Controls on the formation of coastal ventifacts

Knight, Jasper

doi:10.1016/j.geomorph.2004.07.002

Cited by 13 publications

(3 citation statements)

References 32 publications

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“…Previous studies have discussed the mismatch in direction between ventifacts and prevailing wind direction. For example, in northwest Ireland, two ventifact locations 30 m apart have keels oriented 90° difference from each other, and neither corresponds to contemporary wind direction (Knight, 2005). This therefore raises questions in the interpretation of palaeowind direction from relict (non-active) ventifacts.…”

Section: Integrated Coastal Sediment Systems: Linking Dunes and Ventimentioning

confidence: 99%

“…They are found within the intertidal or supratidal zones of sandy beaches and often in association with other coastal sandy landforms such as sand dunes. Ventifacts have been identified in different geomorphic and climatic settings worldwide (Knight, 2008), including in Ireland (Knight and Burningham, 2001;Knight, 2003Knight, , 2005, Great Britain (Bather, 1900;Bosworth, 1910;Braley and Wilson, 1997;Wilson et al, 2002), the USA (Knight and Burningham, 2003), New Zealand (Bishop and Mildenhall, 1994), France (Sellier, 2006), and the Falkland Islands (Wilson and Edwards, 2004). These studies have mainly focused on documenting the presence and morphology of ventifacts in these locations, and their relationships to past and present wind regimes.…”

Section: Introductionmentioning

confidence: 99%

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Sand dunes and ventifacts on the coast of South Africa

Knight

Burningham

2019

Aeolian Research

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The Indian Ocean coast of South Africa is characterized by strong seasonal alongshore winds and high sediment availability, resulting in formation of different types of active and vegetated sand dunes landward of sandy beaches. This study considers the dynamics of windblown sand systems along part of this coastal stretch by presenting geomorphological evidence from ventifacts and sand dunes, which can inform on integrated sand transport and depositional system dynamics, respectively. Crestline positions of supratidal translational dunes were mapped from aerial images (2003-2018); results show a range of responses over different time windows, including systematic migration in particular to the northeast, and crestline rotation. Changes in dune geometry are linked closely to changes in synoptic climate patterns, determining seasonal wind regimes. Exceptionally well developed ventifacts are present on clasts within deflation lags located between translational dune ridges. Based on morphological analysis of ventifacts (n=49), the dominant geomorphically-effective wind direction is from west or northwest, oblique to regional prevailing winds. An important conclusion of this study is that, although both ventifacts and dunes at this site reflect the same wind forcing, they show quite different morphological responses and dynamical behaviours. A reason for such differences may be the role of microtopographic effects on near-surface wind patterns. This means that neither dunes nor ventifacts alone can be used as unambiguous indicators of wind regime, and instead should be viewed as integrated elements of coastal sediment systems.

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Section: Integrated Coastal Sediment Systems: Linking Dunes and Ventimentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Sand dunes and ventifacts on the coast of South Africa

Knight

Burningham

2019

Aeolian Research

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“…The problem is complicated by the fact that, even in some current cases, the origin of such forms is questionable. 'Anchored ventifacts', 'bedrock-cut ventifacts', and 'ventifacted boulders' have been described in temperate coastal areas, including the present-day intertidal zone (King, 1949;Knight, 2002Knight, , 2005Burningham, 2001, 2003). Nevertheless, it should be noted that, in a similar environmental setting, facing the town of Etel (southern Brittany, France), the currently shaped rocks are undoubtedly aquafacts (Fig.…”

Section: Wind-worn Non-mobile Substratesmentioning

confidence: 99%

Criteria for the identification of ventifacts in the geological record: A review and new insights

Durand¹,

Bourquin

2013

Comptes Rendus. Géoscience

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Ventifacts are large clasts (pebble-to boulder-sized) shaped by corrasion (sensu Walther, 1900): abrasion by wind-carried particles. As introduced by Evans (1911), this term was restricted to forms showing one or more facet(s) cut by sandblasting (Windkanter in the German literature), but it was extended by Bryan (1931) to include all windworn elements, whether grooved, carved, striated or truly faceted. Most geomorphologists also extend this term to bedrock surfaces (Greeley and Iversen, 1985;Knight, 2008), but, for reasons discussed below (Section 7), this will not be the case in this paper.Wind-worn stones are climate-sensitive sedimentary features that provide evidence for long periods without any vegetation in terrestrial environments (Glennie, 1970;

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Wind Erosion

Knight

2019

Aeolian Geomorphology

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Controls on the formation of coastal ventifacts

Cited by 13 publications

References 32 publications

Sand dunes and ventifacts on the coast of South Africa

Sand dunes and ventifacts on the coast of South Africa

Criteria for the identification of ventifacts in the geological record: A review and new insights

Wind Erosion

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