Aurorae Chaos is part of a large-scale system of depressions east of the Valles Marineris canyon. The up to 600 kilometers wide irregular shaped basin has a depth of about four kilometers with respect to the surrounding plains. The random pattern of mesas, buttes and knobs on the basin floor is characteristic of so-called 'chaotic terrain', a landscape special to Mars without an Earth analog. In the old highland region of Margaritifer Terra around the Martian equator, numerous chaotic terrains crosscut the highland plateau.