This weird Mars feature is likely a ventifact
- a rock shaped by wind," NASA officials wrote in the image (https://www.nasa.gov/jpl/msl/pia18477/) description .
No way to differentiate the hail of mirrors from the meadow of mullein, the beetlebung from the pinkeltink, the kettlehole from the ventifact
(1996) and the age proposed above for the ventifact beds.
1A) the conglomeratic basal beds of the Prato Solaro member yielded to the authors of this paper many ventifacts: wind worn phenoclasts (Fig.
The presence of ventifacts
suggests, at least partially, re-elaboration of underlying Triassic conglomerates (Segura and Elorza, 2013).
Resting on schist bedrock (Bed 1A) and frost-shattered schist regolith (Bed lb) is a lag deposit of quartz ventifacts (Bed 2).
Macro-crystalline quartz is common as quartz cobbles and ventifacts, as well as a few rare quartz crystal and quartzite artifacts.
Specifically, the occurrence of ventifacts (windworn pebbles, interpreted as markers of arid climate) is not only assigned an undemonstrated chronostratigraphic significance, but even claimed to merit predominance on the occurrence of the cosmopolitan marker Claraia (Valsassina, Orobic Alps, Posenato et al., 1996).
The Valsassina Claraia horizon is located in the middle Servino Formation about 7 m above the basal Prato Solaro Member (Posenato et al., 1996; Sciunnach et al., 1996, 1999), which contains the ventifacts of Cassinis et al.
(2007) reported for the first time from the Prato Solaro Member of the basal Servino the presence of 'ventifacts' (Evans, 1911), interpreted as wind-worn phenoclasts which testify to an arid climate in the depositional area just before the first Triassic transgression (Durand, 1972; Smith and Edwards, 1991; Durand, 2006).
Undoubtedly, as already mentioned, the occurrence of ventifacts is in tune with arid conditions and, with no fossils in the continental successions, they can be interpreted not only as climatic indicators but are also potentially suitable, on account of their stratigraphic position and correlation with other known units, for indicating their presumed age.
The arid climate prevailing in the sedimentation area is attested by the presence of many wind-worn pebbles and cobbles (ventifacts
), not only concentrated in the conglomeratic layers, but also scattered here and there throughout the "Gres vosgien" Fm.