The Casius quadrangle contains a bit of ancient cratered highlands of Terra Sabaea in the southwest corner but is mostly dominated by the pervasively flat, and more youthful, northern lowlands of Utopia Planitia. The east half of the quadrangle is below –4,000 m, while the highlands are close to the 0 m datum. The highland–lowland transition is represented in the Casius quadrangle by broken plateaus and knobs, including the Colles Nili and Nilosyrtis Mensae, which are surrounded by undulating terrain of intermediate roughness. The northern lowlands are extremely smooth at regional scales but are marked locally by various types of topographic scarps, ridges, troughs, mounds and depressions, including Utopia, Cydnus, and Hephaestus Rupēs, Adamas Labyrinthus, and Astapus Colles.