In this quadrangle, the deepest canyon system on Mars and one of the most spectacular in the solar system, Valles Marineris, extends more than 2,500 km across the map, cutting the northern part of the Thaumasia plateau (informal name). Parts of the floor are more than 5,000 m below datum and as much as 10,000 m below the plateau rim. The system of canyons includes Melas, Candor, and Ophir Chasmata, prominent at its central part, Coprates along its eastern part, and Ius and Tithonium Chasmata, forming its western arm. Echus, Hebes, Juventae, and Ganges Chasmata form additional, separate canyons, north of the main canyon system. The canyons of Noctis Labyrinthus, west of the map (MC-17), join Valles Marineris, which connects eastward with the chaos-filled canyons of Capri and Eos Chasmata. Some of the other chasmata are linked to outflow channels north (MC-10) and east of the map (MC-19). Sinai, Solis, and Thaumasia Plana make up high plains that span the western to south–central parts of the Coprates quadrangle. Together they constitute much of the Thaumasia plateau, a dish-shaped, elevated region at 3,000–5,000 m. At their eastern edges, the Thaumasia plateau and Ophir Planum drop as much as 3,000 m down to variably cratered plains of Noachis and Xanthe Terrae, respectively. The informally named Coprates rise is a prominent north-trending mountain range, forming the eastern margin of the Thaumasia plateau, south of Coprates Chasma. Crossing this entire region are north- to northeast-trending wrinkle ridges as well as local sets of narrow grabens and pit chains.