Recent work provides the basis for establishing a stratigraphic column for units within the Superstition cauldron of central Arizona. Two new formations are defined. The Geronimo Head Formation is a Miocene rhyolite tuff containing rhyolite, quartz latite, and basalt lava flows. The Superstition Tuff is a Miocene quartz latite welded tuff composed of three members. The Siphon Draw Member, Dogie Spring Member, and Canyon Lake Member were emplaced in order of decreasing age. The Dogie Spring Member intertongues with the Geronimo Head Formation. Numerous radiometric and fission track dates support the field determination of the stratigraphic sequence.