Scars of Erosion

This large crescent dune in Kaiser Crater shows the scars of many types of seasonal erosional activities. Along its downwind slope are large gullies which are active during winter, when frost drives dune material downslope, carving out channels and creating fan-shaped aprons. On the upwind slope (bottom), dust devil tracks are visible: dark lines and curliques created during the spring season by small wind vortices vacuuming up a thin layer of dust and exposing the dark dune sand. Note: Both the cutout and the above image are rotated so that North is to the right. The map is projected here at a scale of 25 centimeters (9.8 inches) per pixel. [The original image scale is 25.3 centimeters (10 inches) per pixel (with 1 x 1 binning); objects on the order of 76 centimeters (30 inches) across are resolved.] North is up. http://photojournal.jpl.nasa.gov/catalog/PIA21458