Protonilus Mensae (Mars)

From albedo feature at 42N, 315W.

Protonilus Mensae is an area of Mars in the Ismenius Lacus quadrangle. The surface is described as Fretted terrain. This terrain contains cliffs, mesas, and wide flat valleys. (wikipedia entry)

A mensa is a flat-topped prominence with cliff-like edges, i.e. a mesa. On Mars they are named after the nearest named albedo feature on the Schiaparelli or Antoniadi maps.