Marte Vallis is a valley in the Amazonis quadrangle

Amazonis quadrangle

The Amazonis quadrangle is one of a series of 30 quadrangle maps of Mars used by the United States Geological Survey Astrogeology Research Program. The Amazonis quadrangle is also referred to as MC-8 ....

 of Mars, located at 15 North and 176.5 West. It is 185 km long and was named for the Spanish word for "Mars". It has been identified as an outflow channel, carved in the geological past by catastrophic release of water from aquifers beneath the Martian surface.

Marte Vallis is the site of the first discovery of columnar jointing on Mars.