An Etymological Dictionary of Astronomy and Astrophysics

A system of canyons located just south of the Martian equator. The system is about 4000 km long. The central individual troughs, generally 50 to 100 km wide, merge into a depression as much as 600 km wide. In places the canyon floor reaches a depth of 10 km, 6 to 7 times deeper than the Grand Canyon on Earth.

See also: L. Valles Marineris “Mariner’s Valleys,” named after the Mars orbiter Mariner 9, which discovered the Martian canyon in 1971-72. → valley.