Snow Action on Mount Twynam, Snowy Mountains, Australia

Costin, A. B.; Jennings, J. N.; Black, H. P.; Thom, B. G.

doi:10.3189/s0022143000028793

Cited by 8 publications

(3 citation statements)

References 8 publications

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“…Despite possible inaccuracies in the Þeld measurements of snow densities, there can be no doubt that the densities at Sm¿rbotn are comparatively high, the range of values for previous-winter snow being typical of much older Þrn and the value for older Þrn being typical of glacier ice (Paterson 1981). Very high densities for the previous-winter snow were similarly reported by Costin et al (1964) for a snowbed on Mount Twynam, Australia. They argued that recurrent high temperatures and occasional rain during winter might be especially favourable for ÞrniÞcation.…”

Section: Environmental Controls On Snow-push Mechanismsmentioning

confidence: 83%

“…Maruszczak (1961) referred brießy to clasts being moved by snowbeds. Costin et al (1964) reported abrasion tracks on bedrock up to 630 cm long formed in a single year. They put forward similar arguments to those given above to support snowslide as the agent responsible rather than rapid avalanche movement (cf.…”

Section: Snowbed Movementmentioning

confidence: 99%

“…Although the considerable forces exerted by slow movement of a snowbed are well known (e.g. Costin et al 1964Costin et al , 1973Mackay 1963, 1975), the impact of this process on the morphology of a deformable sediment substrate has been largely neglected and seems to have been regarded as limited or non-existent (e.g. Rempp and RothŽ 1934;Thorn 1978;Ballantyne 1985).…”

Section: Introductionmentioning

confidence: 99%

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Snow‐push processes in pronival (protalus) rampart formation: geomorphological evidence from smørbotn, romsdalsalpane, southern norway

Shakesby

Matthews

Berrisford

et al. 1999

Geografiska Annaler: Series A, Physical Geography

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M.S., 1999: Snow-push processes in pronival (protalus) rampart formation: geomorphological evidence from Sm¿rbotn, Romsdalsalpane, southern Norway. Geogr. Ann., 81 A (1): 31Ð45.ABSTRACT. It is demonstrated that pronival (protalus) ramparts can be formed by a snow-push mechanism and need not accumulate in the conventional manner as a result of supranival processes. Ridges in pronival positions up to 1.2 m high and of unequivocal snow-push origin are described from two sites in Sm¿rbotn cirque, Romsdalsalpane, southern Norway. The seven lines of evidence are: (1) parallel abrasion tracks on large boulders embedded in the substrate; (2) displaced surface and embedded clasts with proximal furrows; (3) corrugated (flute-like) substrate surfaces; (4) the sickle-shaped plan-form of the ridges; (5) generally asymmetrical ridge cross-profiles (shallow, concave proximal; steep, convex distal); (6) strong preferred orientations and dips of surface-embedded clasts on ridge proximal slopes; and (7) a subnival/pronival ridge comprising loosely packed diamicton forming along the contact zone between the snowbed and substrate. This evidence indicates ridge formation by snow sliding involving bulldozing of the substrate. Factors considered important in favouring snow push producing distinct pronival ramparts at the sites include: a maritime periglacial climate with heavy winter snowfall and rapid snow-firn conversion producing snow densities of up to 900 kg m -3 ; a deformable substrate with relatively small inputs of rockfall or avalanche debris; and a steep headwall susceptible to snow avalanching and hence enhanced snow supply. Consideration is given to the prospect that larger pronival ramparts can form incrementally by a snow-push mechanism.

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Section: Environmental Controls On Snow-push Mechanismsmentioning

confidence: 83%

Section: Snowbed Movementmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Snow‐push processes in pronival (protalus) rampart formation: geomorphological evidence from smørbotn, romsdalsalpane, southern norway

Shakesby

Matthews

Berrisford

et al. 1999

Geografiska Annaler: Series A, Physical Geography

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Snow cornice dynamics as a control on plateau edge erosion in central Svalbard

Eckerstorfer

Christiansen

Vogel

et al. 2012

Earth Surf Processes Landf

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Snow cornices grow extensively on leeward edges of plateau mountains in central Svalbard. A dominant wind direction, a snowdrift source area and a sharp slope transition largely control the formation of snow cornices in a barren peri‐glacial landscape. Seasonal snow cornice dynamics control bedrock weathering and erosion in sedimentary bedrock on the Gruvefjellet plateau edge in the valley Longyeardalen. Air, snow and ground temperature sensors, as well as automatic time‐lapse cameras on a leeward facing plateau edge were used to study seasonal cornice dynamics. These techniques allowed for monitoring of cornice accretion, deformation and collapse/melting in great detail. The active layer of the top plateau edge is characterized by high moisture content due to rain before freeze‐up in autumn and cornice meltdown during spring thaw. Thus frost weathering there can be very efficient in this otherwise cold and dry environment. Within the first autumn snowstorms, a vertical fully developed cornice was in place (190 cm thick). The backwall surface beneath the thickest part of the cornice remained in the ice segregation ‘frost cracking window’ for almost nine months. Highly weathered rock material from the plateau edge is thus incorporated into the cornice during cornice accretion. Brittle snow deformation leads to the opening of cornice tension cracks between the cornice mass and the snowpack on the plateau. These cracks are a prerequisite for cornice collapses, and often trigger cornice fall avalanches on the slope beneath. In these open cornice tension cracks, weathered rock debris, plucked from the plateau edge, can be visible, demonstrating the erosional property of the cornices. The cornice will either collapse or melt, resulting in suspended sediment transport downslope by cornice fall avalanche or release as rock fall respectively. Therefore, cornices both promote and trigger high weathering rates on Gruvefjellet, and thus control presently the development of the rockwall free faces and the talus cones. Copyright © 2012 John Wiley & Sons, Ltd.

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Temporal dynamics in alpine snowpatch plants along a snowmelt gradient explained by functional traits and strategies

2022

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Alpine snowpatches are characterised by persistent snow cover, short growing seasons and periglacial processes, which has resulted in highly specialised plant communities. Hence, these snowpatch communities are among the most threatened from climate change. However, temporal dynamics in snowpatch microclimate and plant composition are rarely explored, especially in the marginal alpine environments of Australia. Seven snowpatches were categorised into early, mid and late snowmelt zones based on growing season length, with soil temperatures recorded from 2003 to 2020 and plant composition surveyed in 84 1 m² quadrats in 2007, 2013 and 2020. Microclimate, species diversity, plant cover and composition, along with community trait-weighted means and plant strategies were assessed to understand snowpatch dynamics in response to climate change. We found that growing season length and temperatures have increased in late melt zones, while changes were less consistent in early and mid melt zones. There were few changes in species diversity, but increases in graminoids and declines in snowpatch specialists in mid and late melt zones. Community-weighted plant height, leaf area and leaf weight also increased, particularly in mid and late melt zones, while plant strategies shifted from compositions of ruderal-tolerant to stress-tolerant. Here, we show that snowpatch communities are rapidly changing in response to longer growing seasons and warmer temperatures, with the greatest changes occurring where snow persists the longest. The results highlight the climate-induced loss of de ning biotic and abiotic characteristics of snowpatches, as temporal convergence of compositions along snowmelt gradients threatens the novelty of snowpatch plant communities.

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Snow Action on Mount Twynam, Snowy Mountains, Australia

Cited by 8 publications

References 8 publications

Snow‐push processes in pronival (protalus) rampart formation: geomorphological evidence from smørbotn, romsdalsalpane, southern norway

Snow‐push processes in pronival (protalus) rampart formation: geomorphological evidence from smørbotn, romsdalsalpane, southern norway

Snow cornice dynamics as a control on plateau edge erosion in central Svalbard

Temporal dynamics in alpine snowpatch plants along a snowmelt gradient explained by functional traits and strategies

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