A Framework for the Investigation of Medial Moraine Formation: Austerdalsbreen, Norway, and Berendon Glacier, British Columbia, Canada

Eyles, Nicholas; Rogerson, Robert

doi:10.3189/s0022143000021249

Cited by 41 publications

(62 citation statements)

References 37 publications

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“…The model replicates the deposition of debris onto the glacier surface leading to the formation of ablation-dominant and avalanche-type medial moraines on the glacier surface (Benn and Evans, 2010). For simplicity, we neglect englacial thrusting and ice-stream interaction moraines (medial moraines associated with tributary junctions; see Eyles and Rogerson, 1978;Anderson, 2000;Benn and Evans, 2010). These cases can be treated in subsequent modeling that incorporates the 2-D planform complexities of valley glaciers.…”

Section: Debris Depositionmentioning

confidence: 99%

Modeling debris-covered glaciers: response to steady debris deposition

2016

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Abstract. Debris-covered glaciers are common in rapidly eroding alpine landscapes. When thicker than a few centimeters, surface debris suppresses melt rates. If continuous debris cover is present, ablation rates can be significantly reduced leading to increases in glacier length. In order to quantify feedbacks in the debris-glacier-climate system, we developed a 2-D long-valley numerical glacier model that includes englacial and supraglacial debris advection. We ran 120 simulations on a linear bed profile in which a hypothetical steady state debris-free glacier responds to a step increase of surface debris deposition. Simulated glaciers advance to steady states in which ice accumulation equals ice ablation, and debris input equals debris loss from the glacier terminus. Our model and parameter selections can produce 2-fold increases in glacier length. Debris flux onto the glacier and the relationship between debris thickness and melt rate strongly control glacier length. Debris deposited near the equilibriumline altitude, where ice discharge is high, results in the greatest glacier extension when other debris-related variables are held constant. Debris deposited near the equilibrium-line altitude re-emerges high in the ablation zone and therefore impacts melt rate over a greater fraction of the glacier surface. Continuous debris cover reduces ice discharge gradients, ice thickness gradients, and velocity gradients relative to initial debris-free glaciers. Debris-forced glacier extension decreases the ratio of accumulation zone to total glacier area (AAR). Our simulations reproduce the "general trends" between debris cover, AARs, and glacier surface velocity patterns from modern debris-covered glaciers. We provide a quantitative, theoretical foundation to interpret the effect of debris cover on the moraine record, and to assess the effects of climate change on debris-covered glaciers.

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Section: Debris Depositionmentioning

confidence: 99%

Modeling debris-covered glaciers: response to steady debris deposition

2016

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“…Previous studies of temperate glaciers either consider debris transport as part of a largerscale glacier system approach (e.g. Boulton and Eyles, 1979;Drewry, 1986;Small, 1987;Kirkbride, 1995;Evans, 2003), or are concerned only with specific aspects of debris transport, for example the development of medial moraines (Eyles and Rogerson, 1978;Small and others, 1979;Gomez and Small, 1985;Anderson, 2000) or dirt cones (Boulton, 1967;Drewy, 1972;Kirkbride and Spedding, 1996). In this paper we concentrate on the relationship between debris transport processes and glacier structure, in particular the role of folding in medial moraine formation, the formation of dirt cones from englacial debris layers, and the role of crevassing.…”

Section: Introductionmentioning

confidence: 99%

Debris transport in a temperate valley glacier: Haut Glacier d’Arolla, Valais, Switzerland

2005

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ABSTRACT. This paper considers the role of structural glaciology in debris entrainment, transport and deposition at Haut Glacier d'Arolla, a temperate valley glacier in Valais, Switzerland. Sedimentological descriptions and clast analysis have been used to identify relationships between ice structure and debris transport. Relationships identified are (1) debris associated with crevasse traces, (2) the folding of rockfall material incorporated within primary stratification to form medial moraines and (3) dirt cones and englacial debris layers associated with reactivated crevasse traces. A conceptual model is introduced to summarize the manner in which ice structures at Haut Glacier d'Arolla control entrainment and deposition of debris.

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“…The inter-relationships between the source and character of glacial debris and the morphology and development of medial moraines on temperate valley glaciers have been considered in two recent papers (Eyles and Rogerson, 1978;Boulton and Eyles, 1979). Two principal models of medial moraine formation have been postulated.…”

Section: Introductionmentioning

confidence: 99%

Medial Moraines of the Haut Glacier D’arolla, Valais, Switzerland: Debris Supply and Implications For Moraine Formation

Gómez

Small

1985

J. Glaciol.

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ABSTRACT. The Haut Glacier d' Arolla displays three medial moraines: an ablation-dominant moraine east of the glacier centre line, an ice-stream interaction moraine west of the glacier centre line, and a medial-lateral supraglacial moraine complex along the western margin of the glacier. The eastern moraine is formed by the emergence of coarse angular clasts from a series of short longitudinal debris bands 1 km from the glacier terminus; this debris is derived from rock falls at the glacier head-wall, and follows a low-level transport path through the glacier. The western moraine is formed partly by the direct fall of weathered debris on to the ice surface at a point 2.6 km from the snout, but it receives further increments of sediment from extensive longitudinal en glacial debris bands developed from the convergence of two ice streams with lateral englacial debris septa. The medial-lateral moraine complex is formed largely by rock falls from the western valley wall, but is also nourished by a debris layer developed at the base of the small tributary Glacier de la Mitre. This layer crops out at the eastern margin of the re-sultant inset ice stream, and releases more rounded, abraded and comminuted rock fragments to supplement the surface debris cover of supraglacial origin. RESUME.

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A Framework for the Investigation of Medial Moraine Formation: Austerdalsbreen, Norway, and Berendon Glacier, British Columbia, Canada

Cited by 41 publications

References 37 publications

Modeling debris-covered glaciers: response to steady debris deposition

Modeling debris-covered glaciers: response to steady debris deposition

Debris transport in a temperate valley glacier: Haut Glacier d’Arolla, Valais, Switzerland

Medial Moraines of the Haut Glacier D’arolla, Valais, Switzerland: Debris Supply and Implications For Moraine Formation

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