Pio Nono Formation is named in Bibb Co., central GA, as part of the Oconee Group (also new). The Oconee is an apron sand encompassing all of the Late Cretaceous through middle Eocene kaolin and kaolinitic sands of fluvial origin in the Fort Valley plateau and Fall Line Hills districts of the Coastal Plain of GA. The Pio Nono is composed of highly pigmented, kaolinitic, variably sorted, locally pebbly to gravelly sand to sandy kaolin. Strata were formerly included in the Lower Cretaceous of Veatch and Stephenson (1911), the Middendorf Formation of Smith (1929), the Tuscaloosa Formation of Cooke (1943), the Eutaw Formation of Eargle (1955), and the Unnamed Formation of Hetrick (1990), among others. In addition to the type section designated at the Brad Henderson Memorial Stadium in Macon, a reference section is designated at the intersection of US 341 and a county dirt road, 2.35 mi north of the intersection of US 341 and US 80 in Roberta, Crawford Co., GA. This exposure serves as the lower boundary stratotype of the Pio Nono Formation. An exposure in a ravine cut into the western valley wall of the Ocmulgee River, approximately 0.2 mi southeast of the overpass of Mead Road and the Central of Georgia RR on the south side of Macon, Bibb Co., GA, is here designated a reference locality for the top of the formation. Other reference localities include the eastern valley wall of Deep Creek north of the community of Friendship in southeastern Crawford Co., GA; the Georgia Geologic Survey core Houston 9 at Elberta, Houston Co., GA; and the Georgia Geologic Survey core Burke 6, in northern Burke Co. GA. Thickness at the type section is only 11 m, but unit reaches 112 m in the Pulaski Co. core (CGS-3511). Unit unconformably overlies the "Tuscaloosa Formation" of western GA at the base of the Oconee or Piedmont rocks; disconformably underlies the Gaillard Formation (new) of Oconee Group. Late Cretaceous age is based on facies relationships and stratigraphic position as the Pio Nono is not fossiliferous. It grades laterally southward into the Eutaw Formation, which has been biostratigraphically dated as middle Austinian (early Santonian).

Source: GNU records (USGS DDS-6; Reston GNULEX).