Criteria for the identification of ventifacts in the geological record: A review and new insights
Résumé
Ventifacts (wind-worn stones) are typical of terrestrial environments remained very long without any vegetation, under hot or cold climates. Therefore, within the sedimentary record, they can allow recognizing desert conditions, even where no aeolian dune deposits are preserved. There seems that, in the recent literature, pebbles and cobbles from various palaeoenvironments were mistaken for ventifacts. This may partly be explained by the scatter and relative scarcity of illustrations to which refer. The aim of this paper is to help recognizing ventifacts in the sedimentary record, based on a critical review of the diagnostic properties generally used, and on new studies permitting to suggest additional criteria. After an evaluation of the sedimentary contexts favourable to preserving ventifacts, the distinctive characters that could be seen on each one are treated in order of increasing alteration of the original appearance: surface features, medium-scale features (new types of pit especially), and general shape. Finally, the problem of distinguishing between ventifacts and aquafacts is approached.