THEMIS Image of the Day, January 9, 2017. Today’s VIS image shows some of the extensive wind etched terrain in Memnonia Sulci, located south west of Olympus Mons. The linear ridges are called yardangs and form by wind removal of semi-cemented material. The ridges are parallel to wind direction, so the predominate winds that created the yardangs in this image blew NW/SE. At the bottom of the image several of the ridges have been eroded into smaller ridges aligned perpendicular to the large yardangs, indicating winds at a different angle.
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