The Medusae Fossae Formation (MFF), Mars, could be deposits of materials originally formed as hyaloclastites erupted from vents which formed the basal units of Olympus Mons volcano, and subsequently collapsed as landslides to form the aureole materials. These low density hyaloclastites subsequently floated on the northern sea as pumice rafts and drifted to the southwest, where they encountered the boundary of the southern highlands to form the MFF.
