Acidalia Planitia


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Acidalia Planitia

(ass-ă-day -lee-ă) (formerly Mare Acidalium) The most prominent dark marking in the northern hemisphere of Mars; it is a low-lying area more than 2615 km in diameter located just below Mars' north pole and centered on the areographic coordinates 47° N latitude and 22° W longitude (see areography). Much of the region seems to be volcanic in origin and is thought to be covered by black sand resulting from the erosion of dark basalts. There is a preponderance of rampart craters (see Craters) in the area, and ice lies just below the surface. In Mars' distant past, Acidalia Planitia may have been the receptacle for water discharged from adjacent major outflow channels such as Ares Valles. See also Mars, surface features.