Feature Approximate Definition/Analogy with Earth
Albedo feature a geographic area distinguished by amount of reflected light
Facula, faculæ a bright spot
Macula, maculæ a dark spot or irregularity
Regio, regiones a broad geographic region with color or reflectivity distinctiveness
Vastitas, vastitates an extensive, vast plain
Terra, terræ an extensive land mass
Planum, plana a plateau or high plain
Planitia, planitiæ a lowland or low-lying plain
Chaos an area of broken or blocky terrain
Cavus, cavi a hollow or irregular, steep sided depression, usually in clusters
Chasma, chasmata a deep, elongated, and steep-sided depression
Vallis, valles a valley or canyon
Fossa, fossæ a long, narrow depression
Linea, lineæ a straight or curved elongated marking of contrasting color
Virga, virgæ a streak or stripe in a contrasting color
Arcus an arc-shaped feature
Labes a landslide
Fluctus a flow terrain feature
Labyrinthus, labyrinthi a complex of intersecting valleys or ridges
Sulcus, sulci Parallel or sub-parallel furrows and ridges
Dorsum, dorsa a ridge
Sinus a small plain that looks like a bay on a shore
Crater a circular depression or impact feature
Catena, catenæ a chain of craters
Mensa, mensæ a flat-topped prominence with steep sides like a mesa or table
Lingula, lingulæ an extension of plateau having rounded lobate boundaries
Rupes a scarp
Scopulus, scopuli a lobate or irregular scarp
Colles small hills or knobs
Tholus, tholi small, conical mountain or hill
Mons, montes a large mountain
Patera, pateræ an irregular volcano or crater or one with scalloped edges
Undæ dunes