Toney Mountain lies in Marie Byrd Land, a tectonically and volcanically active region of Antarctica. There, a layer of basaltic rocks up to thick underlie a series of felsic volcanic edifices. These basaltic rocks in turn are emplaced above a Paleozoic basement with granite intrusions of Devonian-Cretaceous, which crops out in some mountain ranges. Beneath Toney Mountain, the basaltic floor rises from an elevation of beneath sea level, and the volcano is situated on the floor of a graben. The region is further characterized by a large dome-like uplift, part of the West Antarctic Rift System, and it may reflect the presence of a stationary hotspot.