Fossa (planetary nomenclature)
fossae /ˈfɒsiː/) is a long, narrow depression (trough) on the surface of an extraterrestrial body, such as a planet or moon.The Tharsis quadrangle is home to large troughs (long narrow depressions) called fossae in the geographical language used for Mars.Studies have shown that the volcanoes of Tharsis caused most of the major fossae on Mars.Sinkholes, where the ground falls into a hole (sometimes in the middle of a town) resemble pit craters on Mars.[6][8][9] Knowledge of the locations and formation mechanisms of pit craters and fossae is important for the future colonization of Mars because they may be reservoirs of water.