Of Swirls and Gullies

[n2doc]

This observation is a repeat image of ESP_014185_1095 and ESP_019987_1095. The dune gullies (at edge of the field and here in this subimage) appear active and are anomalous in their location (high latitude).

Tracking definitive changes will be useful in comparison with dune gully activity visible in southern mid-latitudes and the Northern Polar erg. The activity is thought to occur soon after the beginning of the defrosting period.

Perhaps the most striking aspect of this observation are the beautiful swirls of tracks left by dust devils. Like on Earth, dust devils move across the Martian surface, exposing the underlying darker material.
bigger versions
http://hirise.lpl.arizona.edu/ESP_021899_1095