Minor end moraines of the Wisconsin Valley Lobe, north‐central Wisconsin, USA

Ham, Nelson R.; Attig, John W.

doi:10.1111/j.1502-3885.2001.tb00986.x

Cited by 7 publications

(4 citation statements)

References 31 publications

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“…The sedimentological end products (ice‐marginal moraines) in ancient glacial environments can thus be used to reconstruct past glacier dynamics (e.g. Ham and Attig, ; Sutherland et al ., ).…”

Section: Introductionmentioning

confidence: 99%

Sub‐annual moraine formation at an active temperate Icelandic glacier

Chandler

Evans

et al. 2020

Earth Surf Processes Landf

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This paper presents detailed geomorphological and sedimentological investigations of small recessional moraines at Fjallsjökull, an active temperate outlet of Öræfajökull, southeast Iceland. The moraines are characterized by striking sawtooth or hairpin planforms, which are locally superimposed, giving rise to a complex spatial pattern. We recognize two distinct populations of moraines, namely a group of relatively prominent moraine ridges (mean height ~1.2 m) and a group of comparatively low‐relief moraines (mean height ~0.4 m). These two groups often occur in sets/systems, comprising one pronounced outer ridge and several inset smaller moraines. Using a representative subsample of the moraines, we establish that they form by either (i) submarginal deformation and squeezing of subglacial till or (ii) pushing of extruded tills. Locally, proglacial (glaciofluvial) sediments are also incorporated within the moraines during pushing. For the first time, to our knowledge, we demonstrate categorically that these moraines formed sub‐annually using repeat uncrewed aerial vehicle (UAV) imagery. We present a conceptual model for sub‐annual moraine formation at Fjallsjökull that proposes the sawtooth moraine sequence comprises (i) sets of small squeeze moraines formed during melt‐driven squeeze events and (ii) larger push moraines formed during winter re‐advances. We suggest the development of this process‐form regime is linked to a combination of elevated temperatures, high surface meltwater fluxes to the bed and emerging basal topography (a depositional overdeepening). These factors result in highly saturated subglacial sediments and high porewater pressures, which induces submarginal deformation and ice‐marginal squeezing during the melt season. Strong glacier recession during the summer, driven by elevated temperatures, allows several squeeze moraines to be emplaced. This process‐form regime may be characteristic of active temperate glaciers receding into overdeepenings during phases of elevated temperatures, especially where their englacial drainage systems allow efficient transfer of surface meltwater to the glacier bed near the snout margin. © 2020 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd

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Section: Introductionmentioning

confidence: 99%

Sub‐annual moraine formation at an active temperate Icelandic glacier

Chandler

Evans

et al. 2020

Earth Surf Processes Landf

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“…It also provides modern analogues for the formation of larger features that were formed in front of outlet glaciers of ice caps or even the lobes of continental ice sheets during the Quaternary through the up‐scaling of individual processes contributing to moraine formation and their controls (cf. Bennett ; Ham & Attig ; Evans ). This paper presents detailed sedimentological data from a representative selection of annual moraines formed over the last ∼30 years at the snout of Gornergletscher in the southern Central Alps, Switzerland, with the aims of assessing the applicability of existing models of annual moraine formation to an alpine valley glacier and providing fresh insights into moraine‐forming processes and climatic control in such settings.…”

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confidence: 99%

Processes of annual moraine formation at a temperate alpine valley glacier: insights into glacier dynamics and climatic controls

Lukas

2012

Boreas

100

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This paper presents the first detailed sedimentological study of annual moraines formed by an alpine valley glacier. The moraines have been forming since at least AD 1980 by a subsidiary lobe of Gornergletscher, Switzerland that advances up a reverse bedrock slope. They reach heights of 0.5–1.5 m, widths of up to 6 m and lengths of up to several hundreds of metres. Sediments in these moraines are composed of proglacial outwash and debris flow units; subglacial traction till is absent entirely. Based on four representative sections, three genetic process combinations have been identified: (i) inefficient bulldozing of a gently sloping ice margin transfers proglacial sediments onto the ice, causing differential ablation and dead‐ice incorporation upon retreat; (ii) terrestrial ice‐contact fans are formed by the dumping of englacial and supraglacial material from point sources such as englacial conduit fills; debris flows and associated fluvial sediments are stacked against a temporarily stationary margin at the start, and deformed during glacier advance in the remainder, of the accumulation season; (iii) a steep ice margin without supraglacial input leads to efficient bulldozing and deformation of pre‐existing foreland sediments by wholesale folding. Ice‐surface slope appears to be a key control on the type of process responsible for moraine formation in any given place and year. The second and third modes result in stable and higher moraines that have a higher preservation potential than those containing dead ice. Analysis of the spacing and climatic records at Gornergletscher reveals that winter temperature controls marginal retreat and hence moraine formation. However, any climatic signal is complicated by other factors, most notably the presence of a reverse bedrock slope, so that the extraction of a clear climatic signal is not straightforward. This study highlights the complexity of annual moraine formation in high‐mountain environments and suggests avenues for further research.

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“…Minor moraines have low relief (less than 4 m) and are narrow (less than 50 m wide). These moraines most likely formed due to minor readvances of the glacier margin (Ham and Attig, 2001). Small readvances of a glacier's margin can occur on an annual or semiannual basis (Chandler and others, 2016).…”

Section: Morainesmentioning

confidence: 99%