The Mars rover Opportunity used it’s PanCam to take this picture, actually a series of images taken on 29 and 30 October 2014 which is the 4,182nd and 4,183rd Martian day (sol) on Mars! The view is of Knudsen Ridge on the southern edge of the Marathon Valley.
By February 2016, the rover ascended slopes of about 30 degrees onto the flank of Knudsen Ridge, headed for targets of “red zone” material to examine there. A 30 degree slope, pretty good for the old rover.
Marathon Valley cuts generally east-west through the western rim of Endeavour Crater. The valley’s name refers to the distance Opportunity drove from its 2004 landing site to arrival at this location in 2014. The valley was a high-priority destination for the rover mission because observations from orbit detected clay minerals there.
By the way, Knudsen Ridge is an informal name chosen by the Opportunity science team to honor the memory of Danish astrophysicist and planetary scientist Jens Martin Knudsen (1930-2005), a founding member of the team.
Image: NASA/JPL-Caltech/Cornell Univ./Arizona State Univ.