Quantifying the spatial variability of megaripples found in the Wright Valley, Antarctica

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Tilson, Michael N. R.
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University of Guelph

This study provides the first detailed analysis of the gravel ripples found in the Wright Valley, Antarctica. The purpose of this study was to quantify the spatial variability of this unusual form and provide a hypothesis that describes the process of their formation. Transects over the ripples were surveyed and morphometric parameters were extracted from the resulting profiles. Sediment samples taken from the surface and at depth show the material is mostly bimodal with peaks at -3[straight phi] and 2[straight phi] and is poorly sorted regardless of position on the ripple form. There is a weak fining trend in this material as a function of increasing distance from where the ripples originate. The morphometric and grain size data indicate that these ripples are aeolian but that their development is not well constrained by any previous abstraction used to describe ripple morphology. The physical characteristics of these ripples are a result of a unique set of environmental conditions that are present in the Wright Valley, for example cold climate sediment transport and consistently strong winds. It is hypothesized that these ripples are the result of gravity waves and intense saltation over an evolving surface lag.

gravel ripples, Wright Valley, Antarctica, spatial variability, formation