Syrtus Major: This whole quadrant is dominated by the Syrtis Major, which is much the most prominent dark feature on Mars as seen from the Earth. Its had always been regarded as a deep depression, possibly a sea bed, but infact it is a relatively smooth area, and takes the form of a plateau, sloping off to either side.This dramatic image shows a field of dark sand dunes in the Nili Patera region of Syrtis Major. The shapes of these dunes indicate that wind has been steadily transporting the dark sand from the right/upper right toward the lower left.