Exhaustion and steady state models for predicting landslide hazards in the Canadian Rocky Mountains

Crudën, D. M.; Hu, Xincheng

doi:10.1016/0169-555x(93)90024-v

Cited by 107 publications

(74 citation statements)

References 7 publications

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“…In this context, the Lateglacial exposure ages obtained for rockslide or rock avalanche runout debris at four sites in the Cairngorms are of particular interest, as they demonstrate that failure at all four sites occurred within a few millennia of deglaciation, consistent with the notion of rapid paraglacial response and the exhaustion model of Cruden and Hu (1993). The pre-Windermere Interstade uncertainty-weighted mean ages for runout debris in the Lairig Ghru (15.4 AE 0.8 ka) and Strath Nethy (16.2 AE 1.0 ka) imply that failure almost certainly occurred within one or two millennia of deglaciation.…”

Section: Paraglacial Landscape Modificationmentioning

confidence: 84%

“…Gardner, 1980;Luckman, 1981;Rapp and Å kerman, 1993;Abele, 1997). Cruden and Hu (1993) have suggested that the temporal distribution of paraglacial rockslope failures can be approximated by an exhaustion model, whereby the overall probability of rock-slope failure within a mountain area diminishes exponentially with time elapsed since deglaciation, but validating this model has not so far been possible because of lack of reliably dated failures. In the mountains of Great Britain, a small number of rock-slope failures are known to have occurred during the Late Devensian Lateglacial, during the interval between ice-sheet deglaciation and the beginning of the Holocene (e.g.…”

Section: Paraglacial Landscape Modificationmentioning

confidence: 99%

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Exposure dating and reinterpretation of coarse debris accumulations (‘rock glaciers’) in the Cairngorm Mountains, Scotland

Ballantyne

Schnabel

2008

J Quaternary Science

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Relict rock glaciers have considerable potential for contributing to palaeoclimatic reconstruction, but this potential is often undermined by lack of dating control and problems of interpretation. Here we reinvestigate and date four proposed 'rock glaciers' in the Cairngorm Mountains and show that the morphology of only one of these appears consistent with that of a true rock glacier produced by creep of underlying ice or ice-rich sediment. All four features comprise rockslide or rock avalanche runout debris, and the possibility that all four represent unmodified runout accumulations cannot be discounted. Surface exposure dating of the four debris accumulations using cosmogenic 10 Be produced uncertainty-weighted mean ages of 15.4 AE 0.8 ka, 16.2 AE 1.0 ka, 12.1 AE 0.6 ka and 12.7 AE 0.8 ka. All four ages imply emplacement under cold stadial conditions, two prior to the Windermere Interstade of ca. 14.5-12.9 cal. ka BP and two during the Loch Lomond Stade of ca. 12.9-11.5 cal. ka BP. The above ages indicate that paraglacial rock-slope failure on granite rockwalls occurred within a few millennia after deglaciation. The mean exposure ages obtained for runout debris at two sites -Strath Nethy (16.2 AE 1.0 ka) and Lairig Ghru (15.4 AE 0.8 ka) -are consistent with basal radiocarbon ages from Loch Etteridge, 22 km to the southwest (mean ¼ 15.6 AE 0.3 cal. ka BP) and imply widespread deglaciation of the Cairngorms and adjacent valleys before 15 ka and possibly 16 ka.

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Section: Paraglacial Landscape Modificationmentioning

confidence: 84%

Section: Paraglacial Landscape Modificationmentioning

confidence: 99%

Exposure dating and reinterpretation of coarse debris accumulations (‘rock glaciers’) in the Cairngorm Mountains, Scotland

Ballantyne

Schnabel

2008

J Quaternary Science

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“…Most RSFs in the Scottish Highlands occur within the limits of Loch Lomond Stadial glaciation, and are therefore demonstrably of Holocene age. The exhaustion model of paraglacial landscape modification predicts that the frequency of rockslope failure should be greatest immediately after deglaciation and decline in frequency thereafter (Cruden & Hu, 1993;Ballantyne, 2002a). However, reliable dating evidence for the timing of RSFs in the Scottish Highlands is very limited.…”

Section: Distribution and Timing Of Rock-slope Failurementioning

confidence: 99%

“…Ballantyne & Benn, 1994;Curry, 1999aCurry, , 1999b, whereas rock-mass adjustment to glacial unloading may persist for several millennia after deglaciation (e.g. Cruden & Hu, 1993;Ballantyne & Stone, 2004). The exhaustion model assumes steady-state conditions under which there is no change in process-generating or other boundary conditions.…”

Section: Models Of Paraglacial Sediment Yieldmentioning

confidence: 99%

After the Ice: Holocene Geomorphic Activity in the Scottish Highlands

Ballantyne

2008

Scottish Geographical Journal

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A rich variety of processes have modified the glacial landscape of the Scottish Highlands since the last glaciers disappeared 11,500 years ago. Many of these processes can be described as paraglacial (glacially-conditioned): retreat of glacier ice has resulted in exposure of metastable sediment sources (rock slopes, drift-mantled slopes and valley-floor glacigenic deposits) that have been reworked over a range of timescales. Much of the reworked sediment has been deposited in paraglacial sediment stores (talus accumulations, debris cones, alluvial fans, valley fills, river terraces and deltas). The trajectory of paraglacial sediment transfer can be approximated by an exhaustion model. A corollary of this model is that all sediment stores eventually undergo a change from net accumulation to net erosion, reflecting the non-renewable nature of sediment sources. This concept helps to explain why most talus accumulations, debris cones and alluvial fans in the Highlands are now relict, and why many floodplains appear to have experienced an initial period of aggradation followed by later river incision and terrace development. Since deglaciation, rock slopes have experienced paraglacial stress release due to differential deglacial unloading. Many rock slopes have remained stable or experienced gradual adjustment through intermittent rockfall. At over 600 sites, however, large-scale rock-slope failure has occurred, either in the form of catastrophic failure with complete or arrested debris runout, or as major slope deformations. Modification of drift-mantled slopes has been dominated by rainstorm-generated debris flows activity, which have stripped sediment from slopes and redeposited it in debris cones. Radiocarbon dating of buried organic horizons shows that debris flows have occurred intermittently throughout the Holocene. Snow avalanches have played only a localized role in paraglacial sediment transfer. The Holocene alluvial history of the Highlands is poorly understood. Some alluvial fans formed during a few exceptional flood events, and there is evidence that postglacial floodplain aggradation peaked in the late Holocene and was succeeded by floodplain incision and terrace development, possibly reflecting upstream reduction in paraglacial sediment supply. Other processes have operated independently of glacial conditioning. The effects of wind action are dominant in the coastal zone, forming dunefields through aeolian reworking of beach sand, and on plateaux in the form of deflation surfaces and sand sheets. Extensive erosion of plateau-top sands and aeolisols occurred in the period AD 1550-1700, a period of exceptional storminess. Small-scale periglacial processes have also been active on high ground throughout the Holocene, including granular weathering of exposed rock surfaces, the development of small-scale frost-sorted patterned ground on unvegetated terrain, and slow downslope movement of solifluction sheets, solifluction lobes and ploughing boulders.

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“…While the term 'paraglacial' and its application to slope failure are relatively new (Ryder, 1971;Cruden and Hu, 1993), geomorphologists have long been aware that slope form and process are influenced by glaciation and deglaciation, with specific reference appearing in the literature at the beginning of the 1900s. In 1911 for example, geologists noted that destabilisation of slopes in a 'U-shaped' valley in the Tararua Ranges, New Zealand, evident as prominent anti-scarps (uphill facing scarps), indicated a former glaciation (Brook, 2008 …”

Section: Paraglacial Frameworkmentioning

confidence: 99%