WAbanico Formation is a 3 kilometres (9,800 ft) thick sedimentary formation exposed in the Andes of Central Chile. The formation has been deposited in a timespan from the Eocene to the Miocene. Abanico Formation's contact with the overlying Miocene Farellones Formation has been the subject of differing interpretations since the 1960s. A small part of the formation crops out in the Mendoza Province of western Argentina.
WThe Agua de la Piedra Formation is a Late Oligocene geologic formation of the Malargüe Group that crops out in the southernmost Precordillera and northernmost Neuquén Basin in southern Mendoza Province, Argentina.
WThe Barzalosa Formation is a fossiliferous geological formation of the Upper Magdalena Valley and the bounding foothills of the Central Ranges and Eastern Ranges of the Colombian Andes. The formation consists of conglomerates, sandstones and siltstones. The Barzalosa Formation probably dates to the Late Paleogene to Early Neogene period; Oligocene to Early Miocene epochs, and has an approximate thickness of 360 metres (1,180 ft). Fossils of Balanerodus logimus, Lophiodolodus chaparralensis, Xenastrapotherium chaparralensis, Protheosodon sp. and Proadinotherium sp. have been uncovered from the formation in Chaparral, Tolima.
WCaleta Chonos Formation is a geological formation of Oligocene age located around Chacao Channel in southern Chile. The formation overlies Bahía Mansa Metamorphic Complex and is overlain by the Ancud Volcanic Complex. It crops out in northwestern Chiloé Island in the isthmus of Lacuy Peninsula.
WCura-Mallín Group is a heterogeneous group of volcano-sedimentary formations of Oligocene-Miocene age, Colhuehuapian to Laventan in the SALMA classification, in south-central Chile and nearby parts of Argentina. The sediments belonging to the group were deposited in a lacustrine environment and alongside rivers in an intra-arc basin. Southeast of Laguna del Laja Cura-Mallín Group has a thickness of more than 1,800 metres (5,900 ft). The sediments making up the group deposited in an interval between 22 and 8 million years ago.
WThe Dos Bocas Formation is a Chattian, about 26 to 24 Ma, geologic formation of the Progreso Basin in southwestern Ecuador.
WThe Malargüe Group is a group of geologic formations of the Neuquén Basin of the Mendoza, Neuquén, Río Negro and La Pampa Provinces in northern Patagonia, Argentina. The formations of the Malargüe Group range in age between the middle Campanian to Deseadan, an Oligocene age of the SALMA classification, straddling the Cretaceous–Paleogene boundary, about 79 million to 30 million years in age. The group overlies the older Neuquén Group, separated by an unconformity dated to 79 Ma. The rocks of the Malargüe Group comprise both marine and continental deposits which are over 400 m (1312 ft) thick in total.
WThe Santa Teresa Formation is a geological formation of the western Eastern Ranges of the Colombian Andes, west of the Bituima Fault, and the southern Middle Magdalena Valley. The formation spreads across the western part of Cundinamarca and the northern portion of Tolima. The formation consists of grey claystones intercalated by orange quartz siltstones and sandstones of small to conglomeratic grain size. The thickness at its type section has been measured to be 118 metres (387 ft) and a maximum thickness of 150 metres (490 ft) suggested.
WThe Siamaná Formation is a fossiliferous geological formation of the Cocinetas Basin in the northernmost department of La Guajira. The formation consists of conglomerates and limestones. The Siamaná Formation dates to the Paleogene period; Middle to Late Oligocene epoch, corresponding to the Deseadan in the SALMA classification.
WThe Soncco Formation is a Late Eocene to Early Oligocene geologic formation in southern Peru. The base of the formation at the contact with the K'ayra Formation is dated using fission track analysis at 43 Ma and the top, the contact with the Punacancha Formation, at 30 Ma. In other places the Tinajani Formation overlies the Soncco Formation. The formation has a thickness of 1,600 metres (5,200 ft).
WThe Usme Formation is a geological formation of the Bogotá savanna, Altiplano Cundiboyacense, Eastern Ranges of the Colombian Andes. The formation consists of a lower part with predominantly shales with intercalated sandstone beds and an upper sequence with sandstones and conglomerates. The Usme Formation dates to the Neogene and Paleogene periods; Late Eocene to Early Oligocene epochs, and has a maximum thickness of 300 metres (980 ft).