Valles Marineris (named according to the probe To marinade 9 on a proposal of Dr. William Pickering) is a vast system of canyons skirting the equator Martian in the east of the area of the Dôme of Tharsis. Current knowledge makes of it the largest canyon of the solar system.

Valles Marineris is 4000 km long (whereas the circumference of Mars is of 21350 km), 700 km broad and reached depths some 7 km. The existence of Valles Marineris is closely related to that of the dome of Tharsis. This system of parallel canyons was born during rising of Tharsis, to be then reorganized by erosion. Its origin is thus Tectonique contrary to the Large Canyon which results from an erosion by the Colorado river.

The majority of the researchers thus agree to say that Valles Marineris is an enormous tectonic crack in the Martian higher crust which was formed with the lower Hesperien (3,5 billion years) during the cooling of the Planet and was reorganized thereafter by the erosion.

The presence of triangular facets located on the piémonts of the slopes attests a tectonic origin. Nevertheless, the morphology of the slopes seems to be modelled by the erosion (landslides, gullying…).

There exist many depressions and circuses of wrenching like Ophir Chasma.

Surroundings

The canyon extends from the area of Noctis Labyrinthus in the west to the chaotic grounds in the east. The canyon itself consists of several valleys parallel the ones with the others and directed according to the west-east direction (like Candor Chasma and Melas Chasma).