This image, approximately 1.5 x 3 kilometers , shows a sample of eroded Martian terrain in Arabia Terra.
At one time this was a flat smooth terrain, but over time it has been eroded (most likely by the wind) forming depressed, low-lying areas where we see many small dunes. The dunes resemble waves in the ocean, whereas in other areas we see small flat-top hills forming.
Written by: Livio Tornabene, Eric Pilles, Ryan Hopkins and Kayle Hansen (audio: Tre Gibbs) (17 December 2014)
More info and image formats at http://hirise.lpl.arizona.edu/ESP_039113_1915
Image: NASA/JPL/University of Arizona