Figure 6-14 RIVUXG Valles Marineris (a) This mosaic of Viking Orbiter images shows the huge rift valley of Valles Marineris, which extends from west to east for more than 2500 mi (4000 km) and is 400 mi (600 km) wide at its center. Its deepest part is 5 mi (8 km) beneath the surrounding plateau. At its western end is the Tharsis rise. Compare this image with Figure 6-11. (b) This perspective image from the Mars Express shows what you would see from a point high above the central part of Valles Marineris.