Formation of surface features on ventifacts: Modeling the role of sand grains rebounding within cavities

Várkonyi, Péter L.; Laity, Julie E.

doi:10.1016/j.geomorph.2011.10.021

Cited by 15 publications

(8 citation statements)

References 39 publications

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“…Some stone facet configurations are progressive (evolutionary) wind abrasion forms (Várkonyi and Laity, ) such as dreikanter (Walther, ) and Brazil nut (Whitney, ) (Figure c). A few New Jersey ventifacts possess small finger‐like projections of erosion‐resistant inclusions (differential erosion), the demoiselles of Hobbs () or the dedos (Spanish for fingers) of McCauley et al .…”

Section: Resultsmentioning

confidence: 99%

“…Knight (, p. 103) added that ventifacts provide a ‘missing link’, valuable ‘evidence for sand and other abraders…that are in transit between source and sink.’ These points are briefly considered as they relate to southern New Jersey: Proximally sourced, loose, coarse‐ to fine‐grained quartzitic sand associated with coversand and riverine dunes was abundant on the Atlantic Coastal Plain. Although modelling by Várkonyi and Laity () indicates that rebounding sand grains are responsible for ventifact abrasion, dust, or possibly even hardened ice crystals at very low temperature, could also have abraded and polished rock (Schlyter, ). It was difficult to understand the role of saltating sand in the production of fine flutes and grooves beyond the abraded upwind face (Figure b, c).…”

Section: Discussionmentioning

confidence: 99%

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Pleistocene Ventifacts and Ice‐Marginal Conditions, New Jersey, USA

Demitroff

2015

Permafrost & Periglacial

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The Pleistocene environment of the New Jersey Pine Barrens has been interpreted as either cool and moist, with boreal forest, or cold and dry, with semi-desert conditions. The presence of ventifacts is often cited as perfunctory evidence for strong Pleistocene wind action and sparse vegetation. This study examines sites where ventifacts had been reported and identifies abundant pebble-to boulder-sized samples with a wide suite of erosional forms. Faceting occurred when the land was sparsely vegetated, allowing abundant wind-entrained abradants to etch gravel and rocks as a consequence of katabatic winds blowing off the nearby Laurentide Ice Sheet. Most ventifacts occur on upland surfaces and attest to geomorphic stability in this part of the region's otherwise low-relief landscape. Ventifacts were reworked and incorporated within deposits attributed to periglacial mass movement, particularly during climatic amelioration. Aeolian features such as pavement einkante, scallops and weathering pits can evolve only where sustained wind velocities are very high, sand sources are abundant and vegetation is absent. The Pine Barrens' ventifacts provide evidence of cold, dry and windy conditions and aid in the interpretation of landscape evolution.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Pleistocene Ventifacts and Ice‐Marginal Conditions, New Jersey, USA

Demitroff

2015

Permafrost & Periglacial

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“…The detailed geometry of the Eikonal term is of particular interest [ Arnold , ] as it accounts for the formation of sharp edges and planar areas on the abraded particle (Figure a). This was shown in case of asteroids [ Domokos et al ., ] and for the formation of ventifact shapes by wind‐blown sand in deserts [ Knight , ; Várkonyi and Laity , ].…”

Section: Box Equationsmentioning

confidence: 99%

Abrasion model of downstream changes in grain shape and size along the Williams River, Australia

Szabó

Fityus

Domokos

2013

J. Geophys. Res. Earth Surf.

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[1] Modeling pebble abrasion during bed load transport is of fundamental importance in fluvial geomorphology, as it may help to understand downstream fining patterns along gravel bed rivers. Here we review a recently published analytical abrasion model called box equations, which can simultaneously track the shape and size evolution of large pebble populations as the cumulative effect of binary collisions between particles. The model predicts that pebble shapes move away from the sphere and develop sharp edges due to collisional abrasion by sand. We present a field study on the downstream evolution of basalt particle shape and size along the Williams River in the Hunter Valley, Australia. Pebbles get flatter and thinner, and several aquafacts (i.e., abraded pebbles with sharp edges) emerge in the downstream reaches, both suggesting the importance of abrasion by sand. Applying box equations with a few fitted parameters, we present a numerical simulation which reproduces both the shape and size evolution of pebbles along the Williams River. The simulation allows tracking of the shape and size evolution of individual particles as well, revealing an interesting phenomenon that particle size controls shape evolution. Box equations, in combination with existing transport concepts, provide a framework for future shape and size evolution studies in sedimentary environments. In particular, they may help to assess the relative importance of size selective transport versus abrasion in causing downstream fining in gravel bed rivers.Citation: Szabo´, T., S. Fityus, and G. Domokos (2013), Abrasion model of downstream changes in grain shape and size along the Williams River, Australia,

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“…Ventifact formation is influenced by factors similar to those of dunes [10]. Morphodynamic processes, abrasion in particular, can be investigated by means of field investigation [8,[11][12][13][14], numerical simulation [15,16], laboratory simulation [17][18][19][20][21][22][23][24][25], and theoretical analysis [26,27]. Field investigations are commonly time-consuming.…”

Section: Introductionmentioning

confidence: 99%

“…A long-term field observation suggested that the abrasion of the ventifacts located at a small western Arctic coastal settlement had been virtually undetectable over 50 years [14]. As a comparison, the formation and development of facets and surface features by direct impacts of sand grains can be numerically modeled efficiently [15,16]. But the principles of these numerical simulations are weakly supported by physical laws.…”

Section: Introductionmentioning

confidence: 99%

Abrasion rates of ventifacts

et al. 2019

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Although ventifacts are often utilized to determine past and present wind directions and sediment mobilities in arid, coastal, and periglacial environments, their morphodynamics have not been well understood. In this study, based upon the principles of classical mechanics, the abrasion rate of ventifact is analytically expressed by the elastic properties of rock or mineral components and the mass flux density of sediment transported by wind. The unknown abrasion coefficient can be estimated via wind tunnel experiments. The practicability of this novel formula is shown by the calculation of short-term abrasion depth of ventifacts over a desert pavement. It is expected that the current work will improve the quantitative reconstruction of paleo-environments and paleo-climates using ventifacts.

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Formation of surface features on ventifacts: Modeling the role of sand grains rebounding within cavities

Cited by 15 publications

References 39 publications

Pleistocene Ventifacts and Ice‐Marginal Conditions, New Jersey, USA

Pleistocene Ventifacts and Ice‐Marginal Conditions, New Jersey, USA

Abrasion model of downstream changes in grain shape and size along the Williams River, Australia

Abrasion rates of ventifacts

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