TARs on Mars

This HiRISE image shows a valley filled with an assortment of linear ridges. These ridges are often referred to as transverse aeolian ridges, or TAR, and they take a variety of forms. Here they sit at right angles to the direction of the valley, because the topography funnels the wind along the trough.

At this location, some of the TAR have secondary structures, likely small ripples. It is common for sand dunes to be covered in small ripples, often with different orientations that may be shaped by winds redirected by the larger dunes. Here the secondary structures have an unusual radiating/converging pattern, giving the TAR here a feathery appearance.