From Exodus3000 Wiki

The Valles Marineris is a vast canyon system that runs along the Martian equator just east of the Tharsis region and stretches for nearly a quarter of the planet’s circumference. It's system starts in the west with the Noctis Labyrinthus, proceeds east to Tithonium and Ius Chasmata, then Melas and Ophir Chasmata, proceeding to Coprates Chasma, then Ganges, Capri and Eos Chasmata, finally emptying out into an outflow channel composed of chaotic terrain and finally Chryse Planitia. At 2796 miles (4500 Km) long, 124 miles (200 Km) wide and up to 4.8 miles (7.7 Km) deep, the Valles Marineris rift system is larger than any of Earth's largest canyons, and is the largest known crevice in the solar system.

Most researchers agree that Valles Marineris is a large tectonic "crack" in the Martian crust, forming as the planet cooled, affected by the rising crust in the Tharsis region to the west, and subsequently widened by erosional forces. However, near the eastern flanks of the rift there appear to be some channels that may have been formed by water or carbon dioxide.

Valles Marineris was named after the Mariner 9 Mars orbiter of 1971-72 which discovered it and is Latin for Mariner Valleys.

Valles Marineris viewed on Google Mars

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