A path resembling a dotted line from the upper left to middle right of this image is the track left by an irregularly shaped, oblong boulder as it tumbled down a slope on Mars before coming to rest in an upright attitude at the downhill end of the track.
This pair of images covers one of many sites on Mars where researchers use the HiRISE camera on NASA's Mars Reconnaissance Orbiter to study changes in gullies on slopes. Changes such as the ones visible in deposits near the lower end of this gully occur during winter and early spring on Mars.
This April 6, 2014, image from the Context Camera on NASA's Mars Reconnaissance Orbiter was taken as a follow-up to discovery of a possible 2012 impact scar in images from the orbiter's Mars Color Imager. It reveals two craters within the darkened area (at center of the inscribed rectangle).
This March 20, 2014, image from the MARCI camera on NASA's Mars Reconnaissance Orbiter has a dark spot (at center of inscribed rectangle) noticed while the image was being examined for a weather report. Other observations confirmed that the spot is a scar from a space rock hitting Mars in 2012.