Collapse Pit on the S/E Flank of Pavonis Mons (EDM - Absolute Natural Colors; credits for the additional process. and color: Dr Paolo C. Fienga - Lunexit Team)

Caption NASA:"The interior of the Pit consists of sediment-covered Boulders that range in size from approximately 5 meters (approximately 16 ft) to less than 1 meter (approximately 3 feet) in diameter. The interior region of the Pit appears to slope towards the North-West. Such Pits may form from collapse of a surface "roof" below which Lava may long ago have flowed, or as a result of removal of subsurface material due to erosion or extension".