Aeolian (wind-related) processes are probably the dominant ongoing mechanism that modifies the surface of Mars. Large Dark Dunes are particularly common aeolian landforms, first recognized in the early 1970s. However, these are not the only common aeolian landforms seen on Mars: recently, higher resolution images have revealed another distinct population of smaller, ripple-like bedforms that have been termed "Transverse Aeolian Ridges" or "TARs".

PSI Research Scientist Matt Balme, along with Dan Berman, Mary Bourke, and Jim Zimbelman of the Smithsonian Institution, have performed a survey of more than 10,000 high-resolution Mars Orbiter Camera images to search for TARs and to measure their distribution, orientation, and morphology. The aim of their work is to assess whether TARs are active, to identify possible sediment sources and pathways, and to determine the volumes of sediment that they comprise. The first results of this study have just been accepted for publication in the journal "Geomorphology".

The above image, which is 3.03 km wide, is Mars Orbiter Camera image number S0700608, located at 8.81° N and 358.6° E. Layered outcrops can be seen surrounded by TARs, as well as by large dark dunes. The orientations of the TARs appear to be directly influenced by the local topography. The TARs appear to be superposed by the LDDs, indicating that they might be less active than the larger dunes. The close proximity of the TARs and dunes to layered terrain suggests that eroded materials from the layers might provide their sediment source.

Image credit: NASA/JPL/Malin Space Science Systems