Melas Chasma is part of the huge Valles Marineris that cuts into the middle of Mars surface, making it a pretty interesting place: there is abundant evidence for water having flowed here, with ancient water-cut channels visible even from orbit. Also visible are landslides that have created huge fans of rubble at the base of the cliffs. These newest images from ESA’s Mars Express show Melas Chasma, which sinks 9 km below the surrounding surface, making it one of the lowest depressions on the planet. This is just a small part of the bigger Valles Marineris, which stretches for more than 4,000 km across the surface of Mars. Around Melas Chasma, there are lighter-coloured deposits of sulphate components that were probably deposited in a former lake.
These images were captured in 2006 and just released by the Mars Express team. See more details and images at the ESA website.