Ice and Snow as Land-Forming Agents

Swift, Darrel A.; Cook, Simon J.; Heckmann, Tobias; Moore, Jeffrey R.; Gärtner‐Roer, Isabelle; Korup, Oliver

doi:10.1016/b978-0-12-394849-6.00006-8

Cited by 9 publications

(3 citation statements)

References 126 publications

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“…Overdeepenings or closed basins in glacier beds are common features in glaciated landscapes (Cook and Swift, 2012;Swift et al, 2014). Models by Hooke (1991) and Alley et al (2003) predict them to be equilibrium forms that all glacier beds tend towards.…”

Section: Introductionmentioning

confidence: 99%

On the morphological characteristics of overdeepenings in high‐mountain glacier beds

Haeberli¹,

Cochachín²,

Fischer³

et al. 2016

Earth Surf Processes Landf

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Overdeepenings, i.e. closed topographic depressions with adverse slopes in the direction of flow, are characteristic for glacier beds and glacially sculpted landscapes. Quantitative information about their morphological characteristics, however, has so far hardly been available. The present study provides such information by combining the analysis of (a) numerous bed overdeepenings below still existing glaciers of the Swiss Alps and the Himalaya‐Karakoram region modelled with a robust shear stress approximation and (b) detailed bathymetries from recently exposed lakes in the Peruvian Andes. The investigated overdeepenings exist where glacier surface slopes are low (< 5°–10°), occur in bedrock or morainic material and are most commonly a fraction of a kilometre squared in surface area, hundreds of metres long, about half the length in width and tens of metres deep. They form under conditions of low to high basal shear stresses, at cirque, confluence, trunk valley and terminus positions. The most striking phenomenon, however, is the high variability of their geometries: Depths, surface areas, lengths and widths of the overdeepenings vary over orders of magnitude and are only weakly – if at all – interrelated. Inclinations of adverse slopes do not differ significantly from those of forward slopes and are in many cases higher than so far assumed theoretical limits for supercooling of ascending water and corresponding closure of sub‐glacial channels. Such steep adverse slopes are a robust observation and in support of recently developed new concepts concerning the question about where supercooling of sub‐glacial water and closure of ice channels can or must occur. However, the question of when and under what climatic, topographic and ice conditions the overdeepenings had formed remains unanswered. This open question constitutes a key problem concerning the interpretation of observed overdeepenings, the understanding of the involved glacio‐hydraulic processes and the possibility of realistic predictive modelling of overdeepening formation. Copyright © 2016 John Wiley & Sons, Ltd.

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Section: Introductionmentioning

confidence: 99%

On the morphological characteristics of overdeepenings in high‐mountain glacier beds

Haeberli¹,

Cochachín²,

Fischer³

et al. 2016

Earth Surf Processes Landf

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“…If the Mușeteica glacier melted earlier than 12 ka, then we may allow for a slightly higher value of the glacial erosion rate, probably no N0.65 mm yr −1 . Temperate glaciers are able to erode the bedrock at rates between 0.1 and 10 mm yr −1 (Swift et al, 2015, and references therein). In the European Alps, Valla et al (2011) have shown a minimum mean erosion rate of 1 mm yr −1 .…”

Section: Glacial Erosionmentioning

confidence: 99%

Quaternary environmental evolution in the South Carpathians reconstructed from glaciokarst geomorphology and sedimentary archives

et al. 2020

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“…The lakes form when ice melts. The carrying zone is where the bedrock is removed by the action of ice and gravity and is considered the most important glacial erosive process ([60] and the references therein). (B) Landslides are represented by the most general case and shows some associated morphologies.…”

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confidence: 99%

Formation Patterns of Mediterranean High-Mountain Water-Bodies in Sierra-Nevada, SE Spain

Díaz-Hernández

Herrera-Martinez

2021

Water

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At present, there is a lack of detailed understanding on how the factors converging on water variables from mountain areas modify the quantity and quality of their watercourses, which are features determining these areas’ hydrological contribution to downstream regions. In order to remedy this situation to some extent, we studied the water-bodies of the western sector of the Sierra Nevada massif (Spain). Since thaw is a necessary but not sufficient contributor to the formation of these fragile water-bodies, we carried out field visits to identify their number, size and spatial distribution as well as their different modelling processes. The best-defined water-bodies were the result of glacial processes, such as overdeepening and moraine dams. These water-bodies are the highest in the massif (2918 m mean altitude), the largest and the deepest, making up 72% of the total. Another group is formed by hillside instability phenomena, which are very dynamic and are related to a variety of processes. The resulting water-bodies are irregular and located at lower altitudes (2842 m mean altitude), representing 25% of the total. The third group is the smallest (3%), with one subgroup formed by anthropic causes and another formed from unknown origin. It has recently been found that the Mediterranean and Atlantic watersheds of this massif are somewhat paradoxical in behaviour, since, despite its higher xericity, the Mediterranean watershed generally has higher water contents than the Atlantic. The overall cause of these discrepancies between watersheds is not connected to their formation processes. However, we found that the classification of water volumes by the manners of formation of their water-bodies is not coherent with the associated green fringes because of the anomalous behaviour of the water-bodies formed by moraine dams. This discrepancy is largely due to the passive role of the water retained in this type of water-body as it depends on the characteristics of its hollows. The water-bodies of Sierra Nevada close to the peak line (2918 m mean altitude) are therefore highly dependent on the glacial processes that created the hollows in which they are located. Slope instability created water-bodies mainly located at lower altitudes (2842 m mean altitude), representing tectonic weak zones or accumulation of debris, which are influenced by intense slope dynamics. These water-bodies are therefore more fragile, and their existence is probably more short-lived than that of bodies created under glacial conditions.

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Ice and Snow as Land-Forming Agents

Cited by 9 publications

References 126 publications

On the morphological characteristics of overdeepenings in high‐mountain glacier beds

On the morphological characteristics of overdeepenings in high‐mountain glacier beds

Quaternary environmental evolution in the South Carpathians reconstructed from glaciokarst geomorphology and sedimentary archives

Formation Patterns of Mediterranean High-Mountain Water-Bodies in Sierra-Nevada, SE Spain

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