Journal ArticleDOI
Submarine flow tills at Victoria, British Columbia: Discussion
TLDR
In this article, Hicock et al. describe complex submarine outwash cones from Quarternary glacimarine exposures, and they do not question their interpretation of the diamicton sediments in the cones as being submarine flows or slumps from glacial debris; indeed, their descriptions are invaluable for tidewater glacier facies modelling.Abstract:
Hicock et al. describe complex submarine outwash cones from Quarternary glacimarine exposures. I do not question their interpretation of the diamicton sediments in the cones as being submarine flows or slumps from glacial debris; indeed, their descriptions are invaluable for tidewater glacier facies modelling. However, I have some comments on the suggested origin of the flows. Several different configurations of tidewater ice fronts may exist, but few allow the formation and preservation of sediment gravity flow deposits that originate subaerially and flow into the sea. Under polar conditions where glaciers cannot maintain themselves as floating ice tongues or ice shelves, they end in very shallow water and a beach is constructed at the base of their cliffs (e.g., Sugden and John 1976, Fig. 11.94. Most debris is slowly melted out, but rarely flowage may occur. However, such material is highly likely to be reworked by waves and, further, the ice margin in Puget Sound that Hicock et al. describe was probably not under polar-type conditions. In my experience of modem temperate tidewater glaciers in Glacier Bay, Alaska, only restricted conditions allow thick accumulation of supraglacial melt-out tills from englacial debris layers. Ablation of tidewater glaciers occurs more by berg calving rather than upper-surface melting, and ice fronts (at least above tide level) are nearly vertical cliffs. Ice is very crevassed back from the face, and the free face with consequent extensive flow commonly creates large transverse crevasses. Englacial debris layers are exposed across an ice face rather than transversely across the upper surface. However, the sides of each layer may intersect the upper surface of a glacier snout to form supraglacial melt-out debris parallel to the valley walls. Other supraglacial debris is primarily from rockfalls off valley walls and is rubble rather than diamicton. Rarely, some debris flows down the face from the upper edge, but the steepness of slope ensures sorting and separation of particles as the flow proceeds. The larger mass of pebbles and coarse-grained sand particles causes them to fall fasterread more
Citations
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Journal ArticleDOI
Glacimarine processes and inductive lithofacies modelling of ice shelf and tidewater glacier sediments based on quaternary examples
TL;DR: In this article, the authors used information from Holocene sediment and Pleistocene glacimarine sequences with the eight inductive regimes to predict and modelled the lithofacies relationships.
Journal ArticleDOI
Glacimarine sedimentary processes, facies and morphology of the south-southeast Alaska shelf and fjords
Ross D. Powell,Bruce F. Molnia +1 more
TL;DR: In this paper, high basal debris loads up to 1.5 m thick of pure debris and rapid glacial flow, which can be more than 3000 m a−1, combine to produce large volumes of siliciclastic glacimarine sediment at some of the highest sediment accumulation rates on record.
Journal ArticleDOI
Models of glaciomarine sedimentation and their application to the interpretation of ancient glacial sequences
TL;DR: In this article, the authors argue that the importance of ancient glacial sedimentation in the rock record has probably been exaggerated because of oversimplistic interpretations of diamictite sequences.
Journal ArticleDOI
Multiple flow and support mechanisms and the development of inverse grading in a subaquatic glacigenic debris flow
TL;DR: In this paper, the authors studied subaquatic glacigenic debris flows of Late Wisconsinan age and demonstrated that transformations between flow types and sediment support mechanisms can occur simultaneously and serially in sub-aquatic debris flows.
Journal ArticleDOI
Late Pleistocene Morainal Bank Facies at Greystones, Eastern Ireland - An Example of Sedimentation During Ice Marginal Re-Equilibration in an Isostatically Depressed Basin
TL;DR: A late Pleistocene morainal bank is sited in a depocentre to the lee of a major rock ridge, near Greystones, in the western Irish Sea Basin this paper.
References
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Journal ArticleDOI
Glacimarine processes and inductive lithofacies modelling of ice shelf and tidewater glacier sediments based on quaternary examples
TL;DR: In this article, the authors used information from Holocene sediment and Pleistocene glacimarine sequences with the eight inductive regimes to predict and modelled the lithofacies relationships.
Book ChapterDOI
Late Quaternary Subaqueous Outwash Deposits Near Ottawa, Canada
Brian R. Rust,Richard Romanelli +1 more
Journal ArticleDOI
Subaquatic flow tills: a new interpretation for the genesis of some laminated till deposits
TL;DR: In this paper, detailed field mapping, till fabric, granulometric, and thin section investigations indicate that a 500 m long unit of laminated tills and interstratified glaciofluvial and glaciolacustrine sediments, belonging to the Catfish Creek Formation and exposed along the north shore of Lake Erie, Ontario, were deposited contemporaneously into a proglacial lake by coherent subaqueous mass flows of till (subaquatic flow tills).
Journal ArticleDOI
The origin of stratified Catfish Creek Till by basal melting
TL;DR: Sedimentological investigations into the lateral and vertical variation of Late Wisconsinan stratified Catfish Creek Till exposed on the north shore of Lake Erie, in southwestern Ontario, are presented in this article.