Acheron Fossae is a trough in the Diacria quadrangle of Mars.

Despite its crescent shape similar to the nearby aureole surrounding Olympus Mons, it is unrelated to them and predates the aureole which are Amazonian in age while Acheron is Hesperian in age.

The term "fossae" is used to indicate large troughs when using geographical terminology related to Mars.

Troughs, sometimes also called grabens, form when the crust is stretched until it breaks, which forms two breaks with a middle section moving down, leaving steep cliffs along the sides.

This article about geology, geography or other features of the planet Mars or its moons is a stub.