Ripples in the Ripples
Jet Propulsion Laboratory https://www.jpl.nasa.gov/ Aug. 18, 2004
This image taken by the Mars Exploration Rover Opportunity shows the dunes that line the floor of "Endurance Crater." Small-scale ripples on top of the larger dune waves suggest that these dunes may have been active in geologically recent times. The image was taken by the rover's panoramic camera on sol 198 (August 14, 2004).