Olympus Mons Mons aureole deposits (discussed below). Olympus Mons lies at the edge of the Tharsis bulge, an ancient vast volcanic plateau likely formed by the end of the Noachian Period. During the Hesperian, when Olympus Mons began to form, the volcano was located on a shallow slope that descended from the high in Tharsis into the northern lowland basins. Over time, these basins received large volumes of sediment eroded from Tharsis and the southern highlands. The sediments likely contained abundant Noachian-aged phyllosilicates (clays) formed during an early period on Mars when surface water was abundant, and were thickest in the northwest
Ahuna Mons on the opposite side of Ceres, fracturing the outer layers of the area and facilitating the movement of high viscosity cryovolcanic magma (consisting of muddy water ice softened by its content of salts) that was then extruded onto the surface. Crater counts suggest that formation of the mountain continued into the last several hundred million years, making this a relatively young geological feature. Ahuna Mons Ahuna Mons is the largest mountain on the dwarf planet and asteroid Ceres. It protrudes above otherwise smooth terrain, it is not an impact feature, and it appears to be the only mountain of its