An irregular or complex martian structure, with scalloped edges, usually a volcanic caldera. The classic example is Alba Patera (110° W, 40° N), the volcano of largest areal extent on Mars, but only 3 km high. On the jovian satellite Io, the term is used for a volcanic crater surrounded by irregular flows. The name is derived from a type of shallow, ceremonial dish used by the Romans.
Subjects: Arts and Humanities — Earth Sciences and Geography.