This shaded relief painting is based on Viking Orbiter images and shows the Tharsis region of Mars with a map of the western United States for scale. The three large, aligned volcanos are Arsia Mons (lower left), Pavonis Mons (center), and Ascraeus Mons (upper right). Olympus Mons is the volcano at upper left, and a portion of Valles Marineris is on the right. Each of the four large volcanos in this figure is at least 400 kilometers across at its base.
From Meszaros, 1985, Plate 49