What broader categories had long been used to classify the dark areas visible on Mars before Schiaparelli focused on linear features?

Answer

*maria* (seas) and *continenti* (continents)

Dark areas on Mars had previously been categorized broadly as *maria* (seas) and *continenti* (continents) upon which Schiaparelli built his detailed mapping.

What broader categories had long been used to classify the dark areas visible on Mars before Schiaparelli focused on linear features?
MarsSpaceastronomyobservationSchiaparelli