English: This synthetic oblique view shows Ophir Chasma, the northern most one of the connected valleys of Valles Marineris. For scale, the large impact crater in the right corner is about 30 km wide. Ophir Chasma is a large west-northwest-trending trough about 100 km wide. The Chasma is bordered by high-walled cliffs, most likely faults, that show spur-and-gully morphology and smooth sections. The walls have been dissected by landslides forming re-entrants. The volume of the landslide debris is more than 1,000 times greater than that from the May 18, 1980, debris avalanche from Mount St. Helens. The longitudinal grooves seen in the foreground are thought to be due to differential shear and lateral spreading at high velocities.