Syrtis Major Planum (Mars)

This feature is named after an earlier feature.

Syrtis Major Planum is a "dark spot" located in the boundary. It was discovered, on the basis of data from Mars Global Surveyor, to be a low-relief shield volcano, but was formerly believed to be a plain, and was then known as Syrtis Major Planitia. The dark color comes from the basaltic volcanic rock of the region and the relative lack of dust. A possible landing site for the Mars 2020 rover mission is Jezero crater within the region. (wikipedia entry)

A planum is a plateau or high plain. On Mars they are named after the nearest named albedo feature on the Schiaparelli or Antoniadi maps.