The Mare Acidalium quadrangle is dominated by the gently northward-dipping lowland plain of Acidalia Planitia and its contiguous southern neighbor, Chryse Planitia, both lying between 4,000 and 5,000 m below datum. These plains are partly bordered by cratered highlands that rise as much as 3,000 m above the plains – Arabia Terra to the southeast and Tempe Terra to the southwest. The outer margins of these terrae define the mouths of the largest fluvial-type channels anywhere on Mars – the circum-Chryse outflow channels (named for Chryse Planitia, into which the channels collectively emerge, see also MC-10 and MC-11). The regional planitiae contain the generally north–south trending ridge systems of Xanthe Dorsa. Acidalia Mensa is located in the center of the quadrangle and forms an irregularly shaped plateau that rises from 100 to >500 m above the surrounding plains.