This scene covers the boundary scarp between the ancient cratered highlands and the northern plains of Mars over an area east of Mangala Valles (latitude -7 to -3 degrees, longitude 146 degrees to 149 degrees). Ancient river channels run north through the ancient cratered highlands, but are covered north of the scarp by young lava floes. The large impact crater just north of the scarp shows floe-like ejecta lobes, which may form due to the presence of subsurface water or ice. Viking Orbiter picture numbers are: 455S09-17,456S13-20, 457S16-20. Image-processing was done by Alfred McEwen, U.S. Geological Survey, Flagstaff, Arizona.
