Aletschgletscher Bernese Alps Switzerland Valley glaciers are outlet glaciers that provide drainage for ice fields icecaps or ice sheets 15 The flow of these glaciers is confined by the walls of the valley they are found in but they may also form in mountain ranges as gathering snow turns to ice 4 16 The formation of valley glaciers is restricted by formations such as terminal moraines which are collections of unconsolidated rock material or till deposited by the terminus of the glacier Ice free exposed bedrock and slopes often surround valley glaciers 17 providing a route for snow and ice to accumulate on the glacier via avalanches Some examples of valley glaciers include Sermilik Glacier Canada Flaajokull IcelandValley head glaciers Edit Valley head glaciers are types of valley glaciers that are only limited to the valley head 16 An example of this type of valley glacier is Baegisarjokull found in Iceland 12 Fjords Edit True fjords are formed when valley glaciers retreat and seawater fills the now empty valley They can be found in mountainous glaciation affected terrain 18 Some examples of fjords include Hvalfjordur Iceland Hornsund Svalbard Sognefjord Norway An existing valley glacier of this type is Jakobshavn Glacier in GreenlandPiedmont glaciers Edit Elephant Foot Glacier a well known Piedmont glacier in Romer Lake northeastern Greenland 19 Piedmont glaciers are a sub type of valley glaciers which have flowed out onto lowland plains where they spread out into a fan like shape 12 16 Some examples of Piedmont glaciers include Malaspina Glacier USA Endeavor Piedmont Glacier AntarcticaCirque glaciers Edit Lower Curtis Glacier is a cirque glacier in the North Cascades in the State of Washington Cirque glaciers are glaciers that appear in bowl shaped valley hollows 4 12 Snow easily settles in the topographic structure it is turned to ice as more snow falls and is subsequently compressed 12 When the glacier melts a cirque structure is left in its place 4 Some examples of cirque glaciers include Lower Curtis Glacier USA Eel Glacier USAHanging glacier Edit A hanging glacier is a form of glacier that appears in a hanging valley and has the potential to break off from the side of the mountain it is attached to 12 20 As bits and pieces of hanging glaciers break off and begin to fall avalanches can be triggered 20 Examples of hanging glaciers include Eiger Glacier Switzerland Angel Glacier CanadaReferences Edit Introduction to Glaciers National Park Service Archived from the original on 2006 09 03 Treatise on geomorphology Shroder John F 1939 London Academic Press 2013 ISBN 9780080885223 OCLC 831139698 a href Template Cite book html title Template Cite book cite book a CS1 maint others link National Snow and Ice Data Center NSIDC 2006 06 01 a b c d e f g h i j Glacier Types Ice caps National Snow and Ice Data Center nsidc org Retrieved 2019 04 05 a b c d e f g h i j k l Paul Frank Ramanathan A L Mandal Arindan 2017 03 06 Ice Caps International Encyclopedia of Geography People the Earth Environment and Technology John Wiley amp Sons Ltd pp 1 10 doi 10 1002 9781118786352 wbieg0210 ISBN 9780470659632 a b c Society National Geographic 2012 08 16 ice sheet National Geographic Society Retrieved 2019 04 05 Clark P U Dyke A S Shakun J D Carlson A E Clark J Wohlfarth B Mitrovica J X Hostetler S W McCabe A M 2009 08 06 The Last Glacial Maximum Science 325 5941 710 714 Bibcode 2009Sci 325 710C doi 10 1126 science 1172873 ISSN 0036 8075 PMID 19661421 S2CID 1324559 a b Spagnolo Matteo Phillips Emrys Piotrowski Jan A Rea Brice R Clark Chris D Stokes Chris R Carr Simon J Ely Jeremy C Ribolini Adriano 2016 02 22 Ice stream motion facilitated by a shallow deforming and accreting bed Nature Communications 7 1 10723 Bibcode 2016NatCo 710723S doi 10 1038 ncomms10723 ISSN 2041 1723 PMC 4764869 PMID 26898399 a b Mcintyre N F 1985 The Dynamics of Ice Sheet Outlets Journal of Glaciology 31 108 99 107 Bibcode 1985JGlac 31 99M doi 10 1017 S0022143000006328 ISSN 0022 1430 a b Stokes C R Margold M Clark C D Tarasov L 2016 02 17 Ice stream activity scaled to ice sheet volume during Laurentide Ice Sheet deglaciation PDF Nature 530 7590 322 326 Bibcode 2016Natur 530 322S doi 10 1038 nature16947 ISSN 0028 0836 PMID 26887494 S2CID 205247646 a b c Benn Douglas I Astrom Jan A 2018 Calving glaciers and ice shelves Advances in Physics X 3 1 1513819 Bibcode 2018AdPhX 313819B doi 10 1080 23746149 2018 1513819 ISSN 2374 6149 a b c d e f g Bjornsson Helgi 2016 10 05 Origins and Nature of Glaciers The Glaciers of Iceland Atlantis Press pp 3 37 doi 10 2991 978 94 6239 207 6 1 ISBN 9789462392069 Dixon John C Thorn Colin E Darmody Robert G 1984 Chemical Weathering Processes on the Vantage Peak Nunatak Juneau Icefield Southern Alaska Physical Geography 5 2 111 131 doi 10 1080 02723646 1984 10642247 ISSN 0272 3646 a b Howat I M Joughin I Scambos T A 2007 03 16 Rapid Changes in Ice Discharge from Greenland Outlet Glaciers Science 315 5818 1559 1561 Bibcode 2007Sci 315 1559H doi 10 1126 science 1138478 ISSN 0036 8075 PMID 17289940 S2CID 27719836 a b Nick Faezeh M Vieli Andreas Andersen Morten Langer Joughin Ian Payne Antony Edwards Tamsin L Pattyn Frank van de Wal Roderik S W 2013 05 08 Future sea level rise from Greenland s main outlet glaciers in a warming climate Nature 497 7448 235 238 Bibcode 2013Natur 497 235N doi 10 1038 nature12068 ISSN 0028 0836 PMID 23657350 S2CID 4400824 a b c Valley and Piedmont Glaciers U S National Park Service www nps gov Retrieved 2019 04 05 Glacier Dowdeswell J A Batchelor C L Hogan K A Schenke H W 2016 Nordvestfjord a major East Greenland fjord system Geological Society London Memoirs 46 1 43 44 doi 10 1144 m46 40 ISSN 0435 4052 S2CID 133397966 Elephant Foot Glacier at NASA Earth Observatory a b Margreth Stefan Funk Martin Tobler Daniel Dalban Pierre Meier Lorenz Lauper Juerg 2017 Analysis of the hazard caused by ice avalanches from the hanging glacier on the Eiger west face Cold Regions Science and Technology 144 63 72 doi 10 1016 j coldregions 2017 05 012 ISSN 0165 232X Sources EditBenn Douglas I Evans David J A 2010 Glaciers amp Glaciation 2nd ed Abingdon UK Hodder ISBN 978 0 340 905791 External links Edit Media related to Glacial geomorphology at Wikimedia Commons Retrieved from https en wikipedia org w index php title Glacier morphology amp oldid 1135817849, wikipedia, wiki, book, books, library,

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