Rare fossils including the gastropodPeruvispiraaff.imbricataWaterhouse and the bivalveAtomodesmaaff.marwickiWaterhouse indicate a late Lower Permian age for the middle part of the Greenhills Group.Plerophyllumaff.timorenseGerth occurs in a lower horizon of the Greenhills Group. Bands of marble containing shell prisms, rare radiolarians, and other microfossils occur in the upper part of the section.