Chasma
（重定向自Chasmata）
A chasma (plural: chasmata) is a deep, elongated, steep-sided depression. As of January 2013, the IAU has named 118 such features in the Solar System, on Venus (63), Mars (24), Saturn's satellites Mimas (6), Tethys (2), Dione (8) and Rhea (5), and Uranus's satellites Ariel (7), Titania (2) and Oberon (1). An example is Eos Chasma on Mars.