Esker - Wikipedia

An esker, eskar, eschar, or os, sometimes called an asar, osar, or serpent kame, is a long, winding ridge of stratified sand and gravel, examples of which ... Esker FromWikipedia,thefreeencyclopedia Jumptonavigation Jumptosearch Long,windingridgeofstratifiedsandandgravelassociatedwithformerglaciers Forotheruses,seeEsker(disambiguation). EskeratFulufjället,westernSweden Eskerusedasahikingpath AerialviewofapartiallydrownedeskeratBilluddeninnorthernUppland,Sweden.Theshapeismodifiedbycoastalprocesses. Anesker,eskar,eschar,oros,sometimescalledanasar,osar,orserpentkame,[1][2]isalong,windingridgeofstratifiedsandandgravel,examplesofwhichoccuringlaciatedandformerlyglaciatedregionsofEuropeandNorthAmerica.Eskersarefrequentlyseveralkilometreslongand,becauseoftheiruniformshape,looklikerailwayembankments.[3] Contents 1Etymology 2Geology 3Lifeoneskers 4Examplesofeskers 4.1Europe 4.2NorthAmerica 5Seealso 6References 7Externallinks Etymology PortionsoftheDenaliHighwayinAlaskaarebuiltoneskers ThetermeskerisderivedfromtheIrishwordeiscir(OldIrish:escir),whichmeans"ridgeorelevation,especiallyoneseparatingtwoplainsordepressedsurfaces".[4]TheIrishwordwasandisusedparticularlytodescribelongsinuousridges,whicharenowknowntobedepositsoffluvio-glacialmaterial.Thebest-knownexampleofsuchaneisciristheEiscirRiada,whichrunsnearlythewholewidthofIrelandfromDublintoGalway,adistanceof200 km,andisstillcloselyfollowedbythemainDublin-Galwayroad ThesynonymoscomesfromtheSwedishwordås,"ridge". Geology Mosteskersarearguedtohaveformedwithinice-walledtunnelsbystreamsthatflowedwithinandunderglaciers.Theytendedtoformaroundthetimeoftheglacialmaximum,whentheglacierwasslowandsluggish.Aftertheretainingicewallsmeltedaway,streamdepositsremainedaslongwindingridges. Eskersmayalsoformaboveglaciersbyaccumulationofsedimentinsupraglacialchannels,increvasses,inlinearzonesbetweenstagnantblocks,orinnarrowembaymentsatglaciermargins.Eskersformneartheterminalzoneofglaciers,wheretheiceisnotmovingasfastandisrelativelythin.[5] EskerinSimsCornerEskersandKamesNationalNaturalLandmark,Washington,US.(Treesattheedgeoftheeskerandthesinglelaneroadcrossingtheeskertotherightofthephotoprovidescale.) Plasticflowandmeltingofthebasalicedeterminesthesizeandshapeofthesubglacialtunnel.Thisinturndeterminestheshape,compositionandstructureofanesker.Eskersmayexistasasinglechannel,ormaybepartofabranchingsystemwithtributaryeskers.Theyarenotoftenfoundascontinuousridges,buthavegapsthatseparatethewindingsegments.Theridgecrestsofeskersarenotusuallylevelforverylong,andaregenerallyknobby.Eskersmaybebroad-crestedorsharp-crestedwithsteepsides.[5]Theycanreachhundredsofkilometersinlengthandaregenerally20–30metresinheight. Thepathofaneskerisgovernedbyitswaterpressureinrelationtotheoverlyingice.Generally,thepressureoftheicewasatsuchapointthatitwouldalloweskerstoruninthedirectionofglacialflow,butforcethemintothelowestpossiblepointssuchasvalleysorriverbeds,whichmaydeviatefromthedirectpathoftheglacier.Thisprocessiswhatproducesthewideeskersuponwhichroadsandhighwayscanbebuilt.Lesspressure,occurringinareasclosertotheglacialmaximum,cancauseicetomeltoverthestreamflowandcreatesteep-walled,sharply-archedtunnels.[6] Theconcentrationofrockdebrisintheiceandtherateatwhichsedimentisdeliveredtothetunnelbymeltingandfromupstreamtransportdeterminestheamountofsedimentinanesker.Thesedimentgenerallyconsistsofcoarse-grained,water-laidsandandgravel,althoughgravellyloammaybefoundwheretherockdebrisisrichinclay.Thissedimentisstratifiedandsorted,andusuallyconsistsofpebble/cobble-sizedmaterialwithoccasionalboulders.Beddingmaybeirregularbutisalmostalwayspresent,andcross-beddingiscommon.[5] Therearevariouscaseswhereinlandduneshavedevelopednexttoeskersafterdeglaciation.[7]Thesedunesareoftenfoundintheleewardsideofeskers,iftheeskerisnotorientedparalleltoprevailingwinds.[7]ExamplesofdunesdevelopedoneskerscanbefoundinbothSwedishandFinnishLapland.[7][8] Lakesmayformwithindepressionsineskers.Theselakescanlacksurfaceoutflowsandinflowsandhavedrasticfluctuationsovertime.[9] Lifeoneskers EskersarecriticaltotheecologyofNorthernCanada.Severalplantsthatgrowoneskers,includingbearrootandcranberries,areimportantfoodforbearsandmigratingwaterfowl;animalsfromgrizzlybearstotundrawolvestogroundsquirrelscanburrowintotheeskerstosurvivethelongwinters.[10] Examplesofeskers ApartoftheMasonEsker MountPellyorOvayok Europe InSwedenUppsalaåsenstretchesfor250 km(160 mi)andpassesthroughUppsalacity.TheBadelundaåseneskerrunsforover300 km(190 mi)fromNyköpingtolakeSiljan.Pispala'sPyynikkiEskerinTampere,Finlandisonaneskerbetweentwolakescarvedbyglaciers.AsimilarsiteisPunkaharjuinFinnishLakeland. ThevillageofKemnayinAberdeenshire,Scotlandhasa5 kmeskerlocallycalledtheKembHills.InBerwickshireinsoutheastScotlandisBedshielKaims,a3 kmlongexamplewhichisupto15mhighandisalegacyofanice-streamwithintheTweedValley.[11] NorthAmerica GreatEskerParkrunsalongtheBackRiverinWeymouth,MassachusettsandishometothehighesteskerinNorthAmerica(90 ft).[12] Thereareover1,000eskersinthestateofMichigan,primarilyinthesouth-centralLowerPeninsula.ThelongesteskerinMichiganisthe22milelongMasonEsker,whichstretchessouth-southeastfromDeWittthroughLansingandHolt,beforeendingnearMason.[13] EskersystemsintheU.S.stateofMainecanbetracedforupto100miles.[1] TheThelonEskerrunsfor800kilometers(497miles)andstraddlestheborderbetweenNorthwestTerritoriesandNunavutinCanada.[14] UvayuqorMountPelly,inOvayokTerritorialPark,theKitikmeotRegion,Nunavutisanesker. Roadsaresometimesbuiltalongeskerstosaveexpense.ExamplesincludetheDenaliHighwayinAlaska,theTrans-TaigaRoadinQuebec,andthe"Airline"segmentofMaineStateRoute9betweenBangorandCalais.[15]TherearenumerouslongeskersintheAdirondackStateParkinupstateNewYork. Seealso EskersProvincialPark –ProvincialparkinBritishColumbia(BritishColumbia,Canada) Glaciallandform –Landformcreatedbytheactionofglaciers Glaciermorphology –Geomorphologyofglaciers Kame –Moundformedonaretreatingglacieranddepositedonland Tunnelvalley –Glacial-formedgeographicfeature References Trenhaile,Alan(2007).Geomorphology:ACanadianPerspective.DonMills,Ontario:OxfordUniversityPress.pp. 188–191.ISBN 978-0-19-542474-4. ^CollinsEnglishDictionary ^"McGraw-HillDictionaryofScientific&TechnicalTerms".Archivedfromtheoriginalon2015-04-20.Retrieved2015-06-30. ^Gedney,Larry(August1,1984)."Eskers:TheUpside-DownRiverbeds".AlaskaScienceForumArticle#674.Archivedfromtheoriginalon4April2012.Retrieved29September2011. ^Quin,E.G.(gen.ed.)(1983).DictionaryoftheIrishLanguage.Dublin:RoyalIrishAcademy.p. 281.ISBN 0-901714-29-1. ^abcEasterbrook,D.J.(1999).SurfaceProcessesandLandforms.NewJersey:PrenticeHall.p. 352.ISBN 0-13-860958-6. ^Shreve,R.L.,1985,Eskercharacteristicsintermsofglacierphysics,Katahdineskersystem,Maine:GSABulletin,v.96,pp.639–646. ^abcSeppälä,Matti(2004)."Accumulation".WindasaGeomorphicAgentinColdClimates.CambridgeUniversityPress.pp. 207–208.ISBN 9780521564069. ^Seppälä,Matti(1972)."Location,morphologyandorientationofinlanddunesinnorthernSweden".GeografiskaAnnaler:SeriesA,PhysicalGeography.54(2):85–104.doi:10.1080/04353676.1972.11879860. ^Källakademin(2006).KälloriSverige(inSwedish).Sundbyberg:SvenskByggtjänst.p. 196.ISBN 91-7333-104-X. ^NationalGeographicAlmanacofGeography,2005,p.155,ISBN 0-7922-3877-X ^Stone,P.(2012).SouthofScotland(BritishRegionalGeology)(Fourth ed.).BritishGeologicalSurvey.pp. 191–92.ISBN 978-085272-694-5. ^"MountainAndGlacialLandforms:WhatIsAnEsker?".WorldAtlas.2017-04-25.Retrieved2022-07-13. ^"Eskers".Archivedfromtheoriginalon2013-12-03.Retrieved2013-12-02. ^Gray,Charlotte(2004).TheMuseumCalledCanada:25RoomsofWonder.RandomHouse.ISBN 0-679-31220-X. ^DownEastRegion Externallinks WikimediaCommonshasmediarelatedtoEsker. ObliqueaerialphotoofaneskerinWaterford,Maine EskerRiadaWebpage Diagramillustrating(i)tunnelinglacierbeforeretreatofice,forming(ii)meanderingeskerinTheIceMelts:Deposition,p. 6of"PennsylvaniaandtheIceAge"published1999byPADCNRBureauofTopographicandGeologicSurvey TheBridgenorthEsker:geomorphologyandsedimentology vteGlaciersTypes Aufeis Cirque Icecap Icefield Icesheet Iceshelf Icestream Ledoyom Outletglacier Piedmontglacier Rockglacier Valleyglacier Anatomy Ablationzone Accumulationzone Bergschrund Blueice Crevasse Dirtcone Firn Glaciercave Glacierhead Icedivide Icetongue Icefall Lateralmoraine Medialmoraine Moraine Moulin Penitente Randkluft Sérac Terminus Processes Ablation Accumulation Basalsliding Calving Creep Motion Outburstflood Overdeepening Plucking Retreat Starvation Surge Measurements Icecore Massbalance Volcanicrelations Jökulhlaup Subglacialeruption Subglacialvolcano Tuya LandformsErosional Arête Cirque Cirquestairway Cragandtail Fingerlake Fjord Glacialhorn Glaciallake Glacialstriae Hangingvalley P-form Ribbonlake Rochemoutonnée Suncup Tarn Troughlake Troughvalley Tunnelvalley U-valley Valleystep Zungenbecken Depositional Drumlin Erraticblock Moraine Moraine-dammedlake Puljumoraine Rogenmoraine Sevettimoraine Terminalmoraine Tillplain Veikimoraine Glaciofluvial Alpentor Diluvium Esker Giantcurrentripples Kame Kamedelta Kettlehole Outwashfan Sandur Urstromtal Glaciology Category List Template:Periglacialenvironment vteContinentalglaciationsGeneral Cordilleranicesheet LaurentideIceSheet LastGlacialMaximum CanadianShield GlacialhistoryofMinnesota Listofprehistoriclakes Proglaciallake LakeAgassiz LakeChicago LakeTight TeaysRiver Post-glacialrebound Timelineofglaciation LandformsErosional Fjord Glacialstriae Ribbonlake Rochemoutonnée Tunnelvalley U-shapedvalley Depositional Drumlin Erraticblock Moraine Puljumoraine Rogenmoraine Terminalmoraine Tillplain Veikimoraine Glacifluvial Diluvium Esker Giantcurrentripples Kame Kamedelta Kettlehole Outwashfan Sandur NorthAmericaCanada ArrowheadProvincialPark,Ontario BigRock(glacialerratic),Alberta CypressHills(Canada),Saskatchewan EramosaRiver,Ontario EskersProvincialPark,BritishColumbia FoothillsErraticsTrain,Alberta Lion'sHeadProvincialPark,Ontario OriginoftheOakRidgesMoraine,Ontario OvayokTerritorialPark,Nunavut UnitedStates ChippewaMoraineStateRecreationArea,Wisconsin CoteaudesPrairies,SouthDakota Devil'sLakeStatePark,Wisconsin GlacialLakeWisconsin,Wisconsin GlacialLakesStatePark,Minnesota HoriconMarshStateWildlifeArea,Wisconsin IceAgeFloodsNationalGeologicTrail,Idaho,Oregon&Washington IceAgeNationalScientificReserve,Wisconsin IceAgeTrail,Wisconsin InterstateStatePark,Minnesota&Wisconsin KelleysIsland,Ohio KettleMoraineStateForest,Wisconsin LakeBonneville,Utah LakeLahontan,Nevada LakeMissoula,Montana MillBluffStatePark,Wisconsin OneidaLake,NewYork TwoCreeksBuriedForestStateNaturalArea,Wisconsin WithrowMoraineandJamesonLakeDrumlinField,Washington YosemiteNationalPark,California EurasiaandAntarctica Antarctica Hardangerfjord KillaryHarbour LambertGlacier MonteRosa RossIceShelf Svalbard Timeperiods Quaternaryglaciation IllinoianStage Interglacial Interstadial PenultimateGlacialPeriod LastGlacialPeriod LastGlacialMaximum MousterianPluvial Holoceneglacialretreat OldestDryas OlderDryas Pleistocene Pre-IllinoianStage Quaternaryglaciation SangamonianStage Wisconsinglaciation Bølling-Allerødwarming LateGlacialInterstadial Huelmo–MascardiColdReversal YoungerDryas Africanhumidperiod 8.2kiloyearevent 4.2kiloyearevent PioraOscillation LittleIceAge Category vteSedimenttransportWater Coastalsedimenttransport Fluvialprocesses Bedload Suspendedload Bedmaterialload Glacial Glacialflour Glacialoutwash Braidedriver Moraine Esker Drumlin Hillslope Soilcreep Landslide Aeolian Dune Retrievedfrom"https://en.wikipedia.org/w/index.php?title=Esker&oldid=1106106902" Categories:EskersHiddencategories:CS1Swedish-languagesources(sv)ArticleswithshortdescriptionShortdescriptionisdifferentfromWikidataWikipediaindefinitelysemi-protectedpagesCommonslinkisonWikidata Navigationmenu Personaltools NotloggedinTalkContributionsCreateaccountLogin Namespaces ArticleTalk English Views ReadViewsourceViewhistory More Search Navigation MainpageContentsCurrenteventsRandomarticleAboutWikipediaContactusDonate Contribute HelpLearntoeditCommunityportalRecentchangesUploadfile Tools WhatlinkshereRelatedchangesUploadfileSpecialpagesPermanentlinkPageinformationCitethispageWikidataitem Print/export DownloadasPDFPrintableversion Inotherprojects WikimediaCommons Languages العربيةAsturianuAzərbaycancaБеларускаяБеларуская(тарашкевіца)БългарскиCatalàČeštinaCymraegDanskDeutschEestiEspañolفارسیFrançaisGaeilgeGalego한국어Հայերենहिन्दीÍslenskaItalianoעבריתქართულიҚазақшаKernowekLatinaLatviešuLietuviųMagyarNederlands日本語NorskbokmålNorsknynorskPolskiPortuguêsРусскийСрпски/srpskiSuomiSvenskaTürkçeУкраїнськаVõro中文 Editlinks