Geological implications of valley rebound

Matheson, DJ; Thomson, S.

doi:10.1016/0148-9062(74)91987-1

Cited by 4 publications

(5 citation statements)

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“…It has hardly been recognised (cf. Matheson and Thomson, 1973); whether it can geophysically provoke RSF remains unclear. However Grämiger et al (2017) demonstrate that 'rock debuttressing' by even minor bedrock erosion promotes rockmass damage and consequent RSF.…”

Section: Rebound Stressmentioning

confidence: 99%

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Rock slope failure in the British mountains

Jarman¹,

Harrison

2019

Geomorphology

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In this first full review of extant Quaternary Rock Slope Failure (RSF) in the British mountains, we provide a near-complete inventory of 1082 sites, 40% being rock slope deformations, 40% arrested rockslides, and 20% rock avalanches. Current RSFactivity is negligible, and this relict population is predominantly paraglacial, with a parafluvial minority. Its spatial distribution is perplexing, with RSF density varying greatly, both regionally and locally. In the Scottish Highlands, eight main clusters account for 76% of RSF area in 15% of the montane area. Local concentrations occur in all the British ranges, across high and low relief, in core and peripheral locations, and on varied geological and glaciological domains; as conversely do extensive areas of sparsity, even in similar lithologies. Generic interpretations are thus precluded. Geology is only a secondary control. An association with Concentrated Erosion of Bedrock (CEB) is proposed, as a driver of intensified slope stresses. CEB is most evident at those glacial breaches of main divides where the most vigorous recent incision is inferred, and also in some trough-heads. A clear association between RSFs and these 'late-developing' breaches is demonstrated in the Highlands, in 42 localities, with sparsity away from them. It is also seen in seven Lake District localities. Glaciological models identify ice sheet volatility capable of driving breach ramification. High-magnitude paleoseismic events are generally unlikely to have provoked RSF clusters; a few candidates are considered. RSF has been underrated as an agent of mountain landscape evolution in Britain; its spatio-temporal incidence may assist in calibrating regional ice sheet models, and in assessing climate change impacts. We argue that the CEB:RSF association has global relevance in identifying primary drivers of mass movement in bedrock.

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Section: Rebound Stressmentioning

confidence: 99%

“…would require much faster rates (possibly by an order of magnitude). If so, this implies that glacial incision can occasionally operate on a 'catastrophic' scale, analogous with meltwater flood channels (Matheson and Thomson, 1973).…”

Section: Ceb Incision Rates In Late-developing Breaches and Trough-headsmentioning

confidence: 99%

Rock slope failure in the British mountains

Jarman¹,

Harrison

2019

Geomorphology

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“…Valley rebound phenomena appear to be widespread in Central Alberta (Matheson & Thomson 1973). There the release of pressure due to the incision of post-glacial channels causes upwarping of the valley walls with formation of a slightly raised valley rim and a gentle anti clinal flexure in the valley floors.…”

Section: O Rigin Of Superficial Structuresmentioning

confidence: 99%

A Discussion on valley slopes and cliffs in southern England: morphology, mechanics and Quaternary history - Cambering and valley bulging in the Gwash valley at Empingham, Rutland

Horswill

Horton

Penman³

1976

Phil. Trans. R. Soc. Lond. A

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The construction of a dam at Empingham, Rutland has provided an opportunity to investigate the nature and effect of cambering and valley bulging. A detailed lithostratigraphic sequence has been established and the Upper Lias has been divided into a series of micropalaeontological zones. These features have enabled the internal structure of the Upper Lias to be determined in boreholes and at outcrop. The cambering process results in a progressive valley ward thinning which affects almost the entire Upper Lias sequence. The valley bulges are complex anticlinal structures developed in the valley floors. At depth the steeply inclined strata caught up in the valley bulge gives way along a possible decollement plane to largely undisturbed strata. The valley bulge structures occur throughout the valley and their courses are reminiscent of the trends of the modern valley system. This suggests that they may have been developed in the floors of the ancestral drainage system. The superficial structures were developed at the time of the Chalky Boulder Clay glaciation. Subsequent development of the valley has been a process of continued downcutting with landslipping and solifluxion being the dominant processes since the last glaciation. Possible mechanisms for the development of the superficial structures are discussed in the Appendix.

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“…Several writers have investigated the formation and opening of steeply dipping joints parallel to valley walls (Feld, 1966;Ferguson, 1967;Matheson and Thompson, 1973;Nichols, 1980;Ferguson and Hamel, 1981). These references describe a process of rebound that is defined as the expansive recovery of surficial crustal material either instantaneously, time dependently, or both and is initiated by the removal or relaxation of superincumbent loads (Nichols, 1980).…”

Section: Slope Formation At Smugglers Notchmentioning

confidence: 99%