Seasonal variation of crescentic dune morphology and morphometry, Strzelecki–Simpson Desert, Australia

Abstract

The general absence of contemporary dune building in the Australian arid zone finds the occurrence of crescentic dune genesis and evolution at Gurra Gurra waterhole, a somewhat enigmatic event amongst prevalent inactive linear dunescapes. Crescentic dune construction is geographically restricted to areas of dominant unidirectional high windiness and minimal vegetation, parameters that are generally uncommon in arid Australia today. The influence of seasonal multidirectional winds can see dune form undergo continual transition between quasi-equilibrium and disequilibrium. Such dynamic antithesis is depicted in seasonal mathematical comparisons of the planimetric attributes, length and width. Dimensional equilibrium is a transient feature at Gurra Gurra waterhole and not characteristic of this dunescape.

Deformed barchans under alternating flows: Flume experiments and comparison with barchan dunes within Proctor Crater, Mars

“…Barchans have even formed in snow (Masson et al, 1998) and siliciclastic-foraminiferal sands (Kenyon et al, 2002). Although Bagnold (1941) stated that barchans might transform into a rounded mound if exposed to a switch in wind direction, this view is not supported by the observations of Bishop (2001), who studied seasonal variation in barchan shape within the StrzelechiSimpson Desert, Australia. Bishop found that when winds blew from the horns to the toe of the dune (the most leeward point of the barchan body, see Fig.…”

“…2(b)) once forward flow was generated. The ephemeral slipface corresponds to the rear slipface observed by Bishop (2001) in desert areas of Australia. A rear slipface is sensitive to the direction of flow, and is therefore an indicator of flow direction at the time of observation rather than the direction of longterm average flows.…”

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It is generally considered that barchans, isolated crescentic-shaped dunes, develop where wind is unidirectional and the available sand is insufficient to cover the entire dune field; however, Bishop [Bishop, M.A., 2001. Seasonal variation of crescentic dune morphology and morphometry, Strzelecki-Simpson desert, Australia.

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A distribution‐free statistical method for the spatial characterization of dune granulometry: an example from the Strzelecki Desert, South Australia

“…The evolution of crescentic form in the predominately linear dunescape of the Strzelecki Desert occurs in unidirectional, summer southerly winds (Bishop, 2001). Sand mineralogy for the Gurra-Gurra crescentic dunes consists of quartz (≥98%) with accessory ferruginous lithic fragments, tourmaline, plagioclase, and minor zircon and rutile.…”

“…These characteristics indicate the sand source to be the underlying linear dune upon which the crescentic dunes rest. Coupled with an SSE sand-drift potential, as well as the concurrent lowering and mutilation of the linear form, the crescentic dunes evolve in a recycling semi-closed sedimentological system (Bishop, 2001).…”