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dc.contributor.authorIverson, N. R.
dc.contributor.authorMcCracken, R. G.
dc.contributor.authorZoet, L. K.
dc.contributor.authorBenediktsson, Í. Ö.
dc.contributor.authorSchomacker, Anders
dc.contributor.authorJohnson, M. D.
dc.contributor.authorWoodard, J.
dc.date.accessioned2018-09-18T13:47:24Z
dc.date.available2018-09-18T13:47:24Z
dc.date.issued2017-11-20
dc.description.abstractThe drumlin field at the surge‐type glacier, Múlajökull, provides an unusual opportunity to build a model of drumlin formation based on field observations in a modern drumlin‐forming environment. These observations indicate that surges deposit till layers that drape the glacier forefield, conform to drumlin surfaces, and are deposited in shear. Observations also indicate that erosion helps create drumlin relief, effective stresses in subglacial till are highest between drumlins, and during quiescent flow, crevasses on the glacier surface overlie drumlins while subglacial channels occupy intervening swales. In the model, we consider gentle undulations on the bed bounded by subglacial channels at low water pressure. During quiescent flow, slip of temperate ice across these undulations and basal water flow toward bounding channels create an effective stress distribution that maximizes till entrainment in ice on the heads and flanks of drumlins. Crevasses amplify this effect but are not necessary for it. During surges, effective stresses are uniformly low, and the bed shears pervasively. Vigorous basal melting during surges releases debris from ice and deposits it on the bed, with deposition augmented by transport in the deforming bed. As surge cycles progress, drumlins migrate downglacier and grow at increasing rates, due to positive feedbacks that depend on drumlin height. Drumlin growth can be accompanied by either net aggradation or erosion of the bed, and drumlin heights and stratigraphy generally correspond with observations. This model highlights that drumlin growth can reflect instabilities other than those of bed shear instability models, which require heuristic till transport assumptions.en_US
dc.description.sponsorshipU.S. National Science Foundation The Icelandic Research Fund The University of Iceland Research Fund The Energy Research Fund of Landsvirkjun The Carlsberg Foundation The Royal Physiographic Society in Lund, Sweden The Fulbright Foundationen_US
dc.descriptionAn edited version of this paper was published by AGU. Copyright (2017) American Geophysical Union. Source at <a href=https://doi.org/10.1002/2017JF004354> https://doi.org/10.1002/2017JF004354</a>.en_US
dc.identifier.citationIverson, N.R., McCracken, R.G., Zoet, L.K., Benediktsson, Í.Ö., Schomacker, A., Johnson, M.D. & Woodard, J. (2017). A Theoretical Model of Drumlin Formation Based on Observations at Múlajökull, Iceland. Journal of Geophysical Research: Earth Surface, 122(12), 2302-2323. https://doi.org/10.1002/2017JF004354en_US
dc.identifier.cristinIDFRIDAID 1523908
dc.identifier.doi10.1002/2017JF004354
dc.identifier.issn2169-9003
dc.identifier.issn2169-9011
dc.identifier.urihttps://hdl.handle.net/10037/13827
dc.language.isoengen_US
dc.publisherAmerican Geophysical Union (AGU)en_US
dc.relation.journalJournal of Geophysical Research - Earth Surface
dc.rights.accessRightsopenAccessen_US
dc.subjectVDP::Matematikk og Naturvitenskap: 400::Geofag: 450::Kvartærgeologi, glasiologi: 465en_US
dc.subjectVDP::Mathematics and natural science: 400::Geosciences: 450::Quaternary geology, glaciology: 465en_US
dc.subjectglacieren_US
dc.subjectdrumlinen_US
dc.subjectmodelen_US
dc.subjectsurgeen_US
dc.subjecterosionen_US
dc.subjectdepositionen_US
dc.titleA Theoretical Model of Drumlin Formation Based on Observations at Múlajökull, Icelanden_US
dc.typeJournal articleen_US
dc.typeTidsskriftartikkelen_US
dc.typePeer revieweden_US


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