English: Yardangs are made in soft materials that were shaped by the wind. NASA describes this scene thusly: This image of a crater floor in Arabia Terra tells the tale of a long and varied geological history. The layered bedrock in the south of the image records events that occurred eons ago, probably soon after the crater formed.

The tear drop shaped features in the middle of the image resulted from a later episode of erosion by the wind. Persistent winds that alternated seasonally and diurnally from the southwest and from the northeast produced these “yardangs” with aerodynamic shapes that resemble inverted boat hulls. The dark pits to the north of the image were likely formed by recent impacts. The bowl shaped craters, small quantities of modern wind-blown sedimentary infill, and bright ejecta deposits all suggest that these impacts occurred quite recently, possibly at the same time.

Written by: Paul Geissler (6 December 2019)