Ius Chasma is a large canyon in the Coprates quadrangle of Mars at 7° south latitude and 85.8° west longitude.

The word chasma has been designated by the International Astronomical Union to refer to an elongate, steep-sided depression.

Moving east from Noctis Labyrinthus, the canyon splits into two troughs, Tithonium and Ius Chasma in the south.

Some cliffs on Mars show a few darker layers standing out and often breaking into large pieces; these are thought to be hard volcanic rock instead of soft ash deposits.

Probably having been formed in water, sulfate deposits are of great interest to scientists because they may contain traces of ancient life.

[5] Research, in the January 2010 issue of Icarus, described strong evidence for sustained precipitation in the area around Ius Chasma.

[9] It has been known for some time that Mars undergoes many large changes in its tilt or obliquity because its two small moons lack the gravity to stabilize it, as the Moon stabilizes Earth; at times the tilt of Mars has even been greater than 80 degrees[10][11]