Outwash plain - Wikipedia

An outwash plain, also called a sandur (plural: sandurs), sandr or sandar, is a plain formed of glaciofluvial deposits due to meltwater outwash at the ... Outwashplain FromWikipedia,thefreeencyclopedia Jumptonavigation Jumptosearch Plainformedfromglaciersedimentthatwastransportedbymeltwater. Thisarticleisabouttheglacialgeographicalfeature.Forthenon-glacierrelatedfeature,seeAlluvialplain. Thisarticleincludesalistofgeneralreferences,butitlackssufficientcorrespondinginlinecitations.Pleasehelptoimprovethisarticlebyintroducingmoreprecisecitations.(March2018)(Learnhowandwhentoremovethistemplatemessage) SkeiðarársandurinIceland,viewedfromitseasternmarginattheterminusofSvínafellsjökullglacier Anoutwashplain,alsocalledasandur(plural:sandurs[1]),sandr[2]orsandar,[3]isaplainformedofglaciofluvialdepositsduetomeltwateroutwashattheterminusofaglacier.Asitflows,theglaciergrindstheunderlyingrocksurfaceandcarriesthedebrisalong.Themeltwateratthesnoutoftheglacierdepositsitsloadofsedimentovertheoutwashplain,withlargerbouldersbeingdepositedneartheterminalmoraine,andsmallerparticlestravellingfurtherbeforebeingdeposited.SandursarecommoninIcelandwheregeothermalactivityacceleratesthemeltingoficeflowsandthedepositionofsedimentbymeltwater. Contents 1Formation 2Theprototypesandur 3Fossilsandar 4Seealso 5References 6Externallinks Formation[edit] Sandursarefoundinglaciatedareas,suchasSvalbard,KerguelenIslands,andIceland.Glaciersandicecapscontainlargeamountsofsiltandsediment,pickedupastheyerodetheunderlyingrockswhentheymoveslowlydownhill,andatthesnoutoftheglacier,meltwatercancarrythissedimentawayfromtheglacieranddeposititonabroadplain.Thematerialintheoutwashplainisoftensize-sortedbythewaterrunoffofthemeltingglacierwiththefinestmaterials,likesilt,beingthemostdistantlyre-deposited,whereaslargerbouldersaretheclosesttotheoriginalterminusoftheglacier. Anoutwashplainmightcontainsurficialbraidedstreamcomplexesthatreworktheoriginaldeposits.Theymayalsocontainkettlelakes,locationswhereblocksoficehavemelted,leavingadepressionthatfillswithwater.Theflowpatternofglacialriversacrosssandaristypicallydiffuseandunchannelized,butinsituationswheretheglacialsnouthasretreatedfromtheterminalmoraine,theflowismorechannelized. SandursaremostcommoninIceland,wheregeothermalactivitybeneathicecapsspeedsupthedepositionofsedimentbymeltwater.Aswellasregulargeothermalactivity,volcanicactivitygivesrisetolargeglacialburstsseveraltimesacentury,whichcarrydownlargevolumesofsediment. TheGaspéPeninsulathatmakesuptheessentialpartofsouthernQuebec(LowerSt-LawrenceandGaspéareas)alsocontainsseveralexampleofpaleo-sandar,datingfromthePleistoceneicemelt. ThewesternedgeofSkeiðarársandurinIcelandshowsthediffusedrainagechannelstypicalofsandur. Theprototypesandur[edit] Unimpededbytopographicobstructions,sand-bearingkatabaticwindscanbefierceenoughonSkeiðarársandurtostrippaintfromcars.[4]Here,sandisblownintheairinfrontofthepeakLómagnúpur. OneofthesandursfromwhichthegeneralnameisderivedisSkeiðarársandur,abroadsandywastelandalongIceland'ssouth-easterncoast,betweentheVatnajökullicecapandthesea.Volcaniceruptionsundertheicecaphavegivenrisetomanylargeglacialbursts(jökulhlaupsinIcelandic),mostrecentlyin1996,whentheRingRoadwaswashedaway(minorfloodshavealsooccurredsincethen).Thisroad,whichencirclesIcelandandwascompletedin1974,hassincebeenrepaired.The1996jökulhlaupwascausedbytheeruptionoftheGrímsvötnvolcano,withpeakflowestimatedtobe50,000 m3/s(1,800,000 cu ft/s)comparedtothenormalsummerpeakflowof200 to400 m3/s(7,100–14,100 cu ft/s).Netdepositionofsedimentwasestimatedtobe12,800,000 m3(450,000,000 cu ft). ThemainbraidedchannelsofSkeiðarársanduraretheGígjukvísl[ˈciːjʏˌkʰvistl̥]andSkeiðarárivers,whichincurrednetgainsof29and24 cm(11.4and9.4 in)respectivelyduringthe1996jökulhlaup.IntheGígjukvísltherewasmassivesedimentdepositionofupto12 m(39 ft),whichoccurredclosesttotheterminusoftheglacier.TheerosionalpatternsofSkeiðarársandurcanbeseenbylookingatthecentimetre-scaleelevationdifferencesmeasuredwithrepeat-passlaseraltimetry(LIDAR)flownin1996(pre-flood),1997,and2001.Oftheoveralldepositionduringthe1996jökulhlaup,nearlyhalfofthenetgainhadbeeneroded4yearsaftertheflood.Thesetworiversonthesandurdisplaydrasticallydifferenterosionalpatterns.Thedifferenceinsedimenterosioncanbeattributedtothe2 km(1.2 mi)widetrenchneartheterminuswheretheGígjukvíslflows,incontrastwiththeSkeiðará,whichhasbraidedflowsdirectlyontotheoutwashplain.TheGígjukvíslriveriswheresomeofthehighestlevelofsedimentdepositoccurredandalsowherethelargesterosionhappenedafterward.Thisindicatesthatthesemassivejökulhlaupdepositsmayhavealargegeomorphicimpactintheshortterm,butthenetchangeonthesurfacereliefcouldbeminimalafteracoupleyearstoadecade. TheobservedchangeofSkeiðarársandurfromadiffusetoachannelizeddistributarysystemwhereithasthemostobservedsedimentdeposithasasignificantimpactonthedevelopmentofthefluvialsuccessionintheproximalzone.However,inordertohavesustainedactiveaccretionacrosstheentiresandurthereneedstobeadiffuse,multipointdistributionsystem.ThesystemofaccumulationonSkeiðarársandur,whichisaproductofglacierretreat,canbeseenasmultipleregionsofdifferingchannelpatternsthatdistributesedimentacrosstheplainindynamicconfigurations. Fossilsandar[edit] Fossilsandar(i.e.nolongeractive)arefoundinareaswhichwereformerlyglaciated.AnexamplewouldbetheUskValleyofSouthWaleswheretowardstheendofthelasticeage,therecedingUskvalleyglacierleftbehindaseriesofrecessionalmorainesandsandardepositsdown-valleyofthem.Manyofthesandarsurfacesarestillvisiblealbeitdegradedoversucceedingmillennia.[5]ExtensivesandararealsorecordedintheeasternpartoftheCheshirePlainandbeneathMorecambeBay,bothinnorthwestEngland.'Valleysandur'depositsarerecordedfromvariouslocalitiesinthatsameregion.[6] Seealso[edit] KankakeeOutwashPlain Terminalmoraine –Typeofmorainethatformsattheterminalofaglacier References[edit] ^Ritter,DaleF.,R.CraigKochel,&JerryRussellMiller.1995.Processgeomorphology.Dubuque,IA:WmC.Brown,p.349. ^Whittow,John(1984).DictionaryofPhysicalGeography.London:Penguin,1984,p.467.ISBN 0-14-051094-X. ^Gornitz,Vivien(ed.).2009.EncyclopediaofPaleoclimatologyAndAncientEnvironments.Springer:Dordrecht,p.665. ^Leffman,David;Proctor,James(2004).TheRoughGuidetoIceland.RoughGuides.p. 28.ISBN 9781843532897. ^Lewis,S.G.(ed);Maddy,D.(ed);Thomas,G.S.P(chapterauthor)(1997).GeomorphologyoftheMiddleUskValley(chapter)inTheQuaternaryoftheSouthMidlandsandtheWelshMarches(FieldGuide)(1st ed.).QuaternaryResearchAssociation.ISBN 0907780520.{{citebook}}:|first1=hasgenericname(help) ^Aitkenhead,N;et al.(2002).Britishregionalgeology:thePenninesandadjacentareas(4th ed.).Nottingham:BritishGeologicalSurvey.pp. 109–110.ISBN 0852724241. Church,MichaelA.(1972),BaffinIslandsandurs:astudyofarcticfluvialprocesses. GarvinJ.B.(2001),TopographicDynamicsofKerguelenIsland:APreliminarySRTMAnalysis,AmericanGeophysicalUnion,FallMeeting2001 GomezB.,RussellA.J.,FinneganD.C.,SmithL.C.,KnudsenO.(2001),SedimentDistributiononSkeidararsandur,SoutheastIceland,AmericanGeophysicalUnion,FallMeeting2001 HardardottirJ.,SnorrasonA.,ZophoniassonS.,JonssonP.,SigurdssonO.,ElefsenS.O.(2003),GlacialOutburstFloods(Jökulhlaups)inIceland,EGS-AGU-EUGJointAssembly,AbstractsfromthemeetingheldinNice,France,6–11April2003 MagilliganF.J.,GomezB.,MertesL.A.K.,Smith,L.C.SmithN.D.,FinneganD.,GarvinJ.B.,Geomorphiceffectiveness,sandurdevelopment,andthepatternoflandscaperesponseduringjökulhlaups:Skeiðarársandur,southeasternIceland,Geomorphology44(2002)95–113 Hétu,B.,LadéglaciationdelarégiondeRimouski,Bas-Saint-Laurent(Québec):Indicesd'unerécurrenceglaciairedanslamerdeGoldthwaitentre12400et12000BP,GéographiephysiqueetQuaternaire,1998,vol.52,n.3,p. 325-347 SmithL.C.,ShengY.,MagilliganF.J.,SmithN.D.,GomezB.,MertesL.,KrabillW.B.,GarvenJ.B.,Geomorphicimpactandrapidsubsequentrecoveryfromthe1996Skeiðarársandurjökulhlaup,Iceland,measuredwithmulti-yearairbornelidar.Geomorphologyvol.75Is.1-2(2006)65-75 Externallinks[edit] NASApageabouttheSkeiðarársandur AstudyofsandurformationinwesternGreenland 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 vteSedimenttransportWater Coastalsedimenttransport Fluvialprocesses Bedload Suspendedload Bedmaterialload Glacial Glacialflour Glacialoutwash Braidedriver Moraine Esker Drumlin Hillslope Soilcreep Landslide Aeolian Dune Authoritycontrol:Nationallibraries Germany Retrievedfrom"https://en.wikipedia.org/w/index.php?title=Outwash_plain&oldid=1096657814" Categories:OutwashplainsGlaciallandformsGlaciologyHiddencategories:CS1errors:genericnameArticleswithshortdescriptionShortdescriptionisdifferentfromWikidataArticleslackingin-textcitationsfromMarch2018Allarticleslackingin-textcitationsArticleswithGNDidentifiers Navigationmenu Personaltools NotloggedinTalkContributionsCreateaccountLogin Namespaces ArticleTalk English Views ReadEditViewhistory More Search Navigation MainpageContentsCurrenteventsRandomarticleAboutWikipediaContactusDonate Contribute HelpLearntoeditCommunityportalRecentchangesUploadfile Tools WhatlinkshereRelatedchangesUploadfileSpecialpagesPermanentlinkPageinformationCitethispageWikidataitem Print/export DownloadasPDFPrintableversion Inotherprojects WikimediaCommons Languages AzərbaycancaБеларускаяБеларуская(тарашкевіца)CatalàČeštinaDeutschEestiEspañolFrançaisÍslenskaKaszëbscziҚазақшаKernowekКыргызчаLietuviųMagyarNederlandsNorsknynorskPolskiРусскийSimpleEnglishSuomiSvenskaTürkçeУкраїнська Editlinks