A mountain range, which has been informally referred to as the Thaumasia highlands, is prominent in the north-central part of the quadrangle; it lies at elevations of 4–7 km above datum, and forms the southern margin of the Thaumasia plateau (informal name; see Figure 4.2). Cratered highlands of Aonia Terra, interspersed with younger plains and basins, ranging from near datum to 4 km elevation, such as Icaria Planum and Aonia Planum, make up the rest of the area. The outer rim of the Argyre basin is just visible along the eastern edge of the quadrangle.